Overview
2.8 ATA is the standard pressure for acute carbon monoxide poisoning per the Weaver protocol and is also used in some necrotising infection cases. The higher dissolved oxygen tension accelerates CO displacement from haemoglobin and reduces delayed neurocognitive sequelae. Sessions are shorter and typically limited to 1–3 total treatments for CO.
2.8 ATA sits in the emergency HBOT zone, used primarily for conditions where maximum tissue oxygenation and rapid displacement of toxic gases are critical. The Weaver 2002 NEJM carbon monoxide protocol is the paradigm application — three sessions in the first 24 hours of CO poisoning, the first at 3.0 ATA followed by two at 2.0 ATA, reducing delayed neurocognitive sequelae substantially.
US Navy Treatment Table 6 for decompression sickness also operates at 2.8 ATA (60 feet of seawater equivalent). The treatment combines pressure-dependent bubble size reduction with 100% oxygen breathing to accelerate nitrogen elimination from blood and tissue. Variations (Table 6A for severe cases, Table 7 for very severe cases) extend the protocol duration and pressure.
Necrotising soft-tissue infections — gas gangrene, necrotising fasciitis — are also treated at 2.5–3.0 ATA. Hyperoxia at this pressure is directly bactericidal to Clostridium perfringens (gas gangrene) and enhances neutrophil-mediated killing of a broad range of pathogens.
CNS oxygen toxicity risk is higher at 2.8 ATA than at clinical pressures, requiring strict air-break discipline. Barotrauma risk is also higher. These protocols are delivered in multiplace chambers at tertiary emergency hyperbaric facilities with trained chamber attendants.
How It Works
Chamber pressurised to 2.8 ATA (approximately 26.5 psi above atmospheric, 60 feet of seawater equivalent). Compression 15–20 minutes, variable duration at depth (60–90 minutes for CO protocol; much longer for DCS protocols with staged decompression), extended decompression. Oxygen delivery with scheduled air breaks every 20 minutes.
Protocol Parameters
| Pressure | 2.8 ATA (≈ 26.5 psi above atmospheric) |
|---|---|
| Session length | 90 minutes (Weaver protocol for CO: 60 min at 3.0 then 60 min at 2.0) |
| Frequency | 1–3 total sessions for CO; daily for necrotising infection |
| Typical course | 1–3 (CO), 5–20 (soft-tissue infection) |
Indications
- Carbon monoxide poisoning
- Necrotising soft-tissue infection
- Gas gangrene (clostridial myonecrosis)
- Decompression sickness (US Navy Treatment Table 6)
2.8 ATA is reserved for emergency indications requiring maximum oxygen delivery and/or rapid toxic gas displacement. Not used for routine wound-care or neurological HBOT.
Evidence Base
Weaver et al. 2002 NEJM RCT established CO protocol efficacy. UHMS-approved for CO, DCS, and necrotising infection. US Navy Treatment Table 6 is the authoritative DCS protocol.
Cautions & Notes
- Higher oxygen toxicity risk — strict air-break protocol
- Elevated barotrauma risk
- Reserved for acute/emergency use
- Requires experienced emergency hyperbaric facility
Practical Considerations
2.8 ATA treatment is delivered at tertiary hyperbaric facilities with 24/7 emergency capability. The DAN (Divers Alert Network) hotline helps locate facilities for DCS; emergency medical services coordinate for CO and necrotising infection.
Frequently Asked Questions
When is 2.8 ATA appropriate?
Acute CO poisoning (Weaver protocol), decompression sickness (US Navy Table 6), and necrotising soft-tissue infections including gas gangrene. Not for routine wound care or neurological HBOT.
How long is a 2.8 ATA session?
Weaver CO protocol: 90 minutes total. US Navy Treatment Table 6 for DCS: 4–5 hours including staged decompression. Table 6A for severe cases: up to 8 hours.
Where can I get emergency HBOT?
Call the Divers Alert Network (DAN) +1-919-684-9111 (24/7) for DCS. Emergency departments can direct to the nearest hyperbaric facility for CO poisoning. Not every HBOT facility handles emergency indications.
Research disclaimer: This protocol summary is for educational purposes only. HBOT is a regulated medical treatment that must be administered under appropriate professional supervision. Always consult a qualified physician before initiating hyperbaric therapy.