Comparison of normobaric vs. hyperbaric oxygen in the relief of carbon monoxide headache pain

Background: Headache is the most common symptom in carbon monoxide (CO) poisoning. While the mechanism of CO-induced headache is not well defined, it is felt that cerebral vasodilation plays a role. Clinical experience has demonstrated oxygen breathing is effective in resolving CO headache. However, the effectiveness of normobaric oxygen has never been compared to hyperbaric oxygen in this regard. Methods: A 2016 paper by Ocak, et al. reported the response of CO headache pain severity to four hours of normobaric oxygen breathing in 82 patients using a 0-10 analog scale. The demographics, carboxyhemoglobin levels and response to therapy from that report were compared to data obtained by Hampson, et al. in an earlier study, but never published, using the same pain assessment method in 73 patients with CO headache and treated with hyperbaric oxygen. Results: Comparing the normobaric and hyperbaric groups, neither average age nor presenting carboxyhemoglobin levels were significantly different. Baseline pain intensity scores were 6.5 ± 3.1 vs. 6.2 ± 2.6 (p=0.444) and post-treatment scores 1.5 ± 2.6 vs. 1.0 ± 1.5 (p=0.184) respectively on a 0-10 scale. Conclusions: In these two well-matched populations of patients with CO-induced headache pain, degree of resolution was not significantly different between normobaric and hyperbaric oxygen treatment.