Challenging The “Rules” of Scuba Diving: Because Not Everything is Black and White

By Dive Training

September 7, 2017

https://dtmag.com/thelibrary/challenging-rules-scuba-diving/

This article represents the views of the author.  The article has not been fact checked by myself, the Board of Directors or any member of the USA Dive Club.

Copyright Disclaimer under section 107 of the Copyright Act of 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, education and research. Fair use is a use permitted by copyright statute that might otherwise be infringing.

If you’re like most divers, you’ve heard of — and perhaps adhere to — procedures that are considered “normal” within our sport. A few classic “always and nevers” include: always dive with a buddy; always do your deepest dive first; always wear a snorkel; never put your mask on your forehead; always end your dive with at least 500 psi remaining in the tank and — perhaps the number one scuba diving “never” of all time — never hold your breath.

At first glance, these might seem like black-and-white concepts. Except, guess what? They’re not. At least not entirely.

This might sound like I’m on the verge of committing scuba heresy, but please take a couple of deep breaths and keep reading, because in this article we’ll examine — and even challenge — several widely accepted “rules” of scuba.

Rulemaking 101

Human beings are social creatures. We essentially want to be accepted in society, to be viewed as normal. Without diving deep into sociological terminology, the concept of norms provides a key to understanding social influence in general and conformity in particular. Social norms are the accepted standards of behavior of social groups. Behavior that fulfills these norms is called conformity. Social norms often evolve into rules, which are defined as explicit or understood regulations or principles governing conduct within a particular activity. Rulemaking is one of the basic impulses humans have for organizing and simplifying actions.

Norms — and the rules that often evolve from them — provide order in society. These are some of the reasons why most people, most of the time, conform to social norms and abide by certain rules.

The thing about rules is that sometimes they are based more on folklore than fact. And sometimes rules change when new facts are revealed. Take Nitrox diving, for instance. When it was first introduced decades ago there was a big hubbub about it being a dangerous “voodoo” gas that could potentially kill divers. It was condemned by the major scuba diving magazine at the time and banned at popular dive destinations. Now we know differently and divers everywhere are safely using Nitrox.

Those who challenge social norms and set out to bend or even break the rules sometimes find themselves at the center of controversy. They often get branded as troublemakers and might even find themselves at odds with the law. However, these people also tend to be significant change makers.

Let’s examine some commonly accepted scuba rules regarding equipment and dive practices that might be worthy of bending. If nothing else, they’re worth pondering.

Equipment-Related Rules

Always wear a snorkel.

The snorkel is a required accessory for scuba diving students and their instructors to wear during training dives. But once certification requirements are fulfilled there are instances when wearing a snorkel attached to the mask can prove problematic. For instance, it presents a potential entanglement hazard when scuba diving in overhead environments, such as wrecks or caverns. In addition, it can create drag when diving in a current.

Still, a snorkel is a useful accessory when at the surface. In recent years several innovative scuba equipment manufacturers have developed flexible snorkels that roll up small enough to fit in your buoyancy compensator (BC) pocket and/or fold into their own “shell” carrier that clips to the BC. For this reason, I’d like to edit the “always wear a snorkel rule” to read, “always carry a snorkel.” When the dive is done and you’re ready for a surface swim, locate your snorkel, attach it to your mask and you’re good to go.

Never put your mask on your forehead.

Okay, this one is a pet peeve of mine. I wrote about it in the May/June 2016 Final Check column, titled, “What It Looks Like When … Safety is Your Best Practice.” Somehow, somebody got a whole bunch of divers believing that placing the mask on the forehead is the international signal for “diver in distress.” Except, that’s just plain wrong.

It is not uncommon for a panicky diver to jettison the mask and regulator. This action is a panic response, which is an indication, or a sign, that the diver is experiencing a problem. However, it is not a signal, as in “if you are having a problem, put your mask on your forehead to signal you are in distress.” If you surface from a dive and need help, signal, “I am in distress and need help” by waving one or both arms above your head. (It’s also a good idea to use an audible signaling device such as a Dive Alert™ or whistle.) There are plenty of instances when a completely happy, non-panicky diver might place the mask on his or her forehead without incident. That said, there are times when placing the mask on the forehead might not be a good idea, like when you’re in choppy seas. If your practice is to prop your mask on your forehead upon surfacing from a dive instead of leaving it in place, you run the risk of having the mask dislodged by a wave — and getting lost to the deep.

No gloves allowed.

Believe it or not, this is actually a hard-and-fast rule in many tropical dive destinations. In some locations, divers caught wearing gloves while scuba diving, face stiff penalties. (Fines may also apply to dive operators.) The idea behind this rule is that wearing gloves encourages divers to grab — and subsequently damage — delicate corals, whereas barehanded divers will think twice about doing so because they risk being cut by sharp coral or stung by stinging marine creatures.

I wholeheartedly support the environmentally conscious intent behind this rule. However, I do not agree with the practice of strictly prohibiting divers from wearing gloves. Some divers have medical issues requiring them to protect their skin from exposure to sunlight, have clotting issues that turn a simple cut into a medical crisis or run risk of infection due to a cut. These folks shouldn’t need a note from their doctor in order to be allowed to wear gloves while diving.

This month’s Final Check column, “What It Looks Like When … You Are Careful What You Touch,” addresses the potential danger of grabbing a marine-life encrusted mooring line during a safety stop. While no one associated with this magazine promotes the wanton destruction of marine life, we think the ban on dive gloves goes a bit too far. Instead, we’d like to see industry stakeholders continue to promote environmentally safe scuba diving practices that encourage divers to avoid touching corals, while still allowing them to wear gloves when needed. For instance, a diver can easily stash a pair of gloves in a BC pocket and retrieve them for use when grasping an encrusted mooring line during a safety stop.

Always turn the tank valve back a quarter- or half-turn.

This one’s been around forever. And it’s wrong. Don’t do this. Instead, always turn the valve all the way on and leave it that way. Do not turn it back at all.

Apparently, the reason this practice got started is because someone decided that divers might inadvertently “strip” the valve by attempting to turn it on after it was already on. Tank valves are pretty hardy. The chances that you’ll damage a valve are slim. However, if you partially close the valve and then descend to a deep depth, the partially closed valve could restrict the airflow from the valve, making it difficult for you to breathe while on a deep dive. To avoid having problems with restricted airflow at depth always turn the valve all the way on. You are more important than a tank valve. Never turn it back a quarter- or half-turn.

Ruling How We Dive

Never dive alone. Always dive with a buddy.

When recreational scuba diving first started, the relatively crude nature of early dive gear made it necessary for divers to help each other out. The buddy system was born of common sense. It’s hard for many new divers to imagine going on a dive without a BC, submersible pressure gauge (SPG), alternate (or redundant) air source or a dive computer, but all these devices were absent from early dive training. They simply hadn’t been invented yet. Keeping this in mind it’s easy to imagine why having a buddy was considered mandatory. In fact, buddy breathing — sharing one tank and regulator between two divers — was a critically important skill taught in early scuba classes. Over several decades, equipment advances have enabled divers to become safer. And more self-sufficient. Thanks to the development of alternate air sources and redundant air delivery systems, and the fact that buddy breathing itself could be inherently dangerous, the buddy breathing skill has been purged from today’s scuba diving training courses.

Where it was once considered risky and even foolhardy to solo dive, the practice is slowly gaining acceptance. Several major scuba-training agencies offer Solo Diver and/or Self-Sufficient Diver certification courses aimed at increasing diver independence and reducing an individual’s dependence on the buddy system.

However, despite advances in equipment and training, the issue of solo scuba diving remains controversial. Some industry experts argue that buddy diving can carry with it greater potential risks than solo diving. Some recreational divers agree, complaining about being randomly paired with a buddy they’ve just met. Some dive operators prohibit solo diving, insisting that their customers be in buddy pairs or teams, often on guided dives. Still other dive operators allow solo diving for those qualified and equipped to do so.

A word of advice for those who wish to solo dive on a charter: reach out to the dive operator in advance to discuss your solo diving preference. Be willing to provide proof of your solo diving experience. Recognize that the dive operator has the right to deny your request to dive solo and insist that you abide by their stated operational policies. If this is the case, you have the option to seek the services of a dive operator that welcomes solo divers.

It’s also important to note that in certain areas, such as city, county, state or national parks, solo diving might be prohibited. It pays to read the fine print when planning a solo dive inside park waters.

On a personal note, I’ve made my share of solo dives, usually on shallow sites not far from shore. I have enjoyed the freedom and solitude of solo diving without any problems. I think those who are willing to accept responsibility for their own safety as a solo diver should be respected rather than viewed as reckless.

No matter where you stand on the issue of solo diving, I think we all can agree that every diver should train and equip for self-sufficiency and be able to handle potential problems that might arise during a dive.

Always do your deepest dive first.

This rule was considered law for many years, and it is still widely practiced today despite the development of sophisticated dive computer algorithms and new research into decompression sickness. Dive Training’s Senior Editor Alex Brylske revisited this topic earlier this year in an article titled, “Deepest Dive First? The History and Science Behind How We Plan Our Dives,” which ran in the January/February 2017 issue. Here is an excerpt from Brylske’s article:

“The issue of reverse profiles is sometimes confusing because the term actually can have two meanings. First, a reverse profile can refer to a series of repetitive dives where the deepest is not the first in the series. On the other hand, it can also describe a single multilevel dive that doesn’t follow the ‘stair-stepping’ procured described earlier; and the diver finds him or herself in the deeper phase of a dive after completing a shallower segment. Both procedures violate the deep-first rule.

It may surprise you to learn that the deep-first rule is a relative newcomer to the diving liturgy, traceable only back to the 1970s. The story is also an interesting lesson in the history of scuba diving.

A popular assumption is that the recreational scuba diving community simply adopted the deepest-first rule from the US Navy. Such an assumption seems entirely reasonable given that the USN Tables were the first standard for recreational scuba diving. The problem is, it’s not true. The US Navy does not now, nor did it ever, have any prohibition against reverse profile diving. In fact, one of the example dive table problems an older version of the US Navy Diving Manual involved a reverse profile. Likewise, there is no such prohibition in commercial scuba diving. So where did the rule come from?

The first suggestion to make the deepest dive first appears to have been offered in a relatively obscure reference — and only as a suggestion — by a researcher named Dennis Walder in 1968. His rationale was that by making the deeper dive first, one might crush “silent bubbles” — assumed progenitors of decompression illness — making the development of bends less likely on that and subsequent repetitive dives. But this was based primarily on theory and informed speculation, not empirical evidence. Moreover, no reference to any deep-first guideline appeared in any recreational diving literature until 1972, when the following statement was published in PADI’s Basic Scuba Course Manual (a curriculum segment of the then-current PADI Instructor Manual): ‘One very important rule — WE ALWAYS MAKE OUR DEEPEST DIVE FIRST when using the dive tables.’ No rationale was provided, though examples were often included during training showing the aforementioned advantage of avoiding decompression stops.

By the 1980s ‘deep dive first’ was growing beyond a recommendation.

By the 1990s, the mantra of-deep first was firmly ensconced in diver training materials as well as in the psyche of divers; and no prudent diver even considered violating the warning. But by this time dive computers had become standard equipment, and whether by accident or intention, divers were making — and getting away with — repetitive and multilevel reverse profile dives.”

Brylske sums it up by saying, “In all probability, the deep-first rule might never have been challenged had it not been for the widespread use of dive computers. Although the rules say otherwise, no dive computer in existence explodes, calls the police or ceases to function if the user engages in a reverse profile dive.”

Always end the dive with at least 500 psi remaining in your tank.

This statement is uttered during practically every pre-dive briefing in locations all over the world. The rationale behind it is solid; divers should plan their dives well and monitor their gauges carefully to avoid running low on — or out of — air. And responsible dive guides should remind divers to monitor their air supply to avoid an out-of-air emergency.

However, in some instances, well-meaning but overzealous divemasters might take it a bit too far. I’ve heard divemasters jokingly “threaten” divers with penalties, like, “You’ll owe me a 6-pack,” if they surface with less than the mandated 500-psi.

If a diver is nearing the end of a dive and needs to consume air below the 500-psi mark in order to complete a safety stop, the diver should feel comfortable doing so without fear of reprisal by the dive crew, because there’s simply no place for shaming in scuba diving.

Never, ever make contact with the bottom.

If you haven’t wanted to burn me at the stake by now, here goes. Over the years we have occasionally published photos of divers kneeling onthe bottom. This usually results in a flurry of reader letters calling Dive Training out for promoting bad diving practices. Most recently, in the July/August issue, we ran cover photos that feature two divers standing/kneeling on a sandy bottom while on a shark dive at the famous “Tiger Beach” dive site off Grand Bahama Island. I am one of the divers pictured in the photo. I’m not sure where or when the “never touch the bottom” rule got started, but I can assure you there are several instances in which kneeling in the sand is an accepted practice. Tiger Beach is a perfect example. The site is shallow (less than 30 feet [10 m]), there’s usually a moderate current running — and the water is filled with sharks.

For these reasons, attempting to stay neutrally buoyant, kicking hard against a current while hovering a few feet off the seafloor and keeping an eye on the sharks would be impractical — and potentially dangerous. Here, kneeling in the sand is the best practice. Dive operators in other parts of the Bahamas, Fiji, Tahiti, the Maldives and other popular dive destinations follow this practice.

Those who teach underwater photography know it is better to position beginning photographers in a sandy patch adjacent to a reef than to have them crashing into the coral while just starting out with a camera. Yes, the sand biome contains marine life, but in most instances it is not as delicate as fragile corals. A diver who carefully settles on a sandy area will have minimum impact on the environment.

