Hubbry Logo
Hyperbaric medicineHyperbaric medicineMain
Open search
Hyperbaric medicine
Community hub
Hyperbaric medicine
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Hyperbaric medicine
Hyperbaric medicine
Hyperbaric medicine
View on Wikipedia
from Wikipedia
Hyperbaric medicine
A Sechrist Monoplace hyperbaric oxygen chamber at the Moose Jaw Union Hospital, Saskatchewan, Canada
SpecialtyDiving medicine, emergency medicine, neurology, infectious diseases
ICD-9-CM93.95
MeSHD006931
OPS-301 code8-721
MedlinePlus002375

Hyperbaric medicine is medical treatment in which an increase in barometric pressure of typically air or oxygen is used. 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 also effective in certain cases of gas gangrene and carbon monoxide poisoning. There are potential hazards. Injury can occur at pressures as low as 2 psig (13.8 kPa) if a person is rapidly decompressed.[1][2] If oxygen is used in the hyperbaric therapy, this can increase the 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 7.35 psi gauge (0.5 atmospheres above local ambient pressure) using a foot-operated or electric air pump.[3][4][5]

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[6] and the National Fire Protection Association Standard 99, Health Care Facilities Code.[7] 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

[edit]

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;[8] 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.[9]

Medical uses

[edit]

The Undersea and Hyperbaric Medical Society (UHMS) lists 15 supported uses as of 2025:[10]

  1. Air or gas embolism;
  2. Carbon monoxide poisoning including that complicated by cyanide poisoning;
  3. Clostridal myositis and myonecrosis (gas gangrene);
  4. Crush injury, compartment syndrome, and other acute traumatic ischemias;
  5. Decompression sickness;
  6. Central retinal artery occlusion and enhancement of healing in selected problem wounds due to insufficient arterial blood flow, including the diabetic foot;
  7. Exceptional blood loss (anemia);
  8. Intracranial abscess;
  9. Necrotizing soft tissue infections (necrotizing fasciitis);
  10. Osteomyelitis (refractory);
  11. Delayed radiation injury (soft tissue and bony necrosis);
  12. Skin grafts and flaps (compromised);
  13. Thermal burns (early);
  14. Idiopathic sudden sensorineural hearing loss;
  15. Avascular necrosis

These uses are similar to those approved by the US FDA as of 2021.[11]

Mucormycosis, especially rhinocerebral disease in the setting of diabetes mellitus may be supported.[12]

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.[13][14][15] Furthermore, potential side effects pose an unjustified risk in such cases. A Cochrane review in 2016 of autism spectrum found no links to improvements in social abilities or cognitive function. There are also ethical issues with further trials, as the eardrum can be damaged during hyperbaric therapy.[16] Despite the lack of evidence, in 2015, the number of people utilizing this therapy has continued to rise.[17] There is also insufficient evidence to support its use in acute traumatic or surgical wounds.[18]

Hearing

[edit]

There is limited evidence for sudden sensorineural hearing loss within two weeks of onset. It might improve tinnitus presenting in the same time frame.[19]

Chronic ulcers

[edit]

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.[20] For venous, arterial and pressure ulcers, no evidence was apparent that HBOT provides a long-term improvement over standard treatment.[21]

Radiation injury

[edit]

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.[22]

Neuro-rehabilitation

[edit]

As of 2012, there was insufficient evidence to support use in traumatic brain injuries.[23] In acute stroke, HBOT does not show benefit.[24][15]

HBOT in multiple sclerosis has not shown benefit and routine use is not recommended.[14][25]

A 2007 review in cerebral palsy found no difference compared to the control group.[26][27] 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.[26][27] Children experienced seizures and the need for tympanostomy tubes to equalize ear pressure, though the rates was not clear.[26]

Cancer

[edit]

In alternative medicine, hyperbaric medicine has been promoted for cancer. However, a 2011 study by the American Cancer Society reported no evidence it is effective for this purpose.[28] A 2012 review article found "there is no evidence indicating that HBO neither acts as a stimulator of tumor growth nor as an enhancer of recurrence. On the other hand, there is evidence that implies that HBO might have tumor-inhibitory effects in certain cancer subtypes, and we thus strongly believe that we need to expand our knowledge on the effect and the mechanisms behind tumor oxygenation."[29]

Migraines

[edit]

Low-quality evidence suggests it may reduce pain in an ongoing migraine headache.[30] It is not known which people would benefit from this treatment, and there is no evidence that it prevents future migraines.[30]

Side effects

[edit]

Oxygen toxicity is a limitation on both maximum partial pressure of oxygen, and on length of each treatment.

HBOT can accelerate the development of cataracts over multiple repetitive treatments, and can cause temporary relative myopia over the shorter term.[31]

A 2023 review found that negative outcomes (predominantly mild barotrauma (air pressure effect on ear or lung) that could be resolved spontaneously) were experienced by 24% of patients, but they were not prevented from completing the treatment regimen, and no serious side effects, complications or deaths were reported.[32]

Complications

[edit]

There are risks associated with HBOT, similar to some diving disorders. Pressure changes can cause a "squeeze" or barotrauma in the tissues surrounding trapped air inside the body, such as the lungs,[33] behind the eardrum,[34][35] inside paranasal sinuses,[34] or trapped underneath dental fillings.[36] Breathing high-pressure oxygen may cause oxygen toxicity.[37] Temporarily blurred vision can be caused by swelling of the lens, which usually resolves in two to four weeks.[38][39]

There are reports that cataracts may progress following HBOT,[40] and rarely, may develop de novo, but this may be unrecognized and under reported. The cause is not fully explained, but evidence suggests that lifetime exposure of the lens to high partial pressure oxygen may be a major factor. Oxidative damage to lens proteins is thought to be responsible. This may be an end-stage of the relatively well documented myopic shift detected in most hyperbaric patients after a course of multiple treatments.[citation needed]

Ears

[edit]

People have ear discomfort as a pressure difference develops between their middle ear and the chamber atmosphere.[41] This can be relieved by ear clearing using the Valsalva maneuver or other techniques. Continued increase of pressure without equalizing may cause ear drums to rupture, resulting in severe pain. As the pressure in the chamber increases further, the air may become warm.

To reduce the pressure, a valve is opened to allow air out of the chamber. As the pressure falls, the patient's ears may "squeak" as the pressure inside the ear equalizes with the chamber. The temperature in the chamber will fall. The speed of pressurization and de-pressurization can be adjusted to each patient's needs.

Contraindications

[edit]

The toxicology of the treatment has been reviewed by Ustundag et al.[42] and its risk management is discussed by Christian R. Mortensen, in light of the fact that most hyperbaric facilities are managed by departments of anaesthesiology and some of their patients are critically ill.[43]

An absolute contraindication to hyperbaric oxygen therapy is untreated pneumothorax.[44] The reason is concern that it can progress to tension pneumothorax, especially during the decompression phase of therapy, although treatment on oxygen-based tables may avoid that progression.[33] The COPD patient with a large bleb represents a relative contraindication for similar reasons.[45][page needed] Also, the treatment may raise the issue of occupational health and safety (OHS), for chamber inside attendants, who should not be compressed if they are unable to equalise ears and sinuses.[46]

Extra care may be required in people with:

  • Cardiovascular disease[clarification needed]
  • COPD with air trapping – can lead to pneumothorax during treatment.
  • Upper respiratory infections – These conditions can make it difficult for the patient to equalise their ears or sinuses, which can result in what is termed ear or sinus squeeze.[44]
  • High fevers – In most cases the fever should be lowered before HBO treatment begins. Fevers may predispose to convulsions.[44]
  • Emphysema with CO2 retention – This condition can lead to pneumothorax during HBO treatment due to rupture of an emphysematous bulla during decompression. This risk can be evaluated by x-ray.[44][clarification needed]
  • History of thoracic (chest) surgery – This is rarely a problem and usually not considered a contraindication. However, there is concern that air may be trapped in lesions that were created by surgical scarring. These conditions need to be evaluated prior to considering HBO therapy.[44]
  • Malignant disease: Cancers thrive in blood-rich environments but may be suppressed by high oxygen levels. HBO treatment of individuals who have cancer presents a problem, since HBO both increases blood flow via angiogenesis and also raises oxygen levels. Taking an anti-angiogenic supplement may provide a solution.[47][48] A study by Feldemier, et al. and NIH funded study on Stem Cells by Thom, et al., indicate that HBO is actually beneficial in producing stem/progenitor cells and the malignant process is not accelerated.[49]
  • Middle ear barotrauma may occur in children and adults in a hyperbaric environment because of the necessity to equalise pressure in the ears.

Pregnancy is not a relative contraindication to hyperbaric oxygen treatments,[45][page needed] although it may be for underwater diving. In cases where a pregnant woman has carbon monoxide poisoning there is evidence that lower pressure (2.0 ATA) HBOT treatments are not harmful to the fetus, and that the risk involved is outweighed by the greater risk of the untreated effects of CO on the fetus (neurologic abnormalities or death.)[50][51] In pregnant patients, HBO therapy has been shown to be safe for the fetus when given at appropriate levels and "doses" (durations). In fact, pregnancy lowers the threshold for HBO treatment of carbon monoxide-exposed patients. This is due to the high affinity of fetal hemoglobin for CO.[45][page needed]

Mechanism of action

[edit]

The therapeutic consequences of HBOT and recompression result from multiple effects.[52][53]

Pressure

[edit]

The increased overall pressure is of therapeutic value in the treatment of decompression sickness and air embolism as it provides a physical means of reducing the volume of inert gas bubbles within the body;[54] Exposure to this increased pressure is maintained for a period long enough to ensure that most of the bubble gas is dissolved back into the tissues, removed by perfusion and eliminated in the lungs.[53]

The improved concentration gradient for inert gas elimination (oxygen window) by using a high partial pressure of oxygen increases the rate of inert gas elimination in the treatment of decompression sickness.[55][56]

For many other conditions, the therapeutic principle of HBOT lies in its ability to drastically increase partial pressure of oxygen in the tissues of the body. The oxygen partial pressures achievable using HBOT are much higher than those achievable while breathing pure oxygen under normobaric conditions (i.e. at normal atmospheric pressure). This effect is achieved by an increase in the oxygen transport capacity of the blood. At normal atmospheric pressure, oxygen transport is limited by the oxygen binding capacity of hemoglobin in red blood cells and very little oxygen is transported by blood plasma. Because the hemoglobin of the red blood cells is almost saturated with oxygen at atmospheric pressure, this route of transport cannot be exploited any further. Oxygen transport by plasma, however, is significantly increased using HBOT because of the higher solubility of oxygen as pressure increases.[53]

