Cortisone-like drug protects against altitude sickness Scientists from Heidelberg and Zurich publish their findings in "Annals of Internal Medicine"
The well-known cortisone-like drug dexamethasone can prevent high-altitude pulmonary oedema and is also effective in the prophylaxis of altitude sickness. In fact, it is even better in this respect than tadalafil, a medicine often used to remedy erectile dysfunction. These are the findings of a study by sport-medicine experts from the University of Heidelberg's Hospital for Internal Medicine and Zurich's University Hospital published in the October issue of the renowned American journal "Annals of Internal Medicine".
Altitude sickness can be deadly. About 60 percent of mountaineers ascending rapidly to heights of 13,000 feet and more suffer from mountain sickness. 7 percent of them are affected by high-altitude pulmonary oedema. This is caused by lower air pressure at great heights leading to low oxygen levels with detrimental effects on the blood vessels, lungs and brain. The red corpuscles are unable to transport sufficient oxygen molecules to keep the body supplied with an adequate amount of oxygen.
Oxygen deficiency at high altitudes causes blood vessels to contract
The symptoms of acute mountain sickness (headache, nausea, dizziness, etc.) are the expression of a lack of oxygen in the brain. This lack of oxygen causes the blood vessels in the lungs to contract, leading to fluid accumulation that blocks oxygen uptake. This condition is known as pulmonary oedema and seriously impairs the functioning of the lungs. Victims are affected by shortness of breath and breathe in a rapid, shallow manner. The heart beats more rapidly, fits of coughing ensue and body temperature rises. This life-threatening condition frequently rights itself surprisingly quickly if the victim returns to lower altitudes in time.
The scientists from Heidelberg and Zurich tested a total of 29 persons who had already had high-altitude pulmonary oedema. They were asked to ascend the Swiss Monte Rosa massif over 13,000 feet above sea level under constant medical supervision. Before and during the ascent the participants were randomly assigned either dexamethasone, tadalafil or a placebo. Neither the participants nor the medical experts knew beforehand who had been given what. Most of the mountaineers in the placebo group developed high-altitude pulmonary oedema. Only a few members of the tadalafil group were affected and none in the dexamethasone group.
As tadalafil reduces lung artery pressure it was to be expected that it could prevent high-altitude pulmonary oedema. It was also known that dexamethasone prevents acute mountain sickness, which is not true of tadalafil. "The really surprising result of this study," says Professor Dr. Peter Bartsch, medical director of the sport medicine department of the University of Heidelberg's Hospital for Internal Medicine," is that dexamethasone can prevent not only acute mountain sickness but also high-altitude pulmonary oedema." While the effective mechanism has not yet been precisely identified, researchers conjecture that, amongst other things, dexamethasone expands the pulmonary vessels via nitrogen oxide (NO).
Taking cortisone before ascent not (yet) recommended
So should mountaineers with a propensity for high-altitude pulmonary oedema take this cortisone-like drug before they start? Professor Bärtsch does not recommend taking medicine before or during an ascent. A slow ascent restricting stints at altitudes above 6,000-9,000 feet to between 900 and 1,500 feet per day and then resting for the night will normally preclude both acute mountain sickness and high-altitude pulmonary oedema. As the side-effects of dexamethasone may be substantially higher than those of other effective medications, especially if taken for longer than 2 or 3 days, it is not the medicine of choice even if its use is indicated. This may change, however, if the efficacy of dexamethasone can be confirmed and the medication is administered directly to the lungs via inhalation (asthma sprays).
Maggiorini M, Brunner-La Rocca H-P, Peth S, Fischler M, Böhm T, Bernheim A, Kiencke S, Bloch KE, Dehnert C, Lehmann T, Bärtsch P, Mairbäurl H. Both tadalafil and dexamethasone may reduce the incidence of high-altitude pulmonary edema. Ann Intern Med 2006;145;497-506.
(The original article can be requested from the Press Office of Heidelberg University Hospital: firstname.lastname@example.org).
Prof. Dr. med. Peter Bärtsch
Heidelberg University Hospital
Hospital for Internal Medicine (Krehl Hospital)
Innere Medizin VII: Sport Medicine
Im Neuenheimer Feld 410
phone: +49 6221 / 568101
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