Respiratory Effects of Increased Air Flow Resistance in Dogs.

Abstract

Anesthetized dogs were subjected to respiratory stress by imposing various resistances to tracheal air flow. The pattern of breathing and composition of arterial blood was investigated with the following conclusions: (1) When tracheal air flow is so impeded as to produce pronounced changes in inspiratory and expiratory pressures, breathing rates increase, minute volumes may remain relatively uniform and tidal volumes decrease inversely with the pressure differences. (2) Two factors are involved in the accommodation to this respiratory stress. Increasing CO2 tensions act as primary stimuli to more forced inspiration and expiration; and decreasing O2 tensions act as stimuli to more rapid breathing by reducing the time of the expiratory phase of the breathing cycle.