Hyperbaric chambers

[edit]
See also: Diving chamber § Hyperbaric chamber
Collage of 4 images of multiplace hyperbaric chambers
Multiplace hyperbaric chambers, showing control panel, monitoring facilities, and different chamber sizes in Spanish facilities

Construction

[edit]

The traditional type of hyperbaric chamber used for therapeutic recompression and HBOT is a rigid shelled pressure vessel. Such chambers can be run at absolute pressures typically about 6 bars (87 psi), 600,000 Pa or more in special cases.[57] Navies, professional diving organizations, hospitals, and dedicated recompression facilities typically operate these. They range in size from semi-portable, one-patient units to room-sized units that can treat eight or more patients. The larger units may be rated for lower pressures if they are not primarily intended for treatment of diving injuries.[citation needed]

A rigid chamber may consist of:

  • a pressure vessel designed to a code such as ASME Boiler and Pressure Vessel Code
  • viewports to allow the medical personnel to visually monitor the occupants, and can be used for hand signalling as an auxiliary emergency communications method. The major components are the window (transparent acrylic), the window seat (holds the acrylic window), and retaining ring. Interior lighting can be provided by mounting lights outside the viewports. Viewports are a feature specific to PVHOs due to the need to see the people inside and evaluate their health. Other materials have been attempted, but they consistently fail to maintain their seal or have cracks which would progress rapidly to catastrphophic failure. Acrylic is more likely to have small cracks the operators can see and have time to take mitigation steps instead of failing catastrophically.[58] Counterfeit chambers often do not use acrylic windows.[citation needed]
  • one or more human entry hatches – small and circular or wheel-in type hatches for patients on gurneys;[57]
  • the entry lock that allows human entry – a separate chamber with two hatches, one to the outside and one to the main chamber, which can be independently pressurized to allow patients to enter or exit the main chamber while it is still pressurized;[57]
  • a low volume medical or service airlock for medicines, instruments, and food;[57]
  • transparent ports or closed-circuit television that allows technicians and medical staff outside the chamber to monitor the patient inside the chamber;
  • an intercom system allowing two-way communication;[57]
  • an optional carbon dioxide scrubber – consisting of a fan that passes the gas inside the chamber through a soda lime canister;[57]
  • a control panel outside the chamber to open and close valves that control air flow to and from the chamber, and regulate oxygen to hoods or masks;[57]
  • an over-pressure relief valve;[57]
  • a built-in breathing system (BIBS) to supply and exhaust treatment gas;[57]
  • a fire suppression system.[57]

Flexible monoplace chambers are available ranging from collapsible flexible aramid fiber-reinforced chambers which can be disassembled for transport via truck or SUV, with a maximum working pressure of 2 bar above ambient complete with BIBS allowing full oxygen treatment schedules.[59][60][61] to portable, air inflated "soft" chambers that can operate at between 0.3 and 0.5 bars (4.4 and 7.3 psi) above atmospheric pressure with no supplemental oxygen, and longitudinal zipper closure.[62]

Viewports

[edit]

Acrylic windows with PVHO-1 defined standard geometries and design criteria are generally used. Shapes and sizes vary with chamber application and the requirements for the specific use.[63]

The geometries in general use include:[63]

  • Flat circular windows (low pressure)
  • Conical edged windows with flat inner and outer faces (high pressure on one side only)
  • Circular windows with double beveled edges
  • Light pipes

Low pressure, small diameter chambers may use large cylindrical windows fitted inside the metal structure. In some cases the whole cylindrical pressure chamber has been made from an acrylic tube.[63]

The acrylic windows of a hyperbaric chamber have a limited lifespan, which can be expressed as the design life, which is the conservatively estimated life as calculated in the design process, typically about 10 years, and the service life, which is the actual time the window can be safely and legally used when well maintained, properly inspected, and repaired when necessary and possible and which can be as much as twice the design life.[63]

There are three grades of inspection required:[63]

  • Operational inspection of the inner and outer surfaces is included in the checks before first pressurisation of the day by a competent chamber operator, and ensures that the surfaces have not been damaged since the last use.
  • Maintenance inspection is done at specified intervals by a qualified maintenance inspector. This inspection is more thorough and may require removal of the window from the mounting to check for damage that is not visible when installed. This grade of inspection is generally also required for re-commissioning a chamber that has been out of service for longer than a specified period.
  • Seat and seal inspection is done whenever a window has been removed for inspection or repair or a new window installed.

The window is examined to detect crazing, cracks, blisters, discolouration, scratches or pits.[63]

Operating pressures

[edit]

The operating pressure depends on the application. Chambers used for clinical hyperbaric oxygen therapy commonly have a maximum allowable working pressure of 35 pounds per square inch (2.4 bar) with a maximum of about 150 pounds per square inch (10 bar) Chambers used for support of commercial or military diving operations and for research may have a maximum allowable working pressure of up to 1,000 pounds per square inch (69 bar).[63]

Oxygen supply

[edit]
A recompression chamber for a single diving casualty

In the larger multiplace chambers, patients inside the chamber breathe from either "oxygen hoods" – flexible, transparent soft plastic hoods with a seal around the neck similar to a space suit helmet – or tightly fitting oxygen masks, which supply pure oxygen and may be designed to directly exhaust the exhaled gas from the chamber. During treatment patients breathe 100% oxygen most of the time to maximise the effectiveness of their treatment, but have periodic "air breaks" during which they breathe chamber air (21% oxygen) to reduce the risk of oxygen toxicity. The exhaled treatment gas must be removed from the chamber to prevent the buildup of oxygen, which could present a fire risk. Attendants may also breathe oxygen some of the time to reduce their risk of decompression sickness when they leave the chamber. The pressure inside the chamber is increased by opening valves allowing high-pressure air to enter from storage cylinders, which are filled by an air compressor. Chamber air oxygen content is kept between 19% and 23% to control fire risk (US Navy maximum 25%).[57] If the chamber does not have a scrubber system to remove carbon dioxide from the chamber gas, the chamber must be isobarically ventilated to keep the CO2 within acceptable limits.[57]

A soft chamber may be pressurized directly from a compressor.[62] or from storage cylinders.[61]

Smaller "monoplace" chambers can only accommodate the patient, and no medical staff can enter. The chamber may be pressurised with pure oxygen or compressed air. If pure oxygen is used, no oxygen breathing mask or helmet is needed, but the cost of using pure oxygen is much higher than that of using compressed air. If compressed air is used, then an oxygen mask or hood is needed as in a multiplace chamber. Most monoplace chambers can be fitted with a demand breathing system for air breaks. In low pressure soft chambers, treatment schedules may not require air breaks, because the risk of oxygen toxicity is low due to the lower oxygen partial pressures used (usually 1.3 ATA), and short duration of treatment.[citation needed]

For alert, cooperative patients, air breaks provided by mask are more effective than changing the chamber gas because they provide a quicker gas change and a more reliable gas composition both during the break and treatment periods.[citation needed]

Personnel

[edit]

Treatments

[edit]

Initially, HBOT was developed as a treatment for diving disorders involving bubbles of gas in the tissues, such as decompression sickness and gas embolism, It is still considered the definitive treatment for these conditions. The chamber treats decompression sickness and gas embolism by increasing pressure, reducing the size of the gas bubbles and improving the transport of blood to downstream tissues. After elimination of bubbles, the pressure is gradually reduced back to atmospheric levels.[9] Hyperbaric chambers are also used for animals.

As of September 2023, a number of hyperbaric chambers in the US are turning divers with decompression sickness away, and only treating more profitable scheduled cases. The number of hyperbaric medical facilities in the US is estimated at about 1500, of which 67 are treating diving accidents, according to Divers Alert Network. Many facilities only provide hyperbaric treatment for wound care for economic reasons. Emergency hyperbaric services are more expensive to train and staff, and liability is increased.[64]

Protocol

[edit]
Main article: Hyperbaric treatment schedules

Emergency HBOT for decompression illness follows treatment schedules laid out in treatment tables. Most cases employ a recompression to 2.8 bars (41 psi) absolute, the equivalent of 18 metres (60 ft) of water, for 4.5 to 5.5 hours with the casualty breathing pure oxygen, but taking air breaks every 20 minutes to reduce oxygen toxicity. For extremely serious cases resulting from very deep dives, the treatment may require a chamber capable of a maximum pressure of 8 bars (120 psi), the equivalent of 70 metres (230 ft) of water, and the ability to supply heliox as a breathing gas.[53]

U.S. Navy treatment charts are used in Canada and the United States to determine the duration, pressure, and breathing gas of the therapy. The most frequently used tables are Table 5 and Table 6. In the UK the Royal Navy 62 and 67 tables are used.

The Undersea and Hyperbaric Medical Society (UHMS) publishes a report that compiles the latest research findings and contains information regarding the recommended duration and pressure of the longer-term conditions.[65]

Home and out-patient

[edit]
An example of mild portable hyperbaric chamber. This 40-inch-diameter (1,000 mm) chamber is one of the larger chambers available for home.

There are several sizes of portable chambers, which are used for home treatment. These are usually referred to as "mild personal hyperbaric chambers", which is a reference to the lower pressure (compared to hard chambers) of soft-sided chambers. The American Medical Association is opposed to home use or any other use of hyperbaric chambers if it is not "in facilities with appropriately trained staff including physician supervision and prescription and only when the intervention has scientific support or rationale" due demonstrated hazard [66]

In the US, these "mild personal hyperbaric chambers" are categorized by the FDA as CLASS II medical devices and requires a prescription in order to purchase one or take treatments.[67] As with any hyperbaric chamber, the FDA require compliance with ASME and NFPA standards. The most common option (but not approved by FDA) some patients choose is to acquire an oxygen concentrator which typically delivers 85–96% oxygen as the breathing gas.

