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Recompression Therapy

(Hyperbaric Oxygen Therapy)


Richard E. Moon

, MD, Duke University Medical Center

Last full review/revision Jun 2021| Content last modified Jun 2021
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Recompression therapy is administration of 100% oxygen for several hours in a sealed chamber pressurized to > 1 atmosphere, gradually lowered to atmospheric pressure. In divers, this therapy is used primarily for decompression sickness Decompression Sickness Decompression sickness occurs when rapid pressure reduction (eg, during ascent from a dive, exit from a caisson or hyperbaric chamber, or ascent to altitude) causes gas previously dissolved... read more , arterial gas embolism Arterial Gas Embolism Arterial gas embolism is a potentially catastrophic event that occurs when gas bubbles enter or form in the arterial vasculature and occlude blood flow, causing organ ischemia. Arterial gas... read more , carbon monoxide poisoning Carbon monoxide poisoning Various physiologic (eg, oxygen, nitrogen, carbon dioxide) and nonphysiologic (eg, carbon monoxide) gases can cause symptoms during diving. (See also Overview of Diving Injuries.) Oxygen toxicity... read more , and other conditions. A shorter time to start of therapy is associated with a better patient outcome, but therapy should be started anytime within a few days of surfacing. Despite therapy, severe injury predicts a poor outcome. Untreated pneumothorax requires chest tube placement before or at the start of recompression therapy.

The goals of recompression therapy in diving injuries include all of the following:

  • Increasing oxygen solubility and delivery

  • Increasing nitrogen washout

  • Decreasing carbon monoxide concentration

  • Decreasing gas bubble size

  • Reducing tissue ischemia


Because recompression is relatively well tolerated, it should be started if there is any likelihood that it would promote recovery; recompression may help even if started up to several days after surfacing. However, success is lower if started > 48 hours after symptom onset.

Recompression chambers are either multiplace, with space for one or more patients on a gurney and for a medical attendant, or monoplace, with space for only one patient. Although monoplace chambers are less expensive, they have some disadvantages when used for critically ill patients, such as limited access to patients who may require intervention while in the chamber.

Information regarding the location of the nearest recompression chamber, the most rapid means of reaching it, and the most appropriate source to consult by telephone should be known by most divers, medical staff members, and rescue and police personnel in popular diving areas.

Such information is also available from the Divers Alert Network (919-684-9111) 24 hours a day. The Undersea and Hyperbaric Medical Society is another invaluable source of general information about recompression. Physician-to-physician consultation can be obtained through Duke Dive Medicine (919-684-8111).

Recompression protocols

Pressure and duration of treatment are usually decided by a hyperbaric medicine specialist at the recompression facility. Treatments are given once or twice a day for 45 to 300 minutes until symptoms abate; 5- to 10-minute air breaks are added to reduce risk of oxygen toxicity. Chamber pressure is usually maintained between 2.5 and 3.0 atmospheres (atm), but patients with life-threatening neurologic symptoms due to gas embolism may begin with an excursion to 6 atm to rapidly compress cerebral gas bubbles.

Although recompression therapy is usually done with 100% oxygen or compressed air, special gas mixtures (eg, helium/oxygen or nitrogen/oxygen in nonatmospheric proportions) may be indicated if the diver used an unusual gas mixture or if depth or duration of the dive was extraordinary. Specific protocol tables for treatment are included in the US Navy Diving Manual.

Patients with residual neurologic deficits should be given repetitive, intermittent hyperbaric treatments and may require several days to reach maximum improvement.

Complications of recompression therapy

Contraindications to recompression therapy

Patients with pneumothorax require tube thoracostomy How To Do Surgical Tube Thoracostomy Surgical tube thoracostomy is insertion of a surgical tube into the pleural space to drain air or fluid from the chest. Pneumothorax that is recurrent, persistent, traumatic, large, under tension... read more How To Do Surgical Tube Thoracostomy before recompression therapy unless the pneumothorax is small and the patient is being treated in a multiplace chamber with staff and equipment required to treat tension pneumothorax immediately available.

Relative contraindications include

  • Obstructive lung disorders

  • Upper respiratory or sinus infections

  • Severe heart failure

  • Recent ear surgery or injury

  • Claustrophobia

  • Recent chest surgery

Key Points

  • Arrange for indicated recompression therapy as soon as possible.

  • Although delays until treatment reduce the success rates, do not exclude recompression therapy based on the amount of time elapsed since surfacing.

  • If an unstable patient needs recompression therapy, use a multiplace chamber if possible.

  • Patients with pneumothorax generally require tube thoracostomy before recompression therapy.

More Information

The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.

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