Oxygen Staved Off Cluster Headache
ACEP News
January 2010
By Mary Ann Moon
Elsevier Global Medical News
Inhalation of high-dose, high-flow oxygen at the onset of cluster headache appears to abort the attack, according to a report in the Dec. issue of the JAMA.
Oxygen therapy has been found effective in small studies and is recommended in standard guidelines, but it hasn't been widely adopted because until now no high-quality clinical trial has supported it, said Anna S. Cohen, Ph.D., of the National Hospital for Neurology and Neurosurgery, London, and her associates.
She worked with her colleagues at the hospital, Dr. Brian Burns and Dr. Peter J. Goadsby, to conduct a randomized, double-blind, crossover study comparing oxygen therapy with placebo "to try to settle this quarter-century old question so that, if effective, its use can be promoted." The other first-line therapies for cluster headache--triptans--are contraindicated in patients with ischemic heart disease or vascular disease and can only be taken a maximum of two to three times per day, which can be insufficient with this form of headache.
In the study, 109 patients with either episodic or chronic cluster headache were given two compressed air canisters and taught how to use them at home. One canister contained 100% oxygen and the other, regular air.
The subjects were instructed to use one of the cylinders for 15 minutes at the onset of the next headache attack and to use the other cylinder for the same duration for the following attack, switching again for two more attacks that followed, "thus alternating the gases in a [blinded] crossover fashion."
The study subjects recorded treatment effects at 5, 10, 15, 30, and 60 minutes. If they did not experience relief after 15 minutes of inhalation therapy, they could then take whatever rescue medication they wished. The subjects remained in the study for as long as was necessary to treat four attacks.
Results were available for an intention-to-treat analysis for 76 (70%) subjects. This is considered a very low dropout rate, because most of the withdrawals from the study were due to resolution of the episodic bout of cluster headache.
At all time points assessed, oxygen was superior to regular air in relieving cluster headache pain. The active treatment met the primary end points of "pain free at 15 minutes" and "adequate relief at 15 minutes," while the placebo did not.
Oxygen also was more effective than air at relieving the associated symptoms of lacrimation, conjunctival injection, ptosis, periorbital swelling, miosis, blocked or running nose, facial sweating, nausea, photophobia, and restlessness.
Patients also used rescue medications less often after oxygen therapy than after the placebo treatment.
There were no serious adverse events related to either treatment, "which is as expected because oxygen has no known adverse effects at this dose for such short duration of inhalation," Dr. Cohen and her colleagues wrote (JAMA 2009;302:2451-7).
"This is the first adequately powered trial of high-flow oxygen compared with placebo, and it confirms clinical experience and current guidelines that inhaled oxygen can be used as an acute attack therapy for episodic and chronic cluster headache," they added.
"This work paves the way for further studies to optimize the administration of oxygen and its more widespread use as an acute attack treatment in cluster headache."
This study was supported by University College London and Linde Gases (Guilford, U.K.), which supplied the inhalation equipment. Dr. Cohen and her colleagues reported no financial conflicts of interest.