When visiting mountainous areas, have you experienced headache, fatigue or dizziness? You may have suffered from altitude sickness. This condition can be treated and even prevented.Altitude sickness results from breathing a decreased concentration of oxygen while at a high altitude, usually above 8,000 feet. When severe, it can progress to more serious conditions: high altitude pulmonary edema or high altitude cerebral edema. In cases where there is a lengthy exposure to high altitude, some suffer from chronic mountain sickness (Monge's disease). For some perspective, consider that at age 12, I scaled Old Greyback Peak in the San Gorgonio Mountains. At 11,503 feet, Old Greyback is the highest peak in Southern California. Mount Rainer in the state of Washington is the highest peak in the continental United States, reaching an elevation of 14,410 feet, but Pico de Orizaba in Mexico reaches 18,490 feet, Mount Logan in Canada reaches 19,859 feet, and Mount McKinley in Alaska is the highest peak in the Americas at 20,320 feet. The highest peak in Africa is Mount Kilimanjaro at 19,340 feet. These, however, are dwarfed by the very highest peaks in the world, which lie in the region of Nepal, Tibet, India, China and Pakistan. The three highest mountains above sea level are Kanchenjunga at 28,169 feet, K2 at 28,251 feet, and finally, Mount Everest, which reaches a height of 29,028 feet (close to triple the elevation of our local highest peak!). Why does altitude sickness occur? 21% of the air we breathe is made up of oxygen. This percentage remains constant up to 70,000 feet above the Earth. However, as we move higher into the atmosphere, the density of the air decreases. The 21% oxygen content does not change, but the number of oxygen molecules per volume of air declines. The amount of oxygen necessary for mental and physical alertness can become a problem at altitudes of above roughly 10,000 feet. This is why airplane cabin pressure is kept essentially at 8,000 feet, no matter high the plane flies. Higher altitudes also result in greater dehydration, because water vapor is lost from the lungs at a higher rate. Dehydration worsens the symptoms of altitude sickness, as does rate of ascent, altitude attained, and level of physical activity. We vary in our susceptibility to altitude sickness. For some who are otherwise healthy, symptoms may appear at altitudes of even 6,500 feet above sea level. This is a typical altitude for many ski resorts! Symptoms may appear from six to ten hours after ascent and subside within one to two days, and can include headache, fatigue, shortness of breath, nosebleeds, drowsiness, diarrhea, rapid pulse, stomach pain, dizziness, and sleep disturbances. At moderate altitudes, only rarely does this condition become life threatening. If there is too little oxygen reaching the brain (hypoxia), then the body responds by widening blood vessels (local vasodilation), which results in increased blood flow and thus greater capillary pressure. That, in turn, can lead to fluid accumulating in the tissues of the brain or lungs. Symptoms that indicate a more serious condition include persistent dry cough, fevers, shortness of breath even while at rest, headaches, unsteady gait, increasing nausea and gradual loss of consciousness. How can you prevent or decrease the symptoms of altitude sickness? When possible, ascend slowly so that the body has a chance to gradually acclimate to the decreasing oxygen concentrations. For at least the first 24 hours, avoid strenuous activity such as skiing or hiking. Stay well hydrated, and note that alcohol, which tends to dehydrate, should be avoided for at least that first 24-hour period. Treatment for altitude sickness calls for hydration, oxygen supplementation, and immediate descent to lower altitudes. The classic medication used is acetazolamide, which may increase the amount of air inhaled, increase urine output, and improve breathing during sleep. Drugs such as steroids, nifedipine (a blood pressure drug), and sumatriptan (a migraine medication) have also shown positive results. Enjoy your travel, far and wide, high and low, but pay attention to possible warning signs of altitude sickness, and treat accordingly. Dr. Alan Frischer is former chief of staff and former chief of medicine at Downey Regional Medical Center. Write to him in care of this newspaper at 8301 E. Florence Ave., Suite 100, Downey, CA 90240.

********** Published: May 26, 2011 - Volume 10 - Issue 6