Relation of volume history of lungs to respiratory mechanics in anesthetized dogs

Abstract

When anesthetized dogs were allowed to breathe spontaneously or were paralyzed and ventilated in the resting tidal range by means of a pump, pulmonary compliance fell progressively. These changes were immediately reversed following forced inflations of the lungs, while forced deflations caused further compliance reductions. The appearance of the lungs post mortem suggested that closure of air-spaces was at least in part responsible for the compliance reductions. Evidence from measurements of total and ventilatory lung gas volumes indicated that the closed spaces were essentially atelectatic. These findings have been related to other observations made in experimental animals and in man. Submitted on December 29, 1958