Eighty-three patients with
chronic airflow obstruction were examined prospectively to determine the relationships among
wheezing intensity, severity of obstruction, and response to inhaled
isoproterenol. For each patient, expiratory
wheezing scores were assigned during deep unforced breathing and during forced vital capacity efforts at spirometry. Unforced
wheezing scores were independently correlated with severity of obstruction (r = 0.42) and
bronchodilator response (r = 0.46), but these correlations did not permit consistent prediction of either variable for clinical purposes. The highest
wheezing scores, however, were uniformly associated with moderate or severe obstruction. Twenty-nine of 48 patients with
wheezing but only 3 of 35 patients without
wheezing demonstrated 15% or greater improvement in one-second forced expiratory volume after
bronchodilator inhalation (p less than 0.001).
Wheezing during forced exhalation was not correlated with either degree of obstruction or
bronchodilator response.