High Altitude Can Be Hazardous to Your Health : Mountain sickness can strike climbers, hikers and skiers who ascend too quickly. It sometimes requires hospitalization.

Mountain climbing can be challenging, refreshing, exhilarating . . . and put you at risk for altitude sickness. But a modicum of education before ascent can minimize the chance of illness, as well as odds that the condition will turn serious.

Also called mountain sickness, altitude sickness strikes not only mountain climbers but also hikers and skiers who ascend too rapidly. Symptoms do not usually occur below 7,000 feet, said Dr. Ray Sahelian, director of the travel medicine program at Centinela Hospital Airport Medical Clinic. More commonly, it does not become a problem until altitudes of 8,000 to 10,000 feet, SAHELIAN AND OTHER? experts say.

Mountain sickness occurs because of reduced atmospheric pressure--and thus reduced oxygen--at high altitudes. As the oxygen level in your blood declines, other blood chemistry changes occur. If it progresses to severe stages, the illness can be life threatening.

One danger is that many travelers dismiss the usual first symptoms--dizziness, headache, drowsiness, fatigue, nausea and vomiting--as the result of food that didn’t agree with them. “Usually it comes on over a period of hours,” said Dr. Victor Kovner, a Studio City internist with an interest in travel medicine.

Some experience it as a “hangover type feeling,” Kovner said. Other symptoms include facial pallor, shortness of breath and blueness of the skin, Sahelian said. In later stages, there can be facial flushing, irritability, difficulty in concentrating, ringing in the ears and visual disturbances. Loss of appetite, insomnia, heart palpitations and a rapid heart rate are also common.

As soon as symptoms occur, experts recommend descending. “Usually descent helps,” Sahelian said. “If you get better (with descent) you probably do not need medical help.” Some experts recommend descending to the last altitude at which no symptoms occurred. But if symptoms do not subside, medical help should be promptly sought.

Mountain sickness can become more serious if fluid begins to collect in the lungs (pulmonary edema). In this stage, symptoms can include wheezing, vomiting of blood or persistent coughing, Sahelian said. Immediate evacuation to a hospital is vital if mountain sickness reaches this stage.

Altitude sickness can strike anyone, but certain people are more prone. “People who exercise regularly will have an easier time acclimating to altitude than sedentary people,” Sahelian said. “Fit people have a better lung capacity, won’t tire as easily and might be more efficient in their use of oxygen.”

“People with blood disease, such as sickle cell anemia, will have a rougher time adjusting to high altitudes,” Sahelian added, as will anyone with heart and lung problems or with chronic diseases, such as diabetes, that are not under control.

The key to prevention, Sahelian and Kovner agree, is to acclimate yourself. For the first day after you arrive at a high altitude destination, exercise only moderately. “Avoid strenuous exercise and being totally sedentary,” Sahelian said.

Keith Haberl of the Alpine Club of Canada, which organized tours in the Canadian Rockies, agrees. After guests’ arrive, he tells them to spend time sightseeing around town or going on casual hikes before ascending. “If you don’t take it slow, you’re going to be wheezing,” he tells climbers.

Once acclimated, complete the climb gradually. If the goal is to climb a 15,000-foot mountain, Sahelian advises climbing no more than 1,000 feet a day.

Some doctors prescribe Diamox (acetazolamide) as a preventive against mountain sickness, especially for climbs above 13,000 feet. It works by helping to restore the sodium-potassium balance in the blood vessels that is impaired by low oxygen levels. People on the regimen usually begin taking the drug before the trip, Sahelian said. But those who take this preventive course of drugs shouldn’t get a false sense of security. Although it has a 75% success rate, some bodies will not respond to treatment.

Also sometimes used to treat climbers who develop altitude sickness is Dexamethasone, a potent anti-inflammatory drug. But it is controversial, with some doctors saying it should be used only in emergencies.

Other measures to reduce the risk of mountain sickness:

* Consider whether your health is good enough for mountain climbing or whether you should tailor your climbing plan to health conditions. “Pregnant women should not climb above 12,000 or 13,000 feet,” Kovner said. And perhaps not above 10,000, Sahelian suggested.

* Diabetics whose illness is not well-controlled should probably forgo mountain climbing. People with high blood pressure should only climb if their condition is well-controlled. Children under 3 also are at risk, Kovner said, because they aren’t yet capable of verbalizing their symptoms.

* When scheduling a period for acclimation, take into consideration the difference between home and destination altitudes. The amount of time it takes for a body to adjust will vary, depending not just upon the body but upon the amount of altitude it has to adjust for.

“People who live in Los Angeles will have a tougher time mountain climbing than people who live in Denver,” Sahelian said.