Hyperbaric medicine has its own vocabulary. This glossary is the version we wish patients had on their first visit — short, plain definitions for the words you will see in your consult report, your consent form, or this website.
Glossary
Glossary of Hyperbaric Terms
A–E
ATA (Atmospheres Absolute)
A unit of pressure used in hyperbaric medicine. 1 ATA is normal atmospheric pressure at sea level. Most clinical HBOT protocols use 2.0 to 2.4 ATA — roughly equivalent to being 10 to 14 metres underwater. Higher pressures (up to 6.0 ATA) are used in specific emergencies like decompression sickness and gas embolism.
Adjunctive Therapy
Treatment that is added to standard care, not a replacement for it. HBOT is almost always adjunctive — it is delivered alongside wound care, antibiotics, surgery, or other primary treatments, not instead of them.
Barotrauma
Tissue injury caused by pressure changes. The most common form in HBOT is middle-ear barotrauma, which we screen for and prevent through controlled compression and patient training in equalization techniques.
CAQ-HP (Certificate of Added Qualification in Hyperbaric Medicine)
A formal credential held by physicians who have completed additional training and examination in hyperbaric medicine. Both Dr. Vik Agarwal and Dr. Seema Agarwal hold CAQ-HP.
Chamber (Hyperbaric Chamber)
The pressurized enclosure where HBOT is delivered. A monoplace chamber treats one patient at a time; a multiplace chamber treats several. Evolve uses Perry Baromedical Sigma 34 and Sigma 36 monoplace chambers across all clinics.
CSA Z275.1
The Canadian Standards Association safety standard for hyperbaric facilities. Compliance covers chamber construction, fire safety, oxygen handling, staff training, and operational procedures. All Evolve clinics operate to CSA Z275.1.
Decompression
The controlled reduction of pressure at the end of a treatment session, returning the patient to normal atmospheric pressure. Decompression is gradual to allow safe gas exchange.
F–N
Hyperbaric Oxygen Therapy (HBOT)
The medical treatment of breathing 100% oxygen at a pressure greater than 1.0 ATA inside a pressurized chamber. The combination of pressure and oxygen delivers oxygen-tension to tissues at levels that cannot be achieved at the surface.
ISSNHL (Idiopathic Sudden Sensorineural Hearing Loss)
Sudden hearing loss of unknown cause in one or both ears. HBOT, often combined with corticosteroid therapy, is recognized for ISSNHL when started within 14 days of onset (with the most benefit when started early).
Monoplace Chamber
A single-patient hyperbaric chamber. The patient lies on a stretcher inside a clear acrylic cylinder; the chamber is pressurized with 100% oxygen. Treatment staff are immediately outside the chamber and in continuous communication with the patient.
Multiplace Chamber
A multi-patient hyperbaric chamber where patients sit in a pressurized room and breathe oxygen through a mask, hood, or endotracheal tube. Multiplace chambers are used in some hospitals; Evolve uses monoplace chambers.
O–S
OHIP (Ontario Health Insurance Plan)
Ontario’s publicly funded health insurance program. OHIP covers HBOT for 9 specific conditions that Evolve treats. See OHIP coverage for details.
Osteoradionecrosis (ORN)
Bone tissue death caused by radiation therapy, most commonly in the jaw after head-and-neck cancer treatment. HBOT is an established adjunct in the management and prevention of ORN.
Perry Baromedical
The manufacturer of the Sigma 34 and Sigma 36 monoplace hyperbaric chambers used at all Evolve locations.
Sigma 34 / Sigma 36
Specific monoplace chamber models manufactured by Perry Baromedical. The Sigma series is widely used in clinical hyperbaric medicine across North America.
T–Z
TCOM (Transcutaneous Oximetry)
A non-invasive measurement of the oxygen tension in tissue at the skin surface. Used in wound care to assess healing potential and to predict response to HBOT.
UHMS (Undersea & Hyperbaric Medical Society)
The international professional society that publishes the authoritative list of HBOT indications and clinical practice guidelines. Evolve protocols align with UHMS guidance.
WSIB (Workplace Safety and Insurance Board)
Ontario’s workers’ compensation board. WSIB may fund HBOT for accepted work-related injury claims where HBOT is clinically indicated. See WSIB coverage for details.
Medical review
Dr. Vik Agarwal MD CCFP FRCPC CAQ-HP — President, Evolve Medical Group
Dr. Seema Agarwal MD CCFP CAQ-HP — Chief Medical Officer, Evolve Hyperbarics
Last reviewed: May 2026 · Next: May 2027
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