Hyperbaric oxygen therapy


Refers to breathing 100% oxygen while under increased atmospheric pressure.

When an individual receives 100% oxygen under pressure hemoglobin is saturated and can dissolve into the plasma.

Two basic chambers are used: multiplace and monoplace.

Monoplace chambers compresses one patient at a time, while a multiplace chambers treats multiple patients at one time.

100% oxygen at two to three times the atmospheric pressure at sea level and can result in arterial oxygen tension in excess of 20000 mm Hg and oxygen tension of almost 400 mn Hg.

Tissues at rest with normal perfusion extract 5-6 mL of oxygen per deciliter of blood.

At normobaric pressure blood oxygen concentration is 0.3 mL per deciliter.

100% oxygen at normobaric pressure increases amount of blood dissolved in the blood to 1.5 mL/dL and at 3 atmospheres oxygen dissolves to approximately 6 mL/dL.

At 6 mL/dL oxygen level in blood can meet oxygen requirements of resting cells without contribution of hemoglobin.

Oxygen in solution can reach areas that red blood cells cannot, and can provide oxygen when hemoglobin is impaired or dysfunctional.

The formation of inert gas bubbles in blood vessels and tissues causes decompression sickness and air embolism.

Hyperbaric medicine, also known as hyperbaric oxygen therapy (HBOT).

Refers to the medical use of oxygen at a level higher than atmospheric pressure.

Hyperbaric oxygen therapy treats patients with 100% oxygen at greater than 1.0 atmosphere (atm). It can be used to treat selected ischemic problem wounds, wounds caused by radiation, compromised flaps and grafts, and ischemia-reperfusion disorders.

The equipment required consists of a pressure chamber, and a means of delivering 100% oxygen.

Used in the treatment of decompression sickness, gas gangrene and carbon monoxide poisoning.

Approved uses:

Air or gas embolism

Carbon monoxide poisoning

Carbon monoxide poisoning complicated by cyanide poisoning

Central retinal artery occlusion

Gas gangrene due to Clostridal myositis and myonecrosis.

Crush injuries, compartment syndromes and traumatic ischemias

Decompression sickness

Enhancement of healing of diabetic wounds such as diabetic foot ulcers

Diabetic retinopathy

Diabetic nephropathy


Idiopathic sudden sensorineural hearing loss


Intracranial abscess

Necrotizing soft tissue infections


Delayed radiation injury of soft tissue and bony necrosis

Compromised skin grafts and flaps

Thermal burns

Idiopathic sudden deafness

Noise-induced hearing loss

Hyperbaric oxygen therapy has been shown to mitigate reperfusion injuries by temporarily inhibiting neutrophil β2 integrins and inducing activity of antioxidant enzymes and anti-inflammatory proteins.

Multiple studies have been published in the form of case reports with positive outcomes using HBOT for frostbite.

Not efficacious for: autism, cancer, diabetes, HIV/AIDS, Alzheimer’s disease, asthma, Bell’s palsy, cerebral palsy, depression, heart disease, migraines, multiple sclerosis, Parkinson’s disease, spinal cord injury, sports injuries, pressure ulcers, or stroke.

In diabetic foot ulcers it increases the rate of early ulcer healing but does not provide any benefit in wound healing at long term follow up, with no difference in amputation rate.

Suggested benefits in osteonecrosis of the jaw by facilitating wound healing by increasing local tissue oxygen tension, resulting in enhanced collagen production, angiogenesis, bone regeneration and oral tissue epithelialization, overcoming hypoxia, hypocellularity and hypovascularity due to effects of radiation therapy.

In a review of 7 studies there was no consistent evidence supporting hyperbaric oxygen therapy for either the prevention or management of osteonecrosis of the jaw(Sultan A, Dana Farber Cancer Institute).

In a 2004 multicenter trial of hyperbaric oxygen, the study was terminated due to worse outcomes in the hyperbaric arm -19% resolution with hyperbaric oxygen and 32% resolution with placebo (Annane).

Use in cerebral palsy found to have no difference compared to the control group.

May have efficacy in radiation cystitis.

The only absolute contraindication to HO therapy is untreated tension pneumothorax, as it can progress to a tension pneumothorax, especially during the decompression phase of therapy.

Large blebs associated with COPD is a relative contraindication.

HBO therapy is prohibited if they are taking or have recently taking the following drugs: doxorubicin, cisplatin, Antabuse, and mafenide acetate.

Relative contraindications to HBO include: cardiac disease, COPD with air trapping, URI, high fevers, CO2 retention, and malignancy,

Middle ear barotrauma is always a possibility with HBO hyperbaric because of the necessity to equalize pressure in the ears.

