TL;DR: Hyperbaric oxygen therapy (HBOT) is a UHMS-recognised adjunct for acute crush injury, and time-to-treatment is the single biggest predictor of outcome. Canadian referring physicians should consider HBOT consultation within the first 24 hours after surgical stabilisation, ideally within 6 hours of injury. Adjunctive HBOT is associated with reduced tissue necrosis, lower infection rates, and shorter healing time in moderate-to-severe crush injuries. This guide covers patient selection, the referral pathway, the standard protocol, contraindications, and what the 2022-2026 evidence shows.
Hyperbaric oxygen therapy for crush injury is the breathing of 100% oxygen at 2.0 to 2.5 atmospheres absolute (ATA) inside a pressurised chamber, used as an adjunct to surgical management of severely traumatised tissue. The Undersea and Hyperbaric Medical Society (UHMS) lists acute crush injury, compartment syndrome, and other acute traumatic ischaemias among its 15 recognised HBOT indications. For Canadian referring physicians, the central question is rarely whether HBOT helps. The question is whether it can be initiated quickly enough to matter.
This guide is written for emergency physicians, orthopaedic surgeons, plastic surgeons, and trauma teams across Canada who encounter Gustilo grade III open fractures, mangled extremities, degloving injuries, and post-operative tissue at risk. It covers when to refer, where to refer, what to expect, and which patients gain the most from adjunctive hyperbaric treatment. Canada Hyperbarics maintains the national directory of hospitals and regulated facilities capable of accepting acute crush referrals.
Why is timing so critical for HBOT in crush injury?
Crush injury initiates a self-perpetuating cycle of tissue ischaemia and oedema. Direct mechanical damage disrupts microvasculature, interstitial pressure rises, capillary perfusion falls further, and progressively viable tissue becomes hypoxic. Once the cycle is established, the zone of necrosis expands well beyond the initial insult. This pathophysiology is the reason HBOT is most useful in the first hours after injury, before secondary necrosis is locked in.
A 2024 retrospective controlled study of 72 patients with hand crush injuries from Far Eastern Memorial Hospital showed that patients who received their first HBOT session within 72 hours of surgery had a hospital stay of 8.1 days, compared with 15.5 days in the late-treatment group (p = 0.04). Wound healing was also faster in the early group, and the mean number of operations dropped from 2.41 to 1.54. The authors concluded that early HBOT was the modifiable variable most likely to improve outcomes (Chang et al., Wound Repair and Regeneration, 2024 (PubMed)).
A separate Portuguese case series of 19 upper-limb crush injuries reinforced this signal. Among the four patients who developed acute complications such as tissue necrosis or local infection, two had not started HBOT within 24 hours. Late complications including pseudarthrosis and deep infection occurred only in patients whose HBOT was delayed beyond 24 hours (Casimiro et al., Cureus, 2024 (PubMed)). The authors specifically named lack of awareness among referring teams as a leading reason for missed treatment windows.
What is the mechanism of action in traumatic ischaemia?
HBOT delivers four mechanisms relevant to crush injury management:
- Hyperoxygenation by diffusion. At 2.4 ATA breathing 100% oxygen, plasma oxygen content rises roughly 20-fold, allowing oxygen to reach tissue not perfused by red blood cells. This bypasses the failed capillary network in the zone of stasis.
- Vasoconstriction without hypoxia. Hyperoxia causes a 20% reduction in arterial diameter, lowering interstitial pressure and oedema, while oxygen content of perfused tissue remains supranormal. This breaks the ischaemia-oedema cycle.
- Modulation of the inflammatory response. HBOT reduces leukocyte adherence to ischaemic endothelium, blunting the reperfusion injury that follows surgical revascularisation or fasciotomy.
- Antimicrobial and angiogenic effects. Hyperoxia restores neutrophil oxidative killing in hypoxic tissue and stimulates fibroblast collagen deposition and capillary budding, both essential for the eventual coverage decision.
A 2025 scoping review of 19 preclinical crush and tourniquet ischaemia models confirmed that early HBOT initiation produces the largest treatment effect on muscle regeneration, while excessive sessions did not yield additional benefit (Schneider et al., Medical Gas Research, 2025 (PubMed)). Strauss has argued in the official UHMS journal that the strongest mechanistic case for HBOT exists precisely in this window, where the zone of stasis remains salvageable but is rapidly progressing toward necrosis (Strauss, Undersea and Hyperbaric Medicine, 2022 (PubMed)).
Which crush injury patients benefit most from HBOT?
