Exercise ventilatory patterns in normal subjects and patientws with airway obstruction.

Abstract

Patterns of ventilation were recorded by a bag-box system In 11 patients with obstructive lung disease and 6 normal subjects at rest and exhausting exercise. A maximal inspiratory capacity was utilized to determine the segment of the lung volume used for ventilation. Inspiratory and expiratory flows were compared to flows over the same lung volume segment during a forced vital capacity (FVC). On the average, exercise expiratory flow for normal subjects was 63% of FVC flow over the same lung volume; exercise inspiratory flow was 40% of FVC flow. In contrast, the patients on the average exhaled their tidal volumes as rapidly at rest as they exhaled a similar volume during the FVC, and during exercise exhalation was 1.8 times faster than during the FVC; exercise inspiratory flow in patients was 61% of inspiratory flow during a FVC. The surprising ability of patients to achieve faster expiratory flows during exercise compared to the FVC probably relates to a moderation of expiratory pressure during exercise resulting in lesser amounts of airway collapse.