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Drinking and Diving - Waiting for the bubbles to settle

What could be better than enjoying an ice-cold beer as we relax after a dive? It seems to be fairly common practice, but what exactly are the risks and how exactly does alcohol impact diving?

sunset diving
It's lovely to have a beer after diving at sunset like here @purpledive but make sure you don't overdo it!

In this post we will look at the health implications that come with that ‘deco beer’, why and how alcohol interacts with diving and when we can have that beer!

Why is alcohol dangerous and what happens to our bodies when we drink?

Alcohol is a ‘depressant’ drug. Its effects are seen on almost every system in our bodies. In the central nervous system, alcohol interferes with the pathways in the brain, disrupting behaviour and coordination. In the circulatory system, the short-term effect of alcohol raises blood pressure and pulse rate and in the long term can increase the risk of arrhythmias, cardiovascular disease and heart attack. In the gastrointestinal and endocrine systems, alcohol can cause liver damage and the pancreas to produce toxic substances. Alcohol has also been seen to weaken our immune system and increase the risk of a variety of cancers.

One tequila, two tequila three tequila... floor!?

The more we drink, the more alcohol is absorbed in the bloodstream and the more symptoms will appear. According to research;

  • After 1 or 2 units, blood vessels expand and heart rate increases.

  • After another couple of units, we see the effect on the brain as judgement and decision-making become affected. We feel uninhibited, coordination decreases, and balance and memory can be affected.

  • A few more units and reaction times will be significantly slower, and slurring of the speech begins.

  • Any more alcohol and the depressant effect will make you feel drowsy, with highly impaired coordination.

“Don’t break the seal!” You may be familiar with and have experienced this well-known phrase. As soon as you start drinking, the effect seems to reach your bladder very quickly. This (over)reaction is our body's attempt to rid the toxic drug from our system. In addition to this, alcohol blocks the production of the Antidiuretic Hormone (ADH), which is the hormone our bodies release to stop us from peeing too much. With the signal disrupted, our body carries on producing urine, and we become dehydrated.

Why can diving be dangerous after drinking alcohol?

DCS (Decompression Sickness)– Nitrogen, because it is an inert gas, becomes more soluble in the blood. As we dive, nitrogen gas accumulates in the blood and tissues, which upon surfacing, must come back out of solution. The risk here is that if the pressure drops too fast, the gas comes out of solution too fast and creates harmful bubbles in our blood and tissues. This is known as decompression sickness and can potentially be fatal.

The effect of these bubbles can vary, in the most severe case they can make their way to the brain causing a stroke or the heart causing a heart attack, in the less severe cases bubbles become present in our tissues and skin. Some of the signs and symptoms of DCS can be; pain/tingling in the joints, numbness or paralysis, skin itch and altered mental state/confusion. The symptoms can have a delayed onset and can occur between 15 minutes and 12 hours after a dive.

Nitrogen NarcosisAnother problematic factor that can occur when breathing this inert gas at pressure, is that it can have a narcotic effect on the brain and disrupt neuromuscular function. The pathophysiology of this is not fully understood because the Nitrogen atoms inhaled at pressure are chemically unchanged, however, there is a theory that states that at pressure, absorption of the Nitrogen in the lipid part of the cell can produce a narcotic effect.

The signs and symptoms of Nitrogen Narcosis are mental confusion, delayed reaction times and impaired judgement; very similar to alcohol intoxication. The danger here is that Nitrogen Narcosis can affect a diver's judgement and decision-making, allowing them to take risks they wouldn't normally take; again much like being drunk! The effects of Nitrogen Narcosis are fast to develop and quickly reversible, disappearing by adjusting depth.

Dehydration – Dehydration is a lesser talked about risk of diving but nonetheless just as serious. Dehydration reduces blood volume and perfusion to the tissues. The air we breathe when we dive is very dry and our bodies have to compensate for this and humidify the air itself. Additionally, there is a phenomenon that occurs called immersion diuresis; Immersion in water causes peripheral blood vessels to constrict and a fluid shift, sending the blood volume away from the peripheries and to the major organs. Our bodies interpret this shift as fluid overload and in an attempt to correct it, production of the antidiuretic hormone is stopped, thus making us urinate more and lose fluid.

When should I stop drinking before diving?

Being intoxicated while diving is an absolute no-no! But when can we go for a dive after having had a drink? Well, the rate of absorption, elimination and effect of alcohol varies from person to person depending on factors like height, weight, genetics and more. As well as circumstances like food intake, hydration, fatigue, and illness.

There are many ways to test the presence of alcohol in our bodies; through urine, blood and saliva to name a few, each eliminating alcohol at a different rate. Alcohol is broken down in the liver and you cannot speed up the elimination of alcohol; for example, having a cold shower or drinking a coffee can make you feel more alert but will not affect the amount of alcohol in your system. Alcohol has a half-life of around 4 hours and it can take between 7 and 12 hours for alcohol to leave the system, depending on what you are testing and the amount induced. The general rule is to leave 8 hours before activities like driving, which makes it good advice for diving. However, it's important to remember that the effects of alcohol consumption, such as dehydration will remain.

When can I have a drink after diving?

After a dive, we are still ‘bubbling’. Even if we dive safely, staying within our limits and following our dive computer, we will always have Nitrogen circulating in our blood and tissues after a dive. The bubbles are very small and tend to have no adverse effects, they are called silent bubbles or asymptomatic bubbles. Our bodies have to ‘off-gas’ these bubbles, which can take time. Given that it is standard practice to leave 60 minutes between dives to allow for this off-gassing, it would be fair to assume the minimum amount of time before having alcohol should be at least that long. According to decompression theory, this off-gassing (depending on dive profiles, and length of time exposed to Nitrogen), takes up to 12-24 hours before the process is complete and we return to normal.

diving  Nusa Penida
Make sure you drink plenty of water, especially if you had a couple of beers the night before.

What steps can I take to reduce risks?

It is clear to see that drinking alcohol and breathing gas under pressure cause similar effects in our bodies which when combined could exaggerate and amplify symptoms. So how can we reduce risks if you did want to have a deco beer after your next dive?

-Stay hydrated! Both alcohol and diving cause dehydration and block the Anti Diuretic Hormone, so super important to hydrate! Drink plenty of water before, between and after dives.

-Allow time for off-gassing. The longer you wait before drinking alcohol the better, at the very least 60 mins.

-Don’t overdo it. Only have one or two drinks if you are diving the next day or if you have just been diving. It would be very unwise to plan a serious session the day before or the day after a dive!

-Dive conservatively! Listen to your body and dive well within your limits. Ascend slowly, complete a safety stop and of course, always follow your computer!


National Library of Medicine

National Institute on Alcohol Abuse and Alcoholism



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