Decompression sickness (DCS) is what happens when nitrogen bubbles form in tissue after a fast pressure drop. Divers get it. So do altitude pilots.
The standard fix is hyperbaric oxygen at depth-like pressure. This is one of the oldest uses of HBOT. The evidence base is field-built, not stacked with blinded trials.
This is a true emergency. Delay measured in hours can shift outcome from full recovery to lasting nerve injury.
Quick Facts
| Field | Value |
|---|---|
| FDA approval status | Recognized indication (one of 14) |
| UHMS classification | Tier 1 — approved indication, primary therapy |
| Typical protocol | US Navy Treatment Table 6 (2.8 ATA, ~4.75 hours), 1-5 sessions |
| Medicare coverage | Yes — covered under NCD 20.29, 2017 update |
| Insurance prior auth | Not required for emergent treatment |
| Evidence grade | GRADE B (strong consensus, limited modern RCT base) |
The evidence
DCS is one of the few HBOT uses where modern blinded trials do not exist and never will. You can't randomize a hurt diver to sham care.
The evidence is field-built. It comes from case series, Navy logs, and the Divers Alert Network injury data, 2024. DAN tracks about 1,000 dive injuries per year, with detailed follow-up on the chamber cases.
The hyperbaric treatment schedules summary, 2024 and the DAN treating DCS reference, 2024 both confirm that US Navy Table 6 is the dominant protocol worldwide. Complete recovery rates run 76 to 78 percent in pain-only DCS.
A 2015 retrospective on delayed recompression in PMC found that cases treated outside the ideal six-hour window still benefited. The takeaway is that delay reduces but does not eliminate the value of recompression.
The UHMS Indications Manual, 14th edition 2019 rationale for DCS is mechanistic. Hyperbaric oxygen shrinks bubbles, speeds inert gas washout, and re-oxygenates ischemic tissue. It also lowers CNS edema.
Where the evidence is mixed: comparisons between Treatment Table 6 and lower-pressure options like Cx30. Both protocols work. The choice is driven by chamber capacity, gas supply, and case severity.
Mechanism of action
DCS is a bubble disease. Nitrogen comes out of fluid and forms gas bubbles in tissue and blood. The bubbles do direct damage and set off swelling.
Hyperbaric oxygen treats DCS through three paths. First, raising ambient pressure shrinks bubble size. A bubble at sea level shrinks to about a third its size at 2.8 ATA.
Second, breathing pure oxygen at depth pulls nitrogen out of the bubble. The nitrogen goes back into plasma, where it can be exhaled.
Third, starved tissue downstream of the bubble gets oxygen back. This buys time for the bubble to clear before lasting damage sets in.
The mechanism is well-mapped. This is not a case where we are guessing why a treatment works.
Typical protocol
US Navy Treatment Table 6, in standard use since 1967 is the workhorse. It takes the patient to 60 feet of seawater (2.82 ATA) and runs about 4.75 hours.
The patient breathes 100 percent oxygen at 2.82 ATA for three 20-minute periods. Five-minute air breaks split each period. After 75 minutes at depth, pressure drops to 30 feet of seawater (1.9 ATA) for a longer oxygen-and-air segment.
Air breaks exist to limit pulmonary and CNS oxygen toxicity. Long uninterrupted high-pressure oxygen can trigger seizures.
For severe cases or arterial gas embolism, treatment may start with Treatment Table 6A. That table begins with brief compression to 165 feet before stepping back to Table 6 parameters.
Most DCS cases resolve in one or two sessions. Residual symptoms may need follow-up treatments at 2.0 to 2.4 ATA, run daily for 5 to 20 sessions.
Insurance and cost
Medicare covers DCS treatment under NCD 20.29, last reviewed 2017. DCS is a listed covered indication. No prior authorization is required for emergent care.
Commercial insurance generally follows the Medicare framework. Emergent treatment is rarely denied. Cost per emergent multiplace chamber recompression ranges from $1,500 to $4,000, depending on staffing and geography.
The catch: most clinics that offer HBOT do not run 24/7 emergency operations. Emergency recompression chambers cluster at academic medical centers, military bases, and dive-medicine specialty centers.