In parts of the world where strong currents are common, dive operators instruct divers in the use of “current hooks” as a means of having minimum impact on the environment. A current hook, as its name implies, is a large hook attached to a short length of line with a clip at the other end. The clip attaches to a D-ring on a diver’s BC. Divers learn to hook into an area of coral rubble in order to stay put in a strong current. By using the hook, they avoid grabbing the bottom with their hands.

Here’s one more real-world “contact” scenario: If a diver accidentally ventures too close to the reef, rather than kicking to attempt to move farther away, using a one-finger touch of a dead or algae-covered section of reef to carefully push up and away from the reef is likely to prevent the diver from damaging living coral.

The “look but don’t touch” mantra is ideal, but there are instances when it’s not always practical. What I’m suggesting here is careful and conscientious contact with the bottom (and with dead sections of coral) when conditions warrant it.

Always breathe continuously. Never hold your breath.

As I mentioned earlier, this is arguably the “number one rule” of scuba because breath holding while scuba diving can lead to serious injury, even death. However, there’s a however here.

I bring it up in honor of a diver I met years ago. We’ll call her Janet. I guided Janet on her first recreational dives after she got certified. She bought a weeklong dive package and her first day of diving with the dive center where I worked went flawlessly. The conditions were perfect and Janet appeared comfortable in the water. I took a few underwater photos of her, smiling and signaling “OK.” She said she had a great time.

The following morning, she was waiting at the dive shop very early when I showed up for work. She told me she wanted to cancel her dives. When I asked why, Janet explained that she’d been awake most of the night because she was worried that she might have accidentally held her breath at some point during the dive the previous day. She said, “My instructor drilled it into our heads, ‘If you hold your breath, you will die,’ and I’m just afraid. I can’t remember if I held my breath or not, but I don’t want to die.” I explained in great detail why divers should breathe continuously and avoid holding their breath. When I was finished, Janet decided not to give up on scuba diving after all. She sat out the morning dives in favor of some sleep, but was back out on the boat later that afternoon.

So, here’s my little secret about breath holding while scuba diving. I often do it when taking underwater photos. I admit this not to encourage any diver to adopt the practice of holding their breath while on scuba, but rather to add some clarity to the breath-holding issue. If you’re like me and you sometimes briefly hold your breath while stationary, it is unlikely you will risk a lung-expansion injury. The key here is the word “stationary,” as in remaining in place and not ascending. If you hold your breath while ascending, you do indeed put yourself at risk of a potentially serious and possibly fatal lung-expansion injury. This is why scuba instructors drill it into students’ heads to “breathe continuously and never hold your breath.” But if you’re like Janet and you might have briefly forgotten to breathe continuously just for a second, say, when posing for a photo underwater, chances are, you’ll be okay. Still, do as your instructor insists. Breathe continuously and avoid holding your breath.

A Question for You

If you’ve read this article all the way to the end, thank you. I hope you found it thought provoking. However, the take-home message I wish to leave you with isn’t about following rules. It’s about asking questions. Asking why we divers do or don’t do certain things is important. It’s how we learn and understand and it’s also how we grow. Not everything is black and white. I want to encourage you to ask the questions and find the answers and then question the answers if they don’t sound right. This is ultimately how we advance our sport, making it safer and more enjoyable for all.

Educational Blog

Health for Diving: A Primer on Diabetes

By Robert N. Rossier

February 13, 2018

https://dtmag.com/thelibrary/health-diving-diabetes/

This article represents the views of the author.  The article has not been fact checked by myself, the Board of Directors or any member of the USA Dive Club.

Copyright Disclaimer under section 107 of the Copyright Act of 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, education and research. Fair use is a use permitted by copyright statute that might otherwise be infringing.

We all know there are medical factors that can prevent people from diving. Epilepsy, various heart conditions, loss of consciousness, pneumothorax, some chronic diseases and even some forms of anxiety can spell trouble that may be incompatible with diving. But over the years, the list of contraindications has narrowed, allowing more to enjoy exploration of the underwater world.

One condition that has prevented some people from becoming divers is diabetes. Diabetes affects the body’s ability to produce or respond to insulin — a hormone controlling the metabolism of carbohydrates. The result is abnormal carbohydrate metabolism leading to elevated glucose levels in the blood and urine.

While this might sound innocuous, the long-term effects of diabetes are dead serious. Diabetes takes more lives than AIDS (acquired immunodeficiency syndrome) and breast cancer combined, claiming one American life every three minutes. Diabetes is a leading cause of blindness, kidney failure, amputations, heart failure and stroke. What’s more, the incidence of diabetes is growing. According to diabetesresearch.org, the number of reported cases of people living with diabetes has jumped nearly 50 percent in the past decade and it now affects more than 29 million Americans. On a global scale, diabetes afflicts more than 380 million people, and the World Health Organization estimates that by 2030, the number of people living with diabetes will more than double. Clearly, diabetes is a growing health risk and one that could affect our ability to dive safely. But, at least for some, the door has been opened for scuba diving with diabetes — that is, if the proper conditions are met and the proper protocols are followed.

Diabetes is categorized into two primary types, referred to as Type 1 and Type 2. In those with Type 1 diabetes, the pancreas does not produce insulin or it produces insufficient insulin to meet the body’s needs. Individuals with Type 1 diabetes must receive insulin injections regularly in order to metabolize blood glucose (blood sugar). In the more common Type 2 diabetes, the body may not produce enough insulin or the insulin does not trigger the cells to allow proper metabolism of glucose.

Type 1 and Type 2 diabetes are the most common forms of the disease but other forms exist. Many individuals are also diagnosed with pre-diabetes, a condition in which blood sugar is high but not significantly enough to warrant treatment. Unless changes are made to diet and exercise, those with pre-diabetes are likely to join the ranks of individuals diagnosed with diabetes.

To understand the effects of diabetes, we need to have an understanding of some basic human biology. In a normally functioning body, a number of metabolic reactions occur in response to eating. First, the digestion process in the stomach breaks the food down into glucose (a form of sugar), which enters the blood stream and is transported to cells throughout the body. The hormone insulin is secreted by the pancreas, which triggers the cells to allow glucose to enter. Through a process called glycolysis, the glucose is broken down in the production of a molecule called ATP (adenosine triphosphate), which is the source of energy in the cell. Also in response to eating, the cells also synthesize and story fatty acids and proteins. These are all critical functions for a normal, healthy body.

For the person with diabetes, this process simply does not work properly. Type I diabetes is actually an autoimmune condition. The immune system destroys the beta cells in the pancreas, which are responsible for the production of insulin. And without that insulin, glucose does not enter the cells and they run out of energy.

For Type I diabetes, those affected must receive injections of insulin at the appropriate times to control blood glucose levels and allow cells to receive the needed glucose. Eating the right foods at the right time can also help control blood sugar by controlling how much glucose is produced through digestion. Other factors including exercise, stress and general health also affect the body’s need for insulin, so getting the correct timing and dosage for insulin injections can be a challenge.

In Type 2 diabetes, the pancreas has a deficiency of beta cells that create insulin, making it unable to supply enough insulin to the body. In addition, insulin receptors at the cellular level may not respond properly to insulin, limiting the amount of glucose entering the cells and allowing blood glucose to remain elevated. Controlling diet is also important for those with Type 2 diabetes to prevent spikes in blood glucose. Medications are available to help maintain an appropriate low level of blood glucose. For some, additional medications may be available to increase insulin production by the pancreas.

The factors that determine blood glucose levels fluctuate greatly throughout every day, so for a Type 1 diabetic, determining the proper dose of insulin to take can be a complex and sometimes delicate balancing act. Too much insulin means the body consumes too much glucose, which can drive blood glucose to a dangerously low level. This low blood glucose condition, referred to as hypoglycemia, can sometimes be fatal if prompt corrective action is not taken.

With too little insulin, blood glucose can soar to dangerous levels while at the cellular level the body is starved of energy. This condition is referred to as hyperglycemia and it poses a risk of long-term complications.

The goal, then, is to take the necessary steps to maintain a relatively constant blood glucose level as we eat and perform various activities throughout the day. One way that those challenged with diabetes can help avoid the spikes that can come, is to pay attention to what they eat and when they eat it. If such an individual doesn’t eat at the right time or eats too much of the wrong thing (or right thing) at the wrong time, the system can easily be thrown out of balance. In addition to proper eating and dietary habits, other natural remedies have also been widely used to help keep blood sugar levels in check. For example, Gymnema sylvestre is an herb used for centuries in India to help control blood glucose by stimulating pancreatic function.

Numerous factors affect blood glucose levels, as well as overall health for all of us. These are of particular importance to those with pre-diabetes or diabetes. One factor that contributes to elevated blood glucose is stress. The stress hormone adrenaline increases blood glucose, releasing it into the blood to provide a needed boost of energy to meet the fight or flight needs. In a situation such as being chased by a shark, we would react physically by fighting or fleeing and that glucose would soon be used up. But what if instead we remain stationary? Many of us deal with stress on a daily basis, but we don’t deal with that stress by engaging in physical activity. Instead, we are forced to sit and deal with it. One result of that inaction can be elevated blood glucose levels.

Cortisol is a hormone generated by the adrenal glands that can elevate blood glucose. Under conditions of high stress, cortisol provides the body with glucose by tapping into protein stored in the liver. This energy can help an individual in a fight or flight situation. However, if we’re constantly subjected to stress, the resulting chronic elevated cortisol can lead to increased blood glucose levels. To help reduce the effects of stress, we need to find ways to prevent or cope with it. Strategies include everything from exercise to nutrition, hydration, music and meditation.

Sleep is not a luxury — it is a necessity that also has an impact on blood glucose. In fact, a chronic lack of sleep is another form of stress that can result in elevated blood glucose, according to an article in the December 2015 issue of Diabetes Therapy. The National Sleep Foundation recommends seven to nine hours of sleep every night to enjoy its restorative health effects.

Another factor that can predispose individuals to Type 2 diabetes is a chronically low level of Vitamin D. A study reported in Scientific American in 2009, found that 45 percent of Americans are deficient in Vitamin D and more recent studies corroborate a rising trend in Vitamin D deficiencies. But here is the kicker: a Tufts-New England Medical Center study found that those who are chronically low on Vitamin D had a 46 percent increased risk of Type 2 diabetes. While the mechanism of Vitamin D with regards to diabetes is not crystal clear, researchers suspect that Vitamin D enhances the cells’ response to insulin.

As it turns out, precautions against skin cancer may actually be depressing our levels of Vitamin D. In a 2009 Article in Scientific American, co-author Adit Ginde, an assistant professor at the University Of Colorado Denver School Of Medicine, reveals that using a sunscreen with as little as an SPF 15 reduces the skin’s Vitamin D production by 99 percent.

As divers, we understand that hydration is a factor in decompression illness but it is also a factor when it comes to blood glucose levels. As fluid in our circulatory system is decreased due to dehydration, blood glucose becomes more concentrated. This causes an increase in urine production, which worsens the dehydration. The key message here is the importance of maintaining a healthy hydration level through consumption of water and other non-sugary beverages. Drinking water can reduce blood glucose, reduce insulin resistance and reduce hunger. If plain water isn’t enticing enough, try garnishing it with a citrus wedge, cucumber slice or fresh mint leaves.

Exercise is a double-edged sword when it comes to those with diabetes. In general, exercise is an important ingredient in maintaining health for those with diabetes. But for those with Type 1 diabetes, some precautions are in order. Vigorous physical activity should be avoided when blood glucose level is too high (hyperglycemia) and insulin level is too low. Not surprisingly, this precaution is reflected in the diabetic diving protocols.

While the long term effects of diabetes are daunting, the short term effects for a person with Type 1 diabetes can be downright frightening, especially if that individual should be underwater. The effects of hypoglycemia include confusion, blurred vision, impaired judgment, physical impairment, seizures and loss of consciousness. Such conditions are dangerous not only to a diver, but also the diver’s buddy. What’s more, if the symptoms aren’t recognized and properly treated, the diver could be in grave danger.

Steve Prosterman is a Dive Safety Officer at the University of the Virgin Islands and a Hyperbaric Chamber Operator at the St. Thomas Hospital. Diagnosed with Type 1 diabetes in 1967, he became a dive instructor in 1982 and has made well over 10,000 dives with no complications. As he points out, “The main risk of diving and diabetes is the sudden loss of consciousness or altered state of consciousness due to hypoglycemia (low blood sugar). Hypoglycemia generally begins to develop symptoms when the blood sugar falls to 60-70 mg/dl and lower and can also lead to impaired judgment, physical impairment and seizures. For this reason, anyone with a history of reactions with these symptoms should not dive.”

At first blush, we might think that diabetes is an absolute contraindication to diving due to the risk of losing consciousness underwater. But according to the Divers Alert Network (DAN), individuals with diabetes who wish to dive, can dive safely in many cases. In fact, protocols for diving with diabetes have been around for more than a decade now. The caveat is that medical screening and safety protocols must be observed.

According to DAN, the first step for the prospective diabetic diver is to undergo the same medical fitness evaluation as other candidates to ensure no other disqualifying conditions exist. These include such conditions as epilepsy, pulmonary disease, heart disease and others. A person who has advanced diabetes and suffers from secondary complications may also be excluded.

Next, it must be determined that no complications of diabetes exist that may increase the risk of injury while diving. DAN’s guidelines also note that candidates should be 18 years or older (≥16 years if in special training program), with a well-established treatment history and the ability to maintain blood glucose levels efficiently throughout the course of changing demands of daily activities. Those who do not have the ability to control their diabetes (read more here) can be at risk and may not be good candidates for diving. Candidates and divers with diabetes should undergo a mandatory annual medical examination and, if over age 40, should be regularly evaluated for silent cardiovascular disease.

