Understanding Hyperbaric Chamber Types
A hyperbaric chamber is a sealed vessel capable of being pressurised above sea-level atmospheric pressure, allowing patients to breathe oxygen at elevated partial pressures. The clinical effect of HBOT depends on three variables: the chamber pressure (ATA), the inspired oxygen fraction (FiO₂), and the session duration. These, in turn, are shaped by chamber design.
Chambers divide into two broad categories by construction. Hard-shell chambers — rigid steel, aluminium, or thick acrylic — can safely reach the 2.0–3.0 ATA pressures recognised by the Undersea and Hyperbaric Medical Society (UHMS) for medical HBOT. All FDA-cleared medical HBOT devices are hard-shell. Soft-shell chambers — fabric envelopes with electric blowers — operate at 1.3 ATA and are FDA-cleared only for altitude sickness, though a large consumer market uses them off-label.
By patient capacity, chambers divide into monoplace (single patient in 100% oxygen) and multiplace (multiple patients breathing oxygen via mask inside an air-pressurised vessel). Both configurations deliver clinically equivalent HBOT at the same pressure; the choice is driven by facility scale, patient acuity, and the need for in-chamber clinical attendance.
Choosing a Chamber Type
For UHMS-approved clinical HBOT — wound care, radiation injury, emergency indications — hard-shell monoplace or multiplace chambers at 2.0–2.4 ATA are the standard. US Medicare reimbursement is tied to this clinical configuration. Patients should choose UHMS-accredited hospital or clinic facilities.
For off-label neurological HBOT — TBI, long COVID, stroke recovery — the strongest research evidence uses 2.0 ATA in hard-shell chambers (the Efrati Lab protocol). Private hyperbaric clinics with hard-shell chambers at this pressure are the typical delivery setting.
For home or wellness use — altitude sickness, general recovery, off-label protocols — soft-shell 1.3 ATA chambers are the dominant market. Clinical efficacy at this pressure for most indications is weaker than at clinical pressures; patients should set realistic expectations.
For veterinary HBOT — equine performance, canine wound care — species-sized hard-shell chambers at 1.5–3.0 ATA are used at specialty veterinary hospitals.
Chamber Safety
Modern hard-shell chambers are engineered to ASME PVHO-1 pressure vessel standards (US) or EN 14931 (Europe), with periodic recertification throughout a 20+ year operational lifespan. Soft-shell chambers are FDA Class II devices under 21 CFR 868.5470. All chambers require adherence to NFPA 99 fire-safety standards — no open flames, no electronics, cotton-only clothing, no petroleum-based skincare products — because the oxygen-enriched environment dramatically accelerates combustion.