Compliance of the respiratory system and its components in health and obesity

TLDR

The study measured total respiratory system compliance and its components in 24 normal and 12 obese spontaneously breathing subjects. Obese subjects had markedly lower total respiratory compliance (0.052 l/cm H₂O vs 0.119 l/cm H₂O) due to reduced chest wall compliance (0.077 l/cm H₂O vs 0.224 l/cm H₂O), while lung compliance was unchanged; recumbency further reduced compliance in obesity, and total compliance correlated with vital capacity, indicating that increased elastic work on the chest wall drives the higher breathing work in obesity. Submitted on November 2, 1959.

Abstract

The compliance of the total respiratory system and its components was studied in 24 normal and 12 obese spontaneously breathing unanesthetized subjects. The mean compliance of the total respiratory system was .119 l/cm H 2 O in normal individuals, but was .052 l/cm H 2 O in obese subjects. The difference indicated an increased elastic resistance to distention. The compliance of the lung in obese individuals was not different from that of the normals. The compliance of the chest wall was .224 l/cm H 2 O in normal subjects and was .077 l/cm H 2 O in obese individuals. In contrast to normal subjects, total respiratory compliance was markedly reduced by recumbency in obese individuals. This was entirely due to a further increase in the resistance of the chest wall. A significant correlation was demonstrated between vital capacity and total respiratory compliance in normal and obese subjects. It has been estimated that of the increase in the mechanical work of breathing in obesity is due to elastic work done on the chest wall. Submitted on November 2, 1959