General precautions for diving with diabetes include limiting depth to 100 feet (30.5 m), limiting bottom time to one hour and not diving beyond the no-stop limits. It’s also recommended that diabetic divers buddy up with non-diabetic divers and that their buddy be aware of both their condition and the proper procedures to recognize and deal with a hypoglycemic episode.

Since the primary risk comes when a diabetic diver experiences a low blood glucose condition, one key to safe diving is ensuring the blood glucose is at minimum safe level — and stable — at the beginning of a dive (see sidebar). The blood glucose must be high enough prior to starting a dive that the dive can be completed without experiencing an unsafe drop in blood glucose. Measuring blood glucose is quick and easy using one of the many blood glucose monitors available on the market today. Continuous glucose monitors (CGMs) are also available to help monitor blood glucose levels and trends.

Good nutrition is important to everyone’s health and can help prevent the onset of such diseases as Diabetes. For those who suffer with Diabetes or pre-diabetes, staying healthy is, in part, a matter of making the right choices when it comes to dietary intake.

Sugars and other carbohydrates are readily converted to glucose, but the rate at which that occurs is measured by something called glycemic index. A high glycemic index indicates a food will rapidly be converted to glucose, causing a rapid spike in blood sugar. A low glycemic index means that the digestive process for that food is slower, meaning a slow production of glucose and a slower rise in blood sugar. For example, white rice rapidly converts to glucose and has a glycemic index of 72, whereas an apple, which converts much more slowly, has a glycemic index of only 36. However, the glycemic load, which includes the effect of typical portion size, may be an even better measure of a particular food’s effect on blood glucose. 

Another factor that contributes to the rise in blood sugar is the quantity of food eaten. Eating smaller portions results in lower spikes in blood sugar. For those with pre-diabetes or Type 2 diabetes, simply eating smaller portions more frequently can improve the body’s ability to maintain blood sugars in the proper range. Choosing foods with a lower glycemic index and eating healthy portions, can help keep blood glucose in the normal range.

One area of conflicting research centers on the effects of caffeine on blood glucose. A study published in the June 2016 issue of the European Journal of Nutrition found that the risk of developing Type 2 diabetes was reduced for healthy, regular coffee drinkers consuming three to four cups of coffee per day. However, previous evidence suggests that high doses of caffeine can cause blood glucose to spike. The Mayo Clinic suggests that consuming up to 400 milligrams (mg) of caffeine (about four 8-ounce cups of coffee) is safe for most people, but it can cause trouble (spikes or lows) for those with diabetes. Limiting caffeine intake is a likely a good strategy for improved health.

Considering the health effects of Vitamin D, all divers should strive to maintain healthy levels of this vitamin. Many foods are Vitamin D-enhanced and may have a naturally high dose of Vitamin D. These include salmon, tuna, mackerel and vitamin D-fortified dairy products. Taking Vitamin D supplements is another health-wise strategy that could help maintain pancreatic function and help control blood glucose. The advice of nutritionists is to take Vitamin D3 with a meal that contains fat, since Vitamin D is fat-soluble and this enhances uptake. Foods rich in healthy fat include fish, nuts, avocado and olive oil.

The more we learn about human physiology, health and the effects of the underwater environment, the better prepared we are to make safe adaptations to explore the underwater world. Unfortunately, not everyone can safely enjoy scuba diving, but for many of those with diabetes, the door has been opened with safe diving protocols based on solid scientific research.

While the criteria for diving with diabetes may vary from one certification agency to another, some of the basic criteria for safe diabetic diving include good control of blood glucose levels and freedom from severe secondary complications of diabetes. As University of the Virgin Islands Dive Safety Officer and Instructor Steve Prosterman points out, “A candidate for diving should have an understanding of the relationship between the disease and exercise, be able to recognize early and handle low blood sugars on their own and not have had a serious hypoglycemic (low blood sugar) episode within the last 12 months.”

One way that diabetics can measure their ability to control the disease is with a hemoglobin A1C test, which provides a 90-day lookback at blood glucose levels and is a good indicator of how well blood glucose is being controlled. Most doctors will recommend that this test be performed at least twice a year. For diving, it may be suggested that the test results be within 30 percent of the normal range. Results that fall outside that range may indicate that better control of blood glucose is needed before a person undertakes underwater activities such as scuba diving.

Also important to safety is the person’s ability to recognize the early warning signs of hypoglycemia. Divers with diabetes must have a clear insight into the relationship between diabetes and exercise and be able to recognize and respond properly when a low blood glucose situation is developing.

Safe diving for diabetic divers requires strict protocols, as well as the development and use of good practices and habits. DAN recommends that divers make a general self-assessment of their fitness for diving on the day of the dive, as well as maintaining good hydration throughout the days of diving. Specific protocols* for glucose management on the day of diving include the following:

§                             Before entering the water, blood glucose (BG) must be stable or rising with a value greater than or equal to 150 mg dL-1 (8.3 mmol L-1). Divers should complete a minimum of three pre-dive BG tests — performed at 60 minutes, 30 minutes and immediately prior to diving — to evaluate BG trends. It is noted that alterations in the dosage of oral hypoglycemic agents (OHA) or insulin on the evening prior or day of diving may help.

§                             Divers should delay the dive if BG is less than 150 mg dL-1 (8.3 mmol L-1) or greater than 300 mg dL-1 (16.7 mmol L-1).

• Divers must carry readily accessible oral glucose during all dives and have parenteral glucagon available at the surface.
• If hypoglycemia is noticed underwater, the diver should surface (with buddy), establish positive buoyancy, ingest glucose and leave the water.
• Check blood sugar frequently for 12-15 hours after diving to ensure safe levels.
• In order to establish best practices for future diving, diabetic divers should log all dives and include BG test results and all information pertinent to diabetes management.
• For more information, contact DAN and consult your physician.

* Divers Alert Network, Guidelines for Diabetes and Recreational Diving, Proceedings Summary | DAN/UHMS Diabetes and Recreational Diving Workshop.

Also available from DAN: Pollock NW, Uguccioni DM, Dear GdeL, eds. Diabetes and recreational diving: guidelines for the future. Proceedings of the UHMS/DAN 2005 June 19 Workshop. Durham, NC: Divers Alert Network; 2005.

Hypoglycemia is a condition where blood glucose (blood sugar) is low. When levels fall to 60 to 70 mg/dl or less, a dangerous condition exists. Some signs and symptoms of hypoglycemia of which diabetic divers, their buddies and instructors should be aware include:

§                             Excessive hunger

§                             Weakness or dizziness

§                             Confusion

§                             Unresponsiveness or inappropriate responsiveness

§                             Blurred vision

§                             Glazed eyes

§                             Sudden mood changes

§                             Irritability

• Loss of consciousness or altered state of consciousness
• Seizures

Diabetic divers who display these symptoms should follow established protocols. This includes exchanging hand signals to identify the problem, ascending and stabilizing at the surface (both the affected diver and the buddy) and ingestion of carbohydrates by the affected diver. The divers terminate the dive and return to the boat or beach where a blood test is performed. Such events, along with blood glucose results and other details of the event, should be recorded for future reference.

The glycemic index is a measure of how rapidly a food is converted into glucose through digestion. A high glycemic index means a food converts quickly. The glycemic load is a measure of the impact of a typical portion of the food on blood glucose, taking into account the typical portion size.   Numerous online sources are available to provide values for a broad spectrum of foods.

http://divemagazine.co.uk/skills/8907-serious-problems-diving-after-covid19

Copyright Disclaimer under section 107 of the Copyright Act of 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, education and research. Fair use is a use permitted by copyright statute that might otherwise be infringing.

New Advice Cautions Against Rushed Return to Diving for Coronavirus Patients

By Mark 'Crowley' Russell

The Coronavirus pandemic has already had a devastating impact on the scuba diving world – but there's another question on divers' minds: 'What happens if I get it? Can I dive after COVID-19?' And the answer is not straightforward.

An article published in the German magazine Wetnotes (click here for a Google Translated English version) on 15 April gives an insight into the medical problems that scuba divers who have contracted SARS-CoV-2 might face. In it, Dr Frank Hartig, a senior consultant and response crisis coordinator/disaster officer for SARS-CoV-2 at Innsbruck University Hospital in Austria – and a scuba diver himself – describes some of the problems he has already encountered as a physician.

The acronym SARS – as in SARS-CoV-2, the official name of COVID-19 – stands for Severe Acute Respiratory Syndrome. SARS attacks the lungs, and while research into the long-term effects of the novel coronavirus is only just beginning, its physical impacts are all too tragically well known. Lung damage caused by conditions such as pneumonia and acute respiratory distress syndrome (ARDS) has been widely reported. It is also known to attack other organs, including the heart, although cardiac damage may go unnoticed until the heart is actually checked. Although we might not know much about the coronavirus itself, it has long been established that scuba diving with a compromised cardiopulmonary system can lead to serious injury, even death.

In his article, Dr Hartig describes his involvement with six active scuba divers who were hospitalised with conditions brought on by SARS-CoV-2 and who subsequently recovered and were discharged. When they returned for a check-up several weeks later, they all outwardly appeared to be healthy, but a closer examination proved otherwise.

'The first checks of these six divers, who came to the check-up clinically healthy after 5 to 6 weeks, are interesting,' writes Dr Hartig (translated from German). 'In two of them, we saw significant oxygen deficiency when under stress as a typical sign of a persistent pulmonary shunt. In two others, bronchial tubes were still very irritable during exercise, as in asthmatics. Four of the six divers in the check-up CT [scan] still had significant lung changes. None of the six divers can be released for diving for the time being, despite their wellbeing.'

Exercise-induced asthma is a well-known contraindication to diving, and in layman's terms, a pulmonary shunt is when blood fails to pick up more oxygen as it passes through the lungs, which leads to the body being starved of oxygen. It is often caused by fluid in the lungs, also the result of pneumonia and pulmonary oedema, a condition becoming widely recognised as a leading cause of diver fatalities. 

At this stage, any questions over long-term damage to the lungs caused by SARS-CoV-2 would be entirely speculative, but it is clear from Dr Hartig's assessment that divers who have been affected by the coronavirus should not dive until they have had a thorough medical examination – even if they otherwise appear healthy. As Dr Hartig notes, if proper precautions are not taken, 'Young, COVID-healthy people who want to dive again quickly and appear healthy at first could [slip through our fingers].'

A report published on 12 April by the Belgian Society for Diving and Hyperbaric Medicine gives advice to scuba divers who may have contracted and recovered from Covid-19 based on current medical knowledge. To summarise, the report states that:

1.                    Risk of Infection: Someone who has been infected with COVID-19 can still spread the virus to others. In a diving context that would be especially likely when conducting air sharing or rescue training exercises. Before returning to diving, divers should, therefore:

·                                      Wait a minimum of two, preferably three months, if they had symptoms of the virus 

·                                      Wait a minimum of one month if they tested positive for the virus but were asymptomatic.

·                                      Those who have not been tested and never had symptoms may still be susceptible to infection and should 'observe a waiting period' after lockdowns are lifted, which may be variable depending on location and type of diving.

·                                      Divers and dive centres should strictly observe guidelines for gear disinfection as distributed by DAN

2.                    Risk of Pulmonary Barotrauma: People who have had COVID-19 may have significant damage to their lungs for an unknown period of time, possibly permanently, and therefore have an increased risk of pulmonary barotrauma – or lung overexpansion injury – even if they don't make rapid, breath-holding ascents. A diver who was hospitalised with lung-related problems should wait at least three months and undergo complete pulmonary function testing and a high-resolution CT scan of the lungs before returning to diving. Divers who had lung-related symptoms but were not hospitalised are still strongly recommended to have the test.

3.                    Risk of Cardiac Events: Damage to the heart caused by COVID-19 may go unnoticed during the acute phase of the disease, but may lead to heart failure during diving. Therefore, it is recommended that a diver who was hospitalised with cardiac or pulmonary symptoms should, after the three-month waiting period, undergo a thorough cardiac evaluation with echocardiography and exercise testing (exercise electrocardiography – sometimes called the 'stress test'). Those who had symptoms but were not hospitalised are strongly advised to have the tests as well.

1. Pulmonary oxygen toxicity: It appears that some COVID-19 patients' symptoms worsened after being given pure oxygen. Although little is known about an increased pulmonary sensitivity to oxygen, the report suggests it would be 'prudent' to avoid technical diving involving the prolonged breathing of hyperoxic gas with a pO2 of 1.3 ATA or higher. Simple nitrox diving (maximum pO2 of 1.4 ATA) should not present any problem.
   
2. Decompression illness: tiny bubbles of inert gas form even on normal dives and are safely eliminated through the lungs during breathing. However, damage to the lungs may prevent the lungs' 'bubble filter' from working and lead to an arterial gas embolism or other form of decompression illness. Ddivers who have suffered from pulmonary symptoms of COVID-19 should, therefore, remain well within the no-decompression limits of their dives.

Click here for the full report (available in French, Dutch and English)

A complete assessment of the problems that divers might face following a COVID-19 / SARS-CoV-2 infection is undoubtedly many months away and, as Dr Hartig notes, any long-term medical advice will remain speculative until clinical trials have been conducted. 

In the short-term, however, the advice is clear. SARS-CoV-2 can damage the lungs and the heart. Scuba diving with damage to any part of the cardiovascular system can lead to serious injury and death. Much as we might all wish to rush back into the water as soon as we can, doing so without proper medical consideration may cause more harm than good.

 

Thanks to Robert N. Rossier  Dive Training Magazine

https://dtmag.com/thelibrary/the-good-stuff-is-deep-dispelling-common-scuba-myths/

 Copyright Disclaimer under section 107 of the Copyright Act of 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, education and research. Fair use is a use permitted by copyright statute that might otherwise be infringing.

