In a 26-year-old woman with acute carbon monoxide poisoning (carboxyhemoglobin 18%) who is symptomatic with altered mental status and has been intubated, what is the most appropriate next step in management?

Perform Hyperbaric Oxygen Therapy

This intubated patient with severe carbon monoxide poisoning (altered mental status requiring intubation, COHb 18%) should receive hyperbaric oxygen therapy (HBOT) as soon as possible, ideally within 6 hours of exposure. 1

Rationale for HBOT in This Case

This patient meets clear indications for HBOT based on the most recent 2025 Polish Medical Society guidelines:

• Loss of consciousness/altered mental status requiring intubation is an absolute indication for HBOT regardless of COHb level 1
• The patient became unresponsive and required intubation, indicating severe neurological compromise
• COHb of 18% confirms significant exposure, though the level itself doesn't dictate treatment—clinical severity does 1

Why Not the Other Options?

Continuing current FiO2 monitoring alone is inadequate because:

• While 100% normobaric oxygen (NBO2) is essential first-line therapy and should already be running at FiO2 1.0, it only reduces COHb half-life to 60-90 minutes 1
• HBOT at 2.2-2.8 ATA reduces COHb half-life to approximately 23 minutes—dramatically faster 1
• More importantly, HBOT addresses the pathophysiology beyond simple COHb elimination: it reduces oxidative stress, inflammation, ischemia-reperfusion injury, and significantly decreases the risk of delayed neurological sequelae (DNS), which occurs in up to 40% of severe cases 1

Sodium nitrite is completely inappropriate—this is a cyanide antidote that works by inducing methemoglobinemia, which would worsen oxygen-carrying capacity in a CO-poisoned patient 1

Hemodialysis with charcoal filter has no role in CO poisoning, as CO is not removed by dialysis and charcoal does not bind gases 2

Treatment Protocol

Since the patient is already intubated in the ICU:

1. Maintain mechanical ventilation with FiO2 1.0 and PEEP ≥10 cm H2O while arranging HBOT transfer 1

2. Arrange immediate transfer to nearest hyperbaric facility for treatment at 2.2-2.8 ATA for 60-120 minutes 1

3. Timing is critical: HBOT should ideally begin within 6 hours of exposure (acceptable up to 24 hours, but observational data suggest <200 minutes provides greatest benefit) 1

4. Consider a second HBOT session if initial response is inadequate; evidence beyond 2 sessions is limited to case series 1

5. Continue supportive care: IV crystalloids for blood pressure support, monitor for cerebral edema (bradycardia, persistent vomiting, focal neurologic signs), and provide standard ICU organ support 1

Critical Pitfalls to Avoid

• Don't rely on COHb levels alone to guide treatment decisions—clinical severity (loss of consciousness, neurological deficits, cardiac ischemia) trumps any specific COHb threshold 1
• Don't delay HBOT waiting for COHb to normalize with NBO2—the window for preventing DNS closes rapidly 1
• Don't assume normal pulse oximetry rules out severe poisoning—SpO2 cannot distinguish COHb from oxyhemoglobin and may read falsely normal at 100% despite severe tissue hypoxia 1
• Don't withhold HBOT based on transport risks in a patient this severely poisoned—the risk of permanent neurological disability without HBOT far exceeds transport risks 1

Evidence Strength

The 2025 Polish Medical Society guidelines 1 represent the most current expert consensus, explicitly stating HBOT is "always indicated" in patients with persistent neurological symptoms regardless of COHb level. While the recommendation acknowledges it rests on cohort studies rather than randomized trials (making it "conditional"), the consistent observational evidence and biological plausibility strongly support HBOT in severe cases like this one. The 2017 ACEP guidelines 3 note ongoing controversy about HBOT, but even they acknowledge its role in severe poisoning with altered mental status—which this patient clearly has.