Facial Cooling Causes Greater Exercise-Induced Bronchoconstriction in Children with Asthma

Abstract

0462 PURPOSE: Exercising in cold air enhances bronchial response (BR) as compared to exercising in warm air. This may be due to intrathoracic cooling or to increased vagal activity caused by facial cooling. The purpose of this study was to determine the respective contribution to BR of direct (inhalation) and indirect (facial cooling) influences when children exercise in cold air, as well as the combined effect of both. METHODS: 14 children (8 girls, 6 boys) with asthma performed four exercise challenge tests in a climatic chamber, under one of the following conditions: 1) inhaling “warm” air while the face was exposed to “warm” air (WW, 21°C, 25% relative humidity (RH)), 2) inhaling warm air while the face was exposed to cold air (WC, 0°C, 80% RH,), 3) inhaling cold air while the face was exposed to cold air (CC), 4) inhaling cold air while the face was exposed to warm air (CW). The study was analyzed, using a 2-way ANOVA. RESULTS: Forced expiratory volume in the first second (FEV1) and maximal mid-expiratory flow (MMEF) values showed significant reductions during the entire trial, but the extent of reduction differed among the four experimental conditions. There was a significant condition × time interaction for FEV1 (p = 0.001), but not for MMEF (p = 0.10). FEV1 was significantly lower for CC, as compared to WC and CW at 5 and 10 minutes post-exercise. CONCLUSIONS: The combined challenges of inhaling cold air and facial cooling cause the greatest EIB in children with asthma, as compared to either of the isolated cold challenges; the contribution of small airways to flow limitation after exercising in cold air remains unclear. We suggest that vagal mechanisms play an additional role to bronchial cooling in exercise and cold-induced bronchoconstriction.