 

 I remember from years past a particularly eager young diver who was seemingly obsessed with the desire to dive deeper. After all, he had heard that the “really good stuff” was in deep water, and that’s where he wanted to go. The misinformation he had received, combined with his desire to be seen by others as a dashing, daring conqueror of “the deep” conspired to make him a particularly “at risk” individual. Fortunately, through the efforts of a good instructor and more enlightened peers, he learned to be more cautious, and to appreciate the magical, mystical elements of the ocean realm that lay in safer depths.

The diving world is filled with misinformation, misconceptions, misunderstandings and plain-old myths. It’s surprising that even well-educated divers and instructors can unwittingly subscribe to these untruths, and pass them on to others. After all, we were all students, and most of us took as gospel every word uttered from the lips of our instructors. What we may not have realized is that they, too, were victims of myth, misinformation, and misconceptions.

Sometimes, especially when the information seems to make perfect sense, it’s easy to “go along” with what you’ve heard, and pass the bad data on to friends and students. In some cases, the information might be true, but the rationale is unsound. Sometimes the “myth” is partially true, or has an element of fact around which rumor and speculation have been wound. As we wade through the material required at any level of training, we must strive to separate the truth from the fiction, debunk the myths and replace them with accurate, up-to-date, verifiable information. And we need to encourage our dive buddies to do the same.

That said, let’s take a look at some of the more common myths, and the truth surrounding those issues. Among those misconceptions are untruths and myths regarding everything from general diving safety to physiology, physics and marine life.

Myth No.1: Diving is dangerous.

Of course it is. If it wasn’t dangerous, nobody would need training, now would they? What’s important to understand is that while diving presents a multitude of potential hazards, it is a diver’s knowledge, training, judgment and decision making that limits or controls that risk.

In fact, diving has an arguably good safety record. According to Divers Alert Network (DAN) Senior Research Director Petar Denoble, Ph.D., the injury rate for scuba diving is in the range of one per 2,000 participants, or an injury rate of 50 per 100,000. The Insurance Information Institute publishes injury rates substantially higher for many popular sports (2002 data), including basketball (21,300 injuries per 100,000) and golf (140 per 100,000). Diving may have an element of danger, but no more so than many other activities that are generally considered safe.

Myth No.2: Modern scuba gear is virtually foolproof.

There’s no question that modern scuba gear is well-engineered, well-designed, and highly reliable. That said, we still need to account for a fair number of diving accidents that occur each year that appear to be related, at least to a degree, to equipment malfunctions.

Data on equipment problems in diving is notoriously lacking in the industry, but an Australian report on the Diving Incident Monitoring Study (DIMS) prepared a few years back for the SPUMS (South Pacific Undersea Medical Society) sheds some light on the subject. According to the DIMS data, 457 of the 1,000 reported incidents (roughly half) involved equipment, and more than 25 percent of these resulted in harm to the diver. Similarly, DAN data reveals that roughly half of the 89 fatal dive accidents in 2002 involved equipment problems.

While such data might at first blush seem to implicate dive equipment, that perspective shifts when we dig a little deeper. In fact, the studies show that many of the equipment-related diving accidents and deaths are not “true” equipment problems. Example: Of the 52 regulator-related incidents reported in the DIMS data, only 20 were considered actual regulator malfunctions. Running out of air, panic, and other causes contributed to the remaining incidents and accidents. Similarly, while weight belts were implicated in 33 incidents out of 457 reported equipment-related incidents and accidents (7 percent), and were involved in 12 percent of the reported injuries, few of those were actually due to faulty weight belts. Many times the problems resulted from failure to drop the belt in an emergency, tangling of the belt due to improper use or placement, and other training-related issues.

The fact of the matter remains that while our equipment may be highly reliable, it isn’t infallible. Gear is generally good, but it’s no better than the person who maintains and uses it. A diver who isn’t well-trained and prepared, or who uses poorly maintained equipment, may end up suffering the consequences. On the other hand, a diver with the proper training, knowledge, and decision-making skills who takes proper care of his equipment is less likely to suffer a problem.

Myth No.3: The air in my cylinder is safe to breathe.

Air is all around us, and we all know that breathing it is generally more healthy than not. We also know that the compressed air provided by a reputable dive center is usually up to par in terms of meeting the air quality requirements specified by the industry. But we live in an imperfect world, and the incidence of air contamination is perhaps higher than some would like to admit. Informal data from some of the larger independent air testing laboratories suggest that as many as 3 percent to 5 percent of all air stations tested will fail to meet the CGA Grade E standard for diver’s breathing air. As we travel to more remote destinations, the lack of good filtration equipment combined with other factors might add up to a greater likelihood of getting a “bad” air fill.

Here again, knowledge, protocol and common sense can often help us sort out the good from the bad and the ugly. To be safe, we should buy our air from professional air stations that adhere to accepted maintenance protocols, and subject their air to periodic testing by an independent testing facility. Such results should be posted in a conspicuous location. In addition, especially if we’re using nitrox or some other breathing gas, it’s important to verify the oxygen content with a calibrated oxygen monitor.

Myth No.4: If I use a dive computer, I won’t get decompression sickness.

This is probably one of the most common misconceptions among divers today, but be careful how you address it. According to the latest data from DAN, between 70 percent and 75 percent of the divers injured in 2002 were using computers as their means of dive planning. “We have not indicated that dive computers should be blamed for DCS,” Denoble says. “Decompression sickness is dependent on depth-time profile in a probabilistic way: The deeper and longer you dive and faster you come up, the more likely that you will get bent. The ‘Safety Curve’ [no-decompression limits] was meant to indicate low-risk dives, but there is no guarantee that there will be no DCS within the ‘Safety Curve.’ As a matter of fact, many cases of DCS occur after so-called no-decompression dives.” This means that a very small percentage of divers will still get DCS, even if they have a properly operating dive computer, and use it correctly.

On the other hand, we must also understand that dive computers are exactly that — computers — and as such they can readily succumb to the “garbage in equals garbage out” syndrome. While a properly functioning and correctly used dive computer is perhaps a diver’s best friend, they are not infallible, either.

Among the many ways to put that “garbage” into our computers is to make some fairly simple mistakes, like switching computers in the middle of a dive trip (the new computer assumes you haven’t been diving yet); breathing a gas other than that for which the computer is set (air instead of nitrox, or the wrong blend of nitrox); or following inappropriate dive profiles, including “saw tooth” profiles or rapid ascents. Remember that individual physiology, use of alcohol, and challenging environmental conditions can alter the blood flow, gas diffusion, and overall absorption/desorption of nitrogen to the extent that the model used by the computer is invalid for the particular diver on the particular dive. In fact, Dr. Richard Vann of DAN says that the issue of dive computer safety has been the subject of a Project Dive Exploration study, and “the major conclusion is that the dive conditions can have significant effects on risk.”

Myth No.5: Scuba cylinders are indestructible.

Just look at these things. Thick steel and aluminum walls, heavy, and built for high pressure; no wonder they call them “tanks.” While a scuba cylinder may appear to be virtually indestructible, the simple truth is that they are engineered components, and sufficient mistreatment, neglect, or physical damage can render them unsafe. According to sources at Professional Scuba Inspectors (PSI) in Woodinville, Washington, cuts, dings, gouges, dents, corrosion pitting, and bulges must be compared with specific damage limits for each cylinder type. Damage or other conditions that fail to meet the allowable limits cause the cylinder to be condemned. Despite their outward appearance, cylinders aren’t indestructible, and deserve to be properly used, maintained and handled. It’s important to remember, too, that even though the cylinder itself is durable, most damage to the cylinder involves the valve, through which air flows into the first-stage regulator.

Myth No.6: The guide/instructor/buddy will take care of me.

It’s amazing to many of us how easily supposed well-trained divers can turn into “sea sheep,” simply following the herd without asking simple questions like, “where are we going, and how long will we stay?” All too often, divers regard dive guides as unerring, and will simply follow along. And while most of the time professional dive guides will be sufficiently conservative as to avoid decompression obligations, there are exceptions. According to the latest DAN data, 7 percent of the 348 divers injured in 2002 were relying on someone else rather than the tables or their own dive computer. What were they thinking? The take-home lesson for our students is that each of us is responsible for our own safety, and that means doing our own planning.

Other diving myths revolve around physiology and the physics of diving. Here again, we find some common myths and misconceptions that should be cleared up.

Myth No.7: If I feel warm, I am warm.

Unfortunately, our ability to sense heat loss from our own bodies is not as keen as we might expect. According to the “NOAA Diving Manual,” hypothermia can even be a problem when diving in warm waters. According to this source, “A phenomenon called ‘warm water hypothermia’ can occur even in the tropics, especially during long dives and repetitive dives made without adequate rewarming between dives. In warm-water hypothermia, long, slow cooling can take place in water temperatures as warm as 91 degrees Fahrenheit (33 degrees Celsius)… The physiological mechanisms of warm-water hypothermia have been demonstrated in various medical studies, but they still are not clearly understood. The victim in this situation may not shiver, because the drop in core temperature may not be rapid enough to activate the body’s thermoregulator defense mechanism…”

The implications here are clear: We must recognize the importance of wearing proper thermal protection, and understand that this equipment may be just as important in warm water as it is in cold.

Myth No.8: You can’t exceed the no-decompression limits on a single tank.

This is an old myth, stemming from the days when 72-cubic-foot (and smaller) steel cylinders were the standard of the industry, and virtually no one used a dive computer. While it may have seemed a good guideline, it wasn’t true back then, and it isn’t true today, especially when cylinders are larger, and divers go to greater depths wearing better thermal protection and consuming less air per minute.

Myth No.9: Divers should only drink water when diving.

Dehydration is one of the silent enemies of diving. It affects our circulatory system, and thus can alter the physics of gas transfer in the body, predisposing us to decompression sickness. While it’s true that divers should strive to maintain a high level of hydration, there’s a misconception that many of the so-called “sports drinks” are inappropriate for diving. According to Dr. Jolie Bookspan, author of “Diving Physiology in Plain English,” that simply isn’t the case. “Commercial electrolyte and carbohydrate sport drinks are not harmful to divers,” writes Bookspan. “Exercise studies are clear that sport drinks promote rehydration by helping you absorb and retain water. They stimulate your thirst mechanism to keep you drinking, and replace needed water.” According to the “NOAA Diving Manual,” divers should drink warm liquids between dives, and avoid alcohol and caffeine.

A final category of myths revolves around marine life. In fact, there’s a whole world of myths and legends regarding the nature and habits of undersea creatures, and not all the myths are as apparent as the tales of the Loch Ness monster. Here it’s best to turn to the experts, ferret out the truth, and separate it from the fiction.

Myth No.10: Sharks are a major threat to divers.

I think we can blame this one on Hollywood and the popular media. There are more than 400 species of sharks, and most of them will shy away from divers. There are of course exceptions, but proper precautions can drastically limit the risk of attack by the potential “evil-doers.” While sharks can be dangerous in certain circumstances, we’re much more likely to be injured by some other means.

Consider these facts: According to statistics from the International Shark Files project at the Florida Museum of Natural History, and the New York City Health Department, a person is roughly 600 times more likely to be bitten by a dog in New York City than by a shark when in the water. At least in the years 1981, and 1984-87, New York City documented reports of at least 8,000 cases in which a dog bit a human. The highest number of documented shark attacks nationwide in any one of those years was 14, in 1984. The number of lightning strikes offers additional perspective. Nearly as many people have been killed by lightning strikes in Florida than have been attacked by sharks, and only eight of those people have died as a result of shark attacks in Florida.

Some of the good stuff in diving really is deep, but the myths of diving can run even deeper. Legends are fun and myths are magical, but in the context of safe diving, there’s no substitute for cold, hard facts. If we strive to verify the “facts” we hear or have learned, turning to reliable sources for verification, we can help reduce the promulgation of diving myths.

 

Copyright Disclaimer under section 107 of the Copyright Act of 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, education and research. Fair use is a use permitted by copyright statute that might otherwise be infringing.

 

 

https://www.scubadiving.com/training/basic-skills/buoyancy-calculator-how-figure-out-how-much-lead-you-need

 

Buoyancy Calculator: How Much Do You Need in Dive Weights?

Diving weights make all the difference

By John Brumm Updated: April 15, 2019

 

Pool Dive

Pool dive weight test

Kathy Danca Galli

 

It’s the bane of all divers. We want to go down, but the inherent buoyancy in our wetsuits, our BCs, our lungs and our fat cells are all conspiring to keep that from happening.

To overcome the force of buoyancy you have to counterbalance it with ballast weight. The question is, how much in dive weights will you need? While the answer is different for every diver, the goal is the same: carry enough weight to enable you to function efficiently and safely at all depths, and not an ounce more.

Divers are generally taught to define this as being neutrally buoyant at 15 feet deep while wearing an empty BC and carrying a nearly empty tank. But how do you get there? There’s the basic ballpark method — carry 10 percent of your body weight in lead. Or there’s the surface float method — in full scuba gear, load enough weight to enable you to float with the water at eye level (some would say at the hairline).

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But rather than just blindly piling on the lead, why not break it down to find out why you need to carry the weight you do, and what specifically you are counterbalancing. By deconstructing your buoyancy status, you know exactly where your counterweight needs are greatest, and that might reveal ways to reduce the amount of weight you ultimately have to carry. Here’s how:

STEP 1: Calculate for Your Body

How much weight do you need to make your body neutral? Take a few weights into the water wearing just a swimsuit. You will be perfectly weighted when you can hang motionless with half a breath, and sink when you exhale. (Using a snorkel can make this test easier.)

