A hyperbaric chamber, also known as a decompression or recompression chamber, is a sealed chamber in which a patient breathes oxygen at pressures far greater than the normal atmospheric pressure. A hyperbaric chamber is commonly used to treat decompression illness, a condition that may occur when a diver ascends too quickly and, as a result, suffers damages from insufficient pressure compensation. But how does it work?
Why Is Hyperbaric Oxygen Therapy Used for Treating Divers?
When people dive underwater, the increased pressure causes the tissues to absorb more oxygen and nitrogen than usual. While most of the oxygen gets consumed by the tissues, the nitrogen remains dissolved. When nitrogen bubbles from the system, they block the blood vessel and cause a condition known as decompression sickness, or the bends. Common signs of decompression sickness involve joint pain, tingling or numbness in extremities, nausea, headache, and fatigue. Most symptoms start in the first minutes to 12 hours after surfacing, but it could also take a couple of days for them to appear.
The best way to avoid decompression sickness is to adhere to the no decompression limits and bottom times provided by dive tables or dive computers. If a diver violates the no decompression limits, they will need to stay underwater longer and undergo decompression stops to allow the nitrogen to be released from the system slowly. In the unfortunate event that decompression sickness does occur, a patient showing symptoms of the bends will need to be taken to a hyperbaric chamber to be decompressed under emergency medical conditions.
Types of Hyperbaric Chambers
Monoplace Hyperbaric Chambers
Designed to treat one patient at a time, usually in a reclining position, monoplace hyperbaric chambers are clear tubes pressurized with 100% medical grade oxygen. Some monoplace chambers have masks available to provide other types of breathing gas (such as air). A trained hyperbaric technician monitors the patient from outside the chamber throughout the duration of the treatment.
Multiplace Hyperbaric Chambers
Designed to treat multiple patients at the same time, a multiplace hyperbaric chamber also has a hyperbaric technician accompanying the patients inside to monitor them directly or to perform different procedures compatible with high atmospheric pressure. Patients breathe 100% medical grade oxygen via a mask or close-fitting plastic hood. Different mixtures of gas (nitrogen or helium mixtures) can also be given to the patient via a mask.
Soft Hyperbaric Chambers
These mild hyperbaric chambers are made of polyurethane or canvas material and can only compress room air, which contains only 21% oxygen as opposed to the 100% medical grade oxygen used in the hard hyperbaric chambers. Since the FDA does not recognize soft chambers as a medical device for hyperbaric oxygen treatment, they are usually not found in any reputable hospital or medical office. They may sometimes be used during transport to a definitive medical facility.
How Does Hyperbaric Chamber Treatment Work?
Because it is so effective in treating decompression sickness, hyperbaric oxygen treatment has become the definitive treatment for pressure-related diving wounds such as decompression sickness and arterial gas embolism. The hyperbaric chamber treatment serves the purpose of eliminating the nitrogen bubbles from the blood and encourage the cells of the body to repair themselves. Patients are locked in a pressurized environment where they receive extra oxygen. The increased pressure reduces the size of the gas bubbles and the oxygen helps with their evacuation.
The hyperbaric chamber treatment includes three stages:
- Pressurization. The pressure is slowly increased, which may also slightly increase the temperature inside the chamber. Patients will be asked to clear their ears to relieve the sense of fullness in the ears. Pressurization takes typically takes 10-15 minutes.
- Treatment. Once the pressure is taken to the optimal level, the patients will continue to receive 100% oxygen for up to two hours.
- Decompression. After receiving the treatment, the pressure inside the hyperbaric chamber is gradually reduced to normal levels and the temperature may decrease.
Studies show that, on divers suffering from neurological decompression illness, hyperbaric oxygen therapy is more effective when it is received sooner rather than later. There is evidence to support the claim that in order to receive the optimal effect of hyperbaric chamber treatment, a diver with decompression illness should receive treatment within six hours after surfacing from the incident dive.
The treatment is painless; the patient simply lies on the bed or takes a seat and catches up on some rest. Some patients experience a level of discomfort during the pressurization stage because of the increased air pressure on their eardrums. Nonetheless, there are ways to relieve this ear pressure. There may also be some slight discomfort due to the change in temperature.
It is also worth noting that hyperbaric oxygen therapy is not for everyone. People who have recently undergone ear surgery or ear trauma, or have suffered from a cold or fever may not be offered this treatment. There are several other contraindications, including people with an increased risk of hemorrhage, chest surgery, optic neuritis, lung diseases, but also pregnant women.
The number of treatments one requires depends on the body’s response to therapy. The patients are initially put under pressure for several hours after which they need to come back over several days for a series of sessions. During this period, it is forbidden for patients to fly or dive.
Remember to always check that your dive insurance covers hyperbaric therapy in case you need it, because it can get pricey. However, it is wiser to follow the guidelines and always dive safely so that you never need to use a hyperbaric chamber in the first place.