Evaluation of lung function indices for bronchodilator trials. Results of a cross-over study of fenoterol.

In 10 patients with airway obstruction, spirographic indices and maximal expiratory flow rates were measured before inhalation of fenoterol and at different time intervals, for 5 h, following the inhalation of 200 mug of this substance. 10 min after inhalation of fenoterol, there was a statistically significant increase in all lung function indices. A further increase was observed later. 3 h after inhalation of fenoterol, all indices were still significantly higher than control values. No side effects were observed. At all time intervals, the increase of the forced expiratory volume in 1 sec (FEV1.0), peak expiratory flow rate (PEFR) and maximal expiratory flow rate at 50 and 75% of the vital capacity reached a similar level of statistical significance. It is concluded that for the trial of the bronchodilator drugs, any of these indices may be used, and for practical purposes FEV1.0 and PEFR are best suited.