Tip for Shaving Ballast Weight: Lose weight. Also, work to turn your fat to muscle. Fat mass is a lot more buoyant than muscle mass, so any fat you can convert to muscle will lower your buoyancy deficit.

STEP 2: Calculate for Your Exposure Suit

Wearing your exposure suit, get into the water and repeat the procedure outlined in Step 1. Then take the total amount of weight required to get neutral, subtract Step 1’s total, and you’ll have the net buoyancy budget for your exposure suit.

Tip for Shaving Ballast Weight: If water conditions permit, cut down on the thickness of your wetsuit. A wetsuit can have two to three pounds of buoyancy for every millimeter of thickness. If you wear a neoprene drysuit, consider that compressed or crushed neoprene suits have much less buoyancy than standard neoprene. If you wear a fabric drysuit, remember that thinner undergarments have much less buoyancy than the puffy stuff.

 

 

STEP 3: Calculate for Your BC

BCs can be a huge source of inherent buoyancy, especially the older, full-featured models that have lots of traditional-style padding. It used to be common for BCs to carry upwards of four pounds-plus of inherent buoyancy, which means, of course, that you need four pounds-plus of extra lead on your weight belt to compensate for it. Fortunately, most modern BCs carry much less inherent buoyancy.

To test your BC’s inherent buoyancy, submerge it while venting all exhaust valves to bleed air from the bladder. Knead the padding in the shoulders and backpad and behind the pockets to release air bubbles. Slowly rotate the BC to enable any trapped air to escape. Be patient, allow plenty of time for water to displace the air in the material. When you stop seeing bubbles, release the BC into the water column. If it heads to the surface you’ve got some inherent buoyancy to deal with. Add weights until the BC will hang neutrally buoyant in the water. Then count up how many weights it took to get there and you’ll have your number.

Tip for Shaving Ballast Weight: Buy a modern BC. Models that have come onto the market within the last three or four years carry, on average, from one to 2.5 pounds of inherent buoyancy, and some carry none at all. Note: while most manufacturers don’t provide the inherent buoyancy of their BCs, you can always find that info in ScubaLab BC reviews. (https://www.scubadiving.com)

STEP 4: Calculate for Your Tank

The buoyancy characteristics of tanks vary widely. For example, a standard aluminum 80 is 1.6 pounds negatively buoyant when topped off, and 2.8 pounds positively buoyant at 500 psi. That’s close to a four and a half pound buoyancy differential between the beginning of a dive and the end of a dive that, of course, needs to be dealt with by adding ballast weight.

A steel tank, on the other hand, tends to start off negatively buoyant and stay that way. For example, a high-pressure 80 is about nine pounds negative when full and three pounds negative when empty. That’s three pounds that can be removed from your weight system.

Tip for Shaving Ballast Weight: Switch from an aluminum cylinder to a steel cylinder. A properly-weighted diver who goes from an aluminum 80 to, say, a HP steel 80 could theoretically take six pounds off his weightbelt.

STEP 5: Calculate for Everything Else

Gather your reg, gauges, knife, fins and any other items you regularly dive with, place them in a neutrally buoyancy mesh bag, and submerge it. The goal here is primarily to see if the total package is positively buoyant. If it is, add some weight until it becomes neutral. If it’s negative it probably won’t be by much, so consider it a ballast slush fund. It’s not working against you, and that’s all that matters.

STEP 6: Put it All Together

Add it all up. This should be very close to your target ballast weight requirements, and it should also give you a clear picture of where your biggest buoyancy challenges lie. To double-check your calculations, gear up with all the components you measured separately, get back into the water and repeat Step 1. If the above scenario played out like it’s supposed to, you should be floating at eye or forehead level in a relaxed position. When you exhale you should start to slowly sink. If not, you couldn’t be more than a pound or so off your target. Make the final adjustment and go diving.

SALT WATER VS. FRESH?

If most of your diving is done in fresh water springs or lakes, then ballast calculations should be done in fresh water. If you dive mostly in the ocean, then do the calculations in salt water. If you switch back and forth, you’ll need to adjust your ballast needs as you go. Be prepared to add anywhere from 4 to 7 pounds going from fresh to salt water.

 

 

Copyright Disclaimer under section 107 of the Copyright Act of 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, education and research. Fair use is a use permitted by copyright statute that might otherwise be infringing.

https://www.scubaboard.com/community/threads/tale-of-woe-how-i-was-that-diver-non-fatal.590118/

Thank you Ken Kurtis

 

I got this note from a diver I've known for a long time. Although I think there are good lessons to be learned here and suggested he post this, he's a bit embarrassed about what happened given his lengthy diving experience but said if I could sanitize it and make it anonymous, I could share the story. (And it truly isn't me in this tale.) But the point is that even experienced divers can easily make mistakes or take things for granted. The dive that starts off with you checking out mentally could spiral out of control. Fortunately, his only ends up as a story:

The wife and I did a cruise a few months ago. The cruise did not offer any scuba packages, so we contacted local dive shops on some of the islands. We picked based on reviews on TripAdvisor and reading their websites. In the end we decided we would be too busy to dive and left our gear at home (we only took our masks and snorkels), Well as it turns out, while on the cruise we decided to dive on Barbados and Antigua and recontacted the dive operators on those islands. And it did not go very well for me.

First was Barbados. My wife and I were sent down the anchor line first, then a family of resort divers was going to enter with their DM, then our DM was going to come down and guide she and I around. Well I was a little bored and the vis was terrible - maybe 20'. There was a patch of fans and coral a few feet away, so I decided to look at it. I moved in a straight line to it, looked back and made sure I could see her and the concrete anchor, then turned back to the coral. Suddenly a surge came by and vis dropped to about 5 feet. I knew I had screwed up royally, flipped my rental console over to use the compass and swim straight back while I was still oriented to the fans. But there was no compass (I hadn't checked prior to descending), and the surge was moving me around a lot. So I crept back and couldn't find the anchor. So I spent a few minutes swimming a circle pattern, then with great expectations of embarrassment, started my slow ascent of shame. About 20', the sea cleared and I saw the line. I went back down and nobody was there. I stayed a few minutes, then ascended up the line to the boat. When I was about 10', the line went slack as the boat unhooked to go after the family who had been trying to drift dive when the vis went bad and were now at the surface ready for recovery. I popped up (no audio signaling device or sausage) in 3-4' swells and saw the boat leaving. I did get their attention and signaled I was OK and then hung on the mooring buoy for about 20 minutes until after all others were recovered. I was so embarrassed at how I had managed to screw up royally in such a short time in the water. The folks on the boat felt terrible that they took us to a place that had the vis drop out leaving me lost 15 feet from my wife - they thought it was their error, but the wife and I knew it was mine. Second dive 2 miles away was wonderful.

Then Antigua. Here the dive gear was poorly fitting. It was way too small and useless for a fat guy like me. But I did not really mind the tank flopping around as the cummerbund kept coming undone. At about 45' on our way to 65' my reg started breathing very hard.

Inhaling was pulling my mask against my face. So I went to the octo and it was the same. The high pressure gauge was reading a full tank and did not dip as I breathed, so I knew the valve was on. I hesitated before calling the dive, but if it was already having trouble at 45', I did not want to have to be concerned about something failing the rest of the way while on a dive, so I found the DM, explained the situation and was escorted back the boat where I sat out that dive. Second dive with different reg was great.

LESSONS LEARNED
Next time I take my own gear. Or if I rent, I will make sure there is a compass - even in the Caribbean. I should have had a signaling device like a sausage as well. If I had taken my BC, it would have been attached and ready. I also would have been familiar with the gear and it would have fit properly.

The Antigua dive frustration was not my fault, it was just one of those things that was inconvenient, and not a significant risk. If the reg had failed while in a group, there was plenty of air to borrow for a safe return to the boat.

The Barbados dive was a risk of my own creation. I was THAT DIVER. I was headstrong and over confident. As such I inconvenienced others and thereby increased risks by requiring attention that was not then available for the others if they had a problem. As we know most serious dive problems are a series of small risk-increasing events that together become a crisis. I knew better, and yet there I was in the middle of a mess of my own creation.

I thought you might find this a fascinating study in vacation diving on a non-diving vacation. I have been a diver since 1974, you would think I would have known better.

 

Ken Kurtis
NAUI Instr. #5936
Owner, Reef Seekers Dive Co.

THANKS TO DIVE TRAINING MAGAZINE

and

Barry and Ruth Guimbellot

 

https://dtmag.com/thelibrary/shore-diving/

Copyright Disclaimer under section 107 of the Copyright Act of 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, education and research. Fair use is a use permitted by copyright statute that might otherwise be infringing.

 

Have you ever wanted to strike out on your own as a diver? If yes, it’s important to recognize that there’s more to shore diving than gearing up, wading into the water and swimming off. Exciting shore diving opportunities abound, but you’ll need to do a bit of preparation beforehand.

The Perks of Shore Diving

One of the reasons shore dives are so attractive is due to the freedom you and your buddy will have when planning and enjoying your self-guided dives. You are free to choose special sites to explore, whether it is a freshwater quarry, an inland lake or an ocean site with shore access. The timing of the dive is totally up to you and your buddy — and Mother Nature — as you’ll always want to plan your shore dive when conditions are most favorable. You can decide on the time and place to dive, as well as the length and depth of the dive. And those who struggle with motion sickness will tell you they prefer shore diving to sitting on a rocking boat. And one more advantage of shore diving is that it is a cost-effective way to indulge in your passion for diving.

Pre-Dive Preparations

As independent divers, you and your buddy or buddies are responsible for mapping out your plans for the dive trip. To avoid any major problems, begin making plans well ahead of the first dive. Discuss possible dive locations where shore diving is permitted and easily accessible. Complete a checklist of all equipment needed, keeping your dive objective in mind. Also, include items necessary for setting up a base camp.

Even though you’ll be diving on your own, it pays to consult the pros at the dive center nearest your shore diving location. This makes sense and not just because it’s likely where you’ll be getting air fills and buying or renting gear, like extra dive weights or a “diver down” float/flag. They’re also the source for local expertise on your planned dive location. Chances are, they know the local sites well and might even have maps and/or charts to share, along with tips and advice about the best parking spots, entry and exit areas, and more. If it’s your first time exploring a new shore diving site, their experience will likely prove to be invaluable.

Inquire about current weather patterns and tidal variations. Check recommended websites, books or apps for additional information. Site selection will also depend on your objectives, such as exploring a shipwreck or visiting some other underwater feature.

Once at the site, visiting with other divers is also an excellent way to gain information about the area. Ask about the ease or difficulty of the entries and exits. Does the underwater terrain have slippery or sharp rocks? If making a lake shore entry, is the bottom muddy or silty? How is the visibility? Are there any potential hazards you should be aware of?

Arrive at the site early enough to observe the area before gearing up and entering. Watch for boat traffic, kayaking or jet skiers in the area, especially in lakes. Ocean activities such as parasailing, wind surfing and paddle boarding are common and typically close to shore. Keep an eye out for potential environmental challenges, such as rip currents. If you decide the area presents too many challenges, it’s best to move to another location.

Establishing a Base Camp for Shore Diving

Now that you have done your homework and found the best site for you and your buddy, it is time to set up base camp. Avoid high traffic areas and be considerate of others near you when claiming a desired spot. Anything from your car to a large tarp spread on the ground will work. Cars work well if the parking area is near enough to the dive site. You can gear up at the vehicle, stow any personal articles and lock the car before moving to the entry site. Place the key(s) in a secure wetsuit pocket in a dry pouch before beginning your dive.

A tarp spread on the ground is especially handy if you have a non-diving friend who can stay at base camp while you are diving. When spreading the tarp on the ground, be sure to keep it safely above the high water line. Place dive gear around the edges of the tarp, making it easier to gear up without tracking sand or debris onto the tarp. Secure the corners by setting extra weights or other items at each corner.

Stock the base camp with anything you may need. Provide plenty of snacks and fluids, especially water, to enjoy during surface intervals. Other important items to have handy include a first-aid kit, eco-safe sunscreen, emergency information, fully charged cell phones and DAN (Diver’s Alert Network) membership numbers for each diver. Also, remember extra parts for maintaining gear or underwater cameras.

Navigating Entries and Exits

Once the dive site is selected and base camp is set up, decide on the best entry and exit points. Also, determine an alternate exit point in the event conditions change during your dive. When gearing up for a shore dive, don all of your gear but the mask, snorkel and fins. If you wear open-heel fins that accommodate dive boots, consider buying a pair with a rugged outsole. If you normally wear full-foot fins, consider wearing a thin pair of neoprene socks with a non-skid coating on the bottom. This will help you avoid slipping and will also protect your feet from injury as you make your way in and out of the water.

Help each other gear up and then perform a pre-dive buddy check before you enter the water, confirming that your tank is turned all the way on and that all gear is in working order and that you have important accessories such as a compass and dive float/flag and line/reel. If conditions allow, wade into chest-deep water before donning your fins. Start by donning your mask and snorkel and then add air to your buoyancy compensator (BC). Once in the water, as your buddy supports you, slip on the first fin using the Figure 4 method. Switch legs and put on the other fin. Now assist your buddy as he or she dons their fins. If conditions warrant that you don your fins at the water’s edge, you and your buddy can take turns steadying each other. Once you’ve got your fins on, continue to help each other as you carefully shuffle backwards or perform a sideways “crab walk” into the water.

If you intend to do a surface swim out to the dive site, make sure you have plenty of air in your BC for comfort at the surface. You might also wish to switch from regulator to snorkel to conserve gas supply. Plot a compass heading on the way out and reverse the heading when returning to the exit point. Also, use natural navigation like heading along a wall or other natural feature.

