Cold air challenge in children with asthma.

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 degrees 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 post-challenge 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%.