The therapeutic intermittent administration of oxygen in a chamber at greater than sea-level atmospheric pressures (three atmospheres). It is considered effective treatment for air and gas embolisms, smoke inhalation, acute carbon monoxide poisoning, caisson disease, clostridial gangrene, etc. (From Segen, Dictionary of Modern Medicine, 1992). The list of treatment modalities includes stroke.

A type of device used in some areas of medicine that exploits the behavior of gases is hyperbaric chamber treatment. A hyperbaric chamber is a unit that can be sealed and expose a patient to either 100 percent oxygen with increased pressure or a mixture of gases that includes a higher concentration of oxygen than normal atmospheric air, also at a higher partial pressure than the atmosphere. There are two major types of chambers: monoplace and multiplace. Monoplace chambers are typically for one patient, and the staff tending to the patient observes the patient from outside of the chamber (image). Some facilities have special monoplace hyperbaric chambers that allow multiple patients to be treated at once, usually in a sitting or reclining position, to help ease feelings of isolation or claustrophobia. Multiplace chambers are large enough for multiple patients to be treated at one time, and the staff attending these patients is present inside the chamber. In a multiplace chamber, patients are often treated with air via a mask or hood, and the chamber is pressurized.

Hyperbaric chamber treatment is based on the behavior of gases. As you recall, gases move from a region of higher partial pressure to a region of lower partial pressure. In a hyperbaric chamber, the atmospheric pressure is increased, causing a greater amount of oxygen than normal to diffuse into the bloodstream of the patient. Hyperbaric chamber therapy is used to treat a variety of medical problems, such as wound and graft healing, anaerobic bacterial infections, and carbon monoxide poisoning. Exposure to and poisoning by carbon monoxide is difficult to reverse, because hemoglobin’s affinity for carbon monoxide is much stronger than its affinity for oxygen, causing carbon monoxide to replace oxygen in the blood. Hyperbaric chamber therapy can treat carbon monoxide poisoning, because the increased atmospheric pressure causes more oxygen to diffuse into the bloodstream. At this increased pressure and increased concentration of oxygen, carbon monoxide is displaced from hemoglobin. Another example is the treatment of anaerobic bacterial infections, which are created by bacteria that cannot or prefer not to live in the presence of oxygen. An increase in blood and tissue levels of oxygen helps to kill the anaerobic bacteria that are responsible for the infection, as oxygen is toxic to anaerobic bacteria. For wounds and grafts, the chamber stimulates the healing process by increasing energy production needed for repair. Increasing oxygen transport allows cells to ramp up cellular respiration and thus ATP production, the energy needed to build new structures.

Hyperbaric oxygen therapy (HBOT) is well known for treating scuba and deep-sea divers affected by the rapid change in pressure around them. But did you know that HBOT is also used to treat a variety of other health problems, including carbon monoxide poisoning and diabetic foot ulcers?

If you are considering the use of a HBOT device for yourself or a loved one, be aware that some claims of what it can do are unproven. For example, HBOT devices are not proven to cure cancer, Lyme disease, autism or Alzheimer’s disease. The U.S. Food and Drug Administration recommends you check with your health care provider before using a HBOT device to make sure you are pursuing the most appropriate care. If your health care provider recommends HBOT, the FDA advises that you go to a hospital or facility that has been inspected and is properly accredited by the Undersea and Hyperbaric Medical Society.

Hyperbaric oxygen therapy and the FDA’s role

Our body’s tissues need oxygen to function. The air we breathe is 21% oxygen.

HBOT involves breathing 100% (pure) oxygen while in a special space called a hyperbaric chamber. The air pressure inside is raised to a level that is higher than normal air pressure.

The increased air pressure in the chamber helps the lungs collect more oxygen. Getting more oxygen to the tissues that need it can help the body heal and fight certain infections. However, too much oxygen can cause damage to the body.

The FDA regulates both the oxygen used in HBOT and the hyperbaric chambers, which are generally a tube large enough to hold one person or a room that can accommodate more than one person.

Conditions for which hyperbaric chambers are cleared for marketing by the FDA

FDA clearance of a medical device includes a determination that the device has the same intended use as, and is as safe and effective as, another legally U.S.-marketed device of that type. As of July 2021, the FDA has cleared hyperbaric chambers for the following disorders:

• Air and gas bubbles in blood vessels
• Anemia (severe anemia when blood transfusions cannot be used)
• Burns (severe and large burns treated at a specialized burn center)
• Carbon monoxide poisoning
• Crush injury
• Decompression sickness (diving risk)
• Gas gangrene
• Hearing loss (complete hearing loss that occurs suddenly and without any known cause)
• Infection of the skin and bone (severe)
• Radiation injury
• Skin graft flap at risk of tissue death
• Vision loss (when sudden and painless in one eye due to blockage of blood flow)
• Wounds (non-healing, diabetic foot ulcers)

HBOT is being studied for other conditions, including COVID-19. However, at this time, the FDA has not cleared or authorized the use of any HBOT device to treat COVID-19 or any conditions beyond those listed above. The website, clinicaltrials.gov, has more information on HBOT clinical trials for COVID-19 and other conditions.

Risks of hyperbaric oxygen therapy

When HBOT chambers are used for indications cleared by the FDA, HBOT is generally safe, and serious complications are rare.

Because of the increased pressure and increased concentration of the oxygen during HBOT, potential risks include:

• Ear and sinus pain
• Middle ear injuries, including tympanic membrane rupture
• Temporary vision changes
• Lung collapse (rare)

High concentrations of oxygen also pose the risk of fire, which is one reason why the FDA recommends treatment at an accredited facility. Explosions and fires have occurred in HBOT chambers that have not been reviewed by the FDA and are located at unaccredited facilities.

Other hyperbaric devices

The FDA has also cleared a large, zippered bag that is intended to treat altitude sickness only.

These zippered chambers for treating altitude sickness provide pressure but do not attach to oxygen tanks. The FDA has not cleared these bags for use with oxygen tanks or oxygen concentrators. However, the FDA is aware of instances in which people used these bags to create homemade HBOT devices, which can pose the risk of fire and suffocation.