Oxygen saturation as a predictor of prolonged, frequent bronchodilator therapy in children with acute asthma

Objectives To examine if the initial oxygen saturation (SaO(2)) in the Emergency Department is a useful predictor of prolonged frequent bronchodilator therapy (FBT) in children with acute asthma. Study design Prospective cohort study of 273 children, 1 to 17 years of age, requiring systemic corticosteroids. Patients were categorized as needing FBT for >4 hours (n = 166) versus >4 hours (n = 107) and >12 hours (n = 79) versus >12 hours (n = 194). Multiple logistic regression determined the association between SaO(2) and these outcomes. Results Baseline SaO(2) remains a significant independent predictor of FBT for >4 hours (OR = 0.81) and >12 hours (OR = 0.84); 91% of patients with SaO(2) of 90% to 91% had FBT >4 hours and 80% of patients with SaO(2) of less than or equal to89% had FBT >12 hours. Children with SaO(2) of less than or equal to91% are 14.7 and 12.0 times more likely to require FBT for >4 hours and >12 hours, respectively, than those with SaO(2) of 98% to 100%. The interval likelihood ratios for FBT >4 hours were 12.3 for SaO(2) of less than or equal to89%, 6.5 for 90% to 91%, but only 1.8 for 92% to 93%. The likelihood ratios for FBT >12 hours decreased from 9.8 for SaO(2) of less than or equal to89% to 3.5 for SaO(2) of 90% to 91%. Conclusions SaO(2) is a useful predictor of FBT >4 hours if it is less than or equal to91% and of FBT >12 hours if it is less than or equal to89%.