Oxygen is never fed directly into soft chambers but is rather introduced via a line and mask directly to the patient. FDA approved oxygen concentrators for human consumption in confined areas used for HBOT are regularly monitored for purity (±1%) and flow (10 to 15 liters per minute outflow pressure). An audible alarm will sound if the purity ever drops below 80%. Personal hyperbaric chambers use 120 volt or 220 volt outlets. The FDA warns against the use of oxygen concentrators or oxygen tanks with chambers that does not meet ASME and FDA standards, regardless of if the concentrators are FDA approved.[68]

History

[edit]

Hyperbaric air

[edit]

A British physician, Nahaniel Henshaw, proposed what would have been the first hyperbaric chamber for medical treatment of humans in 1662. The steel container was to have been pressurised with air, which at the time was not yet known to contain oxygen, later discovered by Carl Wilhelm Scheele around 1770 and first published by Joseph Priestley in 1775, or carbon dioxide. Although it is widely accepted that the chamber was built and used, there are inconsistencies in the description of the engineering details of construction and use that make it unlikely that it would have been able to seal or withstand the forces involved, and the procedures describe would likely have been fatal.[69]

Victot T. Junod built a chamber in France in 1834 to treat pulmonary conditions at pressures between 2 and 4 atmospheres absolute.[70]

During the following century "pneumatic centres" were established in Europe and the USA which used hyperbaric air to treat a variety of conditions.[71]

Orval J Cunningham, a professor of anesthesia at the University of Kansas in the early 1900s observed that people with circulatory disorders did better at sea level than at altitude and this formed the basis for his use of hyperbaric air. In 1918, he successfully treated patients with the Spanish flu with hyperbaric air. In 1930 the American Medical Association forced him to stop hyperbaric treatment, since he did not provide acceptable evidence that the treatments were effective.[71][72]

Hyperbaric oxygen

[edit]

The English scientist Joseph Priestley discovered oxygen in 1775. Shortly after its discovery, there were reports of toxic effects of hyperbaric oxygen on the central nervous system and lungs, which delayed therapeutic applications until 1937, when Behnke and Shaw first used it in the treatment of decompression sickness.[71]

In 1955 and 1956 Churchill-Davidson, in the UK, used hyperbaric oxygen to enhance the radiosensitivity of tumours, while Ite Boerema [nl], at the University of Amsterdam, successfully used it in cardiac surgery.[71]

In 1961 Willem Hendrik Brummelkamp [nl] et al. published on the use of hyperbaric oxygen in the treatment of clostridial gas gangrene.[73]

In 1962 Smith and Sharp reported successful treatment of carbon monoxide poisoning with hyperbaric oxygen.[71]

The Undersea Medical Society (now Undersea and Hyperbaric Medical Society) formed a Committee on Hyperbaric Oxygenation which has become recognized as the authority on indications for hyperbaric oxygen treatment.[71]

Incidents

[edit]

Fires inside a hyperbaric chamber are extremely dangerous. A review article published in 1997 found 77 human fatalities in 35 different hyperbaric chamber fires that occurred from 1923 to 1996.[74] Further studies indicate while the treatment is often considered safe, the use of hyperbaric equipment comes with risks to the operating personnel when improperly used. Proper equipment maintenance and safety procedures for the use of pressure equipment is mandatory.[75]

  • 1997: Ten patients and a nurse were killed in Milan, Italy after a fire broke out inside a hyperbaric oxygen chamber.[76]
  • 2009: A grandmother and her four year old grandson died after a hyperbaric chamber caught fire and exploded in Florida. The boy was receiving treatment in the chamber for cerebral palsy and had traveled from Italy where the treatment is outlawed to undergo the procedure.[77]
  • 2012: A hyperbaric oxygen chamber exploded in Florida, killing a woman and a thoroughbred horse who was receiving treatment. The explosion occurred after the horse kicked out at the chamber, creating sparks which ignited a fire.[78]
  • 2015: A dog was killed in Georgia when the chamber it was receiving treatment in caught fire and exploded. The dog was being treated for arthritis.[79]
  • 2016: A fire killed four people who were receiving treatment inside a hyperbaric chamber at Mintohardjo Navy Hospital in Jakarta, Indonesia. The fire was reportedly caused by an electrical short circuit. After the fire broke out, operators used a sprinkler system and an emergency shut off system to rescue the victims, but live-saving efforts were prevented as the machine became engulfed in flames.[80]
  • 2016: A man in Victoria, Australia died in a hyperbaric chamber of undisclosed causes while receiving treatment. The practitioners overseeing his care were found responsible for failing to ensure the patient's safety leading to his death. They were later fined AU$716,750.[81]
  • March 2025: A hyperbaric chamber exploded in Michigan, killing a five year old boy.[82][83]
  • July 2025: On Wednesday, July 9, 43-year-old physical therapist Walter Foxcroft was found dead inside a hyperbaric oxygen chamber at his health clinic in Lake Havasu City, Arizona, after the device caught on fire.[84][85]

Society and culture

[edit]

Regulation

[edit]

The use of hyperbaric chambers for medical and therapeutic procedures is generally regulated. Authorities have warned of potential risks to patients receiving treatment in unlicensed facilities, notably in Israel,[86] Canada,[87] and the United States.[88] In Italy, the use of hyperbaric chambers for therapy was severely restricted to limited medical settings after a serious fire which killed ten patients in 1997.[89][90]

In some jurisdictions, the use and availability of HBOT is further restricted at the subnational level. In the U.S. state of North Carolina, several cities including Durham, Raleigh and Charlotte have ordered operators of mild hyperbaric oxygen therapy to close to protect public safety due to a risk of fire.[91]

Unlicensed and fraudulent operators have been subject to prosecution. In Australia, Oxymed Australia Pty Ltd and director Malcolm Hooper were ordered to pay AUS $3 million in fines after advertising hyperbaric therapy against the country's Therapeutic Goods Act.[92] In Canada, certain soft-shelled hyperbaric chambers were removed from the market for a potential risk to patients.[93]

Costs

[edit]

HBOT is recognized by Medicare in the United States as a reimbursable treatment for 14 UHMS "approved" conditions. A 1-hour HBOT session may cost between $300 and higher in private clinics, and over $2,000 in hospitals. U.S. physicians (M.D. or D.O.) may lawfully prescribe HBOT for "off-label" conditions such as stroke,[94][95] and migraine.[96][97] Such patients are treated in outpatient clinics. In the United Kingdom most chambers are financed by the National Health Service, although some, such as those run by Multiple Sclerosis Therapy Centres, are non-profit. In Australia, HBOT is not covered by Medicare as a treatment for multiple sclerosis.[98] China and Russia treat more than 80 maladies, conditions, and trauma with HBOT.[99]

Research

[edit]

Aspects under research include radiation-induced hemorrhagic cystitis;[100] and inflammatory bowel disease,[101] rejuvenation.[102]

Some research found evidence that HBOT improves local tumor control, mortality, and local tumor recurrence for cancers of the head and neck.[103]

Some research also found evidence of an increase in stem progenitor cells[49] and a decrease in inflammation.[104]

Neurological

[edit]

Tentative evidence shows a possible benefit in cerebrovascular diseases.[105] Rats subjected to HBOT after some time following the acute phase of experimentally-induced stroke showed reduced inflammation, increased brain-derived neurotrophic factor, and evidence of neurogenesis.[106] Another rat study showed improved neurofunctional recovery as well as neurogenesis following the late-chronic phase of experimentally-induced stroke.[107]

The clinical experience and results so far published has promoted the use of HBOT therapy in patients with cerebrovascular injury and focal cerebrovascular injuries.[108] However, the power of clinical research is limited because of the shortage of randomized controlled trials.[105]

Radiation wounds

[edit]

A 2010 review of wounds from radiation therapy found that, while most studies suggest a benefit, more experimental research is needed to validate its use.[109]

Respiratory distress

[edit]

People who are having extreme difficulty breathing – acute respiratory distress syndrome – are commonly given oxygen and there have been limited trials of hyperbaric equipment in such cases. Examples include treatment of the Spanish flu[72] and COVID-19.[110]

See also

[edit]

References

[edit]

Further reading

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Hyperbaric medicine

View on Grokipedia
from Grokipedia
Hyperbaric medicine is a therapeutic that employs hyperbaric (HBOT), a treatment in which patients breathe 100% oxygen while enclosed in a pressurized chamber at 2 to 3 times normal , thereby increasing oxygen dissolution in and enhancing delivery to oxygen-deprived tissues. This approach, requiring medical-grade oxygen and adherence to safety standards like ASME-PVHO-1, is prescribed and supervised by qualified physicians to address conditions involving hypoxia, infection, or impaired healing. The mechanism of HBOT promotes physiological benefits such as reducing tissue swelling, eliminating gas bubbles in the bloodstream, stimulating (new formation), and enhancing the body's defenses, which collectively support and combat certain infections. Sessions typically last 90 to 120 minutes at pressures of 1.9 to 3.0 atmospheres absolute (ATA), with the number of treatments varying from a few for acute cases like to 30 or more for chronic wounds. Treatments occur in either monoplace (single-patient) or multiplace chambers, often on an outpatient basis, and are delivered in accredited facilities to minimize risks. Approved indications for HBOT, as recognized by organizations like the Undersea and Hyperbaric Medical Society (UHMS) and the U.S. Food and Drug Administration (FDA), include , , gas embolism, , clostridial myonecrosis (), crush injuries, necrotizing soft tissue infections, , compromised grafts and flaps, acute thermal burns, intracranial abscesses, central retinal artery occlusion, , and delayed radiation tissue injury. It is also a standard adjunct for enhancing healing in selected problem wounds, such as , and in cases of when is not possible. While generally safe, HBOT carries potential risks including injuries or sinus congestion from pressure changes, temporary , lung collapse () in susceptible individuals, and rare leading to seizures; additionally, the oxygen-enriched environment poses a fire hazard, necessitating strict protocols. In August 2025, the FDA issued a safety communication highlighting reports of serious injuries and deaths associated with improper use of HBOT devices, underscoring the importance of using FDA-cleared devices in accredited facilities. Contraindications include untreated and certain agents, underscoring the need for patient screening. Unproven claims for conditions like autism, cancer, Lyme disease, or sarcopenia lack FDA authorization and scientific support. HBOT is not covered by Kaiser Permanente for the treatment of sarcopenia, as it is considered investigational or off-label for this indication.

