Hyperbaric Treatment for Decompression Sickness

HBOT is the primary and definitive treatment for decompression sickness.

If you think you have decompression sickness, call the Divers Alert Network (DAN) 24-hour emergency line immediately: +1-919-684-9111. They can locate the nearest hyperbaric chamber. Don’t wait to see if symptoms improve on their own.

Decompression sickness (DCS), sometimes called “the bends,” is a diving emergency. It happens when nitrogen that dissolved in your tissues during a dive forms bubbles during ascent. Those bubbles cause real damage. HBOT is the only treatment that directly addresses the problem.

For background on how HBOT works in general, visit our guide to hyperbaric oxygen therapy.

What Is Decompression Sickness?

When you dive deep, the increased pressure forces nitrogen to dissolve into your blood and tissues. If you ascend too quickly, the pressure drops before that nitrogen can safely leave your body. It comes out of solution and forms bubbles, the same way CO2 bubbles appear when you open a carbonated drink.

Those bubbles don’t just hurt. They block circulation, trigger inflammation, and damage tissue mechanically wherever they form.

DCS is divided into two types based on where bubbles form and what symptoms result.

Type I

Type I involves milder presentations: joint and muscle pain (the classic “bends”), skin rash or mottling, and lymphatic swelling.

Type II

Type II is more serious. Symptoms include neurological effects like weakness, numbness, paralysis, or confusion. Inner ear involvement causes vertigo, hearing loss, and tinnitus. Pulmonary symptoms, called “the chokes,” present as chest pain, shortness of breath, and cough.

Type II DCS is a medical emergency. Even Type I symptoms should be evaluated right away. What starts mild can progress.

Arterial gas embolism (AGE), which occurs when air enters the arterial circulation due to pulmonary barotrauma, is a separate but related condition. It’s treated the same way and often on the same recompression table.

How HBOT Treats Decompression Sickness

HBOT works on DCS through two mechanisms: physics and biology.

The Physics

Boyle’s Law states that as pressure increases, gas volume decreases. When you’re recompressed inside a hyperbaric chamber, the nitrogen bubbles in your tissues physically shrink. This reduces the mechanical damage they cause and restores blood flow to blocked areas.

The Biology

Breathing 100% oxygen under pressure creates what’s called the “oxygen window.” When pure oxygen replaces nitrogen in the blood, it creates a steep pressure gradient that pulls dissolved nitrogen out of tissues and into the lungs, where it’s exhaled. HBOT accelerates nitrogen elimination significantly faster than breathing air or surface-level oxygen.

The Protocol

Treatment follows US Navy Treatment Tables, which are standardized recompression protocols. The most common is Table 6, which runs at 2.8 ATA for approximately 4 hours and 45 minutes. Severe cases use Table 6A, which includes an initial deeper compression phase. A dive medicine specialist determines which table is appropriate and whether extensions are needed.

Time to treatment matters. The longer bubbles remain in tissues, the more secondary damage they cause. Don’t delay.

When to Seek Treatment

Any symptom appearing within 24 hours of a dive should be treated as possible DCS until proven otherwise. Symptoms don’t always appear immediately. They can be delayed by hours.

Watch for:

Joint pain, especially in shoulders, elbows, or knees
Skin rash, itching, or blotchy discoloration
Unusual fatigue or weakness
Numbness, tingling, or paralysis in any limb
Dizziness, vertigo, or hearing changes
Chest pain or difficulty breathing
Confusion or altered mental status

Don’t fly after a dive incident. Aircraft cabins are pressurized to the equivalent of 6,000 to 8,000 feet. That reduced pressure can make bubble formation worse. Wait until a dive medicine physician clears you. For healthy divers making normal recreational dives, the general guidance is to wait 12 to 24 hours before flying. After a dive incident, don’t fly until you’re evaluated and cleared.

Don’t assume mild symptoms will pass. Type I DCS can progress to Type II. Early HBOT is more effective than delayed treatment.

Call DAN’s 24-hour emergency line: +1-919-684-9111. They’ll locate the nearest hyperbaric chamber and help coordinate your care.

You can also find additional treatment cost information in our HBOT cost guide and coverage details in our insurance guide.

What the Research Shows

The evidence base for HBOT in DCS is strong. It’s been the standard of care in dive medicine for decades.

A 2014 review by Moon et al. in Undersea and Hyperbaric Medicine examined the evidence for HBOT as treatment for DCS. The review confirmed that recompression with hyperbaric oxygen remains the definitive treatment. It also discussed outcomes across different treatment table protocols and patient presentations. (PMID: 24851553)

A 2011 Lancet review by Vann, Butler, Mitchell, and Moon provided a comprehensive overview of decompression illness, its mechanisms, diagnosis, and treatment. The authors concluded that prompt HBOT remains the cornerstone of management for both DCS and AGE. (PMID: 21215883)

Because DCS is a relatively rare condition in a specific patient population (divers), large randomized controlled trials are difficult to conduct. The evidence base relies on case series, registry data, and mechanistic studies. But the clinical consensus across dive medicine is clear: HBOT works, and delays in treatment worsen outcomes.

Frequently Asked Questions

Can I treat mild decompression sickness without HBOT?

Even mild DCS should be evaluated by a dive medicine physician before you decide not to treat it. Some very mild Type I cases resolve with rest and surface oxygen. But delayed HBOT can still improve outcomes and prevent progression to Type II. Don’t self-diagnose. Call DAN at +1-919-684-9111.

How many HBOT sessions does DCS require?

It varies widely. Mild Type I cases may need one or two sessions using US Navy Table 5. Severe Type II cases may require multiple extensions of Table 6A, sometimes over several days. A dive medicine specialist determines the protocol based on your symptoms and response to treatment.

Should I fly after a dive accident?

No. Flying reduces ambient pressure, which can worsen bubble formation. Don’t fly until a dive medicine physician clears you. For routine dives, most guidelines recommend waiting 12 to 24 hours. After an actual DCS incident, the wait time is longer and individually determined.

Where can I find a hyperbaric chamber for DCS?

Contact the Divers Alert Network (DAN) 24-hour emergency line: +1-919-684-9111. They maintain an up-to-date database of hyperbaric chambers worldwide and can help coordinate emergency care. You can also find a provider through our Find a Provider Near You page.

References

Moon RE. Hyperbaric oxygen treatment for decompression sickness. Undersea Hyperb Med. 2014;41(2):151-157. PMID: 24851553
Vann RD, Butler FK, Mitchell SJ, Moon RE. Decompression illness. Lancet. 2011;377(9760):153-64. PMID: 21215883

Medical Disclaimer: This page is for informational purposes only. It does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before pursuing any medical treatment.