Pregnancy is not a relative contraindication to hyperbaric oxygen treatments.

Of therapeutic value when used 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.

Has the ability to drastically increase partial pressure of oxygen in the tissues of the body.

Side effects occur in about 17% of patients..

The most common side effect in this study was middle ear barotrauma.

Other rare barotrauma-related side effects include sinus/paranasal, dental, and pulmonary barotrauma.

Central nervous system (CNS) oxygen toxicity from HBOT can cause grand mal seizure activity.

HBOT associated seizure risk factors include higher treatment pressures, hypoglycemia, CNS tumors, lack of air breaks, carbon monoxide poisoning, and opioid use.

Ocular side effects of HBOT can include: cataract formation and temporary myopic refractory lens changes.

Claustrophobia or anxiety related to confinement can manifest in patients.

Majority of the side effects found were minor and successfully managed with no long-term sequelae.

The oxygen partial pressures achievable with HBOT are much higher than those achievable while breathing pure oxygen at normobaric conditions.

Under normal atmospheric pressure, oxygen transport is limited by the oxygen binding capacity of hemoglobin in RBC’s and very little oxygen is transported by blood plasma.

With HBOT oxygen transport by plasma, however is significantly increased.

HBOT mobilizes stem/progenitor cells from the bone marrow by a nitric oxide, suggesting the possibility of recovery of damaged organs and tissues .

The traditional type of hyperbaric chamber used for HBOT is a hard shelled pressure vessel.

A hard chamber may consist of a pressure vessel that is generally made of steel or aluminum, with the view ports made of acrylic.

There are one or more entry hatches.

An airlock allows patients to enter or exit the main chamber, and there is a small airlock for medicines, instruments, and food.

Two-way communication and visual monitoring is available.

A carbon dioxide scrubber is present, and a control panel outside the chamber to open and close valves that control air flow to and from the chamber, and regulate oxygen to helmets or masks.

A soft chamber may consist of a urethane-coated, nylon-bonded flexible acrylic pressure vessel with steel-weld technology, a full-length dual zipper-sealed opening and an over-pressure valve.

In large multiplace chambers patients and medical staff inside the chamber breathe from either flexible, transparent soft plastic hoods with a seal around the neck, or tightly fitting oxygen masks, which supply pure oxygen.

Patients breathe 100% oxygen most of the time during treatment, but have periods during which they breathe room air to minimize the risk of oxygen toxicity and decompression sickness.

The exhaled gas must be removed from the chamber to prevent the buildup of oxygen.

Small chambers can only accommodate the patient, and no medical staff can enter.

Chambers may be pressurised with pure oxygen or compressed air.

Initially developed as a treatment for diving disorders involving bubbles of gas in the tissues, such as decompression sickness and gas embolism by increasing pressure, reducing the size of the gas bubbles and improving the transport of blood to downstream tissues.

The high concentrations of oxygen in the tissues keep oxygen-starved tissues alive, and have the effect of removing the nitrogen from the bubble, making it smaller until it consists only of oxygen, which is re-absorbed into the body.

The slang term, for a cycle of pressurization inside the HBOT chamber is “a dive”.

An HBOT treatment may require a series of 20 to 40 dives, or compressions.

Compressions last for about an hour and can be administered via a hard, high-pressure chamber or a soft, low-pressure chamber.

Emergency HBOT for decompression illness employ a recompression to 2.8 bars (41 psi) absolute, the equivalent of 18 meters (60 ft) of water, for 4.5 to 5.5 hours with the toxicity of breathing pure oxygen, but taking air breaks every 20 minutes to reduce oxygen toxicity.

For deep dives the management 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.

Rsks associated with HBOT are similar to some diving disorders.

Pressure changes can cause barotrauma in the tissues surrounding trapped air inside the body, such as the lungs, behind the eardrum, inside paranasal sinuses, or trapped underneath dental fillings.

Other risks include the breathing high-pressure oxygen that may cause oxygen toxicity.

Optic lens swelling may cause temporarily blurred vision, and cataracts may progress following HBOT, and a rare side effect has been blindness secondary to optic neuritis may occur.

Inside the chamber patients may notice discomfort inside their ears as a pressure difference occurs between the middle ear and the chamber atmosphere: this can be relieved by the Valsalva maneuver or by jaw manipulation.

Increased pressure may also cause ear drums to rupture.

The pressure may be reduced by a valve allowing air out of the chamber.

Possible benefit in cerebrovascular diseases.

Prescribed for treating chronic wounds associated with radiation exposure, however, no significant evidence found for having either a positive or negative effect on radiation wounds.

Hyperbaric oxygen therapy for patients with breast toxicity is effective in reducing pain and fibrosis in women with late local effects of breast radiation.

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