Peyton A. Eggleston

A standardized method of evaluating exercise-induced asthma

In order to evaluate drug effects on exercise-induced asthma, and to study associated metabolic and pulmonary effects, a method for inducing a consistent response is needed. A method is presented, consisting of 5 min of treadmill exercise sufficiently strenuous to increase a subjects heart rate to 90% of the predicted maximum for age; the airway response is measured frequently for 20 min after exercise. Using this method, 48 asthmatics and 13 nonasthmatics were evaluated. Although none developed severe asthma, a significant airway response occurred in 71% of asthmatics. The severity of exercise-induced asthma depended on intensity and duration of exercise but not on time of day. The method described allows a consistent stress to be applied to a wide age range, and response to this stress was consistent at various ages. Variation of a subjects response following repeated testing was less than that reported with other methods, and could be further reduced by selecting only those subjects with greater than 20% change in one-second forced expiratory volume (FEV1) and by completing studies in less than a month.

A comparison of the asthmatic response to methacholine and exercise

The airway responses to methacholine and to exercise challenges were compared in 45 young adults with asthma. The spirometric response to five minutes of treadmill exercise was first documented. On a separate day methacholine dose-response relationships were determined. All asthmatics had an abnormal response to methacholine, and 36 had an abnormal response to exercise. Methacholine sensitivity and exercise-induced asthma were significantly related (r = 0.69, p less than 0.001), but the relationship was nonlinear; the increased response to exercise related to the logarithm of the methacholine response. Between asthmatics with generally unreactive airways, small variation in methacholine sensitivity was associated with large variations in the severity of exercise-induced asthma; between more responsive asthmatics, there was a smaller effect. It is suggested that exercise-induced asthma is dependent on two factors: a stimulus generated during exercise and a response from abnormal bronchi. The bronchial response may be a limiting factor in asthmatics with less responsive airways.

Otitis media and the immotile cilia syndrome

The immotile cilia syndrome appears to be a congenital defect in the ultrastructure of cilia that renders them incapable of movement. Respiratory tract cilia and sperm are predominantly affected. Bronchiectasis, sinusitis and male sterility are the main clinical findings. Situs inversus may be found. To these findings can be added otitis media.

Bronchodilation and inhibition of induced asthma by adrenergic agonists

In asthma, adrenergic agonists alleviate airflow obstruction and prevent obstructive responses to a variety of stimuli. A rapidly and a slowly metabolized agonist were compared to determine whether bronchodilation is the major mechanism by which these drugs prevent exercise‐induced asthma (EIA). A 200‐µg inhaled dose of the rapidly metabolized agonist, isoproterenol, induced bronchodilation of the same order as terbutaline 500 µg (I‐sec forced expiratory volume [FEV1] increased 9.5% and 10.2%). An hour after isoproterenol, FEV1 was still above baseline (p < 0.02), but EIA was only partially inhibited; the 23% fall in FEV1 was of the same order as the 32% fall after placebo (p > 0.05). One hour after terbutaline, mean resting FEV1 was in the range of that after isoproterenol, but the 10% change after exercise was less than that after placebo and isoproterenol (p < 0.005). Our findings suggest that the two effects have different dose‐response relationships, with higher doses of adrenergic agonists needed to prevent EIA than to maintain bronchodilation.