Frequency and clinical course of acute carbon monoxide poisoning in relation to the kind of emission gas.

The conversion of domestic supply from illuminating to natural gas in 1975 in Kraków was expected to diminish, or even eliminate the threat of CO intoxication. The aim of the study was to compare the frequency and clinical course of CO poisonings (early or delayed medical complication or death) regarding the source of CO (illuminating or natural gas). Under analysis there were adult inhabitants of Kraków treated at the Department of Clinical Toxicology from 1972 to 1974 when the main source of CO was illuminating gas and those treated from 1994 to 1996 i.e. after the conversion of domestic gas supply from illuminating to natural gas. All the cases of people who died at the scene of the accident prior to any treatment were also included. The frequency of acute poisonings among the inhabitants of Kraków was expressed by the incidence rate per 10,000 inhabitants with regard to age and sex. The severity of CO poisoning was estimated considering age, duration of exposure, carboxyhemoglobin (COHb) level, and the neurological state of patients on admission to the Clinic. Significantly higher frequency of suicidal poisonings was noted in the group of patients poisoned with illuminating gas compared to those poisoned with CO produced by incomplete combustion of natural gas (p < 0.001). No significant differences were noted considering the age of patients hospitalised in both periods. Duration of exposure was significantly longer and carboxyhemoglobin level was significantly higher in the group of patients poisoned with illuminating compared to natural gas. Significantly higher frequency of severe poisonings was noted in the group of patients intoxicated with illuminating gas compared to those intoxicated with natural gas. The frequency of acute CO poisonings in the population of Kraków determined by the incidence rate per 10,000 inhabitants was approximated to 2.4 in all the years analysed. The conversion of domestic supply from illuminating to natural gas significantly decreased the mortality rate. No differences in the number of patients suffering from medical complications were found between the two study periods. A higher incidence of late sequalae (psychoorganic and depressive syndromes) was found in the group of patients poisoned with CO produced by incomplete combustion of natural gas compared to illuminating gas.