BRONCHOCONSTRICTION DUE TO COLD WEATHER IN COPD - THE ROLES OF DIRECTAIRWAY EFFECTS AND CUTANEOUS REFLEX MECHANISMS

To clarify how cold weather may induce bronchoconstriction in patients with COPD, a series of challenges were performed in 20 patients with COPD in stable condition as well as in 13 healthy subjects, A whole-bo dy exposure to -17 degrees C during resting nasal breathing was perfor med to study the reflex effects of facial cooling on lung function, In addition, a near-maximal hyperventilation of cold air was performed i n a warm room to study the direct airway effects of cold air, The whol e-body exposure to cold air induced statistically significant bronchoc onstriction in both groups, the maximal decrements in FEV(1) being 9.4 +/-1.4% in the patients with COPD and 10.3+/-0.8% in the healthy subje cts (p=NS), The whole-body exposure to cold air also increased the res ting ventilation, The hyperventilation challenge induced bronchoconstr iction only in the patients with COPD, the maximal decrements in FEV(1 ) being 8.0+/-1.3% and 1.51+/-1.0%, respectively (p<0.01). These resul ts suggest that cooling of the facial skin is predominantly responsibl e for the bronchoconstriction due to cold weather both in patients wit h COPD and in healthy subjects, At high ventilation level, as during h eavy exercise, the direct airway effects of cold air may also contribu te to the bronchoconstriction in patients with COPD, Some patients wit h severe COPD might benefit from wearing protective clothing over thei r face in cold weather.