Diurnal expiratory flow after inhalation of Freons and fenoterol in childhood asthma.

Eighteen children aged 8 to 14 years with bronchial asthma were studied with respect to the diurnal variation in pulmonary expiratory flow and the influence on it of inhalation of Freons and of a beta 2-receptor stimulator, fenoterol. A double-blind technique and randomized order of the different conditions were used. Dynamic spirometric tests were performed every hour from 8 A.M. to 4 P.M. The low expiratory flow in the morning increased during the day and influenced the estimated duration of the beta 2-receptor stimulator. This must be taken into consideration when evaluating the long-term effect of bronchodilator drugs. The Freons acted as irritants and lowered the expiratory flow during the first 2 hr after inhalation. However, this impairment of lung function does not seem to be of any clinical importance when freons are used as propellants for potent beta 2-receptor stimulators such as fenoterol.