Predicting the Need for Hospitalization in Acute Childhood Asthma Using End-tidal Capnography

Abstract

OBJECTIVE: To explore the utility of end-tidal capnography for predicting hospitalization in acute childhood asthma. DESIGN, SETTING, AND PARTICIPANTS: A prospective cohort study of a convenience sample of children 5 to 17 years of age presenting to a pediatric emergency department with an acute asthma exacerbation. Capnography was performed at baseline. The length of the plateau portion of the baseline capnograph waveform was measured in millimeters and divided by the respiratory rate at the time of the measurement to create a ratio. The sensitivity and specificity of the baseline capnography ratio for predicting hospitalization were assessed. MAIN OUTCOME MEASURES: Hospitalization versus discharge from the pediatric emergency department. RESULTS: Thirty-seven patients were enrolled. The hospitalized (n = 12) and discharged (n = 25) groups did not differ in terms of any demographic or baseline characteristics except for pulmonary score and the median baseline capnography ratio. The median ratio was 0.15. Ten (83.3%) of 12 of patients who were hospitalized had a baseline ratio less than 0.15 compared with 8 (32%) of 25 of patients who were discharged from pediatric emergency department (P < 0.05). Controlling for baseline asthma severity, the odds of being hospitalized if the baseline capnography ratio was less than 0.15 were 18.77 (95% confidence interval, 1.91-184.69). CONCLUSION: This pilot study suggests that baseline capnography may be useful as an objective effort-independent tool for identifying children with an asthma exacerbation who are at risk for hospitalization.