Overview

Definition and scope

Hyperbaric medicine, commonly referred to as hyperbaric oxygen therapy (HBOT), is a medical treatment modality that involves the administration of 100% oxygen to patients at elevated atmospheric pressures, typically ranging from 2.0 to 3.0 atmospheres absolute (ATA), to augment oxygen delivery to hypoxic tissues. This increased pressure facilitates the dissolution of a greater volume of oxygen into the bloodstream, enabling enhanced in areas with compromised circulation. The therapy is conducted in controlled environments designed to safely manage these pressures, distinguishing it as a targeted intervention for specific pathological conditions. The scope of hyperbaric medicine is limited to therapeutic applications of HBOT, focusing on clinical outcomes rather than recreational or occupational exposures, such as those encountered in or industrial settings. It primarily involves the use of specialized hyperbaric chambers, including monoplace chambers that accommodate a single patient pressurized with oxygen and multiplace chambers that treat multiple patients simultaneously under air compression with oxygen delivery via masks or hoods. This therapeutic framework excludes non-medical pressurized environments and emphasizes evidence-based protocols approved by bodies like the Undersea and Hyperbaric Medical Society (UHMS). A key distinction of HBOT lies in its contrast to normobaric , where oxygen is provided at sea-level pressure (1 ATA) and transport is largely hemoglobin-dependent, limiting delivery to about 1.3 volumes percent in . In HBOT, the hyperbaric conditions allow oxygen to dissolve directly in plasma, achieving up to 6 volumes percent or more at 3 ATA, thereby bypassing hemoglobin saturation limits and supporting tissue oxygenation even in ischemic or edematous regions. This plasma-mediated mechanism provides a unique advantage for conditions resistant to conventional oxygen supplementation. The foundational concepts of hyperbaric medicine originated in 1662, when British physician Nathaniel Henshaw developed the first documented hyperbaric chamber, termed the "domicilium," to treat respiratory and other ailments through cycles of compression and decompression using . This early innovation laid the groundwork for modern applications, evolving from empirical pressure manipulations to scientifically validated oxygen-enriched therapies.

Principles of hyperbaric therapy

Hyperbaric therapy operates on the principle that elevated atmospheric pressure increases the solubility of oxygen in blood plasma, allowing for hyperoxygenation of tissues independent of hemoglobin saturation. This process, governed by Henry's law—which states that the amount of gas dissolved in a liquid is directly proportional to the partial pressure of that gas above the liquid—enables the delivery of substantially higher oxygen levels to hypoxic or ischemic areas. By breathing 100% oxygen under pressure, plasma can carry oxygen at concentrations up to 20 times greater than at normal atmospheric conditions, addressing conditions involving tissue hypoxia, ischemia, or localized infections where conventional oxygen delivery is insufficient. Pressure in hyperbaric therapy is measured in atmospheres absolute (ATA), where 1 ATA represents the standard sea-level of approximately 14.7 pounds per . Therapeutic sessions typically occur at 2.0 to 2.5 ATA, with patients inhaling pure oxygen for durations of 60 to 120 minutes, allowing sufficient time for oxygen to diffuse into plasma while minimizing exposure risks. These parameters are selected based on the balance between achieving therapeutic hyperoxygenation and avoiding adverse effects, ensuring the of oxygen remains within a safe range for most indications. A key consideration in hyperbaric therapy is the therapeutic window that weighs benefits against risks such as oxygen toxicity, which can manifest as seizures at partial pressures exceeding 1.6 ATA for prolonged periods. Protocols incorporate air breaks—intervals of room air—to reduce the cumulative oxygen dose and mitigate toxicity, maintaining efficacy while keeping incidence rates low, typically below 1 in 10,000 treatments. Effective hyperbaric therapy requires a controlled environment within specialized chambers to manage pressure changes gradually, preventing from unequal pressure equilibration in air-filled spaces like the ears, sinuses, or lungs. Patients undergo pre-treatment assessments and training in equalization techniques, with chamber pressurization occurring at rates of 1-2 ATA per minute to allow safe adaptation.

Mechanism of action

Physiological effects of pressure and oxygen

Hyperbaric oxygen therapy (HBOT) induces hyperoxygenation by significantly elevating the of oxygen in plasma, reaching levels exceeding 2,000 mmHg at 3 atmospheres absolute (ATA), compared to under 200 mmHg under normobaric conditions room air. This supernormal oxygenation dissolves substantial amounts of oxygen directly into plasma—up to 6 mL per 100 mL at 3 ATA—bypassing limitations and effectively alleviating hypoxia in ischemic, wounded, or edematous tissues where diffusion barriers impair access. At the cellular level, HBOT stimulates through upregulation of (VEGF) at both mRNA and protein levels in endothelial cells, promoting new vessel formation essential for tissue repair. It also enhances proliferation and collagen synthesis, key processes in , by improving cellular energy metabolism and production under hyperoxic conditions. Systemically, the elevated oxygen tension triggers arteriolar , which reduces hydrostatic pressure and thereby decreases formation in injured tissues without compromising overall oxygen delivery. Additionally, HBOT exerts antimicrobial effects by generating (ROS) that directly damage anaerobic bacteria, such as Clostridium species, which are highly sensitive to supraphysiological oxygen levels due to their oxygen intolerance. HBOT modulates inflammation by inhibiting pro-inflammatory cytokine release, such as tumor necrosis factor-alpha and interleukin-6, while promoting anti-inflammatory cytokines like interleukin-10, thereby attenuating reperfusion injury following ischemia. This cytokine modulation, combined with reduced neutrophil sequestration and oxidative stress in post-ischemic tissues, helps mitigate secondary damage from inflammation.

Gas laws and oxygen delivery

Hyperbaric medicine leverages fundamental gas laws to enhance oxygen delivery to tissues, particularly in hypoxic conditions. These principles explain how increased ambient pressure and inspired oxygen concentration amplify the solubility and transport of oxygen in the bloodstream, independent of hemoglobin saturation. Henry's law states that the solubility of a gas in a liquid is directly proportional to the partial pressure of that gas above the liquid. Mathematically, this is expressed as C=k⋅PC = k \cdot P, where CC is the concentration of the dissolved gas, kk is the solubility coefficient, and PP is the partial pressure of the gas. In hyperbaric oxygen therapy (HBOT), this law governs the increased dissolution of oxygen in plasma; at elevated pressures, higher partial pressures of oxygen drive more O₂ into solution, significantly boosting the oxygen-carrying capacity of blood plasma beyond what hemoglobin alone can achieve. Dalton's law of partial pressures posits that the total pressure exerted by a mixture of non-reacting gases is equal to the sum of the partial pressures of the individual gases. In the context of HBOT, the of inspired oxygen is calculated as the product of the absolute pressure in atmospheres (ATA) and the fraction of oxygen in the inspired gas; for instance, breathing 100% oxygen at 2 ATA yields a partial pressure of approximately 1520 mmHg (2 × 760 mmHg). This elevated facilitates greater alveolar oxygen uptake and subsequent dissolution in blood, as per . Boyle's law describes the inverse relationship between the pressure and volume of a gas at constant temperature, given by the equation V1P1=V2P2V_1 P_1 = V_2 P_2. In hyperbaric applications, this law explains the compression of gas bubbles, such as those formed in , where increased ambient pressure reduces bubble volume, aiding in their resorption and mitigating vascular obstruction. Under normal conditions at 1 ATA with room air, arterial partial pressure of oxygen (PaO₂) is approximately 100 mmHg, with hemoglobin nearly fully saturated and plasma carrying only about 0.3 vol% dissolved oxygen. In contrast, during HBOT at 3 ATA with 100% oxygen, the dissolved oxygen in plasma rises to around 6 vol%, providing a substantial reserve that can diffuse to oxygen-deprived tissues even if hemoglobin-bound oxygen is limited. This plasma-dissolved oxygen supports aerobic metabolism in ischemic areas, extending diffusion distances up to four times beyond normal.

Clinical applications

Approved indications

Hyperbaric oxygen therapy (HBOT) is approved by the U.S. Food and Drug Administration (FDA) and the Undersea and Hyperbaric Medical Society (UHMS) for 13 to 15 specific indications, respectively, where evidence from randomized controlled trials (RCTs), meta-analyses, and clinical consensus supports its efficacy as a primary or adjunctive treatment. These approvals emphasize conditions involving hypoxia, gas bubbles, or where elevated oxygen delivery under provides therapeutic benefits beyond normobaric oxygen. Typical protocols involve 100% oxygen at 2.0–3.0 atmospheres absolute (ATA) for 60–120 minutes per session, with session numbers ranging from 3–5 for acute cases like to 20–40 for chronic wounds, adjusted based on response. The FDA-approved indications include:
  • Air or gas , where HBOT rapidly reduces bubble size via recompression and enhances tissue oxygenation to mitigate ischemia.
  • , accelerating dissociation (half-life reduced from 4–6 hours on room air to 20–30 minutes at 2.5–3.0 ATA) and decreasing neurological sequelae by up to 46% in symptomatic cases.
  • Clostridial and myonecrosis (), inhibiting production at tissue PO₂ >250 mmHg and improving when combined with and antibiotics (minimum 3–4 sessions).
  • , compartment , and other acute traumatic ischemias, reducing and increasing oxygen delivery by 125% at 2.0 ATA to preserve viability.
  • , the mainstay treatment that recompresses bubbles (e.g., ) according to while improving diffusion gradients for bubble resolution, supported by extensive .
  • Central retinal artery occlusion, delivering oxygen via alternative pathways like choroidal circulation to restore vision if initiated early.
  • Enhancement of healing in selected problem wounds, such as ulcers, through increased oxygenation and to support tissue repair; RCTs and meta-analyses show reduced major amputation rates (e.g., 10.7% vs. 26%) and faster wound closure.
  • Severe when transfusions are unavailable, sustaining oxygen transport via plasma-dissolved oxygen at 2.0–3.0 ATA with air breaks to prevent .
  • Intracranial , as an adjunct for refractory cases, reducing bacterial load with 2.0–2.5 ATA sessions averaging 13 treatments.
  • Necrotizing infections, alleviating hypoxia to boost host defenses and penetration, often requiring multiple daily sessions until stabilization.
  • Refractory , per American Class II recommendations, aiding chronic cases with 20–40 daily 90–120 minute sessions at 2.0–3.0 ATA alongside and antibiotics.
  • Delayed (soft tissue and bony necrosis), promoting neovascularization and faster wound closure as evidenced by RCTs, with protocols like 30 pre- and 10 post-surgical sessions for .
  • Compromised skin grafts and flaps, enhancing in hypoxic or irradiated beds.
  • Acute thermal burns (severe, at specialized centers), reducing and risk as an adjunct.
  • Idiopathic sudden , FDA- and UHMS-approved since 2011 with reaffirmed efficacy in recent reviews, using 2.0–2.5 ATA for 90 minutes daily (10–20 sessions within 14 days) to improve recovery rates by 25–50% when combined with steroids ( from multiple RCTs). Moderate-certainty evidence from meta-analyses shows about a 39% increased likelihood of complete or partial hearing recovery and improved word discrimination scores, especially with early initiation (within days to 2 weeks), severe/profound hearing loss, and protocols at 2.0–2.5 ATA; reflects equivocal evidence with potential benefit balanced against limited clear superiority, availability, and cost.
  • (aseptic osteonecrosis), promoting bone repair, reducing pain, and improving function in early-stage cases as an adjunct therapy, UHMS-approved in 2024.
These indications are backed by high-level evidence, including RCTs for and , and consensus guidelines for others, with UHMS updating its list as of 2020 and no major FDA changes through 2025. HBOT is not an approved indication by the UHMS for routine post-surgical recovery, orthopedic procedures, or knee surgery specifically. HBOT's role leverages hyperoxygenation to address underlying , such as bubble collapse or enhanced effects, without supplanting standard care.

