December 12, 2008
Causes of death on Mount Everest examined
Most deaths during expeditions to the summit of Mount Everest occur during descents from the summit in the so-called
death zone, U.S. researchers said.
Paul Firth of Massachusetts General Hospital said thousands of climbers have attempted to reach the summit of 8,850-meter, or 29,000-foot, Mount Everest since the 1920s. The international research team, which included investigators from three British hospitals and the University of Toronto, reviewed available expedition records including the Himalayan Database.
The study, scheduled to be published in the British Medical Journal, found the factors most associated with the risk of death were excessive fatigue, a tendency to fall behind other climbers and arriving at the summit later in the day. Many developed symptoms such as confusion, a loss of physical coordination and unconsciousness, which suggest high-altitude cerebral edema, a swelling of the brain that results from leakage of cerebral blood vessels.
Symptoms of high-altitude pulmonary edema, which is involved in most high-altitude-related deaths, were surprisingly rare.
We also were surprised at how few people died due to avalanches and ice falls in recent years -- those usually happen at lower altitudes, and overwhelmingly people died during summit bids above 8,000 feet -- and that during descents, the mortality rate for climbers was six time that of sherpas, Firth said.