THE KINETICS OF LUNG VENTILATION

Abstract

Theoretical considerations indicate that the work involved in breathing a mixture of 80% He-20% O will be less than in breathing air only if there is turbulence of the air. For streamline flow He-0 mixtures require 10% more work than air, but when air flow is turbulent, He-O, mixtures may require only 1/3 as much work as air. The work expended in ventilating lungs of anesthetized dogs is detd. from time records of the tracheal pressures obtained with a glass spoon manometer. Diagrams of pressure as a function of the vol. in the lungs permit a direct measurement of the elasticity and the viscous resistance of the lungs. There is no significant difference between air and He-0 mixtures in 4 normal and one pilocarpinized dog. Constriction of the tracheal cannula producing turbulence increases the work more for air than for He-0 mixtures. A large part of the viscous resistance to breathing is located in the tissues and not in the gas since the lung shows adaption to changes in vol. which accounts for a large part of the work of ventilation. Pressure vol. diagrams calculated from data in the literature are shown for human subjects breathing normally. They are calculated from simultaneous records of intrapleural pressure and air velocity.