摘要：

Essential manifestations of pulmonary emphysema are retarded expiratory airflow and incomplete expiration (1-3). These occur even though the patient makes a strenuous muscular effort to expel the vital capacity air as quickly and coml)letely as possible. Inspiration is, by contrast, relatively unimpeded. The circumstances suggest the presence of expiratory obstruction, which is aggravated by increasing the expulsive force, in other words, a check valve type of obstruction. To determine whether such a mechanism exists we employed the method of Neergaard and Wirz (4) which, under suitable conditions, provides a continuous record of pleural pressure and rate of airflow. From these one may compute pulmonary pressure, by which we mean the pressure in the terminal air spaces; together with lung tension. The latter designates the net elastic recoil of the lungs, or "elastance" (5), expressed in centimeters of water pressure, under static conditions, at a particular lung volume. It represents the pressure required to maintain the lungs at that degree of distension when no air is passing in or out of the organs. Relevant observations on the lunigs at necropsy, anid on the gross behavior of the major airways dutring forceful expiration were also inlcluded.

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