Emergency department screening for unsuspected carbon monoxide exposure

Carbon monoxide (CO) is the leading toxic cause of death in the United States today. Unsuspected exposure to this gas will sometimes result in clinically significant, but undiagnosed, toxicity. A high incidence of such unsuspected exposures would make screening for these worthwhile among high-risk populations. We conducted a two-part study to determine the value of screening for unsuspected CO exposure in a population of patients presenting to an emergency department. The first part of our study involved the prospective screening of ED patients using CO breath analysis, regardless of their chief complaint. In the second part, COHGB levels of all patients who underwent arterial blood gas analysis during the study period were reviewed retrospectively. Of 1,038 patients screened by this combined approach, only 29 (2.8%) had abnormal CO breath readings and/or COHGB levels. Of a condensed subgroup of 152 patients defined retrospectively by chief complaint, eight (5.3%) had abnormal values. We conclude that routine screening of ED patients for unsuspected CO exposure is not practical. Although yield increases when patients are screened in a more selective manner on the basis of chief complaint, such an increase still does not appear to justify the screening process.