Cold air challenge in children with asthma

Abstract

A study was designed to determine the sensitivity and specificity of a cold air bronchial provocation test. A total of 18 children with asthma (mean age 12 years) and 18 normal children (mean age 14 years) were studied. The cold air challenge consisted of a 4 min period of isocapnic hyperventilation of subfreezing air (mean temperature − 15°C). In‐Induced response in forced expiratory volume in 1 sec (FEV₁) expressed as a percentage of predicted normal values was obtained at 4, 6, and 8 min post‐challenge. The average response to the cold air was a 27% decrease of FEV₁ in asthmatics, which was significantly different from that of the normal children, who showed no statistically significant drop. In both the asthmatic and normal groups, the maximal drop in FEV₁ had occurred by the time measurements 4 min post‐challenge had been made. At that time, the smallest overlap was observed between normal and asthmatic children. This suggests that the fourth minute postchallenge can be chosen as a cut‐off time to distinguish normal from asthmatic children. Considering a decrease of FEV₁ greater than 10% as a positive test, the sensitivity of the cold air challenge was 95% and the specificity was 89%.