Aspirin Can Be Used to Prevent Headache at High Altitudes

ABSTRACT & COMMENTARY

Synopsis: In a group of 29 volunteers, aspirin taken prophylactically was more effective than placebo at preventing headache at high altitudes.

Source: Burtscher M, et al. BMJ 1998;316:1057-1058.

Burtscher and coworkers point out that, at altitudes of 3000-5000 m (9900-16,500 feet), about 20-50% of skiers and mountaineers experience headache, the main symptom of acute mountain sickness. Although most mountaineers know that they should avoid climbing great heights too early on and too fast, they may not always act accordingly. The use of drugs to prevent and treat headaches at high altitudes is, therefore, widespread, with aspirin being one of the most commonly taken. Burtscher and colleagues tested the efficacy of aspirin as prophylaxis against headache at high altitudes (600 m or 1980 feet).

Twenty-nine volunteers with a history of headache at high altitude were randomly assigned in a double-blind fashion to receive placebo (8 men, 6 women; mean age, 38 years) or 320 mg aspirin (9 men, 6 women; mean age, 38 years). After examination at low altitude (600 m), subjects were transported to high altitude (3480 m) for 24 hours. They were given three tablets, one every four hours, starting one hour before arrival at high altitude. They scored headache on a four-point scale (0 = none, 1 = mild, 2 = moderate, 3 = severe) and measured heart rate, blood pressure, and arterial oxygen saturation one hour before and three, seven, 10, and 19 hours after arrival. In addition, subjects exercised for two minutes by stepping up and down a 24-cm step 60 times at low altitude and 2-5 hours after arrival at high altitude, during which they continuously monitored gas exchange, heart rate, and oxygen saturation.

Seven subjects given placebo and only one given aspirin developed mild to severe headache (P = 0.01 for differences in proportions). Although mean oxygen saturation was not different between the two groups three hours after arrival at high altitude, the individual values were accurate predictors of the subsequent development of headache. Those who had taken aspirin developed headache at lower oxygen saturation than those who had taken placebo (< 83% vs < 88%). The difference between mean heart rates at the end of the exercise test at high and low altitudes was smaller in those who had taken aspirin (134 [7] vs 118 [10] beats/min) than those who had taken placebo (142 [13] vs 116 [15]; P = 0.01).

COMMENT BY RALPH R. HALL, MD, FACP

Hackett has shown that the incidence of headache at high altitude increases when the oxygen saturation declines.1 As stated, the aspirin prevented headache without improving oxygenation and pretreatment with aspirin raised the headache threshold. An interesting finding was that aspirin was associated with a less pronounced increase in pulse rate in the treated group vs. those taking placebo. The difference in respiratory rate, however, was not statistically significant.

Although aspirin is readily available without prescription, thus easily obtained, in my opinion, other preparations are more effective and should be considered. Diamox (250 mg every 8-12 hours beginning at least 24 hours prior to ascent and for 24-48 hours at altitude or 500 mg of sustained release preparation (one capsule daily) may prevent the adverse physiologic responses to altitude to a greater degree than aspirin. This treatment has withstood the test of time.

An interesting new treatment is the use of Ginko biloba extract (EGb 761). Roncin et al recruited 44 subjects and studied them during a Himalayan expedition.2 The subjects were randomized into two groups. One group received 160 mg of EGb 761 per day in two divided doses, and the other group received placebo. The prophylactic efficacy of the treatment with EGb 761 was clearly demonstrated. No subject in the treated group developed cerebral symptoms (e.g., headache, etc.) vs. eight subjects in the placebo group who developed cerebral symptoms of acute mountain sickness (AMS). Three subjects in the treated group developed pulmonary symptoms of AMS, while 18 of the untreated group developed symptoms. The studies were done at altitudes up to 5400 m (17,820 feet).

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References

    1. Hackett PH, et al. Lancet 1976;ii:149-154.

    2. Roncin JP, et al. Aviat Space Environ Med 1996; 67:445-452.