A comparison of pulmonary function in extrinsic and intrinsic bronchial asthma.

Abstract

The dynamic and static lung volumes, arterial blood gas tensions, and pulmonary diffusing capacity were measured in 292 patients with extrinsic asthma (reactive skin tests) and 63 patients with intrinsic asthma (nonreactive skin tests) when the one-second forced expiratory volume was less than 70 per cent of forced expiratory volume. the only significant difference between the 2 groups was that the patients with extrinsic asthma were younger and had higher mean values for residual volume in per cent of predicted normal values and for the ratio of residual volume to total lung capacity. in the asthmatic patients as a whole, as airway obstruction increased, the lungs became progressively hyperinflated and increasing hypoxemia occurred. Hypocapnia occurred with milder degrees of airway obstruction, and the arterial carbon dioxide tension tended to return to normal as the airway obstruction increased. Pulmonary diffusing capacity decreased with increasing airway obstruction as did the Krogh factor. a study of...