Decompression sickness

Can drinking wine provide benefits for divers?

Historically, alcohol was used to treat bends in Greek sponge divers. In the late 1980s attempts to verify the possible beneficial effects of ethanol on prevention of DCS led to prevailing opinions that there was no proven benefit and that divers should not drink and dive. On the other hand, the assumption that wine drinking has beneficial effects on general health is still propagated.

wine_shutterstock_85339912The so called “French paradox” fueled a search for possible healthful components in wine that, as some researchers posted, protect French people from heart disease despite their fat rich diet and high blood cholesterol levels. Tannins and phenolics, a large group of substances that together make up to 0.1% of wine mass and determine the color and the taste of wine, were identified as beneficial substances. The most intriguing and studied phenolic is resveratrol which is now also sold as a dietary supplement.

Studies of resveratrol in vitro (on cellular cultures or in various models of biochemical systems) have shown anti-oxidant and other effects that with basic biological processes may provide protection against aging, various diseases and death. Further animal studies appeared to confirm beneficial effects. Some of the suspected mechanisms involving resveratrol included functions of endothelial cells (inner lining of blood vessels) and platelets which are also affected in diving. If resveratrol could prevent endothelial cell dysfunction and platelet aggregation, it may help to avoid decompression sickness. Recent resveratrol studies claimed several additional health benefits that could be appealing to divers.

The first claim is that resveratrol has beneficial effects on
skeletal and cardiac muscle functions similar to what is seen with endurance exercise training.1  Wouldn’t it be nice to work on your fitness by relaxing and sipping wine after a long workday rather than going to the gym and sweating?

The second claim is that resveratrol improves brain perfusion and provides neuroprotection2, both of which may be helpful in reducing risk of decompression sickness. Why not drink wine before or after diving?

Unfortunately, there is only one problem with all these studies; the amount of resveratrolDelicious  portion of  fresh salmon fillet  with aromatic herbs, used is equivalent to drinking 50 to 3000 liters of wine per day. It is far more than is needed to get drunk. It’s enough to dive in. Thus, drinking red wine does not seem to be a practical prophylaxis of decompression sickness.

But don’t despair. Even French Paradox is not due to wine drinking as was believed forty years ago. Most population studies indicate that health and longevity may be associated with overall diet. The benefits of French diets appear to come from plenty of fresh vegetables, moderate caloric intake and physical activity rather than just from wine. The French diet has a lot in common with the so called Mediterranean Diet which is widely considered most favorable. In fact, in 2010 it was acknowledged by UNESCO as an Intangible Cultural Heritage of Humanity. (http://www.unesco.org/culture/ich/en/RL/mediterranean-diet-00884)

This story illustrates a common wisdom that there is no one single dietary supplement that could provide what mortals want. To stay healthy and fit for diving, adopt a healthy diet3 and, if you drink wine, limit yourself to one glass with your meal. More importantly, do not drink before the dive.

For quick orientation about healthy meal check MyPlate

http://health.gov/dietaryguidelines/2015/guidelines/chapter-3/strategies-for-action/#callout-myplate

 

References

  1. Dolinsky VW, Kelvin E. Jones EJ, Robinder S. Sidhu SS, Mark Haykowsky M, Michael P. Czubryt MP, Tessa Gordon T, and Jason Dyck   Improvements in skeletal muscle strength and cardiac function induced by resveratrol during exercise training contribute to enhanced exercise performance in rats. J Physiol 590.11 (2012) pp 2783–2799
  2. Otto MA. Resveratrol improves cerebral perfusion in type 2 diabetes. Clinical Endocrinology News Digital Network. January 17, 2016 http://www.clinicalendocrinologynews.com/specialty-focus/diabetes/single-article-page/wdc-resveratrol-improves-cerebral-perfusion-in-type-2-diabetes/1fe1ba3439a5ae9dc24b003d21793512.html
  3. US Department of Health and Human Services and US Department of Agriculture 2005 – 2020 Dietary Guidelines for Americans. 8th December 2015. Available at health.gov/dietaryguidelines/2015/guidelines/.

