Prevention of high-altitude pulmonary edema by nifedipine

Article Abstract:

Air pressure decreases with increases in altitude; the most important and immediate effect of this decrease is a reduction in the amount of oxygen entering the blood. The body can adapt slowly to life at higher altitudes, but a rapid rise in altitude cannot be compensated for immediately. One of the more serious potential consequences of rapid transition to a higher altitude is the development of pulmonary edema. In this condition, the lungs begin to fill with fluid that has leaked out from the blood vessels in the lungs. A small fraction of the population seems to be particularly vulnerable, but even people who are not vulnerable show some signs of pulmonary edema when examined with 24 hours of climbing more than 4,500 meters. Pulmonary edema can be completely cured by the use of oxygen, but among mountaineers in the Himalayas, where supplemental oxygen may not be available and descend not possible, about half of those who develop pulmonary edema will die. The details of the physiological responses leading to pulmonary edema are not clear, but a key step seems to be the development of hypertension in the arteries of the lungs. This pulmonary hypertension then forces fluid out of the blood vessels. The ability of capillary blood vessels to retain fluid may also be impaired at high altitude, but this is not certain. Nifedipine is commonly used to treat heart disease because of its ability to relax and dilate blood vessels. Since this action reduces hypertension, nifedipine has been used successfully in treating high-altitude pulmonary edema. Since nifedipine successfully treats the edema, researchers investigated whether it might prevent it as well. In an investigation was performed involving 21 mountaineers who had developed signs of pulmonary edema in the past. A climb from 1,130 to 4,559 meters in 22 hours induced pulmonary edema in 7 of 11 volunteers taking a placebo and in only 1 of 10 subjects taking nifedipine. The authors caution that the best preventive measure for high-altitude pulmonary edema is increasing altitude more slowly over a greater period of time. (Consumer Summary produced by Reliance Medical Information, Inc.)

Drug therapy, Mountain sickness, Altitude sickness

---

When lungs on mountains leak: studying pulmonary edema at high altitudes

Article Abstract:

Mountain climbers who ascend rapidly, beyond 2,500 to 3,000 meters in altitude, may develop pulmonary edema. This condition can be treated by descending to a lower altitude or by taking oxygen. If these solutions are not available, as many as half of those suffering from pulmonary edema may die. In pulmonary edema, fluid collects in the lungs; symptoms include cough, fatigue, and difficulty breathing. Pulmonary edema may result from a variety of causes, and precisely why high-altitude climbing causes edema is poorly understood. Examination of the fluid in the lungs provides some evidence that the blood vessels in the lungs have begun to leak. There have been cases in which pulmonary edema has been associated with cerebral edema, suggesting that other tissues also leak. However, leakage of the blood vessels alone does not seem to be a sufficient explanation. An important contribution to the development of high-altitude pulmonary edema may arise from hypertension in the arteries of the lungs. Researchers have found that nifedipine, a drug that relaxes arteries, is effective in treating high-altitude pulmonary edema. In the October 31, 1991 issue of The New England Journal of Medicine, researchers report that nifedipine can not only cure high-altitude pulmonary edema, but can prevent it as well. The test group consisted of mountain climbers who had previously experienced symptoms of edema and were therefore presumed to be susceptible. After a test climb, symptoms of pulmonary edema were more common among the placebo group than in the group given nifedipine. The most appropriate treatment for high-altitude pulmonary edema is still descent, oxygen administration, or, preferably, both. However, if a person known to be susceptible to the effects of high-altitude pulmonary edema is climbing to an area where rapid descent may not be possible, then nifedipine prophylaxis may be appropriate. (Consumer Summary produced by Reliance Medical Information, Inc.)

editorial

---

Inhaled nitric oxide for high-altitude pulmonary edema

Article Abstract:

The inhalation of nitric oxide may improve high-altitude pulmonary edema, the accumulation of fluid in the lungs as atmospheric pressure falls. This life-threatening condition, associated with arterial constriction in the lungs, is often seen in mountain climbers. Researchers observed the effect of inhaled nitric oxide among 18 mountaineers prone to high-altitude pulmonary edema and 18 mountaineers without this condition at an altitude of 4,559 meters. Inhaling nitric oxide for 15 minutes lowered the pressure in lung arteries and improved oxygenation among the climbers with pulmonary edema, and worsened oxygenation in those without pulmonary edema. According to lung perfusion analysis in four people, nitric oxide directed blood flow away from the areas retaining fluid to other parts of the lungs.

Care and treatment, Nitric oxide, Altitude, Influence of, Endothelium-derived relaxing factors

Similar abstracts:

• Abstracts: Prognostic implications of hepatic adhesion, invasion, and metastases at diagnosis of Wilms' tumor. Late effects of treatment for Wilms' tumor: a report from the National Wilms' Tumor Study Group
• Abstracts: Detection of human immunodeficiency virus DNA and RNA in semen by the polymerase chain reaction. Quantification and comparison of HIV-1 proviral load in peripheral blood mononuclear cells and isolated CD4+ T cells
• Abstracts: Effects of Medicaid drug-payment limits on admission to hospitals and nursing homes. part 2 Emergency department use and subsequent hospitalization among members of a high-deductible health plan
• Abstracts: Prospective evaluation of maternal serum human chorionic gonadotropin levels in 3428 pregnancies. Free alpha-subunit of human chorionic gonadotropin in Down syndrome
• Abstracts: Allogenic bone marrow transplantation in multiple myeloma. Effect of priming with granulocyte colony-stimulating factor on the outcome of chemotherapy for acute myeloid leukemia

This website is not affiliated with document authors or copyright owners. This page is provided for informational purposes only. Unintentional errors are possible.