Sympathetic influence on alveolar surface activity in hyperventilated dog

Abstract

Hyperventilating IPPB, intermittent positive-pressure breathing, with a frequency of 32 beats/min and inspiratory pressure of 30 cm H2O, was administered for 14 h to open-chested anesthetized dogs in which nerves to 1 bronchus were operatively blocked. In the nerve-intact lungs, the lung stability index calculated from the pressure-volume relationship decreased with the duration of the hyperventilating IPPB (correlation coefficient r = 0.66, P < 0.001), and atelectasis and hemorrhage appeared. In the nerve-blocked lungs, the index did not decrease during the 14 h of hyperventilating IPPB, and the appearance was almost normal. After pharmacologic sympathetic block with phenoxybenzamine, the lung stability index of both the operatively nerve-blocked lung and the nerve-intact lung was not decreased by hyperventilating IPPB. A sympathetic block can protect pulmonary surface activity from the adverse effects of hyperventilating IPPB.