The prevalence of carboxyhemoglobinemia in New Yorkers and its effects on the coronary and systemic circulation.

Carboxyhemoglobin saturations ranging from 8.11 to 1.56% were found in a sample of more than 1,000 individuals engaged in various activities in New York City. The difference from lowest to highest carboxyhemoglobin in nonsmokers was 1.58%; in smokers it was as great as 5.0%. Experimental elevation of carboxyhemoglobin to levels similar to that seen in cigarette smokers produced a decrease in arterial and venous oxygen tensions and an increase in cardiac output and coronary blood flow. In contrast to the effect on the systemic vascular bed, carbon monoxide inhalation produced a decrease in myocardial oxygen extraction. These observations suggest that changes in coronary blood flow are a useful indicator of the effects of carbon monoxide when hemodynamically significant coronary artery disease prevents the expected increase in myocardial blood flow.