Hyperbaric medicine is the branch of medicine in which clinical therapies are delivered in pressurized vessels containing prescribed barometric pressures of gases such as air or oxygen. The immediate effects include reducing the size of gas emboli and raising the partial pressures of the gases present. Initial uses were in decompression sickness, and it is also effective in certain cases of gas gangrene and carbon monoxide poisoning. There are risks associated with hyperbaric therapy, including barotrauma, and, if pure oxygen is used, a fire hazard. Hyperbaric oxygen therapy (HBOT) is the medical use of greater than 99% oxygen at an ambient pressure higher than atmospheric pressure, and therapeutic recompression. The equipment required consists of a pressure vessel for human occupancy (hyperbaric chamber), which may be of rigid or flexible construction, and a means of a controlled atmosphere supply. Treatment gas may be the ambient chamber gas, or delivered via a built-in breathing system. Operation is performed to a predetermined schedule by personnel who may adjust the schedule as required. Hyperbaric air (HBA) consists of compressed atmospheric air (79% nitrogen, 21% oxygen, and minor gases) and is used for acute mountain sickness. This is applied by placing the person in a portable hyperbaric air chamber and inflating that chamber up to 14–28 kilopascals (2–4 psi) using a foot-operated or electric air pump. Chambers used in the US made for hyperbaric medicine fall under the jurisdiction of the Federal Food and Drug Administration (FDA). The FDA requires hyperbaric chambers to comply with the American Society of Mechanical Engineers PVHO Codes and the National Fire Protection Association Standard 99, Health Care Facilities Code. Similar conditions apply in most other countries. Other uses include arterial gas embolism caused by pulmonary barotrauma of ascent. In emergencies divers may sometimes be treated by in-water recompression (when a chamber is not available) if suitable diving equipment (to reasonably secure the airway) is available.
Scope Hyperbaric medicine includes hyperbaric oxygen treatment, which is the medical use of oxygen at greater than atmospheric pressure to increase the availability of oxygen in the body; and therapeutic recompression, which involves increasing the ambient pressure on a person, usually a diver, to treat decompression sickness or an air embolism by reducing the volume and more rapidly eliminating bubbles that have formed within the body.
Medical uses The Undersea and Hyperbaric Medical Society (UHMS) lists 15 supported uses as of 2025:
Air or gas embolism; Carbon monoxide poisoning including that complicated by cyanide poisoning; Clostridal myositis and myonecrosis (gas gangrene); Crush injury, compartment syndrome, and other acute traumatic ischemias; Decompression sickness; Central retinal artery occlusion and enhancement of healing in selected problem wounds due to insufficient arterial blood flow, including the diabetic foot; Exceptional blood loss (anemia); Intracranial abscess; Necrotizing soft tissue infections (necrotizing fasciitis); Osteomyelitis (refractory); Delayed radiation injury (soft tissue and bony necrosis); Skin grafts and flaps (compromised); Thermal burns (early); Idiopathic sudden sensorineural hearing loss; Avascular necrosis These uses are similar to those approved by the US FDA as of 2021. Mucormycosis, especially rhinocerebral disease in the setting of diabetes mellitus may be supported. Treatment efficacy of HBOT for most of these conditions is based on testing at 2-3 bar (atmospheres of pressure), but it is also marketed at lower pressures (and lower costs) despite lack of evidence of efficacy. There is insufficient evidence for use in autism, cancer, diabetes, HIV/AIDS, Alzheimer's, asthma, Bell's palsy, cerebral palsy, depression, heart disease, migraines, multiple sclerosis, Parkinson's, spinal cord injury, sports injuries, or stroke. Furthermore, potential side effects pose an unjustified risk in such cases. A 2016 meta-analysis found no evidence of improvements in social abilities or cognitive functioning in autistic individuals treated with HBOT. The paper also noted conducting further trials would be ethically fraught, as studies had not revealed efficacy, but documented that HBOT can cause minor-grade ear barotrauma events. Despite the lack of evidence of benefit, in 2015, the number of people utilizing this therapy has continued to rise. There is also insufficient evidence to support its use in acute traumatic or surgical wounds.
Hearing There is limited evidence for sudden sensorineural hearing loss within two weeks of onset. It might improve tinnitus presenting in the same time frame.
Chronic ulcers HBOT in diabetic foot ulcers increased the rate of early ulcer healing but does not appear to provide any benefit in wound healing at long-term follow-up. In particular, there was no difference in major amputation rate. For venous, arterial and pressure ulcers, no evidence was apparent that HBOT provides a long-term improvement over standard treatment.
Radiation injury There is some evidence that HBOT is effective for late radiation tissue injury of bone and soft tissues of the head and neck. Some people with radiation injuries of the head, neck or bowel show an improvement in quality of life. Importantly, no such effect has been found in neurological tissues. The use of HBOT may be justified to selected patients and tissues, but further research is required to establish the best people to treat and timing of any HBO therapy.
Neuro-rehabilitation As of 2012, there was insufficient evidence to support use in traumatic brain injuries. In acute stroke, HBOT does not show benefit. HBOT in multiple sclerosis has not shown benefit and routine use is not recommended. A 2007 review in cerebral palsy found no difference compared to the control group. Neuropsychological tests also showed no difference between HBOT and room air and based on caregiver report, those who received room air had significantly better mobility and social functioning. Children experienced seizures and the need for tympanostomy tubes to equalize ear pressure, though the rates was not clear.
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