Obesity and Acute Mountain Sickness

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The summary below is from the full report titled "Obesity: Associations with Acute Mountain Sickness." It is in the 19 August 2003 issue of Annals of Internal Medicine (volume 139, pages 253-257). The authors are G. Ri-Li, P.J. Chase, S. Witkowski, B.L. Wyrick, J.A. Stone, B.D. Levine, and T.G. Babb.

What is the problem and what is known about it so far?

Acute mountain sickness can occur when a person ascends rapidly to 8000 feet (2400 meters). Symptoms of mountain sickness include headache, nausea, poor sleep, and general fatigue. An inexpensive drug (acetazolamide) taken the day before and during ascent reduces the symptoms of acute mountain sickness. Acute mountain sickness is more likely to occur after rapid ascent and poor acclimatization to high altitude. Obesity may promote acute mountain sickness. Its role is still unclear, largely because studies of the effects of obesity during rapid ascent are difficult to carry out during climbs in the mountains.

Why did the researchers do this particular study?

To find out whether obese men are susceptible to developing acute mountain sickness.

Who was studied?

Nine obese and 10 nonobese men. The average body mass index (weight in kilograms divided by height in meters squared) of obese and nonobese men was 37 kg/m² and 25 kg/m², respectively.

How was the study done?

The men were studied in a large room called a decompression chamber. Removing air from the chamber created the effect of being at high altitude. Each man filled out a questionnaire about any symptoms of acute mountain sickness at sea level. Air was removed from the chamber to simulate an ascent to an altitude of 12,000 feet (3658 meters). Each man filled out the questionnaire again after being at simulated high altitude for 6 hours, 12 hours, and 24 hours. The researchers also measured the amount of oxygen in the men's blood.

What did the researchers find?

The obese men had worse symptoms of acute mountain sickness at high altitude. During sleep at high altitude, obese men also had much lower blood oxygen levels.

What were the limitations of the study?

The study was small and conditions didn't simulate real life, since the men in the decompression chamber were inactive. Some people get acute mountain sickness during vigorous physical exercise at high altitude.

What are the implications of the study?

Obesity may be associated with increased risk for acute mountain sickness.