The European Committee for Hyperbaric Medicine (ECHM) and UHMS both support adjunctive HBOT for patients with crush injury severity that places limb viability at risk. Use the following clinical screen to decide whether to initiate a hyperbaric consult:
| Clinical feature | HBOT consult indicated? |
|---|---|
| Gustilo grade III open fracture | Yes, particularly IIIB and IIIC |
| Severe soft tissue degloving with questionable flap viability | Yes |
| Compartment syndrome post-fasciotomy with persistent ischaemia | Yes |
| Mangled extremity with vascular repair and reperfusion injury risk | Yes |
| Hand or upper-limb crush with multiple structures involved | Yes |
| Compromised free flap or skin graft after primary coverage | Yes |
| Isolated minor crush with no compartment or vascular concern | No |
| Patient with active untreated pneumothorax | No (absolute contraindication until resolved) |
The Strauss severity score is the most widely cited bedside tool for stratifying crush injury and selecting patients for hyperbaric referral. It assesses skin integrity, tissue viability, perfusion, and bony stability. Severity grades of moderate or severe correlate with the largest absolute benefit from adjunctive HBOT.
What does the current evidence base show?
The HBOT evidence base for crush injury comprises one randomised controlled trial (Bouachour 1996), several retrospective controlled studies, multiple case series, and consistent preclinical data. The 1996 Bouachour RCT in 36 patients with severe limb crush injuries showed complete healing without secondary surgery in 17 of 18 HBOT patients versus 10 of 18 in the placebo group. Subsequent observational evidence has supported and extended these findings.
A seven-patient case series of lower-extremity trauma from Indonesia documented HBOT use across crush injury, gas gangrene, electrical burn, and chemical burn presentations. All seven patients achieved limb salvage and return to daily activity, with no treatment-related complications (Oley et al., Annals of Medicine and Surgery, 2022 (PubMed)). A detailed case report from Brazil documented complete functional recovery in a paramedic with a high-energy hand crush, with HBOT credited for limiting necrosis to the distal phalanx of one digit (Neto et al., Journal of Trauma and Injury, 2022 (PubMed)).
A 2024 evidence-based primer in the Journal of Emergency Medicine groups crush injury alongside decompression sickness, arterial gas embolism, central retinal artery occlusion, carbon monoxide poisoning, necrotising soft tissue infection, and symptomatic anaemia as the seven emergency conditions where transfer to a hyperbaric facility is justified (Samson et al., Journal of Emergency Medicine, 2024 (PubMed)). This is currently the most useful single reference for emergency department teams.
How should you refer a Canadian patient for emergency HBOT?
The HBOT referral pathway in Canada depends on the province and the level of the receiving trauma centre. The general sequence is the same across the country:
- Stabilise and assess. Complete primary survey, achieve haemodynamic stability, and address life-threatening injuries before transfer. HBOT does not replace damage-control surgery.
- Identify the nearest hyperbaric facility. Use the Canada Hyperbarics directory of hospitals and regulated facilities to locate the closest chamber capable of accepting acute referrals. Acute crush patients require a hospital-based monoplace or multiplace chamber, not a community wellness centre.
- Phone the on-call hyperbaric physician directly. Faxed or emailed referrals lose hours. Discuss timing of last surgical intervention, current haemodynamic status, presence of chest tubes, and any seizure history.
- Pre-transfer screening. Confirm tympanic membrane integrity or document plan for myringotomy, exclude untreated pneumothorax with chest imaging, document current oxygen saturation, and review medications for ototoxicity and seizure threshold.
- Transport with monitoring. Air transport requires altitude considerations. Most Canadian air ambulance services pressurise to 8,000 feet, which is acceptable for crush patients without untreated air-filled spaces.
- Document timing. Record the time of injury, the time of surgical stabilisation, and the time HBOT was initiated. This is important for both clinical follow-up and quality improvement.
For a deeper dive into the screening process, see the Canada Hyperbarics conditions directory and the regulatory overview at Health Canada.
What is the standard HBOT protocol for acute crush injury?
The Strauss protocol, endorsed by the UHMS Hyperbaric Oxygen Therapy Indications committee, prescribes the following regimen for acute crush injury:
- Pressure: 2.0 to 2.5 ATA
- Session duration: 90 minutes of oxygen breathing, with 5-minute air breaks every 30 minutes
- Frequency: Three sessions in the first 24 hours, then twice daily for two days, then once daily for two to four days
- Total course: Typically 8 to 12 sessions, extended if compromised flaps or grafts are present
Mean session counts in published case series typically range from 5 to 32, with the Chang 2024 cohort averaging 18.2 sessions per patient. The treatment course is shorter than the chronic wound or osteonecrosis protocol because the goal is acute rescue of viable tissue rather than long-term tissue remodelling.
Are there contraindications or risks to consider before referral?
The only absolute contraindication to HBOT is untreated pneumothorax. The chamber pressurisation phase will not equalise an air-filled space without communication to the airway, and the depressurisation phase risks tension pneumothorax. Place a chest tube before transfer if there is any clinical or radiological concern.
