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Time = Brain in Carbon Monoxide Poisoning

November 19, 2021

Written by Rebecca White

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Patients treated with hyperbaric oxygen therapy (HBO2) within 6 hours of carbon monoxide (CO) exposure had better 6-month neurocognitive outcomes than patients who received treatment within 6-24 hours. Poor outcomes increased as time-to-treatment increased.

Why does this matter?
HBO2 likely decreases mortality and improves cognitive outcomes in patients with symptomatic CO poisoning. While initiation within 24 hours of exposure is recommended, previous studies have suggested better outcomes if it is started within 6 hours. When it comes to HBO2 for CO poisoning, is time really brain?

Don’t Dilly-Dally
This retrospective, single-center study of 706 patients with symptomatic CO poisoning compared neurocognitive outcomes based on HBO2 delay intervals. Patients were classified into early (≤6 hours) or late (6-24 hours) groups based on time from CO exposure to HBO2 initiation. The late group was further divided into Case-1 (6-12 hour) and Case-2 (12-24 hour) groups.

After propensity score matching, the early group showed significantly fewer poor outcomes at 6 months than the late group, as measured by Global Deterioration Scale (p=0.027). The early group also had significantly fewer poor outcomes than the Case-2 group at 1 month (p=0.035), and both Case-1 (p=0.033) and Case-2 (p=0.004) groups at 6 months. As treatment interval increased, the number of patients with poor prognoses increased (p=0.008).

This study is limited by its observational design and by the challenge of pinpointing exact CO-exposure time. Though it did not compare late HBO2 with no HBO2, the increase in poor prognoses as time-to-treatment increased suggests that we should still initiate treatment as quickly as we can.

Effect of Hyperbaric Oxygen Therapy Initiation Time in Acute Carbon Monoxide Poisoning. Crit Care Med. 2021 Oct 1;49(10):e910-e919. doi: 10.1097/CCM.0000000000005112.

What are your thoughts?