Exhaled carbon monoxide screening for environmental tobacco smoke exposure in preanesthetic children

SummaryObjective: Exposure to environmental tobacco smoke (ETS) is associated with an increased risk of perioperative adverse events in children. The purpose of this study was to evaluate exhaled carbon monoxide (CO) as a preoperative ETS screening tool in children. Methods: Five hundred and one children aged 6-15 years were enrolled. The child's guardian completed a questionnaire that surveyed environmental exposures to CO and ETS. A preoperative urine sample was obtained from children who assented and were able to void, and urine cotinine values were measured. Exhaled CO was measured using the EC50-Micro Smokerlyzer^® (Bedfont Scientific Ltd, UK). Results: Four hundred and fifty-one subjects completed the study, and urine samples were obtained from 83. 25% of subjects were classified as exposed to ETS based on questionnaire results. Exhaled CO values did not correlate with either the qualitative (questionnaire) or quantitative (urine cotinine) measurements of ETS exposure. Exhaled CO predicted a urine cotinine/creatinine ratio >10 with a sensitivity of 10% and a specificity of 85%. Conclusion: Exhaled CO measured by this device is not a useful preoperative screening tool for ETS exposure in children. Because exhaled CO has been used successfully to monitor ETS exposure in adolescents, we believe that its failure in our population is as a result of the limited ability of small children to perform vital capacity maneuvers in order to provide an adequate endtidal sample.