There are several reasons why medical experts do not recommend putting recreational divers with DCS back into the water to recompress.
In spite of that, this guide explains why the technique of recompressing a diver underwater actually takes place in certain areas of the world.
It's a controversial topic, but the emergency use of underwater oxygen treatment for decompression sickness is accepted in some countries.
In general, returning a diver underwater for recompression therapy can work because it helps to resolve the gas bubbles in the tissues.
So, why do most hyperbaric experts boycott the widespread use of this critical life-saving practice?
Well, to avoid being listed in diving accident case reports, management of DCS requires a significant amount of equipment and training.
Plus, anyone untrained in the diagnosis of decompression sickness runs the risk of complicating the situation further. In fact, recompression therapy (no matter whether in a chamber or in water) comes with no guarantee of a successful outcome - even when the conditions are ideal.
The main concern with in-water recompression protocol (IWR) is that victims might exit in a worse condition, due to (any or all):
Yet, the technique of IWR has saved the lives of scuba divers for many years. This is especially so in areas with no emergency action plan to follow and in remote areas where hyperbaric facilities are some distance away.
The scuba diving death rate is low when you compare it to some other sports. Even so, most medical professionals will present strong arguments against recompressing divers in water - and few will be in favour of the technique.
Those in favour see it as an alternative to chamber recompression in remote scuba diving locations. In areas such as these, there is no hyperbaric chamber nearby - nor adequate means of transporting patients suffering from the most common diving injuries to a facility elsewhere.
Taking the diver with suspected DCS back underwater is the first part of this technique.
As a result, there will have been no time (nor adequate medical facility) to have conducted the DAN neurological assessment.
The initial basis for returning an injured diver back below the surface is to drive inert gas bubbles back into solution (usually nitrogen).
Driving gas bubbles back into solution helps to reduce decompression sickness symptoms, such as extreme fatigue and weakness.
Next, the bent diver needs to make a slow ascent back to the surface while decompressing. The aim is to achieve an orderly elimination of the excess gas.
Here's the thing:
The in-water recompression technique is a relatively simple in concept. But, for it to be a practical solution for DCS injury, the procedure needs all of the following:
Thus, unless there is a positive outcome, unsuccessful attempts at treating DCS symptoms in water can result in a patient ending up in a worse condition than if there was no attempt made at all.
At the time of writing, a clearcut division between the medical and research communities still exists about the pros and cons of carrying out in-water recompression. There are several key reasons why critical challenges may arise, including:
For the sake of clarity, anyone responding to serious scuba diving injuries should be following the generalised rules and should be providing the best help they can.
In most cases, you should remove any diver who develops symptoms consistent with the bends underwater diving hazard (DCS).
You should also attempt to deliver appropriate first aid techniques at the surface. This applies even in situations where definitive medical care may be unavailable or delayed.
Many years ago, doctors used the U.S. Navy treatment tables to treat divers in chambers. At that time, the diver would be breathing a standard air mixture - instead of pure oxygen.
For one reason or another, they had a high failure rate. Thus, using normal air for in-water recompression is also likely to have similar outcomes.
However, there are documented cases of a successful outcome when an injured diver was breathing oxygen during the underwater recompression procedures (returning to an environment of increased pressure).
As a general rule, recompression takes place in a hyperbaric treatment chamber. This kind of facility is used to treat divers who may be suffering from scuba diving disorders and maladies that may respond to oxygen therapy.
The treatment in this type of chamber simulates a higher ambient pressure. In turn, it recompresses gas bubbles (nitrogen).
A slow decrease in pressure has the same effect of making a very slow ascent, allowing for the tissues to degas the nitrogen. At the same time, there will be an increase in the partial pressure of oxygen (pO2) in the body tissues.
Placing a glass of water inside this kind of chamber will help to show how in-water recompression works. So, if you decrease the pressure surrounding the water, the amount of gas dissolved in the water will also decrease.
The short video presented by DAN explains more about the framework that medical staff use to manage decompression sickness cases in remote locations.
Disclaimer: Almost all of the scuba diving articles contained in this website are from personal experiences. But, situations involving the remote management of DCS is not one of them. In most cases, the resources needed to conduct successful in-water recompression exceed the ability of most recreational divers. Moreover, Divers Alert Network (DAN) does not recommend that symptomatic divers be recompressed while breathing standard air in the water. In some areas of the world, divers are treated with in-water recompression because of a lack of chamber facilities.