Always monitor your gas supply and remember to plan your dive so you have plenty of breathing gas remaining for your return to the exit area. Many divers plan their dive by “thirds” — using a third of a tank for the outbound dive, a third for the return, leaving the remaining third in reserve in case of emergency.

Shore diving is best when the surf is mild. Rough surf with large waves can be dangerous and should be avoided. If this situation occurs, consider other possibilities such as using a dock or stairs to enter and exit.

Learning how to execute shore dives can be an exciting addition to your diving adventures. Just remember to do your pre-dive homework, practice necessary safety procedures and enjoy the freedom and fun scuba diving from shore has to offer.

Shore Access. A Sure Thing?

Many inland dive sites, such as lakes and quarries, are privately owned. Coastal areas are open to the public but might be situated in areas with privately-owned homes or businesses nearby or are within state or national parks. When planning a shore dive, it’s important to find out how to gain access legally — and respectfully.

When diving a private site or visiting a state or national park, an entrance fee might be required and you might also need to show proof of certification, proof of divers’ insurance (DAN or other) and you might need to sign a liability waiver and agree to abide by the owners’ rules of operation.

When using public access to ocean sites, be considerate of private homeowners. This includes avoiding parking in private parking areas, keeping the noise to a minimum and being discrete when changing out of wet wetsuits.

 

 

Our thanks to Diver Training Magazine

https://dtmag.com

The Doctor Will See You Now: Diving Fitness and

Medical Examinations

                                                                                          By Alex Brylske

I'm sure that there are places where I’m more ill at ease than in a doctor’s office, but I can’t really think of one. This isn’t to say that I don’t take my health care seriously. My doc is an affable and competent person whom, like it or not, I visit on a fairly regular basis. Over the past several years I’ve been poked, probed, palpated, stuck, irradiated and imaged in every way imaginable, and some that aren’t so. Heck, I even get my teeth cleaned twice a year. However, I’m not one who runs out to the doctor for a hangnail or at the first sign of a cold. In fact, as testament to my abhorrence to anything medical, there have only been two occasions in my entire adult life when I visited a doctor for something other than preventive care.

My fear and loathing of medicos goes back to my childhood. I had had two operations by the time I was 6 years old, and that much hospital experience for one so young definitely has an effect. Even as a teenager, as much as I dreamed of becoming a diver, I was initially reluctant to get certified when I learned that it would require a medical examination.

Of course, knowing one’s level of fitness is essential to safe diving because, regardless of how easy it has become, surviving underwater subjects our bodies to some pretty stressful and unforgiving situations. But what exactly constitutes “fitness to dive,” and how can we assess that? Does determining our fitness always require the insight of a trained medical professional? These questions have been debated since the beginning of recreational diving and, as in most fields, opinions and practices have changed over the years. Even today, polices on prequalification medical exams and diving fitness are not universal.

The What and Why of ‘Fitness’

In scuba diving, when it comes to assessing fitness, times have certainly changed. Years ago, many were reluctant to even consider diving because they thought it was deep, dark and dangerous. Today, it’s just the opposite. Many are lulled into diving because they view it as simple, safe and easy. Indeed, diving takes place in a relatively weightless environment, which may make it seem effortless, but it does require a degree of both health and stamina.

In determining what fitness means to you, understand that there’s no single answer; it means different things to different people. The first issue to consider in evaluating your fitness level is where and what type of diving you plan to do. Obviously, enjoying a shallow reef in the Florida Keys on a still summer morning is far less demanding than braving 8-foot seas to dive the wrecks off the New Jersey coast. Although this may seem obvious, it’s amazing how many folks will assume that their Florida Keys fitness is all they need when they one day decide to dive New Jersey or California. Your well-being demands that you be honest about what you want from the diving experience, and make sure that you don’t exceed the conditions on which you’ve based your fitness decision.

Still, even if you do decide that you’re only interested in relatively “easy” conditions and environments, things don’t always go as planned. Even the best conditions can change rapidly, and it’s these unforeseen circumstances that cause a lot of accidents. So, whatever you expect, assume that once in a while, at least, conditions will be worse; perhaps much worse. This means that you must possess not only the level of fitness required for what you normally encounter, but a “reserve,” just in case. Granted, assessing, acquiring and maintaining an appropriate level of fitness may not be easy, but never forget that Murphy’s Law is always right around the corner ready to bite you on the backside when you least expect it.

Whether you expect it or not, on any dive you may encounter long surface swimming, have to contend with strong, changing currents or just deal with being at the surface in conditions akin to a washing machine during the rinse cycle. All require more fitness than walking from your easy chair to the fridge. Unanticipated and strenuous physical tasks are part of the diving experience in any environment; therefore you must not have any health conditions, or take any medications, that may impede your performance.

Assessing your fitness also isn’t a one-time event. When I started diving as a young teenager, there were few physical tasks a diver might encounter that I couldn’t handle. But to assume that’s still the case more than three decades later is a recipe for disaster. So, the next time you’re filling out your logbook, take a few minutes to ask yourself a few simple questions: Did I encounter conditions that were close to or beyond my physical capabilities? How likely is it that these conditions may occur again? Do I need to reconsider my “comfort envelope” or try to improve my fitness? The answers require a great deal of self-honesty, but the exercise may be the best thing you’ll ever do for your health and well-being.

Finding a clear method to assess and quantify your level of fitness isn’t always easy, but there are some basics you can keep in mind. First, if you can’t walk around the block without a rest, or if you’ve never even tried, diving at any level probably isn’t something you should try (or continue). At least, not until you’ve improved your conditioning. A very minimal guideline for fitness is the ability to walk a mile (1.6 km) within 12 minutes. If you can’t do this, you should plan to exercise for at least 20 minutes four or five time per week, but only after you’ve gotten the approval of your doctor. And if possible, add swimming with fins to your routine. A useful measure that I’ve always given my own students, based on years of teaching experience, is this: No one should consider themselves prepared for a certification course who cannot swim at their own pace, using a mask and fins, at least 200 yards (182 m) without stopping and/or becoming exhausted.

Restrictions and Red Flags

Aside from physical fitness, divers and would-be divers must also consider how any existing medical conditions can affect their health and safety. Surviving in an environment that’s 800 times denser than the atmosphere can present problems that might never arise while sitting in your living room, or even engaging in moderate physical activity on terra firma.

First, let’s consider temporary conditions such as colds, flu, injury or even pregnancy. All should be considered reasons to curtail diving until the effects have passed. Colds, flu or allergy attacks cause swelling or blockage in the sinuses and eustachian tubes, which means pressure equalization will be difficult or impossible. Injuries can leave you with restricted strength, stamina or mobility, and can even put you at a greater risk of decompression sickness due to alterations or restrictions in blood flow. Furthermore, when diving with an injury, the accompanying pain could mask symptoms of decompression sickness. So it’s best to postpone diving until you’re fully healed. Lastly, diving while you are or could be pregnant is considered a no-no for one simple reason: We just don’t know enough about its effect on the developing fetus, so why take the chance? Can any hour spent underwater be worth the risk to a child’s life or quality of life?

It should be obvious that you must take into account the effect of any medications. This goes for both prescribed and over-the-counter (OTC) meds. Frankly, most medications have no effect on diving, but some definitely do. They may cause drowsiness or fatigue, which may make you more susceptible to nitrogen narcosis, or impede your thinking at just the time thinking is most critical. Other medications, as well as illicit drugs, can affect heart rate even in those without heart problems. Clearly, if you plan to dive, it’s especially important to read the warning labels before using any drugs. And it’s just downright stupid to dive while taking any recreational drugs.

Another concern that’s foreign to any landlubber taking meds is whether and how the increased pressure at depth can affect any drug. There is always a possibility of such an unexpected reaction to medications, and some drugs are noted particularly for pressure-induced side effects. But the problem is that these reactions can vary from diver to diver, and even from day to day. So, the first step in preventing a dangerous situation is knowing well in advance what side effects any medication has on you before using it while diving. It isn’t smart to pop a pill for the first time just as you’re about to enter the water. This is true even of common OTC drugs like cold and allergy or seasickness medications.

The effect of diving on prescription medication can be a very complex issue, and requires a knowledgeable doctor’s advice. Regardless, always remind your doctor that you’re a diver when he or she prescribes a med. And, if your doc isn’t up on how diving can affect your condition or medications, you should be prepared to provide some resources. (See the sidebar “Educating Your Doctor” on Page 34.)

Some medical conditions aren’t temporary, and these can have major consequences for divers. Two of the more common concerns are asthma and diabetes. Both are becoming epidemic in many regions of the world, including North America, the Caribbean, and the islands of the South Pacific; and many believe that this is the result of lifestyle and the degrading quality of our environment. This is a serious problem for all segments of society, but it poses additional problems for the diving community. For decades there has been much debate about whether to allow those with either condition to dive; and at one time the answer was quite simple: no. But many have questioned such a ban on diving, and today, after careful medication evaluation, some asthmatics are permitted to dive.

Diabetes, as well, is a chronic condition that’s been recently reconsidered by diving medical experts. Today, rather than a blanket disqualification, divers and diving candidates with diabetes are evaluated on a case-by-case basis with an appropriate medical specialist. A similar situation exists for one of the most common disorders in almost every developed society: cardiovascular disease. (For more information, see “The Heart of the Matter,” Dive Training, April 2006.) Research and debate continue regarding both asthma and diabetes, and it’s likely more issues and findings will appear.

This Will Only Hurt a Little

Whether you’re a diver or not, the cornerstone of good health is a regular physical exam. Opinions on how often this should happen seem to vary; and to be perfectly honest, after graduating from college I didn’t set foot in a doctor’s office for almost 20 years. But that all changed when I hit the big 4-0, a milestone no one should ignore. Since then I’ve had regular annual checkups, along with the associated diagnostic, age-appropriate tests involving treadmills, CAT scans, endoscopes, rubber gloves and assorted other accouterments of medical technology.

The issue of physical examinations for divers has undergone quite an evolution. Even today, policy varies from country to country. As I mentioned, when I got certified, everyone was required to first secure medical approval from a physician before being accepted into a class. But in North America, that hasn’t been the case for a long time. As many of you no doubt know from your experience, some of you had to have physical exams, while others didn’t.

North American-based diver training organizations require that all candidates for instruction complete the Recreational Scuba Training Council’s “Medical History Statement and Questionnaire.” (A copy of the form can be downloaded from many sources; just type in the search term “RSTC medical form.”) As the form explains, its purpose is to find out if a perspective diving student should be examined by a doctor before participating in training. A “yes” response to any question doesn’t necessarily disqualify someone from diving, but it does indicate that there could be a pre-existing condition that may affect safety. Therefore, the candidate must seek the advice of a physician before engaging in diving activities.

Some believe that this approach is inadequate, contending that everyone new to diving should first have medical clearance from a physician. In fact, some countries such as Australia require this. But is this additional expense and inconvenience really warranted? Some who have studied the matter don’t think so. For instance, the UK Sport Diving Medical Committee found that examination by a physician was largely unhelpful in identifying divers with significant medical conditions, and concluded that a health questionnaire, like the current medical history form, is perfectly sufficient. A similar result came from a study six years ago published in the British Journal of Sports Medicine.

However, this selective nature of medical exams does not apply to some divers. All commercial divers, including professionals such as divemasters, dive control specialists, assistant instructors and instructors, are required to have full medical clearance before they’re accepted into training. Scientific divers, including most divers in university programs and those working under the guidelines of the American Academy of Underwater Sciences (AAUS), also require full medical evaluation before training, and while active in such programs.

For recreational divers, the current medical standard has been in effect for almost two decades. The questionnaire was developed by the Undersea and Hyperbaric Medical Society (UHMS) and Divers Alert Network (DAN). (More information about the form is contained in “Assessing Your Medical Fitness to Dive” on Page 36.)

In the end, however, the final arbiter of who can enter a diving course, for medical reasons or otherwise, is that of the instructor. In fact, based solely on his or her judgment, an instructor may require anyone to secure medical approval from a physician, even if the candidate has indicated no affirmative answers on the questionnaire.

We all like to think the best of ourselves. And often our image doesn’t reflect reality. Usually, this has little potential to do harm to anything but our ego. But fitness for diving is a different matter. When it comes to fitness, lying to yourself or others can put both you and your buddy at serious risk. Remember, no diver ever thought that they weren’t coming back from their dive.

Educating Your Doctor

As we all know doctors are very busy people. Their medical school training is intense, and with continuing advances in medical research, they have to know more and more. So, it’s no surprise that a subject like diving medicine doesn’t receive much, if any attention, in either medical school or afterward. In fact, if a doctor doesn’t take up diving personally, he may know less about diving medicine than a knowledgeable scuba instructor. This isn’t intended as a slam. It’s just that, in the scheme of things, scuba diving isn’t a very common activity. So, most doctors only rarely deal with divers and would-be divers. As a result, when it comes time for a diving medical exam, you may find yourself in the delicate situation of having to educate your doctor.

But the situation isn’t as daunting as it may sound. The RSTC “Diving Medical Statement and Questionnaire” contains a section designed just for this purpose: “Guidelines for Recreational Scuba Diver’s Physical Examination.” It includes three pages of detailed instructions with 16 medical references. So, when you show up to your doc’s office, be sure that you take a copy of the entire six-page form, not just the part he or she has to sign.

The guidelines discuss areas of concern for divers, and what to look for in a medical assessment. Temporary, relative and severe risk conditions are listed for the neurological, pulmonary, gastrointestinal, orthopedic, hematological, metabolic/endocrinological and otolaryngological systems. There’s also a segment on behavioral health. At a minimum, the examination should include these points. The list of conditions is not all-inclusive, but contains the most commonly encountered medical problems.

