Initial oxygen saturation as a predictor of admission in children presenting to the emergency department with acute asthma

Abstract

Background: Previous studies have looked at the relationship between initial oxygen saturation (SaO2) and the need for admission in children presenting with an acute asthma exacerbation. If initial SaO2 value is indeed predictive of admission, then the admission process could be initiated sooner, and time spent in the emergency department could be potentially lessened. Study objective: The objective of the current study was to examine whether initial room air SaO2 in children presenting to the ED with acute asthma is a reliable predictor of hospital admission. Methods: This was a prospective multicenter study during 1997 and 1998 at 44 North American EDs as part of the Multicenter Airway Research Collaboration. Inclusion criteria were physician diagnosis of acute asthma and age between 2 and 17 years. The association between hospital admission and SaO2 was examined by using logistic regression. Likelihood ratios were used to assess the diagnostic value of SaO2. Results: Of the 1,184 children enrolled in the current study, 1,040 (88%) had a documented initial SaO2 value on room air. The mean age of the cohort was 8±4 years, with a mean initial SaO2 of 95%±4%. Overall, 241 (23%) children were admitted to the hospital. The mean SaO2 value of children admitted to the hospital was 93%±5% versus 96%±3% for those not admitted (P <.001). The admission rate decreased with increasing SaO2; 73% (30/41) of children with an SaO2 value of 88% or less were admitted versus 8% (7/88) with an SaO2 value of 100%. In the logistic regression model, children with an SaO2 value of 88% or less were 32 (95% confidence interval 11 to 89) times more likely to be admitted than those with an SaO2 value of 100%. The likelihood ratio for admission was 12 for children with an SaO2 value of 88% or less (42/1,040) but decreased to 4.6 for children with an SaO2 value of 91% or less (130/1,040) and 2.7 for children with an SaO2 value of 94% or less (333/1,040). Conclusion: This large, clinical multicenter study does not support earlier findings that SaO2 alone is a clinically useful predictor of hospital admission in children who present to the ED with acute asthma. [Ann Emerg Med. 2002;40:300-307.]