It’s Hard to Keep Up When Symptoms of Altitude Sickness Strike

Altitude sickness can mean misery for veteran mountain climbers and sedentary tourists alike. The condition occurs because of reduced atmospheric pressure, and thus reduced oxygen, at high altitudes, and “there is no way of predicting” who will get it, says Dr. Charles Houston, a retired professor of environmental medicine at the University of Vermont and the author of several books on the topic.

Acute mountain sickness, the mildest form of the disorder, can occur after an ascent to 7,000 or 8,000 feet--or perhaps lower--and may be accompanied by loss of appetite, nausea, vomiting, fatigue, dizziness, sleeping difficulties, confusion and a staggering gait. Acute mountain sickness does not usually cause any long-term damage, Houston says. But experts say travelers should be aware that the condition can strike anyone who travels to high altitudes.

“The important factor is the altitude, not the activity,” says Dr. Kyle Howell, an emergency physician at Mammoth Hospital in Mammoth Lakes, Calif., a ski resort at an elevation of 7,900 feet. At his emergency department, he says, they see “a fair amount” of altitude sickness affecting visitors.

Some recent findings may help mountain climbers, in particular, reduce their risk.

In July, Japanese researchers reported that a faulty gene may cause one type of altitude sickness that affects even strong and healthy climbers. Researchers have long suspected a genetic predisposition to the disorder. The researchers, from Shinshu University School of Medicine in Matsumoto, compared 41 subjects with a history of high altitude pulmonary edema, or HAPE, a severe form of altitude sickness, with 51 subjects who had no such history.

They found that those with a history of HAPE were more likely to have variations in a gene that helps maintain lung function. None of the control subjects tested positive for the gene variations, but more than a quarter of the HAPE subjects had them. Researchers concluded that these defects may help explain why some people are susceptible. The research appeared in the online version of the journal Circulation; to see the abstract, go to www.circ.ahajournals.org and search by the keyword HAPE.

Although a test showing the presence of the gene variation can’t predict with certainty that someone will always suffer altitude sickness, the Japanese team hopes to replicate the findings in other populations.

Their findings apply just to HAPE, which is characterized by fluid in the lungs, extreme fatigue, breathlessness even at rest, cough, chest tightness and blue or gray lips and nails. But there are other forms of altitude sickness, including high altitude cerebral edema, or HACE, in which the brain swells and functions abnormally. A person with HACE, which is also considered a severe form of the disorder, may be lethargic and confused and lack coordination, resulting in a staggering walk that makes him appear intoxicated.

Common-sense measures can reduce the risk of mountain sickness. Climbers should ascend at a rate that lets their bodies acclimate. It’s impossible, experts say, to know just how many feet of elevation per day or hour is wise because everyone adjusts differently.

Some experts suggest taking acetazolamide (Diamox) before and during the climb. It’s thought to work, the manufacturer says, by making the blood more acidic; this increases the drive to breathe, resulting in greater oxygen intake.

For climbers who want a more natural approach, some experts say ginkgo biloba can also help, at least in reducing the severity of altitude sickness if it does occur.

Earlier this year, Dr. Janet Onopa and her colleagues from the University of Hawaii and the Kapiolani Clinical Research Center in Honolulu decided to test ginkgo as a preventive measure. They gave 12 climbers ginkgo (60 milligrams three times a day) and 14 climbers a placebo. The doses started a day before rapid ascent from sea level to nearly 14,000 feet and continued for five days.

The ginkgo “lowered the incidence [of altitude sickness] but it was not statistically significant,” she says. Seven of the 12 climbers on ginkgo suffered mountain sickness, compared with 13 of 14 of the placebo-treated climbers.

But the ginkgo did reduce the severity of illness once it occurred, the Hawaiian team found. Only two of the ginkgo-treated climbers became severely sick; nine of those treated with placebo did.

Houston doesn’t discourage climbers who want to try ginkgo. But, he says, “Diamox is better.”

The Hawaiian researchers will next compare ginkgo with Diamox. “Our gut feeling is ginkgo is not quite as good as Diamox,” Onopa says. But, she adds, ginkgo is available over the counter, while Diamox requires a prescription. And some climbers prefer ginkgo because it is a “natural” remedy.

Climbers should be alert to any symptoms of altitude sickness, experts say. Immediate descent and medical attention are advised. Treatment includes rest, fluids and mild pain relievers, among other options.

In mild cases of acute mountain sickness, Howell says, travelers can sometimes stay at altitude and wait until they acclimate. But a person with an underlying health problem, such as a heart or lung disorder, may suffer more severely. Because the symptoms of mountain sickness are often alarming, Howell cautions mountain-sick travelers to seek medical care.

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Healthy Traveler appears twice a month. The writer can be reached at kathleendoheny@earthlink.net