CARBON MONOXIDE POISONING, FATIGUE

Alaska, Mount McKinley

On May 28,1985, Raymond Weinrich (30) and Charles Wolf (34) had climbed up to 5250

meters on the West Buttress route on Mt. McKinley. They arrived about 2330 on their ninth day after leaving basecamp and were both fatigued. Weinrich elected to crawl into an already established igloo for the evening while Wolf set up his tent.

The igloo was occupied by Ken Leary, who cooked most of the evening and into the morning with his MSR stove. Weinrich had problems sleeping due to a severe headache, and in the morning felt totally incapacitated. When Wolf came over to the igloo, he found Weinrich crying due to the severe pain.

About 0915 on May 29, Wolf came over to my tent to ask for assistance. Upon examination I found Weinrich to have a pulse of 120/m, respirations of 26/m, and complaining of a severe headache. We moved him from the poorly ventilated igloo and into Wolf’s tent. Once out of the igloo, he was extremely ataxic and almost could not walk. Wolf and I hooked Weinrich up to 02 and made him drink fluids.

I made a radio call to the Medical Research Group and talked to Dr. Peter Hackett, who advised me of already deteriorating weather, and recommended bringing Weinrich down immediately.

By 1115 Weinrich had greatly improved. His headache had gone away and his ataxia was better. Wolf took Weinrich off the 02, and by 1215 we were ready to start descending the West Buttress. Wolf helped Weinrich down the buttress as I belayed over the more exposed sections., The weather had closed in and the winds increased to 30-40 knots. Weinrich continued to improve as we descended, and at 1830 we made it to the medical camp. Upon examination, Weinrich was diagnosed as having CO poisoning. (Source: Roger Robinson, Mountaineering Ranger, Denali National Park)

Analysis

Cooking in an unvented igloo can predispose climbers to AMS and cause CO poisoning. It is imperative that climbers who cook in tents or caves make sure they are well vented, particularly at altitude.

To diagnose whether a person has CO poisoning or cerebral edema on site at high altitude is difficult. Usually CO poisoning will show a drastic improvement after removal from the poisoned environment, but it can lead to more severe altitude illness. Delaying the decision to descend, especially when the weather is deteriorating, could prove to be a fatal mistake.

The symptoms of CO poisoning mimic AMS and cerebral edema. CO combines with hemoglobin in the blood, in preference to oxygen, and therefore reduces the amount of oxygen reaching the brain. In effect, it is like suddenly being taken to a higher altitude. It thus contributes to altitude illness, and is both dangerous and insidious. Prevention by adequate ventilation is of paramount importance. Ventilation in a tent is a function of the wind speed and the vent area; in an igloo or cave it is a function of the diameter of the vent hole. A fist-sized vent hole guarantees adequate ventilation for properly operating stoves. At the first sign of a headache, CO exposure should be considered and ventilation increased. Treatment of CO poisoning is hyperventilation, preferably with oxygen. Descent also increases the oxygen pressure and is helpful. CO poisoning is probably more common than we realize, and may be misdiagnosed as AMS. (Source: Scott Gill, Mountaineering Ranger, Denali National Park, and Dr. Peter Hackett, Denali Medical Research Group)