Emerging and investigational uses

Hyperbaric oxygen therapy (HBOT) is being investigated for its potential in treating (TBI) and , with recent studies indicating enhancements in through upregulation of (BDNF). A 2024 review highlighted that HBOT at pressures of 1.5-2.0 atmospheres absolute (ATA) promotes BDNF release and signaling pathways, supporting neuronal repair and functional improvements in TBI patients. Similarly, 2024 research on stroke demonstrated HBOT's role in modulating cellular mechanisms to foster brain recovery and , though clinical outcomes vary and require further validation. In and (ME/CFS), 2024-2025 trials have shown HBOT to alleviate symptoms such as , , and sleep disturbances. A published in Nature Scientific Reports in 2024 reported significant improvements in , sleep quality, psychiatric symptoms, and pain following HBOT protocols, with longitudinal follow-up confirming sustained benefits at . Additional 2025 observational data indicated therapeutic effects on core ME/CFS symptoms, including enhanced cognitive function and reduced , with sham-controlled designs supporting efficacy in up to 50% of participants based on symptom score reductions. These findings suggest HBOT's potential via induction, though larger trials are needed for approval. As an adjunct to cancer therapy, HBOT is explored for reducing tumor hypoxia, thereby enhancing radiotherapy and radiochemotherapy outcomes. A 2025 review in Biomedicine & Pharmacotherapy emphasized that HBOT improves oxygen delivery to hypoxic tumor regions, increasing radiosensitivity, drug penetration, and DNA damage in preclinical models of various cancers, including gliomas and metastases. Clinical studies from 2024-2025 further noted neutral or inhibitory effects on tumor growth without promoting metastasis, positioning HBOT as a safe enhancer for standard treatments, though not yet standard of care. For anti-aging and regenerative purposes, 2025 research underscores HBOT's ability to mobilize stem cells and lengthen telomeres while reducing senescent cells. Protocols involving 2 ATA for 60-90 sessions have been linked to increased circulating stem/progenitor cells and over 20% telomere elongation in peripheral blood mononuclear cells, as extended from foundational studies and recent validations. These effects are attributed to HBOT's modulation of and senescence pathways, potentially slowing biological aging, with emerging evidence from reviews supporting its role in healthy aging. However, HBOT is considered investigational or off-label for sarcopenia (age-related muscle loss), lacks FDA approval for this indication, and is not covered by Kaiser Permanente for the treatment of sarcopenia. Other investigational applications include migraines, pain relief, recovery, and orthopedic surgery recovery such as knee procedures (e.g., total knee arthroplasty or ACL reconstruction), supported by randomized controlled trials (RCTs) but lacking regulatory approval. For , 2023-2025 RCTs demonstrated HBOT's superiority over pharmacological interventions in reducing pain, improving , and enhancing emotional function, with meta-analyses confirming benefits in tender point counts and global assessments. In migraines, preliminary evidence suggests reduced frequency through vasoconstrictive effects and , while studies indicate accelerated tissue repair, and orthopedic surgery investigations show reduced inflammation, pain, and improved healing, though evidence remains preliminary and protocol-dependent.

Procedures and equipment

Hyperbaric chambers

Clinical hyperbaric oxygen therapy (HBOT) utilizes hard-sided chambers at pressures of 2-3 atmospheres absolute (ATA) with patients breathing 100% oxygen under medical supervision. Hyperbaric chambers are specialized pressure vessels designed to administer hyperbaric oxygen therapy (HBOT) by enclosing patients in a controlled environment of elevated while they breathe oxygen-enriched air. These chambers must adhere to stringent standards to ensure structural integrity and safety during pressurization, typically using medical-grade oxygen to enhance tissue oxygenation under pressure. There are two primary types of hyperbaric chambers used in clinical settings: monoplace and multiplace. Monoplace chambers accommodate a single patient and are pressurized directly with 100% oxygen, allowing the patient to breathe the chamber atmosphere without additional masks; these are often constructed as horizontal tubes made of acrylic or for visibility and durability. Multiplace chambers, in contrast, can treat multiple patients simultaneously along with medical staff, and are pressurized with while oxygen is delivered via individual masks, hoods, or endotracheal tubes to avoid enriching the entire chamber environment with pure oxygen. This design enables attendant intervention during treatment but requires more complex gas management systems. In contrast, mild HBOT (mHBOT) employs soft-sided, lower-pressure (1.3-1.5 ATA) chambers, often for non-medical or wellness uses, which lack FDA clearance for therapeutic indications and are not equivalent to clinical HBOT. Construction of hyperbaric chambers prioritizes materials capable of withstanding high pressures without failure, typically using aluminum or for the hull to meet pressure vessel codes. Chambers are certified under the ASME PVHO-1 standard for pressure vessels for human occupancy, which mandates rigorous testing, including hydrostatic pressure tests at 1.5 times the maximum allowable working pressure, to verify safety. Viewports, essential for monitoring, are made of shatter-resistant acrylic designed to endure pressures exceeding 3 atmospheres absolute (ATA), with regular inspections required to detect stress cracks or that could compromise . Standard operating pressures for HBOT range from 2.0 to 3.0 ATA, sufficient to dissolve increased amounts of oxygen in plasma for therapeutic effects on conditions like and decompression illness. In emergency scenarios, such as severe decompression illness or arterial gas embolism, chambers may be capable of reaching up to 6 ATA to rapidly reduce gas bubble size, following protocols like the US Navy Table 6A. Safety features are integral to chamber design to mitigate risks from and oxygen-enriched atmospheres. Redundant pressure relief valves automatically vent excess pressure to prevent over-pressurization, while , including CO2 extinguishers and water deluge setups, address the heightened risk in oxygen-rich environments. systems facilitate communication between patients and operators, and built-in physiological monitoring allows real-time tracking of such as (ECG) and (SpO2) through pressure-resistant penetrators. As of 2025, portable soft-shell hyperbaric chambers have gained popularity for outpatient and home use, offering mild pressurization up to 1.3-1.5 ATA in inflatable, non-rigid enclosures made of durable fabrics like ballistic nylon; however, these are not FDA-cleared for clinical HBOT indications and are primarily marketed for wellness applications rather than approved medical therapy.

Treatment protocols

Treatment protocols in hyperbaric oxygen therapy (HBOT) follow standardized procedures to ensure safety and efficacy, with the United States Navy Treatment Table 6 serving as a foundational model adapted for various applications. This table involves compression to 2.8 atmospheres absolute (ATA), followed by periods of 100% oxygen breathing interspersed with 5-minute air breaks to mitigate oxygen toxicity risks. In clinical practice, a common protocol uses 2.4 ATA with air breaks every 30 minutes during the oxygen phase to prevent central nervous system oxygen toxicity. Compression and decompression occur at controlled rates of 0.1 to 0.2 ATA per minute to minimize barotrauma risks, such as middle ear or sinus squeeze. A typical HBOT session begins with a pre-treatment assessment, including an otoscopic examination to evaluate function and identify potential risks, alongside a review of contraindications like untreated . The patient then enters the chamber, where compression to the target pressure takes 8 to 10 minutes, followed by 60 to of oxygen breathing at the prescribed depth. Decompression follows at a similar controlled rate, with post-treatment observation for at least 30 minutes to monitor for delayed effects like or transient . Protocols vary based on acuity: acute scenarios may involve intensive schedules, such as three sessions per day initially, while chronic conditions typically require 20 to 40 sessions delivered five days per week. These regimens are tailored within monoplace or multiplace chambers, as described in sections. Mild HBOT (mHBOT), often conducted outpatient using soft-sided chambers at approximately 1.3 ATA, has limited supporting its efficacy and is not recommended for severe cases. The 2025 Undersea and Hyperbaric Medical Society (UHMS) guidelines emphasize caution against unsupervised mHBOT use due to risks from unapproved devices and lack of medical oversight. Oversight of HBOT sessions is provided by certified hyperbaric technicians and physicians trained to UHMS standards, including a minimum 40-hour introductory course and hands-on clinical for technologist through the National Board of Diving and Hyperbaric Medical Technology.

