Pulmonary function in different animals

¹ Department of Physiology, University of Rochester School of Medicine and Dentistry, Rochester, New York

Relaxation pressure-volume curves have been determined from the lungs and thorax of mice, rats, rabbits and dogs. From these data figures are obtained for body weights, vital capacity and compliance. These are compared with similar data for man and calculated values for tidal volumes and frequency of breathing obtained from the literature. Calculations were made of the elastic work of breathing per breath and per minute. All values were plotted on double log paper against body weight so that they could be expressed as proportional to some power of body weight. It was found that compliance, tidal volume, vital capacity and elastic work per breath are all nearly proportional to the first power of the body weight while the elastic work per minute, like the rate of oxygen consumption, is proportional to the 0.7 (or 0.73) power of body weight. It is concluded that lungs of large and small animals tend to have the same compliance per unit of vital capacity and require the same pressure for the intake of one tidal volume. A large lung may therefore be regarded as equivalent to many smaller lungs in parallel.

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