AIRWAY RESPONSIVENESS TO COLD AIR AND HYPERPNEA IN NORMAL SUBJECTS AND IN THOSE WITH HAY-FEVER AND ASTHMA

Abstract

Multiple aspects of pulmonary mechanics were measured before and after bronchial challenges of hyperpnea with cold air inhalation in 20 normal control subjects, 16 subjects with hay fever and 44 asymptomatic asthmatic patients. These challenges had no effect on the lung function of the normal subjects. In the hay fever group, postchallenge mechanics changed a small but significant amount, e.g., mean decrease in forced expiratory volume in 1 s (FEV1) was -5.1 .+-. 1.7% (SEM [standard error of the mean]). The asthmatics had a much more marked response (mean fall in FEV1, -32.7 .+-. 2.6%). There was considerable overlap between the responses of the normal subjects and those with hay fever, but no overlap between asthmatic and normal subjects. The only subjects with hay fever whose responses overlapped the asthmatic response were those with histories of occasional wheezing episodes. Use of hyperpnea and subfreezing air is apparently a very sensitive and highly specific means of detecting increased air reactivity.