Risks and safety

Side effects and complications

Hyperbaric oxygen therapy (HBOT) is associated with several side effects, the most common of which is , occurring in 20-30% of treatments due to pressure changes during compression and decompression phases. This condition, also known as ear squeeze, results from inability to equalize pressure and manifests as , hearing , or tympanic membrane rupture; it is managed through patient education on autoinsufflation techniques such as the Valsalva or Toynbee maneuver, with decongestants used prophylactically. For recurrent cases, insertion of tympanostomy tubes may be necessary to facilitate pressure equalization. Sinus squeeze, a related affecting the , occurs less frequently and presents with facial pain or epistaxis, typically managed similarly with decongestants and slower compression rates to allow equalization. Another common visual side effect is reversible , induced by hyperoxia's impact on the crystalline lens, affecting up to 25% of patients after prolonged exposure at pressures of 2.0 ATA or greater, with a progression of about 0.25 diopters per week of treatment. This myopia generally resolves within 3-6 weeks post-therapy without intervention. Oxygen toxicity represents a more serious risk, with pulmonary manifestations such as cough, substernal , or reduced emerging after extended exposures beyond 2.4 ATA, though these are rare in standard protocols limited to 90-120 minutes per session. oxygen toxicity, primarily seizures, is even rarer, with an incidence of less than 0.1% (approximately 1 in 2,000-3,000 treatments), and is prevented through scheduled air breaks to reduce oxygen . Upon occurrence, seizures are self-limiting and treated by immediate oxygen cessation, with no long-term neurological sequelae reported. Other complications include , which can affect a small of patients (reported incidences varying from <1% to 15%) in monoplace chambers, which can be mitigated with anxiolytics, cognitive behavioral techniques, or referral to multiplace chambers. Fire risk, while rare due to stringent protocols prohibiting , flammables, and ensuring oxygen monitoring, remains a potential hazard in enriched oxygen environments. As of August 2025, the FDA has reported incidents of fires associated with HBOT devices resulting in serious injuries and deaths, emphasizing the need for strict adherence to manufacturer instructions and safety protocols. An untreated , if present despite screening, can progress to tension under hyperbaric conditions, necessitating urgent decompression. Overall, the incidence of serious complications from HBOT is less than 1%, as confirmed by recent Undersea and Hyperbaric Medical Society (UHMS) data emphasizing low risk with proper patient screening and protocol adherence. Management is primarily symptom-based, focusing on prevention through , gradual pressure changes, and monitoring, ensuring the therapy's safety profile remains favorable for approved indications. In September , fatalities related to HBOT prompted discussions on enhanced state-level regulations to address safety in both clinical and non-traditional settings.

Contraindications and patient selection

Hyperbaric oxygen therapy (HBOT) requires careful patient screening to identify that could lead to serious complications due to pressure changes and high oxygen exposure. The only absolute is an untreated , as compression can cause expansion and progression to a life-threatening tension . Another absolute is the presence of intraocular gas, such as after certain eye surgeries, due to the risk of irreversible vision loss from gas expansion under pressure. Relative contraindications are conditions that increase risk but may allow HBOT with precautions, monitoring, or mitigation strategies. These include severe chronic obstructive pulmonary disease (COPD) with air trapping or bullous disease, which heightens the risk of barotrauma from unequal pressure equalization in the lungs. Certain chemotherapy agents, such as doxorubicin, pose risks of enhanced cardiotoxicity and should be discontinued at least 24 hours prior to treatment. Bleomycin use requires evaluation for pulmonary fibrosis risk if within six months of administration, while cisplatin may impair wound healing but is permissible in emergencies. Other relative contraindications encompass pregnancy (due to potential fetal oxygen toxicity, though HBOT may be used in life-threatening cases like carbon monoxide poisoning), active upper respiratory infections (increasing barotrauma risk from Eustachian tube dysfunction), and claustrophobia (which can be managed with sedation or anxiolytics in mild cases). Implanted devices, such as pacemakers or cochlear implants, necessitate verification of pressure tolerance, typically safe up to 4 atmospheres absolute (ATA). Uncontrolled epilepsy, high fever above 39°C, or recent thoracic surgery also warrant caution and specialist consultation.
CategoryExamplesRationale and Management
AbsoluteUntreated ; Intraocular gasRisk of tension pneumothorax or blindness; Treat with prior to HBOT.
RelativeSevere COPD with ; chemotherapy; ; Active URI; , toxicity enhancement, fetal risks, Eustachian dysfunction, anxiety; Monitor closely, adjust medications, or use alternatives like .
Patient selection for HBOT begins with confirming the diagnosis aligns with Undersea and Hyperbaric Medical Society (UHMS)-approved indications, such as or ulcers, through a thorough and . A multidisciplinary team, including hyperbaric physicians, pulmonologists, and otolaryngologists ( specialists), conducts the assessment to evaluate lung function, rule out contraindications via chest X-ray or CT imaging for blebs or bullae, and ensure overall fitness. is essential, detailing risks like (referencing mechanisms from physiological effects sections), benefits, and treatment expectations to promote compliance. Screening tools, such as UHMS guidelines and risk stratification checklists, help categorize patients by urgency and burden. Special populations require tailored selection. In , HBOT is generally safe with adjusted lower pressures (e.g., 1.5-2 ATA) to minimize risks like , and indications include approved conditions such as , with close monitoring for behavioral compliance. For elderly patients, comprehensive screening is critical, focusing on cardiovascular stability (e.g., >35%) and metabolic control (e.g., glucose levels between 100-300 mg/dL) to avoid under . In both groups, relative contraindications like uncontrolled or are addressed through optimization prior to therapy.

History

Early developments

The foundations of hyperbaric medicine trace back to the , when early observations on the effects of and gases on respiration laid groundwork for later therapeutic applications. Flemish and physician Jan Baptista van Helmont, in the 1620s, conducted experiments demonstrating how altered gaseous environments influenced breathing and bodily functions, recognizing distinct "airs" beyond normal atmosphere that affected physiological processes. This work on gas dynamics and respiration provided conceptual precursors to pressurized therapies, though practical applications emerged later. By 1662, British clergyman and physician Nathaniel Henshaw constructed the first documented hyperbaric chamber, known as the "domicilium," a sealed wooden structure equipped with to compress or rarefy air for treating acute and chronic diseases; he posited that increased aided conditions like fevers while decompression benefited pulmonary issues. In the , hyperbaric techniques gained traction amid industrial demands, particularly for addressing caisson disease—a form of —affecting workers in pressurized environments like and tunneling projects. As early as the , French physician Jacques-François-Auguste Pravaz and others built chambers in for respiratory ailments, but practical use intensified with infrastructure booms; for instance, during the 1870s construction of bridges and tunnels, recompression with hyperbaric air alleviated symptoms in afflicted laborers by reducing nitrogen bubble formation in tissues. A notable advancement came in 1878 when French surgeon J.A. Fontaine erected a large hyperbaric chamber in , accommodating up to 10 patients, to treat diverse conditions including , , and nervous disorders through exposure up to 3 atmospheres absolute (ATA); Fontaine later developed a mobile hyperbaric , performing surgeries under to enhance outcomes. These pre-oxygen era efforts relied solely on ambient air compression, which was limited by risks such as , mechanical failures, and insufficient oxygen delivery at greater depths, often resulting in relative tissue hypoxia despite elevated total . International developments, including in and , contributed to early chamber designs and applications for respiratory and diving-related conditions. The early marked a shift toward hyperbaric oxygen therapy (HBOT), with pivotal experiments addressing surgical and decompression challenges. Dutch Ite Boerema pioneered HBOT's clinical potential in the , conducting animal studies in using the Dutch Navy's hyperbaric facilities to explore oxygen at 3 ATA during ; these demonstrated that hyperoxygenation could extend circulatory arrest times up to an hour without irreversible damage, enabling complex procedures like total body perfusion replacement. Boerema's work extended to human applications in the early 1960s, including surgeries for congenital heart defects under hyperbaric conditions to mitigate ischemia. Concurrently, the US Navy formalized HBOT adoption post-World War II for treating diving accidents, building on wartime research to standardize recompression protocols that reduced incidence among submariners and divers by rapidly dissolving inert gas bubbles with pure oxygen. The first documented human use of HBOT for occurred in the mid-1960s, when British D.J.T. Perrins showed accelerated closure in ischemic wounds through enhanced oxygenation, stimulating and synthesis.

Modern advancements

In the 1960s and , hyperbaric oxygen therapy (HBOT) gained formal recognition and regulatory approval in the United States, marking a pivotal shift toward standardized clinical use. The Undersea Medical Society, later renamed the Undersea and Hyperbaric Medical Society (UHMS), was established in 1967 to advance research and practice in undersea and hyperbaric medicine. By 1976, the UHMS Hyperbaric Oxygen Therapy Committee outlined 13 approved indications for HBOT, including , , and , which aligned with emerging FDA oversight of hyperbaric chambers as medical devices. These developments helped transition HBOT from experimental applications to evidence-based treatment protocols, emphasizing safety and efficacy in controlled environments. During the 1980s and , HBOT expanded to address radiation-induced injuries and reinforced its role in managing , reflecting growing clinical evidence and technological refinements. The UHMS approved HBOT for delayed radiation tissue damage in the , recognizing its ability to promote and reduce hypoxia in affected tissues. For , HBOT became a standard intervention, with protocols demonstrating reduced neurological sequelae through accelerated toxin elimination. Concurrently, multiplace hyperbaric chambers—capable of treating multiple patients simultaneously—became standardized in major medical centers, enabling efficient delivery of therapy at pressures up to 3 atmospheres absolute (ATA) while incorporating built-in breathing systems for oxygen administration. Undersea and hyperbaric medicine was recognized as a subspecialty by the starting in 1991, with further approvals through 2000. The 2010s saw innovations in HBOT accessibility and new indications, driven by advancements in chamber technology and expanded approvals. In 2011, the UHMS approved HBOT for idiopathic sudden , supported by evidence of improved outcomes when administered within 14 days of onset, often as adjunctive to steroids. These advancements emphasized patient-centered delivery, reducing logistical barriers while maintaining therapeutic pressures of 2.0-2.5 ATA for 60-90 minutes per session. Note that low-pressure portable chambers (1.3-1.5 ATA), while increasing access for wellness applications, are not approved for standard HBOT indications and have faced FDA warnings for unproven uses as of 2021-2025. A landmark validation came in 2002 through multiple Cochrane systematic reviews, which confirmed HBOT's benefits for conditions like chronic wounds and , highlighting reduced healing times and lower amputation rates in ulcers. Entering the 2020s, research has integrated HBOT with for cancer, with studies from 2023-2025 showing enhanced tumor penetration by immune cells and improved response rates to checkpoint inhibitors in hypoxic solid tumors. Telemedicine-enabled monitoring has also advanced, allowing real-time vital sign tracking during sessions via wireless systems, particularly post-COVID protocols to minimize infection risks. Global adoption surged following trials; for instance, randomized controlled studies in 2023-2025 demonstrated HBOT's efficacy in alleviating , , and sleep disturbances, with over 40 sessions at 2.0 ATA yielding sustained improvements in .

