Hyperbaric Oxygen Therapy

Last updated date: 12-May-2023

Originally Written in English

Hyperbaric Oxygen Therapy


Hyperbaric oxygen therapy is a treatment in which a patient breaths 100 percent oxygen occasionally while within a treatment chamber at a pressure greater than that of sea level. Both in the United States and across the world, hyperbaric oxygen treatment has a long and varied history.

From its early usage in warfare through bridge construction, and through several introductions to medical advancements, it has been discussed and refined until its eventual adoption in multiple fields of patient care. From wound treatment to military applications, hyperbaric therapy is used in a variety of patient care settings, including single monoplace chambers and multipatient settings in larger chambers.


What is Hyperbaric Oxygen Therapy?

hyperbaric oxygen treatment (HBOT)

Breathing 100% oxygen while under higher atmospheric pressure is known as hyperbaric oxygen treatment (HBOT). HBOT is an ancient therapy that dates back to the 1600s. A British priest called Henshaw established and ran the first well-known chamber. He constructed the domicilium, which was used to cure a variety of ailments. The chamber could be inflated with air or left empty by utilizing bellows.

The French surgeon Fontaine, who constructed a pressurized, transportable operating theatre in 1879, carried on the notion of treating patients under higher pressure. The 1928 structure was 6 floors tall and 64 feet in circumference. The hospital's pressure might exceed three atmospheres. The hospital was terminated in 1930 because to a lack of scientific proof that such treatment relieved sickness. During WWII, it was disassembled for scrap.

The military kept using hyperbaric oxygen. The research of Paul Bert, who proved the harmful effects of oxygen (causing generalized convulsions), and J. Lorrain-Smith, who demonstrated pulmonary oxygen toxicity, were employed with Navy divers. Time to convulsions was used to quantify and assess exposure durations to oxygen at varying depths of water.


The number of HBOT treatment centers in the United States may be insufficient. Only 43 of the 361 chambers discovered across the country were suited to manage high-acuity patients. HBOT is useful in the treatment of decompression sickness, arterial gas embolisms, and acute carbon monoxide poisoning.


Hyperbaric Oxygen physiology

Hyperbaric Oxygen physiology

The majority of oxygen in the blood is coupled to hemoglobin, which is 97 percent saturated under normal pressure. However, some oxygen is carried in solution, and owing to Henry's rule, this amount increases under hyperbaric circumstances. Tissues extract 5-6 mL of oxygen per deciliter of blood while at rest, assuming appropriate perfusion.

At normobaric pressure, administering 100 % oxygen increases the amount of oxygen dissolved in the blood to 1.5 mL/dL; at 3 atmospheres, the dissolved-oxygen content is approximately 6 mL/dL, which is more than enough to meet resting cellular requirements without any contribution from hemoglobin. Because the oxygen is in solution, it can reach places where red blood cells may be unable to pass, and it can also offer tissue oxygenation when hemoglobin concentration or function is reduced.

Hyperoxia produces vasoconstriction in normal tissues, however this is compensated for by increased plasma oxygen content and microvascular blood flow. However, this vasoconstrictive impact reduces posttraumatic tissue edema, which aids in the treatment of crush injuries, compartment syndromes, and burns.

HBOT causes an increase in the production of oxygen free radicals, which oxidize proteins and membrane lipids, damage DNA, and interfere with bacterial metabolic processes. HBO is very efficient against anaerobes and aids the oxygen-dependent peroxidase system, which allows leukocytes to destroy germs.

Furthermore, evidence is mounting that HBOT affects the amounts of proinflammatory mediators, potentially dampening the inflammatory cascade. More research is needed to fully understand this intricate connection.

HBOT has the potential to reduce cardiac output since it is known to reduce heart rate while maintaining stroke volume. At the same time, HBOT raises afterload via systemic vasoconstriction. In people with severe illness, this combined action can aggravate congestive heart failure. Clinically substantial deterioration of congestive heart failure, on the other hand, is uncommon.


Hyperbaric oxygen therapy and the FDA’s role

Hyperbaric oxygen therapy

The tissues in our bodies require oxygen to operate. The air we breathe contains 21% oxygen. HBOT entails inhaling 100% (pure) oxygen while in a particular room known as a hyperbaric chamber. Inside, the air pressure is increased to a level greater than normal.

The higher air pressure in the chamber aids in the collection of oxygen by the lungs. Increasing the amount of oxygen delivered to tissues in need can help the body repair and fight infections. Too much oxygen, on the other hand, can be harmful to the body.

The FDA oversees both the oxygen used in HBOT and the hyperbaric chambers, which are often a tube large enough to house one person or a room large enough to hold many people.


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

A medical device's FDA approval involves a decision that it has the same intended purpose as, and is as safe and effective as, another lawfully U.S.-marketed product of that sort. The FDA has approved hyperbaric chambers for the following disorders as of July 2021:

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


HBOT is being researched for a variety of diseases, including COVID-19. However, the FDA has not certified or permitted the use of any HBOT device to treat COVID-19 or other conditions other than those indicated above at this time.


