INFLUENCES OF CHANGING BODY POSITION UPON PULMONARY VENTILATION

Abstract

In twenty eight patients with cardiac diseases, seven patients with pulmonary siseases, eight patients with other diseases, changes of vital capacity, maximal breathing capacity, breathing reserve ratio, tidal volume, and expiratory reserve volume were measured in the following body positions: sitting, right lateral, left lateral, supine positions.
In all groups, vital capacity, maximal breathing capacity and expiratory reserve volume were less in the lateral position than in the sitting position, and least in the supine position. These changes were most evident in patients with pulmonary diseases, therefore, the increase of ventilatory resistance seemed to be the chief causal element ot orthopnea in pulmonary patients.
In comparing vital capacity and maximal breathing capacity in the right lateral position with those in the left, in cardiac patients, values in the former position were larger than in the latter as far as average of the changes was concerned, and in other two groups the reverse situation was observed.
Breathing reserve ratio was not so markedly changed by changing body position.
In cardiac patients, the influences of circulatory failure upon the pulmonary congestion and the easy fatigabiliyt of respiratory muscles seemed to be the important causal elements of orthopnea and trepopnea.