Where to get it
Not every UHMS-accredited site handles emergent DCS. Many wound-care HBOT clinics run weekday business hours. They lack staff trained for diver-injury management.
For emergent care, the DAN emergency hotline, available 24/7 since 1980 is the first call. DAN routes injured divers to the nearest functional recompression chamber. The network covers the US, Caribbean, and many international dive destinations.
The UHMS accredited facility directory, current 2026 lists sites with accreditation, but not all keep on-call DCS coverage. We cover what UHMS accreditation does and does not verify in our UHMS accreditation guide.
Patients should also verify chamber clearance via our FDA-cleared chambers list. DCS treatment requires a multiplace chamber capable of 2.8 ATA, not a soft-shell wellness setup.
Limitations and contraindications
The absolute contraindication is untreated pneumothorax. Compressing the chest with an unresolved pneumothorax can convert a benign collapse into a tension pneumothorax.
Relative contraindications include severe COPD with bullae, recent ear or sinus surgery, claustrophobia, and seizure disorders. Each requires case-by-case judgment in the emergent setting.
Pregnancy is not a contraindication for emergent DCS. The risk-benefit math favors treatment for the mother. Fetal outcomes in case series have been generally good.
Delay is the biggest practical limit on outcome. DCS treated within six hours has the best recovery rate. Outcomes decline progressively after 24 hours, though even late cases respond.
Active research
The ClinicalTrials registry, current 2026 lists active studies on DCS protocols. Some compare standard Table 6 against shorter or other schedules. The research focus has shifted toward picking the best protocol for each case.
The Diving and Hyperbaric Medicine journal, 2024 archive tracks much of this work. Recent registries look at first-treatment outcome differences and at the role of recompression for inner ear DCS specifically.
Active questions include the role of pre-hospital normobaric oxygen, the value of intravenous lidocaine as an adjunct, and optimal pressure for spinal cord DCS.
How this compares to off-label HBOT uses
DCS is a true emergency indication with mechanistic logic and decades of operational evidence. This sits at the opposite end of the spectrum from wellness-clinic off-label HBOT.
Off-label HBOT for long COVID, traumatic brain injury, and anti-aging makes claims that are not backed by FDA approval or UHMS endorsement. For context on how that gap matters, read our analysis of institutional silence on HBOT and our breakdown of marketing-driven HBOT claims.
DCS is what HBOT was originally designed for. The fact that other indications now share the chamber should not be read as equivalence in evidence.
Frequently asked questions
How fast does HBOT need to start after a dive injury?
The earlier the better. Within six hours is the operational target. Cases treated within 24 hours still respond well. Later treatment helps but with diminishing return.
Is one Treatment Table 6 enough?
For most pain-only DCS, yes. About 76 to 78 percent of cases resolve in one session. Persistent neurologic symptoms typically need follow-up daily treatments at lower pressure.
Can a portable soft-shell chamber treat DCS?
No. DCS requires 2.8 ATA, which soft-shell chambers cannot reach. They are not cleared by the FDA for DCS treatment.
What about altitude DCS in high-altitude pilots?
Same treatment framework. Recompression to 2.8 ATA reverses bubble formation regardless of whether the pressure drop came from ascent from depth or ascent into altitude.
Does insurance ever deny emergent DCS treatment?
Rarely. The Medicare framework covers it and most commercial plans follow. The bigger practical barrier is finding a chamber, not getting paid for one.
Sources
- US Navy Treatment Table 6 — Wikipedia summary, 2024
- DAN treating DCS reference, 2024
- Delayed recompression retrospective analysis, PMC 2015
- UHMS Indications Manual, 14th edition 2019
- Divers Alert Network — current research, 2024
- CMS NCD 20.29 Hyperbaric Oxygen Therapy, 2017
- Diving and Hyperbaric Medicine journal, 2024 archive
- UHMS accredited facility directory, current 2026
Medical disclaimer
This page is medical journalism, not medical advice. Decompression sickness is an emergency. Anyone with suspected DCS should call DAN at +1-919-684-9111 or local emergency services immediately. HBOT for DCS treats the condition; it does not cure all underlying injury, and outcome depends heavily on time-to-treatment. Talk to a hyperbaric-trained physician about any HBOT decisions.