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Carbon Monoxide poisoning
Carbon monoxide (CO) poisoning within tents and snow caves is a real and
probably overlooked problem. It is potentially an even greater problem
at altitude because of the multiplicity of risk factors for CO toxicity.
Despite multiple anecdotal reports of climbers perishing from CO
poisoning on Himalayan peaks circulating in climbing circles, the danger
does not appear to be widely recognized.
Diagnosing CO poisoning in the early stages may be difficult because of
the nonspecific nature of symptoms and (at altitude) their similarity to
AMS. The masking of symptoms when subjects are sedentary exacerbates the
problem, and these are likely to be the occasions when individuals are
subjected to the highest CO levels, such as resting and cooking in tents
for hours during inclement weather. All attempts must be made to prevent
CO concentration from reaching dangerous levels; safety can be enhanced
by the use of small portable CO detectors.
Summary of risk factors (and proposed precautions) for carbon monoxide
poisoning in tents:
-- Cooking (Avoid prolonged simmering, keep stove highly pressurized,
use white pure fuels, use small diameter pans, use maximal blue flame
and avoid low flames)
-- Yellow flame (Turn stove off, repressurize, relight, maximize tent
ventilation for a few minutes)
-- Inadequate tent ventilation (Ventilation area at least 50cm2, CO
egress port as high as possible, O2 ingress port as low as possible,
higher risk in zero wind conditions)
-- Insidious onset of symptoms if sedentary (beware headache and fast
heart rate, make regular trips outside to unmask symptoms, ventilate
tent at regular intervals, ventilation does not have to be continuous)
-- Dehydration (stay well hydrated)
-- Snow holes tend to be worse than tents (beware of all of the above)
-- Hyperventilation (more exposure to CO)
-- High altitude
-- Tent icing and snow cover (makes tent less porous -- keep cleaned to
allow air flow)
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