Hyperbaric Oxygen Chamber

Overview

A hyperbaric oxygen chamber is a sealed pressure vessel that delivers 100% oxygen at elevated atmospheric pressures (2–3 atmospheres absolute). First deployed clinically in 1960s treatments for decompression sickness in divers, hyperbaric oxygen therapy is now used to accelerate wound healing in diabetic ulcers, promote bone repair post-surgery, treat gas gangrene, and manage radiation-induced tissue damage in cancer patients. The monoplace design accommodates a single patient supine or reclined.

The fundamental physiology: at elevated pressure, oxygen dissolves into blood plasma according to Henry's law, bypassing normal red-blood-cell limitations. This hyperoxic plasma perfuses damaged or ischemic tissues where normal hemoglobin saturation proves insufficient. Sessions typically run 60–120 minutes at 2.4–2.8 bar absolute (roughly double sea-level oxygen partial pressure), repeated daily for weeks depending on diagnosis.

How it Works

The patient enters through the hinged door hatch and lies supine. The operator closes and secures the hatch gasket, then initiates pressurization via the control panel. The compressor motor drives an air pump that gradually raises chamber pressure while the patient performs Valsalva maneuver or uses nasal equalization to prevent barotrauma in the middle ear.

Once at therapeutic depth (typically 2.4 bar), oxygen delivery begins. A pressure regulator meters 100% oxygen from a supply cylinder into the breathing circuit, typically a nasal mask or sealed hood. As the patient inhales pure oxygen, a CO₂ scrubber canister removes exhaled carbon dioxide, preventing hypercapnic acidosis and oxygen toxicity. The chamber pressure is continuously monitored by a pressure sensor feeding back to the control panel.

The viewing ports allow the treatment operator and standby personnel to observe the patient for signs of distress. At session end, the operator activates controlled decompression via a solenoid vent valve, bleeding chamber pressure down over 10–15 minutes to prevent rapid pressure change injuries.

Safety Systems

The safety system is layered. A mechanical relief valve set to 3.2 bar absolutely vents if pressure overshoots; a thermal cutoff halts the compressor if internal temperature exceeds 70°C (from friction-heated compressed air); and a manual emergency vent needle valve allows the operator to safely decompress the chamber in any emergency.

The pressure vessel itself is designed and certified per ASME Section VIII Division 1, the North American standard for unfired boilers and pressure vessels. All welded seams undergo 100% radiography; stress relief is performed post-fabrication. The sealing system, door hatch and elastomer gasket, is inspected and certified annually.

Clinical Use

Standard protocols vary by diagnosis. Diabetic foot ulcers typically receive 40–60 sessions over 8–12 weeks; post-surgical bone fusion may require 30–40 sessions. Acute decompression sickness receives immediate recompression, often at 2.8 bar. Radiation cystitis or proctitis from cancer treatment uses chronic protocols of 30–40 sessions at 2.4 bar. The underlying dose metric is cumulative oxygen exposure in pressure-time-depth space, balancing therapeutic benefit against risk of oxygen toxicity (CNS toxicity is rare at 2.8 bar or lower; pulmonary toxicity risk increases with long-term daily use).

Contraindications include untreated claustrophobia, chemotherapy with cisplatin (which increases oxygen toxicity risk), and uncontrolled seizure disorder. Patients must be able to equalize middle-ear pressure or have ventilation tubes placed beforehand.

Specifications

Monoplace chambers are the medical standard globally. Multiplace chambers (accommodating 2–14 patients plus an attendant) are deployed in some large wound centers but add operational complexity. The monoplace is preferred for its simplicity, lower compressor power, and ability to deliver pure oxygen via mask rather than air at higher pressure.