The Bends: Facts & Myths of Decompression Sickness Part 2

In part one of the Bends Facts & Myths, we looked at the history of Decompression Sickness (DCS), as well as signs and symptoms, competing models to explain why it happens, and more. In part 2, we dive deeper into the bends, looking at how treatment works and what happens to you after taking a DCS hit. Also, before you rush to pack up your mask, snorkel, and underwater iPhone case to head off on your next tropical dive adventure, read on to find out the best and most important way to prevent DCS from happening in the first place.

How Does A Recompression Chamber & Therapy work

Recompression chambers are pretty simple machines that are over a century old. They are sealed air-tight chambers where the pressure inside can be increased to a specific depth. Chambers vary in size from small coffin-sized portable ones to much larger affairs with space for multiple patients, medics, and tenders.

As a rule, a diver in need of recompression is placed in a chamber and then taken to the desired depth (determined by the treatment table). Generally, At that point, they will be given pure oxygen to breathe through a mask. Since they are in a dry environment, there is no risk of drowning if they suffer an oxygen seizure, and the mask is simply removed for the event to stop. The patient will then breathe pure oxygen with air brakes for the duration of the session. Typically, chamber sessions last between 2 and 6 hours, although exceptional therapy tables exist that last longer in severe cases.

One of the biggest myths about chambers is that the pressure causes the bubble in the diver's body to go back into solution and then be eliminated through breathing. This is not true. Forcing a bubble back into solution requires significantly more pressure than what is delivered during a chamber therapy session. The pressure in a chamber can make the bubble a little smaller; however, most of the healing effects come from the high-pressure oxygen and flushing out all the inert gas out of the diver's system, including slowly but surely removing gas from the bubble until it disappears.

One thing to remember is that recompression chambers are not just for treating divers with DCS. They are used for a wide range of medical treatments. Chambers sessions have been proven to assist in the healing of wounds and are often used to assist victims with bad injuries to soft tissues. They are also now being used as a cutting-edge treatment for anoxic brain injuries.

What About In Water Recompression?

In-water recompression is one of those subjects whispered about in the dark corners of the diving world. Imagine you are on a dive boat far out from any medical facilities ( a matter of multiple days or even a week or more), and a diver takes a DCS hit; what are your options?

While you can support the diver with oxygen, that ultimately will not cure them. It will slow the decline, but eventually, the diver will suffer the consequences of the DCS hit. that is where the risky process of in-water recompression may be useful. (In fact, there are several well-known published protocols about how to perform in-water recompression). Recompression is never recommended in water but can serve as a last resort with trained diver medics. Since, ultimately, doing something is better than doing nothing.

One thing to remember is that in-water recompression is incredibly risky due to the serious danger posed by an oxygen seizure in the water. However, most protocols call for the diver to be using a full face mask and be attended by at least two other divers at all times during their session. As chamber technology has developed and more and more vessels heading to remote areas for exploration are now equipped with a chamber, the use and importance of in-water recompression have diminished. However, it could get someone out of trouble and save a life in a worst-case scenario!

Once You are Treated for the Bends Everything is Good

One of the biggest misconceptions about DCS is that after taking a hit, you get treated in a chamber and are ready to go again. Sadly, this is far from the truth; only in rare occasions and in the mildest forms of DCS will you walk away totally unscathed after treatment.

When a DCS event occurs in your tissues, it is an injury like any other injury to your body and will generally leave a trace. Take a close look at your knees; you will probably see a very faint scar or two or six, depending on how much of a crazy kid you were in elementary school. While the older you get, the fewer scars are noticeable to almost everyone. You will always know where to find them since they never go away. It is very much the same case with a DCS event; only the scars are on the inside of your body!

This scarring issue is why divers who have taken a DCS hit are more prone to taking another hit in the same area since it is already damaged. In addition, it is also why in some serious cases of DCS, while after extensive treatment in a recompression chamber, a diver may appear completely fine, they will never be able to dive again. Due to the extreme risks of them taking another decompression hit.

This internal scarring is why a lot of older divers may also start to feel aches and dullness after a dive at these scarring spots, which tells them that maybe they are pushing the limits a little too much! This is why it is best to do absolutely everything in your power to prevent a DCS hit from happening in the first place.

The Best Way To Prevent Decompression Sickness

Preventing DCS is impossible; however, you can take multiple steps to substantially reduce the risks of sustaining a decompression event. However, remember you can mitigate and reduce the risk. You can never eliminate it entirely!

Hydration, Hydration and Even More Hydration.

Ask any diving physician based at a tropical warm, sunny destination what the primary cause of DCS is, and the answer will virtually always be the same: Dehydration! The importance of proper hydration in preventing DCS cannot be stressed enough.

When you are dehydrated, you can end up with a substantially reduced volume of fluid in your system. this results in a much lower volume of Blood Plasma, causing your blood to be more “viscose” and reducing the perfusion of your tissues.

The effect of this thicker blood is to throw your entire gas transport system out of balance. You no longer efficiently transport oxygen or eliminate inert gases and carbon dioxide from your tissues. This reduced efficiency essentially makes all your NDL and limits mean nothing since your body no longer fits the typical model.

Staying hydrated can be tricky, especially in a hot tropical climate. The trick to staying hydrated is little and often. Avoid drinking large volumes of water in single hits; drink water continuously throughout the day, giving your body the best chance to absorb and process the fluids. (your body can only process a limited volume per hour). A good rule of thumb lots of divers use to determine if they are hydrated enough is to monitor the color of their urine. It should be colorless to mild straw-colored; anything darker, and you are probably slightly dehydrated.

Hydration is so important that many technical divers, including the author of this article, will refrain from consuming diuretics (alcohol, coke, coffee, and others) for at least 24-48 hours before conducting deep technical dives. Proper hydration is the first step in setting yourself up for success and avoiding DCS when diving!

Physical Fitness and Conditioning

Arguably the second most important way to try and preventing a DCS event is through being in good shape. Being in good shape generally means you have a lower body fat percentage than average, and you will generally have improved circulation and oxygen transport. Both of these are important factors in preventing DCS.

There is a direct correlation between the percentage of body fat and the incidence of DCS. Divers carrying more body fat are more likely to suffer a DCS hit. Therefore, any steps you take to reduce your body fat percentage (not your weight) will help reduce your risk of suffering a DCS hit.

Similarly, having a circulatory system tuned through exercise and which is more efficient at transporting oxygen around your body, means it is also more efficient at removing inert gasses and carbon dioxide. This increased gas transport efficiency also reduces your chances of getting the bends on dive!

Dive Conservatively To Avoid the Bends

Diving conservatively will go a long way toward preventing you from getting the bends. Aside from keeping your depth shallow, avoid long dives close to No Decompression limits—or heavy repetitive diving over several days. Dive within your physical limits and be aware of your body. Don't push the limit if you have a deep dive scheduled and wake up not feeling 100%. Instead, opt for a day off or a very easy shallow dive.

In addition, you want to keep your profiles clean. Avoid sawtooth profiles and make very slow, gradual ascents- the slower, the better. Finally, remember that every dive should end with a safety stop at 5m/15ft for 3 minutes. The safety stop acts as a quasi-deco stop allowing you to off gas a little more while you are still in the water. Developing a safe, conservative approach to diving is key to a long and fun diving journey!

Final Thoughts

Decompression is complex, and understanding it requires years of study and practice. Thankfully most divers do not need to have in-depth knowledge. Instead, divers need to have a safe working knowledge of the best practices, and which procedures and protocols to follow, and which to avoid. Arguably the best advice is to dive conservatively, stay fit and drink plenty of water, and most recreational divers should be okay!