Making Sense of Hyperbaric Chambers

Although hopefully you’ll never need to use one, here we’ll explain exactly what hyperbaric chambers are and how they work.

We’ve all heard the words “in the unlikely event of an accident,” during a dive briefing and seldom give it a second thought. We don’t typically consider an unplanned trip to a recompression chamber when planning a dive vacation. And although hopefully you’ll never have to use one, here we’ll offer some information on hyperbaric chambers, how they work and what to expect if an unexpected event occurs.

Hyperbaric chambers – what exactly are they?

Hyperbaric chambers are tiny rooms — capsules, really. They’re large enough to hold two or more people at a time depending on the facility. The chamber is sealed while the pressure inside the chamber as well as the oxygen content slowly increases. It’s possible to attain and keep different ambient pressures inside the chamber to simulate the body’s experience at depth.

As we know, when we’re underwater the higher ambient pressure means our body tissues are absorbing more nitrogen. Upon surfacing, the pressure around a diver’s body decreases drastically, which leads to the evacuation of the absorbed nitrogen.  While other factors can put divers at higher risk of getting decompression illness, it usually happens when a diver either stays too deep for too long (absorbing more nitrogen) or ascends too quickly (resulting in an accelerated release of nitrogen). When nitrogen moves out of a diver’s cells too quickly it forms expanding bubbles. This can lead to DCI symptoms and likely a trip to a hyperbaric chamber.

The chamber works by simulating a higher ambient pressure, which recompresses the nitrogen bubbles. The pressure slowly decreases, simulating a very slow ascent, which allows a diver’s tissues to slow degas the nitrogen. Simultaneously, the partial pressure of oxygen in the body tissues increases. This is called hyperbaric oxygen therapy, wherein a higher blood-oxygen content speeds the healing of body cells. Basically, the body heals more efficiently when exposed to higher concentrations of oxygen.

Decompression chambers vs. recompression chambers

We can categorize hyperbaric chambers into two types in relation to scuba divers: decompression chambers and recompression chambers. Recompression chambers treat DCI in scuba divers, as well as preventing it in certain cases.

We use decompression chambers for surface-supplied divers, usually commercial divers who spend lots of time underwater. The chamber allows the divers to decompress out of the water instead of making long decompression stops while submerged. Decompression chambers can be either in the water or, more commonly, on land.

So, where is the closest chamber?

Ask the staff at the dive center in your destination and it’s not uncommon to hear that the closest hyperbaric chamber is at least a couple of hours’ flight away. Regardless, it’s important to make sure you know the location of the closest hyperbaric chamber. You should know approximately how long it would take to get there, and whether there is ample emergency oxygen for the trip.

Speaking to the dive center about their emergency plans will not only prepare you in the unfortunate event of a dive emergency but will also give you some insight into their safety procedures.

I have to go to a chamber — now what?

Amir Hadanny from the Sagol Center for Hyperbaric Medicine and Research and his colleagues found that between 76 and 78 percent of patients who were treated for DCI in a hyperbaric chamber recovered fully. Late recompression (48 hours or longer after the accident occurred) showed to be nearly as effective as immediate treatment, especially if the treatment was based on the U.S. Navy Table 6. However, timely treatment of DCI is vital to decrease the size of the nitrogen bubbles and avoid any additional injury.

Treatment takes at least a few hours. If the chamber is using the U.S. Navy Table 6, patients will be compressed to a depth of 59 feet (18 m) while breathing oxygen, then slowly decompressed to 29 feet (9 m), eventually reaching surface pressure. This procedure usually takes around 4 hours and 45 minutes.

Treatment might span a number of days with the longest session on the first day. Treatment will continue until the patient reaches a ‘treatment plateau’ and shows no symptoms between treatments.

Once treatment ends, the medical professional will advise the diver on when s/he can dive again. Divers should make sure to get medical clearance before returning to the water.

The importance of dive insurance

The cost of hyperbaric treatment including hospital bills, doctors’ fees and transportation to the facility (often with a helicopter) can easily reach tens of thousands of dollars. Having good dive insurance, such as DAN, is absolutely vital. Dive insurance companies offer a variety of plans. These range from cover for a few days to yearly and even lifetime coverage. It is definitely worth investing in comprehensive dive emergency coverage for your next dive trip.

According to DAN, injuries sustained by the accumulation of a number of small bubbles can cause as much damage as a car accident. If you suspect that you have DCI, do not delay treatment. Start breathing 100 percent oxygen and contact your medical professional or dive-insurance company immediately to assist a speedy transfer to the nearest hyperbaric chamber. Cutting your holiday short is a small price to pay for a continued lifetime of diving.