In this randomized, placebo-controlled, double-blind crossover trial, Cohen and colleagues examined the effectiveness of high-flow-rate inhaled oxygen in the treatment of cluster headaches. A total of 57 patients with episodic cluster headaches and 19 with chronic cluster headaches were included in the analysis. Patients received compressed air cylinders containing either air or 100% oxygen, labeled as "treatment 1" and "treatment 2," respectively. They were told to begin treatment at symptom onset, administering either the air or oxygen at 12 L/min for 15 minutes, and to alternate the cylinders for each successive attack. If symptoms persisted after 15 minutes, patients were allowed to take rescue medication.

Fifteen minutes after treatment, oxygen relieved pain in 116 (78%) of 150 attacks, while air relieved pain in 29 (20%) of 148 attacks. The difference between oxygen and air was statistically significant. Similarly, after 30 minutes, more attacks were pain free after oxygen treatment (72 [73%] of 150 attacks) than after air (19 [24%] of 148 attacks). Rescue medication was needed in fewer attacks treated with oxygen (28%) than treated with air (53%). No serious adverse events were reported with either treatment.

The authors concluded that high-flow-rate inhaled oxygen may be a safe and effective treatment for both episodic and chronic cluster headaches. They suggest, however, that further studies be conducted.-SDSJ