The guidelines define “temporary risks” as those that are responsive to treatment, allowing the student to dive safely after they have been resolved. “Relative risks” refer to conditions that exist but, in the judgment of the physician, are not contraindicated for diving. Finally, “severe risk” implies that an individual is believed to be at substantially elevated risk of decompression sickness, pulmonary or otic (ear) barotrauma or altered consciousness with subsequent drowning, compared with the general population. In these cases, as the guidelines state, “The consultants involved in drafting this document would generally discourage a student with such medical problems from diving.”

The guidelines conclude by informing physicians that medical professionals of the Divers Alert Network (DAN) associated with Duke University Health System are available for consultation. If you find that your doc would like even more insights, here are some additional references:

“Medical Examination of Sport Scuba Divers,” 3rd Edition, A.A. Bove, M.D., Ph.D (ed.), Best Publishing Company, P.O. Box 30100, Flagstaff, AZ 86003-0100.

“The Physician’s Guide to Diving Medicine,” C.W. Shilling, C.B. Carlston and R.A. Mathias, Plenum Press, New York, New York (Available through the Undersea and Hyperbaric Medical Association, Bethesda, Maryland)

Assessing Your Medical Fitness to Dive

The “Diving Medical Statement and Questionnaire” has been produced under the auspices of the Recreational Scuba Training Council and endorsed by the Undersea and Hyperbaric Medical Society (UHMS), Divers Alert Network (DAN) and more than two dozen of North America’s top diving medical specialists. To assess whether an individual should have medical clearance to enroll in a scuba course, here are the areas it addresses:

First, the questionnaire addresses those over 45 years of age. For this group, a positive response to smoking, high cholesterol, family history of heart attack or stroke, high blood pressure, diabetes (even if controlled by diet alone), or if you are receiving medical care means a trip to the doctor’s office.

It then goes on to ask all applicants if they have or have ever had any of several medical conditions, listed below; and if they take any prescribed medications for anything other than malaria prophylaxis or birth control. Female diving candidates are asked whether they are, could be or are attempting to become pregnant.

Again, an affirmative response to any of these questions or conditions, and a doctor’s approval is required for continuing with your wishes to become a certified diver.

§                             Asthma, or wheezing with breathing, or wheezing with exercise.

§                             Frequent or severe attacks of hay fever or allergy.

§                             Frequent colds, sinusitis or bronchitis.

§                             Any form of lung disease.

§                             Pneumothorax (collapsed lung).

§                             Other chest disease or chest surgery.

§                             Behavioral health, mental or psychological problems (panic attack, fear of closed or open spaces).

§                             Epilepsy, seizures, convulsions or take medications to prevent them.

§                             Recurring complicated migraine headaches or take medications to prevent them.

§                             Blackouts or fainting (full/partial loss of consciousness).

• Dysentery or dehydration requiring medical intervention.
• Any dive accidents or decompression sickness.
• Inability to perform moderate exercise (i.e., walk 1 mile [1.6 km] within 12 minutes).
• Head injury with loss of consciousness in the past five years.
• Recurrent back problems.
• Back or spinal surgery.
• Diabetes.
• Back, arm or leg problems following surgery, injury or fracture.
• High blood pressure or take medicine to control blood pressure.
• Heart disease.
• Heart attack.
• Angina, heart surgery or blood vessel surgery.
• Sinus surgery.
• Ear disease or surgery, hearing loss or problems with balance.
• Recurrent ear problems.
• Bleeding or other blood disorders.
• Hernia.
• Ulcers or ulcer surgery.
• A colostomy or ileostomy.
• Recreational drug use or treatment for, or alcoholism in the past five years.
  

 A Note from DAN

As of 1/1/20 the Guardian policy is no longer offered to divers age 70 and older.

Preferred and master plans are still available.

 

Health for Diving: A Primer on Diabetes

 

By Robert N. Rossier      Dive Training Magazine

https://dtmag.com/thelibrary/health-diving-diabetes/

Health for Diving: A Primer on Diabetes

We all know there are medical factors that can prevent people from diving. Epilepsy, various heart conditions, loss of consciousness, pneumothorax, some chronic diseases and even some forms of anxiety can spell trouble that may be incompatible with diving. But over the years, the list of contraindications has narrowed, allowing more to enjoy exploration of the underwater world.

One condition that has prevented some people from becoming divers is diabetes. Diabetes affects the body’s ability to produce or respond to insulin — a hormone controlling the metabolism of carbohydrates. The result is abnormal carbohydrate metabolism leading to elevated glucose levels in the blood and urine.

While this might sound innocuous, the long-term effects of diabetes are dead serious. Diabetes takes more lives than AIDS (acquired immunodeficiency syndrome) and breast cancer combined, claiming one American life every three minutes. Diabetes is a leading cause of blindness, kidney failure, amputations, heart failure and stroke. What’s more, the incidence of diabetes is growing. According to diabetesresearch.org, the number of reported cases of people living with diabetes has jumped nearly 50 percent in the past decade and it now affects more than 29 million Americans. On a global scale, diabetes afflicts more than 380 million people, and the World Health Organization estimates that by 2030, the number of people living with diabetes will more than double. Clearly, diabetes is a growing health risk and one that could affect our ability to dive safely. But, at least for some, the door has been opened for scuba diving with diabetes — that is, if the proper conditions are met and the proper protocols are followed.

Defining Diabetes

Diabetes is categorized into two primary types, referred to as Type 1 and Type 2. In those with Type 1 diabetes, the pancreas does not produce insulin or it produces insufficient insulin to meet the body’s needs. Individuals with Type 1 diabetes must receive insulin injections regularly in order to metabolize blood glucose (blood sugar). In the more common Type 2 diabetes, the body may not produce enough insulin or the insulin does not trigger the cells to allow proper metabolism of glucose.

Type 1 and Type 2 diabetes are the most common forms of the disease but other forms exist. Many individuals are also diagnosed with pre-diabetes, a condition in which blood sugar is high but not significantly enough to warrant treatment. Unless changes are made to diet and exercise, those with pre-diabetes are likely to join the ranks of individuals diagnosed with diabetes.

Physiology of Diabetes

To understand the effects of diabetes, we need to have an understanding of some basic human biology. In a normally functioning body, a number of metabolic reactions occur in response to eating. First, the digestion process in the stomach breaks the food down into glucose (a form of sugar), which enters the blood stream and is transported to cells throughout the body. The hormone insulin is secreted by the pancreas, which triggers the cells to allow glucose to enter. Through a process called glycolysis, the glucose is broken down in the production of a molecule called ATP (adenosine triphosphate), which is the source of energy in the cell. Also in response to eating, the cells also synthesize and story fatty acids and proteins. These are all critical functions for a normal, healthy body.

For the person with diabetes, this process simply does not work properly. Type I diabetes is actually an autoimmune condition. The immune system destroys the beta cells in the pancreas, which are responsible for the production of insulin. And without that insulin, glucose does not enter the cells and they run out of energy.

For Type I diabetes, those affected must receive injections of insulin at the appropriate times to control blood glucose levels and allow cells to receive the needed glucose. Eating the right foods at the right time can also help control blood sugar by controlling how much glucose is produced through digestion. Other factors including exercise, stress and general health also affect the body’s need for insulin, so getting the correct timing and dosage for insulin injections can be a challenge.

In Type 2 diabetes, the pancreas has a deficiency of beta cells that create insulin, making it unable to supply enough insulin to the body. In addition, insulin receptors at the cellular level may not respond properly to insulin, limiting the amount of glucose entering the cells and allowing blood glucose to remain elevated. Controlling diet is also important for those with Type 2 diabetes to prevent spikes in blood glucose. Medications are available to help maintain an appropriate low level of blood glucose. For some, additional medications may be available to increase insulin production by the pancreas.

A Balancing Act

The factors that determine blood glucose levels fluctuate greatly throughout every day, so for a Type 1 diabetic, determining the proper dose of insulin to take can be a complex and sometimes delicate balancing act. Too much insulin means the body consumes too much glucose, which can drive blood glucose to a dangerously low level. This low blood glucose condition, referred to as hypoglycemia, can sometimes be fatal if prompt corrective action is not taken.

With too little insulin, blood glucose can soar to dangerous levels while at the cellular level the body is starved of energy. This condition is referred to as hyperglycemia and it poses a risk of long-term complications.

The goal, then, is to take the necessary steps to maintain a relatively constant blood glucose level as we eat and perform various activities throughout the day. One way that those challenged with diabetes can help avoid the spikes that can come, is to pay attention to what they eat and when they eat it. If such an individual doesn’t eat at the right time or eats too much of the wrong thing (or right thing) at the wrong time, the system can easily be thrown out of balance. In addition to proper eating and dietary habits, other natural remedies have also been widely used to help keep blood sugar levels in check. For example, Gymnema sylvestre is an herb used for centuries in India to help control blood glucose by stimulating pancreatic function.

Contributing Factors

Numerous factors affect blood glucose levels, as well as overall health for all of us. These are of particular importance to those with pre-diabetes or diabetes. One factor that contributes to elevated blood glucose is stress. The stress hormone adrenaline increases blood glucose, releasing it into the blood to provide a needed boost of energy to meet the fight or flight needs. In a situation such as being chased by a shark, we would react physically by fighting or fleeing and that glucose would soon be used up. But what if instead we remain stationary? Many of us deal with stress on a daily basis, but we don’t deal with that stress by engaging in physical activity. Instead, we are forced to sit and deal with it. One result of that inaction can be elevated blood glucose levels.

Cortisol is a hormone generated by the adrenal glands that can elevate blood glucose. Under conditions of high stress, cortisol provides the body with glucose by tapping into protein stored in the liver. This energy can help an individual in a fight or flight situation. However, if we’re constantly subjected to stress, the resulting chronic elevated cortisol can lead to increased blood glucose levels. To help reduce the effects of stress, we need to find ways to prevent or cope with it. Strategies include everything from exercise to nutrition, hydration, music and meditation.

Sleep is not a luxury — it is a necessity that also has an impact on blood glucose. In fact, a chronic lack of sleep is another form of stress that can result in elevated blood glucose, according to an article in the December 2015 issue of Diabetes Therapy. The National Sleep Foundation recommends seven to nine hours of sleep every night to enjoy its restorative health effects.

Another factor that can predispose individuals to Type 2 diabetes is a chronically low level of Vitamin D. A study reported in Scientific American in 2009, found that 45 percent of Americans are deficient in Vitamin D and more recent studies corroborate a rising trend in Vitamin D deficiencies. But here is the kicker: a Tufts-New England Medical Center study found that those who are chronically low on Vitamin D had a 46 percent increased risk of Type 2 diabetes. While the mechanism of Vitamin D with regards to diabetes is not crystal clear, researchers suspect that Vitamin D enhances the cells’ response to insulin.

As it turns out, precautions against skin cancer may actually be depressing our levels of Vitamin D. In a 2009 Article in Scientific American, co-author Adit Ginde, an assistant professor at the University Of Colorado Denver School Of Medicine, reveals that using a sunscreen with as little as an SPF 15 reduces the skin’s Vitamin D production by 99 percent.

As divers, we understand that hydration is a factor in decompression illness but it is also a factor when it comes to blood glucose levels. As fluid in our circulatory system is decreased due to dehydration, blood glucose becomes more concentrated. This causes an increase in urine production, which worsens the dehydration. The key message here is the importance of maintaining a healthy hydration level through consumption of water and other non-sugary beverages. Drinking water can reduce blood glucose, reduce insulin resistance and reduce hunger. If plain water isn’t enticing enough, try garnishing it with a citrus wedge, cucumber slice or fresh mint leaves.

Exercise is a double-edged sword when it comes to those with diabetes. In general, exercise is an important ingredient in maintaining health for those with diabetes. But for those with Type 1 diabetes, some precautions are in order. Vigorous physical activity should be avoided when blood glucose level is too high (hyperglycemia) and insulin level is too low. Not surprisingly, this precaution is reflected in the diabetic diving protocols.

Diving with Diabetes

While the long term effects of diabetes are daunting, the short term effects for a person with Type 1 diabetes can be downright frightening, especially if that individual should be underwater. The effects of hypoglycemia include confusion, blurred vision, impaired judgment, physical impairment, seizures and loss of consciousness. Such conditions are dangerous not only to a diver, but also the diver’s buddy. What’s more, if the symptoms aren’t recognized and properly treated, the diver could be in grave danger.

Steve Prosterman is a Dive Safety Officer at the University of the Virgin Islands and a Hyperbaric Chamber Operator at the St. Thomas Hospital. Diagnosed with Type 1 diabetes in 1967, he became a dive instructor in 1982 and has made well over 10,000 dives with no complications. As he points out, “The main risk of diving and diabetes is the sudden loss of consciousness or altered state of consciousness due to hypoglycemia (low blood sugar). Hypoglycemia generally begins to develop symptoms when the blood sugar falls to 60-70 mg/dl and lower and can also lead to impaired judgment, physical impairment and seizures. For this reason, anyone with a history of reactions with these symptoms should not dive.”

At first blush, we might think that diabetes is an absolute contraindication to diving due to the risk of losing consciousness underwater. But according to the Divers Alert Network (DAN), individuals with diabetes who wish to dive, can dive safely in many cases. In fact, protocols for diving with diabetes have been around for more than a decade now. The caveat is that medical screening and safety protocols must be observed.

According to DAN, the first step for the prospective diabetic diver is to undergo the same medical fitness evaluation as other candidates to ensure no other disqualifying conditions exist. These include such conditions as epilepsy, pulmonary disease, heart disease and others. A person who has advanced diabetes and suffers from secondary complications may also be excluded.

