Respiratory control and work of breathing in obese subjects

Abstract

Lung volumes, arterial blood gases, respiratory control system sensitivity, and oxygen cost of breathing were studied in obese but otherwise normal individuals and compared to similar studies in nonobese control subjects. Respiratory control system sensitivity as measured by the response to 5% carbon dioxide in air was normal in most obese subjects but reduced in certain obese individuals indistinguishable from the others on the basis of clinical evaluation or resting air studies. While breathing 5% carbon dioxide, the ventilation required to maintain any given alveolar carbon dioxide tension was directly dependent on weight. Oxygen cost of breathing in the ventilation range of 10–30 l/min. was elevated in 4 of 12 obese subjects, and in 6 of 9 obese subjects in the range of 20–40 l/min. There was no correlation between oxygen cost of breathing and respiratory control system sensitivity. Submitted on April 29, 1960