End-tidal carbon dioxide measurements in children with acute asthma

A noninvasive method to assess ventilation may aid in management of children with acute asthma. The purpose of this study was to evaluate the association between end-tidal carbon dioxide (EtCO2) values and disease severity among children with acute asthma.

This was a prospective, blinded, observational study of children 3-17 years old treated for acute asthma in a pediatric emergency department (ED). EtCO2 measurements were taken before the initiation of therapy and after each nebulization treatment (maximum of three). Peak expiratory flow rate (PEFR), Pediatric Asthma Severity Score (PASS), oxygen saturation, and disposition were recorded. Treating physicians, unaware of the EtCO2 results, made all treatment decisions, including disposition.

One hundred children were enrolled. The mean initial EtCO2 value was 35 mm Hg (95% confidence interval = 34.3 to 36.1 mm Hg). The mean disposition EtCO2 value was 33.3 mm Hg (95% confidence interval = 32.6 to 34.4 mm Hg). PEFR measures were completed on 43 patients and PASS recorded on 100 patients. There was an overall trend toward lower EtCO2 values during treatment (p < 0.01). Sixteen patients were admitted. Initial EtCO2 values were lower among children admitted to the hospital (35.6 mm Hg vs. 32.9 mm Hg; Mann-Whitney U test; p < 0.02). EtCO2 values at disposition did not differ between groups based on PEFR, PASS, or hospital admission.

Noninvasive bedside measurement of EtCO2 values among children with acute asthma is feasible. EtCO2 values did not distinguish children with mild disease from those with more severe disease. Further data are needed to clarify the association between EtCO2 values and other indicators of disease severity, particularly in children with more severe disease.