Unapproved uses

HBOT is now being offered as an alternative therapy by an increasing number of providers. Some refer to it as a "wonder treatment," claiming that it can assist with a variety of ailments.

HBOT chambers are popping up in a variety of settings, from hospital outpatient departments to spas. There are even chambers for use at home. While some of the claims seem plausible, the FDA has expressed worry about the hazards of using HBOT "off label."


The FDA point out that they have not approved HBOT as a treatment for the following:

HBOT should only be used for the approved uses. Otherwise, a person may lose time and money while also risking adverse consequences. The FDA has advised that using HBOT for unapproved uses may aggravate an existing condition.


How is hyperbaric oxygen works?

hyperbaric oxygen chamber

A pressure chamber, which can be rigid or flexible in design, and a mechanism of providing 100 percent oxygen are required for hyperbaric oxygen treatment. The procedure is carried out according to a specified timetable by qualified staff who monitor the patient and may change the schedule as needed.

HBOT was first used to treat decompression sickness, and it has since shown to be extremely efficient in treating illnesses such as gas gangrene and carbon monoxide poisoning. More recent studies have looked at whether it may help with other disorders like cerebral palsy and multiple sclerosis, but no meaningful evidence has been identified.

In most cases, therapeutic recompression is also available in a hyperbaric chamber. It is the only therapy for decompression sickness, and it can also be used to treat arterial gas embolism induced by ascending pulmonary barotrauma. In an emergency, provided adequate diving equipment (to reasonably secure the airway) is available, divers may be treated by in-water recompression (when a chamber is not accessible).


Contraindications of hyperbaric oxygen therapy

Untreated pneumothorax is an unequivocal contraindication to hyperbaric oxygen treatment. The rationale for this is that there is risk that it will proceed to tension pneumothorax, particularly during the decompression phase of therapy, albeit treatment on oxygen-based tables may prevent this advancement. For similar reasons, the COPD patient with a big bleb is a relative contraindication. Furthermore, the treatment may bring up the topic of occupational health and safety (OHS), which the therapist has faced.

The following are relative contraindications, which require careful attention by specialized physicians before HBO therapies may begin:

  • Cardiac disease
  • COPD with air trapping – can lead to pneumothorax during treatment.
  • Upper respiratory infections – These diseases might make it difficult for the patient to equalize their ears or sinuses, resulting in ear or sinus tightness.
  • High fevers – In most situations, the temperature should be brought down before beginning HBO therapy. Fevers can lead to convulsions.
  • Emphysema with CO2 retention – Because of the rupture of an emphysematous bulla, this condition might result in a pneumothorax during HBO therapy. An x-ray can be used to assess this risk.
  • History of thoracic (chest) surgery – This is seldom a problem and is rarely seen as a contraindication. However, there is worry that air may become trapped in surgical scarring sites. Before pursuing HBO treatment, these conditions must be considered.
  • Malignant disease: Cancer thrives in blood-rich settings, while high oxygen levels may inhibit them. HBO therapy of cancer patients offers a challenge since HBO both improves blood flow via angiogenesis and elevates oxygen levels. Taking an anti-angiogenic vitamin may be beneficial.
  • Because of the need to equalize pressure in the ears, middle ear barotrauma is always a factor in treating both children and adults in a hyperbaric environment.


  • Pregnancy may not exclude hyperbaric oxygen treatments, although it may preclude underwater diving. Lower pressure HBOT treatments are not detrimental to the baby in situations when a pregnant woman has carbon monoxide (CO) poisoning, and the danger involved is offset by the larger risk of the treated effects of CO on the fetus (neurologic abnormalities or death.) HBO treatment has been established in pregnant individuals to be safe for the unborn when administered at suitable amounts and "doses" (durations). In fact, pregnancy reduces the threshold for HBO therapy in individuals who have been exposed to carbon monoxide. This is owing to fetal hemoglobin's strong affinity for CO.


Complications of hyperbaric oxygen therapy

While it is normally quite safe, Hyperbaric Oxygen Therapy, like other medical therapies, includes the potential of consequences that, in rare cases, might be life-threatening and/or result in severe or long-term impairment.

Barotrauma of the ear

Injury caused by elevated pressure is referred to as barotrauma. The most common consequence of HBO is ear barotrauma. The middle ear is an air-filled hollow beneath the ear drum that communicates to the throat via the eustachian tube, a slit-like duct. If the air pressure in the middle ear cannot be equalized with the external pressure during compression, the eardrum may bow inward, causing discomfort and perhaps rupture, resulting in hearing loss.

Round or oval window rupture

A round or oval window rupture is a condition associated with ear barotrauma. The round and oval windows are membranes that separate the fluid-filled inner ear from the air-filled middle ear. Excessive attempts to equalize pressure in the middle ear can occasionally result in increased pressure in the inner ear and rupture of these membranes. The end outcome is deafness. While the rupture of these windows is not directly connected to pressure changes, it is related to maneuverers utilized to avoid another issue.

Sinus squeeze

The sinuses, like the middle ear, are air-filled chambers in the skull. Failure to balance the pressure between the sinuses and the external environment causes significant discomfort and, in some cases, sinus hemorrhage.

