Effect of Hyperbaric Oxygen Therapy Initiation Time in Acute Carbon Monoxide Poisoning

Hyperbaric oxygen therapy (HBO2) is recommended for symptomatic patients within 24-hour postcarbon monoxide poisoning. Previous studies have reported significantly better outcomes with treatment administered within 6 hours after carbon monoxide poisoning. Thus, we aimed to compare the neurocognitive outcomes according to HBO2 delay intervals.Retrospective analysis of data from our prospectively collected carbon monoxide poisoning registry.A single academic medical center in Wonju, Republic of Korea.We analyzed the data of 706 patients older than 16 years treated with HBO2 with propensity score matching. Based on carbon monoxide exposure-to-HBO2 delay intervals, we classified patients into the early (control, less than or equal to 6 hr) and late (case, 6-24 hr) groups. The late group was further divided into Case-1 (6-12 hr) and Case-2 (12-24 hr) groups. We also compared mild (nonintubated) and severe (intubated) groups.HBO2.After propensity score matching, Global Deterioration Scale scores at 6 months postcarbon monoxide exposure showed significantly fewer poor outcome patients in the early than in the late group (p = 0.027). The early group had significantly fewer patients with poor outcomes than the Case-2 group (p = 0.035) at 1 month and than the Case-1 (p = 0.033) and Case-2 (p = 0.004) groups at 6 months. There were significantly more patients with poor prognoses at 6 months as treatment interval increased (p = 0.008). In the mild cohort, the early group had significantly fewer patients with poor 6-month outcomes than the late group (p = 0.033).Patients who received HBO2 within 6 hours of carbon monoxide exposure had a better 6-month neurocognitive prognosis than those treated within 6-24 hours. An increase in the interval to treatment led to an increase in poor outcomes.