FDA Approved Uses for Hyperbaric Oxygen Therapy: Decompression Sickness and Gas Embolism

Hyperbaric oxygen therapy was originally developed primarily to treat diving injuries, and these conditions remain among the most firmly established of all the FDA approved uses for hyperbaric oxygen therapy. Understanding how HBOT addresses decompression sickness and arterial gas embolism, and why timing is so critical for these conditions, is essential for divers, dive operators, and anyone who spends time in or around diving environments.

The Physics of Decompression Sickness

When a diver breathes compressed air at depth, the increased ambient pressure causes nitrogen to dissolve into the blood and tissues at elevated concentrations. If ascent is too rapid, this dissolved nitrogen comes out of solution, forming bubbles in the blood vessels and tissues. These bubbles can cause joint pain (the bends), neurological symptoms, pulmonary complications, and in severe cases, paralysis or death.

HBOT treats decompression sickness through a combination of mechanisms. First, elevated chamber pressure physically compresses the nitrogen bubbles, reducing their size according to Boyle's law. Second, breathing 100 percent oxygen creates a concentration gradient that drives nitrogen out of the tissues and into the lungs for elimination. Third, HBOT reduces the inflammatory damage triggered by bubble formation in vessel walls and surrounding tissue.

Gas Embolism: A Related Emergency

Arterial gas embolism occurs when gas enters the arterial circulation, typically through lung barotrauma during ascent or through medical procedures. The consequences depend on where the gas lodges, but cerebral gas embolism, where air bubbles block blood flow to the brain, is particularly devastating and requires immediate treatment.

For iatrogenic cerebral arterial gas embolism, research shows the probability of favorable outcome falls from approximately 65 percent with immediate HBOT to about 30 percent when treatment is delayed by 15 hours. The time-critical nature of this condition underscores the importance of recognizing symptoms quickly and accessing hyperbaric care without delay.

Treatment Protocols

Among the FDA approved uses for hyperbaric oxygen therapy, decompression sickness and gas embolism typically use the US Navy Treatment Tables, which are standardized recompression protocols developed over decades of dive medicine experience. These tables specify the pressure, oxygen breathing schedule, and treatment duration based on symptom severity.

Most cases are treated at 2.8 ATA using a structured schedule of oxygen breathing interrupted by air breaks to reduce oxygen toxicity risk. Severe cases may require extended or repeated treatment sessions.

Recognizing Symptoms That Require Treatment

Divers and their companions should know the symptoms that suggest decompression illness:

• Joint or limb pain (the bends), often affecting the shoulders, elbows, hips, or knees

• Skin mottling or itching (cutaneous symptoms)

• Breathing difficulties or chest pain (pulmonary symptoms)

• Neurological symptoms including numbness, weakness, confusion, or visual changes

• Extreme fatigue disproportionate to the dive profile

• Symptoms emerging within 24 to 48 hours of a dive

Any suspicion of decompression illness should prompt immediate contact with dive medicine services. In the United States, the Divers Alert Network provides 24-hour emergency dive medicine consultation.

Availability at Dive Destinations

Global dive destinations have varying HBOT availability. Thailand's dive tourism infrastructure is particularly well developed, with centers treating up to 500,000 visiting divers annually. Liveaboard operations often have access to emergency HBOT through partner facilities at nearby ports. In more remote locations, emergency evacuation to a hyperbaric facility may be necessary.

Divers who travel to remote locations should research HBOT availability at their destination before diving and ensure they carry adequate dive accident insurance that covers hyperbaric treatment and evacuation if necessary.

Outcomes and Prognosis

When treated promptly with appropriate HBOT protocols, most divers with decompression sickness achieve full or near-full recovery. The key variables are symptom severity, time to treatment, and appropriate protocol selection. Mild cases treated within a few hours often resolve completely with a single treatment table. Severe cases with neurological involvement may require multiple sessions and extended recovery periods.

Conclusion

Decompression sickness and gas embolism represent the historical origins of clinical HBOT and remain among its most clearly validated applications. The FDA approved uses for hyperbaric oxygen therapy in these conditions reflect decades of evidence from both laboratory research and clinical practice in dive medicine. For anyone who dives recreationally or commercially, understanding these conditions and having a plan for rapid access to HBOT care is an essential component of responsible dive safety.