Diagnostic room-air pulse oximetry: effects of smoking, race, and sex

ObjectiveWe sought to determine the distribution of oximetry (Spo2) values in awake, asymptomatic adults and the effect of personal characteristics on these values.MethodsUsing a cross-sectional design, we sampled oximetry readings in awake, asymptomatic adults in an emergency department setting. Personal characteristics were analyzed using logistic regression, with lower oximetry readings, defined by the 20th percentile, as the dependent variable.ResultsOf 871 eligible subjects, 50 (5.7%) had an Spo2 value less than 97%, and 13 (1.5%) had an Spo2 value less than 96%. Lower readings were associated with the following characteristics (odds ratio with 95% confidence interval): male sex, 3.8 (2.5-5.6); age ≥60 years, 2.4 (1.3-4.5); white race, 5.3 (3.6-7.8); obesity, 3.2 (2.1-4.8); history of asthma, 3.2 (1.6-6.2). Smoking was not associated with lower Spo2 values.ConclusionRoom-air Spo2 values less than 97% are rare in asymptomatic, awake adults. White race and male sex are associated with lower Spo2 readings.