CARDIAC ADAPTATIONS AT EVEREST.

Sometimes humans do irrational things, just because it is thrilling. Climbing mount Everest is one of those irrational things that people do for not-so-cheap thrill. Costing about USD 1000,000 per attempt ( rough estimate ), as till June 2007, 11,000 climbers have attempted Everest, 3,304 have made it, and 209 have lost their lives trying. A mortality rate of about 1:15.
A few of my colleagues have tried to reach Everest base camp ( not foolish enough to try Everest itself ), and return safely, although there were episodes of altitude sickness.
In my reading this week, I came across an article detailing the experience of 14 doctors ( mostly anaethetist ), who studied the effects of Everest base camp, on cardiac function. Led by Dr Cameron Holloway, and funded by University of London CASE, the 14 doctors, had a baseline MRI and echocardiogram. They then flew to Katmandu ( 1,300M ), and then fly to Lukla ( 2,850M ). From Lukla, they trek 11 days with 2 days rest to Everest base camp ( 5,300 M ). They spend 3 days at Everest base camp, and then return down, and flew back to London where they had their MRI and echocardiogram again, and again at 6 months. Of course, they wanted to document, as scientifically as possible, the cardiovascular changes to low oxygen concentration.
At base camp, the O2 saturation was about 70-80% average. They found ( for all our benefit ), that 11 days trek and 3 days at basecamp, does not change cardiac output, stroke volume, or LV ejection fraction. It however does reduce LV mass ( reduce by about 11% ), and also LV diastolic function. Total body weight also reduces by about 3%. All these adaptive changes are reversible and at 6 months, they all return to normal. Among these 14 healthy doctors, there were no clinically significant complications. I had a patient a long time ago ( an old professor of cardiac surgery ) who went to Everest base camp, and developed acute pulmonary edema, and had to be evacuated from Everest base camp.
I think these information is important for all preparing to climb high altitudes, and also help us to understand physiological changes in people suffering from low O2 concentration, as perhaps in COPD.
Interesting piece of work, documented in the February issue of the Journal of Federation of American Societies for Experimental biology.

GongXiFaCai