Skin Mottling after Diving May Be Result of Brain Lesions Caused by Gas Bubbles

Cutaneous decompression sickness (DCS), or “skin bends,” most often manifests as skin mottling on the torso, upper arms and buttocks to various degrees. An associated marbled look to the skin is sometimes referred to as cutis marmorata. While cutaneous DCS is most likely related to gas occurring in body — after decompression or due to lung barotrauma or some medical procedures — there generally is no accepted explanation how the free gas is related to skin changes.

Possible explanations include the occurrence of gas bubbles in subcutaneous tissues, occlusion of subcutaneous arteries with circulating bubbles bypassing the lung filter (as with a patent foramen ovale), inflammatory reaction bubbles present locally or bubbles causing endothelial injury at remote locations.

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Can a Test Identify Divers Who May Be More Susceptible to DCS?

Are some divers prone — or resistant — to gas bubbles after diving?

Decompression sickness (DCS), which may occur in divers after decompression from a dive, is dependent on the combined dose of gas saturation during the dive and the rate and magnitude of decompression. However, there is a great variability of outcomes in subjects exposed to the same dive profiles. The variability decreases as the severity of exposure increases.

DCS is correlated with the degree of venous gas emboli (VGE), or “bubbles”, in circulation after a dive. Generally, the higher the VGE grade (more bubbles) the greater the probability of DCS, and vice versa. Similar to DCS, there is a great variance in the probability of VGE appearing postdive. Some researchers who practice VGE detection have hinted that some divers bubble after most dives and may exhibit a high bubble grade (HBG) and others tend not to bubble at all or rarely exhibit HBG. The former are often labeled as bubblers (or high bubblers), while the latter are labeled as nonbubblers (or low bubblers).

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Do Viagra and other PDE5 Inhibitors Increase the Risk of DCS in Humans?

Phosphodiesterase type 5 (PDE5) inhibitors — such as Viagra, Cialis, Levitra, Vivanza, Mvix and Lodenafil — are a class of popular drugs prescribed to treat erectile dysfunction and are often sold on the black market as sexual-function enhancers. It is reasonable to assume that many divers use PDE5 inhibitors while on a diving vacation, although the drugs’ possible effects on decompression safety have not been studied previously. In a recent paper, Blatteau et al.1 presented the results of a study on rats treated with sildenafil (Viagra) and then exposed to a simulated dive.

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Bubble Production in Divers Who Have Had DCS

Venous gas embolism (VGE), or bubbles, in divers postdive indicates that their decompression was too fast, their bodies became supersaturated and free gas emerged from solution in tissues. The occurrence of free gas is considered a necessary condition for decompression sickness (DCS), which can happen even without VGE. However, the presence of VGE increases the number and types of possible harms to the body and thus the probability of DCS.

A number of studies indicate variability in proneness to DCS among divers; however, the question of whether divers who have suffered DCS produce bubbles more readily in general has not been answered yet. To answer this question, researchers would need to identify “bubblers” and “nonbubblers” and observe the outcomes of their dives over some period of time, which would require a lot of resources and time.
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Use of Transcriptomes to Study Stress and Acclimation in Diving

Biological organisms maintain their functional integrity in varying environmental conditions through the activity of the innate immune system and controlled inflammation. During scuba diving, divers are exposed to greater than usual environmental changes, which challenges the entire body. The circulatory system is specifically stressed with an elevated partial pressure of oxygen and by decompression-induced gas bubbles on ascent to the surface. When the stress caused by the pressure changes exceeds a certain threshold, a variety of symptoms may occur after return to the surface — this is usually called decompression sickness (DCS).

DCS has been associated with the presence of a free gas phase in blood and tissues but we know little about the biological pathways and processes involved. While involvement of immune and inflammation cells and processes has been indicated previously, measurable changes are rarely present in asymptomatic divers, making it difficult to study the transition of physiological adaptive stress response into maladaptive or pathological reactions leading to loss of organ functions. We have reported in this blog about recent microparticle studies that may potentially shed more light on this gray area.

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