Acute neurological admission and exposure to carbon monoxide

Abstract

Carbon monoxide poisoning produces central nervous system hypoxia and frequently presents clinically in occult form. From December 1994 to March 1995 we screened 305 patients admitted for acute neurological problems to St. Luke's hospital for exposure to Carbon monoxide by determining blood carboxy-haemoglobin levels on admission. A questionnaire on indoor air pollution was also administered. Three cases of acute intoxication are documented. The mean carboxy-haemoglobin of the other 302 patients was 3.24% (95% CL 0-7.4, n=43) for smokers and 0.73% (95% CL 0-1.90, n=259) for non- smokefs. Five non-smokers and two smokers had levels higher than the upper limit. This level was probably only clinically signi{icant in one case of a heavy smoker with transient ischaemic attack. There were no cases of exposure amongst strokes (n=141), epileptic fits (n=39), or episodes of loss of consciousness (n=87). However 3 out of 29 patients with impairment of consciousness without focal neurological signs had intoxication. Although this intoxication does not appear to be very common, a high index of suspicion must be maintained, as 34% o{the patients questioned had at least one potential source of carbon monoxide within their household. For this reason we suggest that, information on indoor heating should be part of routine history taking of acute neurological problems, particularly when impaired consciousness is persistent in the emergency room. Carboxy-Hb levels should be taken when there is even the slightest suspicion of exposure, as early treatment of this intoxication with high concentration oxyġen therapy is very effective.