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Acute Mountain Sickness: Scientists Laid Low by a High Adventure

December 06, 1987|JANNY SCOTT | Times Staff Writer

No one promised it would be a dream weekend.

The idea hatched by 10 friends and colleagues from San Diego was to work all day Friday, drive most of the night, sleep a few hours in a motel, rise before dawn, drive straight up a mountain and become violently sick.

It worked like a charm.

They arrived in Bishop long after midnight. The motel had mishandled the booking, so they slept four to a room. Up at 5 a.m., there was no time for a real breakfast. They headed up White Mountain on a bellyful of doughnuts.

By 8,000 feet, they were still feeling chipper. But at 12,000, one man was too addled to pitch his own tent. With a splitting headache and no appetite, he lumbered into his sleeping bag and lay there for the next 24 hours, groaning.

The cook had fallen into a trance over the rice and vegetables. Another woman had developed a "blinding" headache. When they reached 13,500 feet the next day, she collapsed on the ground--nauseated, vomiting, unable to move.

All in all, they pronounced the weekend a great success.

The purpose of the trip, led by a neurologist at Scripps Clinic and Research Foundation in La Jolla, was to study acute mountain sickness, a condition believed to afflict perhaps a third of all people who travel to altitudes above 8,000 to 10,000 feet.

Specifically, the Scripps project aimed to test the theory that the symptoms are caused at least in part by dilation of arteries in the brain. The test used a new device capable of measuring through the skull the speed at which blood is traveling.

The results, which the Scripps researchers intend to publish, showed clear increases in cerebral blood flow. The researchers say they were also able to trace those increases to dilation of blood vessels in the brain.

Acute mountain sickness and responses to altitude are attracting increasing attention as people resort to hiking, climbing and skiing for recreation. Currently, 44 million people worldwide are believed each year to experience altitudes over 8,000 feet.

Some scientists also study acute mountain sickness for what it reveals about medical conditions that deprive people of oxygen, like lung and heart disease. They use acute mountain sickness to study how oxygen deprivation affects the functioning of the brain.

The military, too, is interested in the effects of "going to altitude"--that is, going above 8,000 feet--because many mountainous areas worldwide are of strategic importance to the United States and troops might one day be forced to fight at high altitudes.

But many details of the condition remain poorly understood.

It is not known why certain people are susceptible, even though the condition was documented centuries ago by the Conquistadors and even Marco Polo. Nor is it known why people become sick at widely varying altitudes.

One researcher said 25% to 30% of all mountain climbers seem to suffer from some symptoms. Some speculate that perhaps 60% of all climbing accidents stem from the loss of judgment that comes with mountain sickness.

They said as many as 1% of all climbers go on from mountain sickness to experience cerebral and pulmonary edema--a swelling condition that causes respiratory and brain problems and can be fatal.

A milder form of brain swelling appears to be the cause of mountain sickness, researchers seem to agree. But it is unclear whether the swelling comes from increased blood flow or a build-up of fluid caused by cells malfunctioning from lack of oxygen.

It may come from both.

"One of the last and greatest frontiers in altitude medicine is the brain and why it malfunctions at altitude," said Dr. Allan Hamilton, who does altitude research for the U.S. Army in Natick, Mass. "That and lung problems are the No. 1 issues that stop people from going to heights and kill people when they go up too fast."

The condition may also have economic significance.

Dr. Charles Houston, a retired professor of medicine and environmental health at the University of Vermont, participated five years ago in a study that found that 17% of all tourists at eight Colorado resorts experienced some symptoms of mountain sickness.

Assuming that those symptoms were sufficient to deter those tourists from spending just $10 on food or drink, Houston concluded that symptoms of acute mountain sickness cost Colorado resorts about $50 million a year.

So experiments are being conducted worldwide in which scientists and volunteers "go to altitude"--climbing Mt. Everest, the Himalayas, Mt. McKinley and Pikes Peak, and spending weeks on the ground in so-called hyperbaric chambers that simulate the same experience.

Some of the participants are scientists with a professional interest. Others are soldiers or recreational climbers interested in performance "at altitude." Even when aware of the misery of acute mountain sickness, researchers say, people almost invariably volunteer.

'Beat People Away'

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