Tooth squeeze

Air-filled gaps in teeth can be caused by recent dental treatment. The failure to equalize the pressure in these pockets can cause discomfort and even tooth breakage.

Pneumothorax or pulmonary barotrauma

Pulmonary barotrauma is caused by pressure changes that cause air to escape from the lungs into the chest cavity, resulting in a fallen lung, or pneumothorax. This is more common in people with air trapping lesions in the lungs, such as those found in emphysema or asthma. These air-filled pockets will begin to grow during decompression, and if the pressure is not alleviated by the airways in the lungs, these pockets will explode.

This expelled air can produce excess pressure in the chest cavity, resulting in difficulties breathing and low blood pressure, which can lead to death if left untreated. The treatment comprises of removing air from the chest cavity by putting a needle through the chest wall and then introducing a chest tube to re-expand the lung.

Oxygen toxicity seizures

The high level of oxygen in the blood during HBO treatments can be harmful to the central nervous system and cause seizures. While this is uncommon during clinical hyperbaric treatments, it does happen and may be more common in persons who have a history of seizure problems or hypoglycemia (low blood sugar). The treatment consists of just withdrawing the patient's supplementary oxygen, which will end the seizure.

Pulmonary oxygen toxicity

Increased oxygen concentrations can be harmful to the lungs. Prolonged exposure to high oxygen levels can result in chest discomfort, difficulty breathing, and, finally, respiratory failure. When the oxygen concentration is reduced in the early stages of the illness, the lungs quickly recover to baseline.

Thus, pulmonary oxygen toxicity is uncommon in clinical practice due to the intermittent nature of HBO therapies. On the other hand, in severely sick patients who must be kept on supplementary oxygen between treatments, or in patients who require extremely frequent or protracted treatment sessions, this might be a worry.

Decompression sickness

Decompression sickness, sometimes known as the bends, is caused by the absorption of nitrogen into the blood by breathing air (which is approximately 80% nitrogen) at higher ambient pressure. This is more of a worry for inside attendants, who breathe air throughout treatment than for patients, who breathe 100% oxygen. This can be a problem if a patient needs to be disconnected from oxygen for extended periods of time during the dive. Decompression illness can cause discomfort, brain impairment, cardiac collapse, and, in extreme cases, death.


Frequently asked question about Hyperbaric oxygen therapy

Hyperbaric oxygen therapy

  • What to expect after Hyperbaric oxygen therapy?

Hyperbaric oxygen treatment takes place in a pressurized, enclosed environment. You can either lie down or sit up straight. A tailored oxygen breathing hood is put over your head, allowing oxygen to dissolve in your plasma instantaneously. This increases the pace at which concentrated oxygen is delivered to sick tissue. The breathing hood is given oxygen until the oxygen level reaches 100%. (the air we breathe only contains 21 percent oxygen). At the same time, the pressure surrounding your body gradually rises above normal air pressure.

The combination of pure oxygen and increased pressure pulls oxygen into your bloodstream more quickly and efficiently. As a result, the oxygen level in your blood is elevated above what would be possible with regular air pressure. This additional oxygen is given to your bodily tissues via your bloodstream.


  • How Many Sessions Will I Need?

The number of sessions required is determined on your condition and response to therapy. Some emergency treatments (for example, carbon monoxide poisoning) may only take a few sessions, whilst others (for example, diabetic foot ulcer) may require more than 30.


  • What is the Length of an HBOT Session?

A typical hyperbaric oxygen therapy session lasts two hours.


  • How to Prepare for HBOT Treatment?

To ensure that you are appropriately prepared for each treatment session, our hyperbaric medicine experts will go over the following information with you in detail.


  • What are Products and Medications to Avoid?

Caffeine and cigarettes narrow blood arteries, limiting the amount of blood that can be transported to your tissues. As a result, it is advised that you avoid caffeine and smoke during your therapy.

Some drugs might alter your body's response to oxygen. It is critical that you discuss any and all drugs you are presently taking with your doctor before beginning hyperbaric therapy.


  • What is the Cost of HBOT?

A one-hour HBOT treatment may cost $300 or more in a private clinic and more than $2,000 in a hospital. Physicians in the United States may legally prescribe HBOT for "off-label" diseases such as stroke and migraine.

These patients are seen at outpatient clinics. Most chambers in the United Kingdom are funded by the National Health Service, while others, such as those managed by Multiple Sclerosis Therapy Centers, are not. HBOT is not covered by Medicare in Australia as a therapy for multiple sclerosis. HBOT is used to treat over 80 diseases, illnesses, and traumas in China and Russia.



Hyperbaric oxygen therapy (HBOT) is a form of treatment used to hasten the healing of carbon monoxide poisoning, gangrene, non-healing wounds, and infections in which tissues are oxygen-starved. Although the FDA presently approves just 13 applications for HBOT, some people believe it may have additional advantages.

HBOT may have broader applications. However, like with other healthcare options, caution is advised. People who receive HBOT for unauthorized purposes may discover that providers lack the necessary credentials or that the facilities are dangerous or inefficient. They may spend money or suffer long-term consequences.