Evaluation of pre- and posttreatment pulse oximetry in acute childhood asthma

Objectives: To evaluate the utility of pre- and posttreatment O₂ saturation (SpO₂) for prediction of admission or relapse after ED release in acute asthma exacerbations using a standardized treatment protocol. Design: A prospective, double-blind, observational study was performed at a pediatric ED. Children with acute asthma were enrolled upon ED presentation. SpO₂ was measured prior to treatment and after disposition decision. Two experienced physicians determined disposition based on history and physical examination alone, while blinded to SpO₂. Relapse of released patients was determined by telephone follow-up. Results: A pretreatment room-air SpO₂ of ≤91% had a sensitivity of 0.24, a specificity of 0.86, and a likelihood ratio of 1.77 to predict admission/relapse. A posttreatment room-air SpO₂ of ≤91% had a sensitivity of 0.34, a specificity of 0.98, and a likelihood ratio of 16.43 to predict admission/relapse. Conclusions: As opposed to some previous studies, this study found pretreatment SpO₂ to be a relatively poor predictor of admission. A posttreatment SpO₂ of ≤91% occurred in a minority (32%) of patients, but increased the odds of admission 16-fold and may be used as an adjunct to objectively confirm the need for admission.