Societal aspects

Regulation and training

In the United States, the (FDA) regulates hyperbaric chambers as Class II medical devices, requiring premarket notification under the 510(k) process to ensure safety and effectiveness for approved uses. Medicare provides coverage for (HBOT) under 14 specific indications approved by the Undersea and Hyperbaric Medical Society (UHMS), including decompression illness, , and diabetic foot ulcers, as adjunctive therapy when standard treatments fail. The UHMS issues position statements on HBOT indications and practices, serving as authoritative guidelines for clinical application and safety. Internationally, the European Committee for Hyperbaric Medicine (ECHM) harmonizes standards across Europe through its Code of Good Practice for Hyperbaric Oxygen Therapy, which outlines minimum requirements for facilities, equipment, and personnel to ensure and treatment efficacy. The (WHO) recognizes HBOT as a standard intervention for decompression illness in contexts, emphasizing its role in of gas and related conditions. Training for HBOT practitioners in the follows UHMS guidelines, where physicians must complete an approved introductory course of at least 40 hours of didactic and hands-on instruction in hyperbaric medicine, followed by proctored experience including at least 5 patient consultations and attendance at 25 hyperbaric sessions for privileging. Hyperbaric technicians obtain through the National Board of Diving and Hyperbaric Medical Technology (NBDHMT), which requires formal training, a preceptorship of at least 480 clinical hours, and passing a comprehensive examination to demonstrate competency in chamber operations and safety protocols. Facility accreditation enhances safety oversight, with options including UHMS accreditation, which evaluates compliance with clinical standards, or The certification, recognized as complementary for hyperbaric programs to meet rigorous quality and criteria. In August 2025, following reports of fires resulting in serious injuries and deaths, the FDA issued a safety communication reminding user facilities to report serious adverse events involving hyperbaric chambers, such as deaths or injuries, within 10 days to the MAUDE database under existing Reporting (MDR) requirements, and emphasizing adherence to manufacturer instructions and fire prevention protocols. For off-label HBOT applications beyond FDA-approved indications, ethical guidelines from UHMS and professional bodies emphasize and, for investigational uses, require oversight by an (IRB) to protect rights and ensure scientific rigor in emerging protocols.

Access and costs

Access to (HBOT) remains limited by significant economic barriers and geographic disparities, particularly in 2025. , individual HBOT sessions typically cost between $200 and $500, depending on the facility and location. A full course of treatment for chronic wounds, often requiring 20 to 40 sessions, can total $10,000 to $20,000 or more when not covered by . Home hyperbaric units, usually soft-shell chambers operating at lower pressures, range from $5,000 to $20,000 but are largely unregulated for medical use, raising concerns about safety and for therapeutic applications. Insurance coverage for HBOT is restricted to FDA-approved indications, such as , , and ulcers, with Medicare and reimbursing up to 20 to 40 sessions per course for these conditions. Private insurers vary widely in their policies, often approving coverage only for on-label uses while frequently denying claims for off-label applications like or symptoms. For example, Kaiser Permanente does not cover HBOT for the treatment of sarcopenia (age-related muscle loss), as it is considered investigational or off-label for this indication and not among the FDA-approved indications. This selective reimbursement exacerbates costs for patients seeking HBOT beyond standard protocols. Geographic access further compounds these challenges, with approximately 1,200 hyperbaric facilities operating in the as of 2025, predominantly concentrated in urban areas. Rural regions face acute shortages, as the high cost of equipment and staffing limits facility development outside major cities, leading to burdens for patients in underserved areas. Globally, disparities are even more pronounced, with HBOT availability severely restricted in low-income countries due to limitations and constraints; for instance, specialized centers are rare even in parts of , where only isolated initiatives, such as a recent facility in , provide limited access. Emerging trends in 2025 are beginning to address some logistical barriers through technological integration. platforms now enable remote monitoring and consultations for HBOT patients, reducing the need for frequent in-person visits and improving accessibility in remote or rural settings. In , post-COVID funding has supported clinical trials for HBOT in management, enhancing availability through subsidized programs in countries like the and , where registries and placebo-controlled studies have demonstrated potential benefits. Equity issues persist, particularly for vulnerable populations. Veterans exhibit higher utilization of HBOT for (TBI), often through clinical trials despite routine coverage denials by the ; in 2025, bills such as S.2737 and H.R.1336 were introduced to establish pilot programs for HBOT in TBI and PTSD treatment, alongside highlighted in a documentary. efforts continue for expanded insurance inclusion, including for emerging applications like anti-aging research, where HBOT shows promise in countering age-related cellular decline but remains off-label and uncovered by most plans.

Research directions

Neurological applications

Hyperbaric oxygen therapy (HBOT) has emerged as a promising adjunctive treatment for various neurological conditions, particularly those involving and . By delivering 100% oxygen at pressures greater than 1 atmosphere absolute (ATA), HBOT enhances oxygen delivery to hypoxic brain tissues, promotes , and modulates inflammatory pathways. Recent meta-analyses indicate significant improvements in neurocognitive outcomes for conditions like (TBI) and , with mechanisms including reduced levels of pro-inflammatory cytokines such as TNF-α and IL-6, which mitigate neuronal damage and support recovery. In TBI, a 2024 systematic review and meta-analysis indicated that HBOT enhances neurocognitive outcomes. Similar benefits extend to stroke, where HBOT supports and improves neurological function, as evidenced by enhanced cognitive scores in post-stroke patients. These gains are attributed to HBOT's ability to reduce and preserve mitochondrial integrity, though protocols varied across studies without standardization. For neuro-rehabilitation in (PCS), a 2025 of 26 adults with childhood TBI reported notable improvements after at least 40 HBOT sessions at 2 ATA, including executive function gains of 5.94 ± 8.88 points (p=0.0028) and enhancements of 8.50 ± 9.09 points (p=0.00003), independent of injury age (mean 23.6 years post-TBI). These findings suggest HBOT induces neuroplastic changes that alleviate persistent symptoms, with effect sizes indicating moderate to large improvements (r=0.628 for executive function). Research into neurodegenerative diseases like (AD) and (PD) highlights HBOT's potential for amyloid clearance and cognitive support. A 2024 meta-analysis of randomized controlled trials with AD patients showed HBOT improved Mini-Mental State Examination (MMSE) scores and reduced oxidative stress markers like (MDA), with preclinical rodent models demonstrating enhanced Aβ plaque degradation in the cortex and hippocampus. For (MCI) in early AD or PD, 2025 Phase II trials are exploring mild HBOT at 1.5 ATA, building on preclinical data showing reduced Aβ-induced toxicity; however, a 2025 protocol for PD-MCI meta-analysis underscores the need for more RCTs to confirm efficacy. Addressing evidence gaps, HBOT has shown benefits for neurological symptoms in post-viral conditions. A 2025 prospective registry study reported that a majority of patients with severe brain fog experienced symptom reduction after HBOT, with improvements in quality-of-life scores () and enhanced executive function via induction. Similarly, a 2025 preprint on (ME/CFS) found HBOT improved clinical symptoms and functional capacity, reducing fatigue through mitochondrial support and restoring thalamic connectivity in affected patients. Despite these advances, challenges persist in neurological HBOT applications, including unclear optimal dosing—varying from 1.5-2.5 ATA over 20-60 sessions—and the paucity of large-scale RCTs to establish long-term and . HBOT for neurological conditions remains investigational and is not approved by organizations like the FDA or UHMS as of November 2025, with ongoing debates regarding in larger trials. Ongoing trials emphasize the need for standardized protocols to bridge these gaps and confirm benefits beyond small cohorts.

Wound healing and oncology

Hyperbaric oxygen therapy (HBOT) has been investigated for its role in promoting , particularly in chronic conditions where tissue oxygenation is impaired. In ulcers, a 2024 and of randomized controlled trials demonstrated that HBOT significantly increases the complete rate compared to standard care alone, with odds ratios indicating a substantial benefit in ulcer closure within 6 to 12 weeks. For venous leg ulcers, evidence is more limited, but a 2023 reported that HBOT reduces ulcer area and supports partial , though it does not consistently achieve complete resolution. These effects are attributed to HBOT's enhancement of , synthesis, and activity in hypoxic beds. In radiation-induced wounds, HBOT serves as an effective adjunct for managing , a severe complication following radiotherapy for head and neck cancers. Clinical studies have shown response rates of up to 87% in complete resolution or significant improvement of necrotic bone and soft tissue, with HBOT promoting neovascularization and reducing in irradiated tissues. A 2025 systematic review confirmed these outcomes, noting that HBOT protocols of 30-40 sessions at 2.4 atmospheres absolute pressure yield durable healing in 80-90% of cases when combined with conservative or surgical management. Emerging research extends HBOT's wound healing applications to respiratory distress syndromes involving alveolar damage, such as (ARDS) and pneumonia. Trials from 2023 to 2025 have indicated that HBOT reduces proinflammatory markers and improves oxygenation through anti-inflammatory mechanisms that mitigate storms and endothelial damage. For instance, a 2023 case-control study reported enhanced and decreased infection severity biomarkers in hypoxemic patients after 10 HBOT sessions. In oncology, HBOT is explored as an adjunct to radiotherapy (RT) and chemotherapy to address tumor hypoxia, a key barrier to treatment efficacy. A 2025 review in Biomedicine & Pharmacotherapy highlighted that HBOT sensitizes hypoxic tumor regions by increasing oxygen delivery, thereby augmenting RT-induced DNA damage and chemotherapy penetration, with preclinical models showing improved tumor control. Specifically for head and neck cancers, HBOT combined with RT has been considered safe and may support local control as a hypoxic modifier, though evidence on survival benefits remains limited. Preclinical studies further demonstrate that HBOT enhances immunotherapy by improving immune cell oxygenation and T-cell infiltration into the tumor microenvironment, potentially overcoming resistance in solid tumors. Current research gaps include HBOT's potential in anti-aging wound prevention, where a 2024 Frontiers in Aging review described how HBOT reverses in fibroblasts by lengthening telomeres and modulating , suggesting applications in preventing age-related impaired . Additionally, combining HBOT with therapies shows promise for regenerative repair; a 2018 study found that HBOT boosts proliferation and , accelerating closure in chronic wounds by 20-30% in animal models. Looking to the future, personalized HBOT protocols tailored to tumor hypoxia via imaging modalities like could optimize outcomes in , allowing dose adjustments based on real-time oxygenation levels to maximize radiosensitization while minimizing toxicity. Such approaches may integrate HBOT with advanced imaging to target hypoxic niches selectively in heterogeneous tumors.

