Hyperbaric oxygen therapy (HBOT) is the medical use of oxygen at a higher than atmospheric pressure.
The therapeutic principle of HBOT lies in a drastically increased partial pressure of oxygen in the tissues of the body. While under normobaric conditions (i.e. under atmospheric pressure), oxygen transport is limited by the oxygen binding capacity of red blood cells, HBOT makes use of oxygen transport by blood plasma. The increased overall pressure is of therapeutic value when HBOT is used in the treatment of decompression sickness.
The main indications (some controversial) for HBOT are:
- Carbon monoxide poisoning
- Decompression sickness
- Severe infection by anaerobic bacteria (such as gas gangrene)
- Air or gas embolism
- Enhancement of healing in problem wounds
- Severe uncorrected anemia
HBOT is usually done in a "hard shelled" pressurized chamber. Such chambers can be run at various levels of pressure. Pressure is measured in ATA (atmospheres absolute) which corresponds to the number of "atmospheres" of pressure. We normally exist at 1 ATA. There are also soft sided HBOT chambers, which are often used for home treatment. (Some of these are also used in clinics.) These are usually referred to as "mild chambers", which is a reference to the lower ATA capacity of soft sided chambers. (The ones commercially available in the USA go up to 1.3 ATA only.)
Some hospitals have HBOT chambers. There are also HBOT chambers that run at stand-alone facilities. The application of HBOT requires a prescription (in the USA).
HBOT is quite expensive, with a session costing $100 to $200 in the USA. In the UK there is are non-profit HBOT chambers, which are run by the Multiple Sclerosis society.
HBOT is often done in a series of 40 treatments, but not always.
In Canada and the United States, the U.S. Navy Dive Charts are used to determine the configuration of therapy for a given ATA pressure.
Slang for pressurization inside the HBO chamber is "a dive"; as in, "The patient will be going for 40 dives."
There are risks associated with HBOT, mostly having to do with the changes in pressure and oxygen toxicity. Pressure changes can cause a 'squeeze' in any area of trapped air inside the body, such as behind the eardrum, inside sinuses, or even trapped underneath fillings. One of the more common side-effects of oxygen toxicity is a seizure.