Relative contraindications and considerations include:
- Recent thoracic surgery or bullous lung disease (CT chest if uncertain)
- Active upper respiratory tract infection or severe sinus disease (myringotomy may be required)
- Uncontrolled seizure disorder (oxygen toxicity threshold may be lower)
- Doxorubicin chemotherapy within 7 days, bleomycin exposure, or cisplatin therapy
- Pregnancy (case-by-case discussion with the hyperbaric physician)
- Severe claustrophobia (multiplace chamber preferred)
Adverse events reported in the Chang 2024 cohort were zero, consistent with the broader literature showing that supervised in-hospital HBOT carries an extremely low complication rate. Middle ear barotrauma is the most common minor complication and is preventable with patient coaching and Valsalva technique. Oxygen toxicity seizures occur in approximately 1 in 10,000 sessions at standard pressures.
How does HBOT for crush injury compare to other UHMS emergency indications?
Among the UHMS-recognised emergency indications, crush injury sits in the same time-sensitive category as decompression sickness, arterial gas embolism, central retinal artery occlusion, and necrotising soft tissue infection. All five share the principle that earlier treatment produces better outcomes, and that delay beyond a defined window substantially reduces benefit.
| Indication | Optimal time-to-treatment | UHMS evidence grade |
|---|---|---|
| Decompression sickness | Within 6 hours | Standard of care |
| Arterial gas embolism | Within 6 hours | Standard of care |
| Central retinal artery occlusion | Within 24 hours | Recommended |
| Carbon monoxide poisoning (severe) | Within 6 hours | Recommended |
| Crush injury | Within 24 hours, ideally 6 hours | Recommended adjunct |
| Necrotising soft tissue infection | Within 24 hours | Recommended adjunct |
| Compromised graft or flap | Within 24 hours of compromise | Recommended adjunct |
Frequently asked questions from referring physicians
Should I delay surgery to start HBOT first?
No. HBOT is adjunctive, not a substitute. Surgical debridement, fracture stabilisation, and vascular repair must proceed first. HBOT is initiated as soon as the patient is haemodynamically stable post-operatively, ideally within the first 24 hours.
What if the nearest hyperbaric chamber is hours away?
Consult by phone first. The hyperbaric physician will help you weigh the benefit of transfer against the risks. For severe crush injury with viable tissue at risk, transfer is usually justified up to 24 hours post-injury. Beyond 48 hours, the marginal benefit declines significantly.
Is HBOT for crush injury covered by provincial health insurance?
Hospital-based HBOT for UHMS-recognised indications, including crush injury, is generally covered under provincial hospital insurance plans when delivered as an inpatient service. This includes OHIP, MSP, AHCIP, RAMQ, and other provincial plans. Coverage of outpatient continuation depends on the province and the receiving facility. Confirm with the receiving hyperbaric service.
Can I refer to a community wellness centre for acute crush care?
No. Acute crush injury management requires a hospital-based or hospital-affiliated multiplace or monoplace chamber with critical care capability. Community wellness chambers and mild HBOT facilities are not equipped or staffed for this acuity. The Canada Hyperbarics facilities directory identifies which centres accept acute referrals.
What documentation should accompany the patient?
Send the operative report, current vital signs and oxygen requirement, recent chest imaging, current medications including any chemotherapy within 7 days, allergies, last tetanus update, and any prior history of seizures or pneumothorax.
How long is each HBOT session and how disruptive is it for the patient?
A typical acute crush injury session is 90 minutes of treatment time inside the chamber, plus compression and decompression of approximately 10 minutes each. Patients on continuous monitoring or ventilation can be treated in a multiplace chamber with an attending nurse or respiratory therapist inside.
What outcomes should I expect to see if HBOT is working?
Reduction in surrounding tissue oedema is often visible within 24 to 48 hours. The most clinically meaningful endpoints are reduced number of return-to-theatre events, smaller eventual area of debridement, and improved viability of compromised flaps and grafts.
Where to refer your next acute crush injury patient
Canada Hyperbarics maintains the most current national directory of hospitals and regulated facilities capable of accepting acute crush injury referrals. The directory identifies which centres operate 24/7 acute services, the type of chamber available, and the on-call contact pathway. For referring physicians who want to keep a province-specific shortlist, the directory filters by province and facility type.
For supplementary clinical reading, the Undersea and Hyperbaric Medical Society publishes the authoritative HBO indications manual, and the Canadian Undersea and Hyperbaric Medical Association (CUHMA) provides Canadian practice guidance and continuing education.
Bottom line for referring physicians: If you would not delay vascular repair or fasciotomy, do not delay the call to the hyperbaric service. The first 24 hours are the window where adjunctive HBOT changes outcomes most.
This content is for informational purposes only and does not constitute medical advice. Clinical decisions about HBOT referral should be made in consultation with a qualified hyperbaric physician based on the individual patient’s presentation. Canada Hyperbarics is an independent information resource and does not provide direct clinical care.