References

  1. https://www.mayoclinic.org/tests-procedures/hyperbaric-oxygen-therapy/about/pac-20394380
  2. https://www.fda.gov/consumers/consumer-updates/hyperbaric-oxygen-therapy-get-facts
  3. https://www.uhms.org/resources/featured-resources/hbo-indications.html
  4. https://www.fda.gov/medical-devices/letters-health-care-providers/follow-instructions-safe-use-hyperbaric-oxygen-therapy-devices-letter-health-care-providers
  5. https://www.ncbi.nlm.nih.gov/books/NBK448104/
  6. https://pmc.ncbi.nlm.nih.gov/articles/PMC8465921/
  7. https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/hyperbaric-oxygen-therapy
  8. https://www.ncbi.nlm.nih.gov/books/NBK470481/
  9. https://medlineplus.gov/ency/article/002375.htm
  10. https://pmc.ncbi.nlm.nih.gov/articles/PMC6690283/
  11. https://www.med.upenn.edu/pennhyperbarics/history-at-penn
  12. https://emedicine.medscape.com/article/1464149-overview
  13. https://woundreference.com/p/topic?id=gas-laws
  14. https://www.ncbi.nlm.nih.gov/books/NBK482231/
  15. https://www.ncbi.nlm.nih.gov/books/NBK459191/
  16. https://www.ncbi.nlm.nih.gov/books/NBK430743/
  17. https://pmc.ncbi.nlm.nih.gov/articles/PMC4297009/
  18. https://pmc.ncbi.nlm.nih.gov/articles/PMC5467109/
  19. https://pmc.ncbi.nlm.nih.gov/articles/PMC3495382/
  20. https://www.ncbi.nlm.nih.gov/books/NBK482485/
  21. https://pmc.ncbi.nlm.nih.gov/articles/PMC8884396/
  22. https://pmc.ncbi.nlm.nih.gov/articles/PMC4495753/
  23. https://pmc.ncbi.nlm.nih.gov/articles/PMC8851036/
  24. https://pmc.ncbi.nlm.nih.gov/articles/PMC12111948/
  25. https://pmc.ncbi.nlm.nih.gov/articles/PMC10858389/
  26. https://pmc.ncbi.nlm.nih.gov/articles/PMC6147229/
  27. https://www.openanesthesia.org/keywords/hyperbaric-oxygen-therapy/
  28. https://health.mil/Reference-Center/Publications/2025/07/25/Hyperbaric-Oxygen-Therapy-and-TBI
  29. https://www.nejm.org/doi/full/10.1056/NEJMoa013121
  30. https://pmc.ncbi.nlm.nih.gov/articles/PMC6367868/
  31. https://diving-rov-specialists.com/index_htm_files/scient-c_490-hyperbaric-oxygen-deco-sickness_2021-update.pdf
  32. https://www.sciencedirect.com/science/article/pii/S0741521419321573
  33. https://www.uhcprovider.com/content/dam/provider/docs/public/policies/comm-medical-drug/hyperbaric-topical-oxygen-therapy.pdf
  34. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD005005.pub5/full
  35. https://www.uhms.org/14-idiopathic-sudden-sensorineural-hearing-loss-new-approved-on-october-8-2011-by-the-uhms-board-of-directors.html
  36. https://pmc.ncbi.nlm.nih.gov/articles/PMC9605195/
  37. https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2024.1453055/full
  38. https://www.acep.org/uhm/newsroom/march-2024/announcing-hbos-newest-indication-avascular-necrosis
  39. https://pubmed.ncbi.nlm.nih.gov/24984320/
  40. https://pmc.ncbi.nlm.nih.gov/articles/PMC11496187/
  41. https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2024.1450134/full
  42. https://chicagoneuro.com/hbot-stroke-recovery-what-science-says/
  43. https://www.nature.com/articles/s41598-024-53091-3
  44. https://www.medrxiv.org/content/10.1101/2025.10.29.25339096v1.full
  45. https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2024.1354088/full
  46. https://www.sciencedirect.com/science/article/pii/S0753332225008972
  47. https://pubmed.ncbi.nlm.nih.gov/39923138/
  48. https://www.mdpi.com/1648-9144/61/3/385
  49. https://www.frontiersin.org/journals/aging/articles/10.3389/fragi.2024.1368982/full
  50. https://www.scivisionpub.com/pdfs/regenerative-longevity-medicine-hyperbaric-oxygen-therapy-as-a-cornerstone-for-healthy-aging-3714.pdf
  51. https://aha-hyperbarics.com/hbot-science/regenerative-medicine-and-hbot/
  52. https://www.nature.com/articles/s41598-024-62161-5
  53. https://jmedicalcasereports.biomedcentral.com/articles/10.1186/s13256-025-05453-2
  54. https://www.mdpi.com/2039-7283/13/3/53
  55. https://pubmed.ncbi.nlm.nih.gov/40594255/
  56. https://pubmed.ncbi.nlm.nih.gov/38225877/
  57. https://www.uhms.org/images/Safety-Articles/safe_design_and_operation_of.pdf
  58. https://www.uhms.org/images/Safety-Articles/guidelines_for_clinical_mult.pdf
  59. https://www.uhms.org/images/Accreditation-Documents/Fourth_Edition_UHMS_Accreditation_Manual_Final_6-4-2018.pdf
  60. https://www.uhms.org/images/DCS-and-AGE-Journal-Watch/antonellli_guiding_principle.pdf
  61. https://www.ncbi.nlm.nih.gov/books/NBK499820/
  62. https://hbotresearch.org/best-soft-shell-hyperbaric-chambers/
  63. https://www.eubs.org/documents/DHM%20Sep2012%20Suppl%20Treatment%20tables.pdf
  64. https://woundreference.com/p/topic?id=hbo-treatment-indication-with-protocol
  65. https://www.uhms.org/pt/resources/featured-resources/medfaqs-frequently-asked-questions-faq/safety-technical/treatment-protocol.html
  66. https://www.sciencedirect.com/science/article/abs/pii/S0196070917307329
  67. https://www.uhms.org/images/CPG/UHM_42-3_CPG_for_DFU.pdf
  68. https://www.hyperbaricmedicalsolutions.com/the-complete-guide-to-hyperbaric-oxygen-therapy
  69. https://www.uhms.org/images/Safety-Articles/Hyperbaric%20Safety%20bullet%20%20v4.17.25%20Clean-u.pdf
  70. https://www.uhms.org/education/credentialing/certification-cht-chrn-dmt.html
  71. https://pmc.ncbi.nlm.nih.gov/articles/PMC10232961/
  72. https://www.uhms.org/resources/publications/undersea-hyperbaric-medicine-journal.html
  73. https://www.uhms.org/pt/uhm-search/uhm-journal-volume-51-2024/number-4/680-manuscript.html
  74. https://stateline.org/2025/09/15/deaths-prompt-state-lawmakers-to-consider-new-hyperbaric-oxygen-therapy-rules/
  75. https://www.ncbi.nlm.nih.gov/books/NBK557661/
  76. https://www.medrxiv.org/content/10.1101/2022.06.20.22276590v1
  77. https://www.intechopen.com/chapters/66258
  78. https://www.jameslindlibrary.org/van-helmont-jb-1648/
  79. https://pmc.ncbi.nlm.nih.gov/articles/PMC8682815/
  80. https://www.ddrc.org/hyperbarics/history-of-hbo/
  81. http://www.nimbot.com/Med/Hyperbarics/Life%20Without%20Blood.pdf
  82. https://pmc.ncbi.nlm.nih.gov/articles/PMC7827759/
  83. https://pmc.ncbi.nlm.nih.gov/articles/PMC6251354/
  84. https://www.abms.org/wp-content/uploads/2024/11/2023_24_ABMSCertReport_FNLPosting11_1.pdf
  85. https://www.fda.gov/medical-devices/safety-communications/do-not-use-hyperbaric-oxygen-therapy-unproven-treatment-conditions-fda-safety-communication
  86. https://www.cms.gov/medicare-coverage-database/view/ncd.aspx?ncdid=12
  87. https://www.eubs.org/?page_id=227
  88. https://applications.emro.who.int/emhj/0601/emhj_2000_6_1_93_99.pdf
  89. https://www.uhms.org/images/Position-Statements/UHMS_Cred_and_Priv_Guide_2022_final_Apr_2022_V2_Final28.pdf
  90. https://nbdhmt.org/certified-hyperbaric-technologist-training-and-certification/
  91. https://www.uhms.org/accreditation/accreditation-for-hyperbaric-medicine.html
  92. https://pubmed.ncbi.nlm.nih.gov/12067147/
  93. https://www.uhms.org/resources/approved-indications.html
  94. https://www.congress.gov/bill/119th-congress/senate-bill/2737
  95. https://www.cbs42.com/business/press-releases/cision/20251106DC18094/the-hyperbaric-institute-releases-film-va-denies-hbot-for-tbi-ptsd-as-22-veterans-die-daily
  96. https://www.neurology.org/doi/10.1212/WNL.0000000000211724
  97. https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2025.1641033/full
  98. https://www.frontiersin.org/journals/aging-neuroscience/articles/10.3389/fnagi.2024.1360148/full
  99. https://www.nature.com/articles/s41598-025-11539-0
  100. https://karger.com/dem/article/54/3/187/916434/Hyperbaric-Oxygen-Therapy-Improves-Motor-Symptoms
  101. https://pmc.ncbi.nlm.nih.gov/articles/PMC10965274/
  102. https://journals.sagepub.com/doi/10.1177/15385744231162924
  103. https://onlinelibrary.wiley.com/doi/10.1111/iwj.14427
  104. https://amj.amegroups.org/article/view/6298/html
  105. https://ro-journal.biomedcentral.com/articles/10.1186/s13014-025-02680-1
  106. https://www.researchgate.net/publication/365510879_Hyperbaric_oxygen_therapy_for_COVID-19_patients_with_respiratory_distress_treated_cases_versus_propensity-matched_controls
  107. https://www.mdpi.com/2077-0383/12/1/8
  108. https://pmc.ncbi.nlm.nih.gov/articles/PMC3510426/
  109. https://pmc.ncbi.nlm.nih.gov/articles/PMC10543083/
  110. https://onlinelibrary.wiley.com/doi/full/10.1002/advs.202100233
  111. https://pubmed.ncbi.nlm.nih.gov/30104981/
  112. https://advanced.onlinelibrary.wiley.com/doi/full/10.1002/anbr.202300162
  113. https://www.nature.com/articles/s41467-024-49156-6
Add your contribution
Related Hubs
User Avatar
No comments yet.