Overview
A clinical HBOT session is a multi-phase process typically spanning 90–120 minutes from the patient's arrival at the facility through final documentation. UHMS-accredited facilities follow standardised protocols at each phase. This page covers the standard workflow for a 2.0–2.4 ATA session — the pressure range covering most UHMS-approved wound-care indications and research-stage neurological protocols. Emergency HBOT protocols (US Navy Treatment Table 6, Weaver CO protocol) have additional specific steps not covered here.
Phase 1: Patient Arrival & Pre-Session Screening
Patients arrive 20–30 minutes before scheduled session start. The hyperbaric team performs the pre-session screening checklist:
- Vital signs — temperature, blood pressure, pulse, pulse oximetry. Fever (temperature ≥38°C) typically defers the session due to seizure-threshold reduction.
- Blood glucose check (diabetic patients) — target pre-session glucose > 120 mg/dL to prevent in-chamber hypoglycaemia. Snack provided if below target.
- Ear equalisation check — otoscopic review on first session; patient confirmation of equalisation technique readiness.
- Clothing and skincare compliance — cotton-only clothing; no lotions, hair products, aerosols, or petroleum-based products on skin. Patients change into facility-provided cotton gowns if needed.
- Removal of all prohibited items — jewellery, electronic devices (phones, hearing aids with lithium batteries, insulin pumps), contact lenses in some protocols.
- Verbal review of today's session — pressure, duration, air-break schedule. Confirm informed consent is on file.
- Last toileting — patients should void before entering the chamber.
Phase 2: Chamber Entry & Pre-Compression
In monoplace chambers, the patient enters feet-first on a sliding stretcher, lies supine, and the chamber door is secured. The intercom is tested; the patient is given earplugs or ear-equalisation instructions as needed. For multiplace chambers, patients enter the chamber room, are seated or positioned, and are fitted with their breathing hood or mask. Chamber attendants enter and position themselves to support the patients. The chamber door is closed and secured.
Phase 3: Compression (10–15 minutes)
Compression proceeds at approximately 1–2 psi/min equivalent — slow enough to allow ear equalisation. The chamber technologist monitors the pressure gauge and watches/listens for signs of patient discomfort. If any patient reports ear pain, compression is paused until equalisation is achieved. The compression phase ends when the target pressure (typically 2.0 or 2.4 ATA for routine protocols) is reached.
Phase 4: At-Depth Oxygen Breathing (60–90 minutes)
Once at pressure, patients begin breathing 100% oxygen. In monoplace chambers, this is the chamber atmosphere directly. In multiplace, patients breathe through hoods or oronasal masks on the overboard oxygen delivery system. The chamber technologist monitors:
- Chamber pressure stability
- Patient status via intercom check every 10–15 minutes
- Oxygen delivery system function (multiplace)
- Signs of CNS oxygen toxicity (VENTIDC: Visual, Ear, Nausea, Twitching, Irritability, Dizziness, Convulsion)
Phase 5: Air Breaks (every 20–30 minutes)
Scheduled 5-minute air breaks are mandatory at 2.0 ATA and above to reduce CNS oxygen toxicity risk. During an air break, patients breathe chamber air (monoplace) or disconnect their oxygen mask and breathe room air through the chamber environment (multiplace). The chamber technologist tracks air-break timing precisely — deviation from the air-break schedule is a leading contributor to CNS oxygen toxicity events.
Phase 6: Decompression (10–15 minutes)
Decompression proceeds at a controlled rate — typically 1–2 psi/min equivalent for routine protocols. Faster emergency decompression is used only when clinically necessary. During decompression, the chamber technologist watches for signs of pulmonary barotrauma (chest pain, dyspnoea, haemoptysis) and reversed ear-equalisation issues (less common than during compression). Patients should breathe normally throughout decompression — breath-holding is the primary risk factor for pulmonary barotrauma.
Phase 7: Chamber Exit & Post-Session
Once surface pressure is reached, the chamber door is opened and the patient exits. The hyperbaric team performs post-session assessment:
- Vital signs recheck
- Blood glucose recheck (diabetic patients) — HBOT typically lowers glucose by 20–50 mg/dL
- Otoscopic examination if any ear discomfort reported during the session
- Patient-reported symptoms (headache, fatigue, visual changes, nausea)
- Review of any technical issues or adverse events during the session
- Confirmation of next session schedule
Phase 8: Documentation
Each session is documented in the patient's hyperbaric record. For CMS-reimbursed sessions, documentation requirements include:
- Specific indication and ICD-10 code
- Pressure, FiO₂, session duration, air-break schedule actually delivered
- Pre- and post-session vital signs and relevant measurements (e.g. TcPO₂ for wound-care protocols)
- Any adverse events or deviations from protocol
- Patient response to treatment
- Physician supervision documentation (CPT 99183 billing requirement)
- Interim progress assessment every 10 sessions (or every 2 weeks) for continued-coverage justification
Interim Reassessment
At session 10 (or every 2 weeks), the hyperbaric team conducts formal interim reassessment. For wound-care protocols this includes repeat wound measurement, photography, TcPO₂ measurement, and documentation of healing progress. For neurological protocols this may include repeat cognitive or functional measures. CMS continued-coverage decisions depend on documented progress at these interim points.
Emergency Response
Facilities maintain readiness for in-chamber emergencies. Monoplace: emergency decompression protocols for seizure, respiratory distress, or cardiac event. Multiplace: in-chamber clinical response plus staged decompression per protocol. All staff maintain BLS certification; hyperbaric physicians are immediately available throughout treatment hours. Fire response follows NFPA 99 protocols with chamber-specific suppression systems and evacuation plans.
Educational use only: This workflow summary is a general reference for understanding standard HBOT session delivery. Specific facility protocols vary; all HBOT delivery must follow facility-specific SOPs, physician supervision requirements, and UHMS/NFPA 99 standards. Not a substitute for formal CHT, CHRN, or hyperbaric physician training.