Next, it must be determined that no complications of diabetes exist that may increase the risk of injury while diving. DAN’s guidelines also note that candidates should be 18 years or older (≥16 years if in special training program), with a well-established treatment history and the ability to maintain blood glucose levels efficiently throughout the course of changing demands of daily activities. Those who do not have the ability to control their diabetes (read more here) can be at risk and may not be good candidates for diving. Candidates and divers with diabetes should undergo a mandatory annual medical examination and, if over age 40, should be regularly evaluated for silent cardiovascular disease.

General precautions for diving with diabetes include limiting depth to 100 feet (30.5 m), limiting bottom time to one hour and not diving beyond the no-stop limits. It’s also recommended that diabetic divers buddy up with non-diabetic divers and that their buddy be aware of both their condition and the proper procedures to recognize and deal with a hypoglycemic episode.

Since the primary risk comes when a diabetic diver experiences a low blood glucose condition, one key to safe diving is ensuring the blood glucose is at minimum safe level — and stable — at the beginning of a dive (see sidebar). The blood glucose must be high enough prior to starting a dive that the dive can be completed without experiencing an unsafe drop in blood glucose. Measuring blood glucose is quick and easy using one of the many blood glucose monitors available on the market today. Continuous glucose monitors (CGMs) are also available to help monitor blood glucose levels and trends.

Food Sense for All

Good nutrition is important to everyone’s health and can help prevent the onset of such diseases as Diabetes. For those who suffer with Diabetes or pre-diabetes, staying healthy is, in part, a matter of making the right choices when it comes to dietary intake.

Sugars and other carbohydrates are readily converted to glucose, but the rate at which that occurs is measured by something called glycemic index. A high glycemic index indicates a food will rapidly be converted to glucose, causing a rapid spike in blood sugar. A low glycemic index means that the digestive process for that food is slower, meaning a slow production of glucose and a slower rise in blood sugar. For example, white rice rapidly converts to glucose and has a glycemic index of 72, whereas an apple, which converts much more slowly, has a glycemic index of only 36. However, the glycemic load, which includes the effect of typical portion size, may be an even better measure of a particular food’s effect on blood glucose. (See sidebar.)

Another factor that contributes to the rise in blood sugar is the quantity of food eaten. Eating smaller portions results in lower spikes in blood sugar. For those with pre-diabetes or Type 2 diabetes, simply eating smaller portions more frequently can improve the body’s ability to maintain blood sugars in the proper range. Choosing foods with a lower glycemic index and eating healthy portions, can help keep blood glucose in the normal range.

One area of conflicting research centers on the effects of caffeine on blood glucose. A study published in the June 2016 issue of the European Journal of Nutrition found that the risk of developing Type 2 diabetes was reduced for healthy, regular coffee drinkers consuming three to four cups of coffee per day. However, previous evidence suggests that high doses of caffeine can cause blood glucose to spike. The Mayo Clinic suggests that consuming up to 400 milligrams (mg) of caffeine (about four 8-ounce cups of coffee) is safe for most people, but it can cause trouble (spikes or lows) for those with diabetes. Limiting caffeine intake is a likely a good strategy for improved health.

Considering the health effects of Vitamin D, all divers should strive to maintain healthy levels of this vitamin. Many foods are Vitamin D-enhanced and may have a naturally high dose of Vitamin D. These include salmon, tuna, mackerel and vitamin D-fortified dairy products. Taking Vitamin D supplements is another health-wise strategy that could help maintain pancreatic function and help control blood glucose. The advice of nutritionists is to take Vitamin D3 with a meal that contains fat, since Vitamin D is fat-soluble and this enhances uptake. Foods rich in healthy fat include fish, nuts, avocado and olive oil.

The more we learn about human physiology, health and the effects of the underwater environment, the better prepared we are to make safe adaptations to explore the underwater world. Unfortunately, not everyone can safely enjoy scuba diving, but for many of those with diabetes, the door has been opened with safe diving protocols based on solid scientific research.

Considerations for Candidates

While the criteria for diving with diabetes may vary from one certification agency to another, some of the basic criteria for safe diabetic diving include good control of blood glucose levels and freedom from severe secondary complications of diabetes. As University of the Virgin Islands Dive Safety Officer and Instructor Steve Prosterman points out, “A candidate for diving should have an understanding of the relationship between the disease and exercise, be able to recognize early and handle low blood sugars on their own and not have had a serious hypoglycemic (low blood sugar) episode within the last 12 months.”

One way that diabetics can measure their ability to control the disease is with a hemoglobin A1C test, which provides a 90-day lookback at blood glucose levels and is a good indicator of how well blood glucose is being controlled. Most doctors will recommend that this test be performed at least twice a year. For diving, it may be suggested that the test results be within 30 percent of the normal range. Results that fall outside that range may indicate that better control of blood glucose is needed before a person undertakes underwater activities such as scuba diving.

Also important to safety is the person’s ability to recognize the early warning signs of hypoglycemia. Divers with diabetes must have a clear insight into the relationship between diabetes and exercise and be able to recognize and respond properly when a low blood glucose situation is developing.

Glucose Management: Procedures for Diabetic Divers

Safe diving for diabetic divers requires strict protocols, as well as the development and use of good practices and habits. DAN recommends that divers make a general self-assessment of their fitness for diving on the day of the dive, as well as maintaining good hydration throughout the days of diving. Specific protocols* for glucose management on the day of diving include the following:

§                             Before entering the water, blood glucose (BG) must be stable or rising with a value greater than or equal to 150 mg dL-1 (8.3 mmol L-1). Divers should complete a minimum of three pre-dive BG tests — performed at 60 minutes, 30 minutes and immediately prior to diving — to evaluate BG trends. It is noted that alterations in the dosage of oral hypoglycemic agents (OHA) or insulin on the evening prior or day of diving may help.

§                             Divers should delay the dive if BG is less than 150 mg dL-1 (8.3 mmol L-1) or greater than 300 mg dL-1 (16.7 mmol L-1).

§                             Divers must carry readily accessible oral glucose during all dives and have parenteral glucagon available at the surface.

§                             If hypoglycemia is noticed underwater, the diver should surface (with buddy), establish positive buoyancy, ingest glucose and leave the water.

§                             Check blood sugar frequently for 12-15 hours after diving to ensure safe levels.

§                             In order to establish best practices for future diving, diabetic divers should log all dives and include BG test results and all information pertinent to diabetes management.

§                             For more information, contact DAN and consult your physician.

* Divers Alert Network, Guidelines for Diabetes and Recreational Diving, Proceedings Summary | DAN/UHMS Diabetes and Recreational Diving Workshop.

Also available from DAN: Pollock NW, Uguccioni DM, Dear GdeL, eds. Diabetes and recreational diving: guidelines for the future. Proceedings of the UHMS/DAN 2005 June 19 Workshop. Durham, NC: Divers Alert Network; 2005.

Symptoms of Hypoglycemia

Hypoglycemia is a condition where blood glucose (blood sugar) is low. When levels fall to 60 to 70 mg/dl or less, a dangerous condition exists. Some signs and symptoms of hypoglycemia of which diabetic divers, their buddies and instructors should be aware include:

§                             Excessive hunger

§                             Weakness or dizziness

§                             Confusion

§                             Unresponsiveness or inappropriate responsiveness

§                             Blurred vision

§                             Glazed eyes

§                             Sudden mood changes

§                             Irritability

§                             Loss of consciousness or altered state of consciousness

§                             Seizures

Diabetic divers who display these symptoms should follow established protocols. This includes exchanging hand signals to identify the problem, ascending and stabilizing at the surface (both the affected diver and the buddy) and ingestion of carbohydrates by the affected diver. The divers terminate the dive and return to the boat or beach where a blood test is performed. Such events, along with blood glucose results and other details of the event, should be recorded for future reference.

Glycemic Index and Load

The glycemic index is a measure of how rapidly a food is converted into glucose through digestion. A high glycemic index means a food converts quickly. The glycemic load is a measure of the impact of a typical portion of the food on blood glucose, taking into account the typical portion size. The values shown in the table below are just a few examples to give you an idea of how foods affect blood glucose and some are quite surprising. As the data suggests, even minor adjustments to diet can have a large impact on blood glucose control. Numerous online sources are available to provide values for a broad spectrum of foods.

 

https://www.tdisdi.com/diving-redundant-air-source/?utm_source=eNewsletterPro&utm_medium=email&utm_campaign=Do_you_dive_with_redundant_air%3F__5288&fbclid=IwAR1rwdf6ZnwUQR-mFcNi4efgHHQhAW3adYj9EUazsOLwhp6weFLUA1_UuOQ

 

Thanks to SDI/TDI and Mark Manthey for this article.

 

Diving with redundant air source for recreational divers

By Mark Manthey

Diving with an alternate air source (octopus) is something all divers do. However, not many recreational divers use a REDUNDANT air source. That is a completely independent air source (second cylinder, first stage, and second stage regulator set). For most recreational diving, your buddy is your redundant air source. However, in the Great Lakes region, where divers often dive below 100 feet in cold water, redundant air sources such as a pony cylinder are common, almost standard equipment for recreational divers.

So, where, when, and why dive with a redundant air source?

Should these dives be considered a technical dive? Now, that’s a great question, but we won’t address that here. Clearly, the ability to bailout of a dive, and to be self-reliant, gives divers in a catastrophic gas loss situation (such as second stage freeflow) more, better and safer options to surface safely without panic, without the assistance of a buddy.

·          Depth, due to the longer ascent time. At 130ft or, 40m, assuming a 30ft, or 10m per minute ascent rate, and a 3-minute safety stop, the total ascent time would be about 7 minutes. Depending on the gas loss rate, there may not be enough gas in the cylinder for the diver to safely surface.

·          Overhead environments such as a LIMITED penetration wreck dive, or ice diving. (This kind of diving may not require decompression)

Many options are available for diving with a redundant air source;

·          Back mounted doubles with a manifold. This configuration is favored by many technical divers. The manifold allows the diver to access the gas in both cylinders from a single regulator, and each cylinder has a first and second stage regulator. It may sound like overkill, but it’s a great setup, and I dive with them as a recreational diver often, on deep dives.

·          Sidemount. In recent years, sidemount configurations have gained popularity, and for good reason. Sidemount offers two independent cylinders, and easily accessed valves. Many sidemount divers use two 80cf aluminum cylinders, as they are widely available on nearly any dive boat, offering the diver 160 cubic feet of gas.

·          Single cylinder with H-valve. The H valve offers the redundancy of doubles, on a single cylinder. It’s compact and lightweight.

·          Pony cylinder. Pony cylinders come in a wide variety of sizes and mounting options. The key is to find the one right for your planned dive. Pony cylinders range from just two or three cubic feet, to 40 cubic feet. A small pony cylinder may be only good for a minute or two for deep dives but should be ok for bailout on shallow dives. In my estimation, its best to get larger pony cylinders. If you’re going to make the investment, you should give yourself the largest margin of safety for the money you spend. Pony cylinders have a variety of mounting options.

Again, you should choose the one right for you. Generally, they are either slung on the left side, or mounted on the right side of the divers’ main cylinder by a mounting bracket. I prefer to sling them. This allows the diver to easily manipulate the valve or hand off the cylinder to another diver if needed. A back mounted pony keeps the cylinder neatly tucked out of the way, and is favored by public safety divers, because it keeps it from dragging through the mud and muck they commonly find themselves in. However, this setup makes it difficult to manipulate the valve if needed.

Diving with redundant air sources offers safer and better options in an emergency, however, there are some issues that should be considered.

1.Plan your dive, dive your plan

First, there is no good reason for running out of air under normal diving conditions. Plan your dive, dive your plan. Use the rule of thirds and calculate a turn pressure that allows you to safely reach your exit point with adequate air pressure remaining. All divers should be in a position to surface with roughly one-third of their remaining gas pressure. Redundant air sources are for emergency use only and should not be used in calculating the depth and duration of your dive. If you need to use your redundant air source, the dive is over, and you’re in bailout mode.

2. Practice using it

Second, if you’re going to dive with a redundant air source, make sure you and your dive buddies are familiar with how to use it, and practice, practice, practice deploying it. Did I mention you should practice deploying, and using, a redundant air source? Ok, good. It is spooky how quickly learning how to deploy a pony becomes second nature. When diving with a pony, for example, I dive with the regulator charged and the valve shut off, to prevent an accidental gas loss. I make sure all my buddies know that if they need to use it, it will only have two or three breaths in the line until I can open the valve. I know some divers that always dive with their pony valves open. It’s not right or wrong, just a preference.

3. Valve shut off

Valve shut down is not a skill generally learned at the recreational level of diving. However, in a situation where a diver is having a catastrophic gas loss, I firmly believe it to be appropriate for the affected valve to be shut down. Shutting down the valve will save the remaining gas in the cylinder, and it could then be used later if needed. This also needs to be planned and practiced, practiced, practiced with buddies. I have had second stage freeflows myself, on occasion, and have assisted several divers with them. The freeflow is almost always caused by second stage icing due to cold water. Once the valve is shut off for a minute or so, the regulator has a chance to thaw, and will function normally again once the valve is turned back on. In my personal preference, I always position the cylinder on my BCD high enough so that I can shut down my own valve. A buddy may also assist with valve shutdown and opening. If the gas in the cylinder is simply allowed to deplete, the diver will lose the ability to power inflate their BCD or drysuit, once they reach the surface. They would then have to remember to orally inflate. This one simple thing could cause an already distressed diver to panic.

In conclusion, diving with redundant air sources allows a diver to mitigate some risk, however, they also come with risks of their own. I believe it is impossible to mitigate one risk without accepting a risk of one sort or another. Every diver must make that decision for themselves.