Effects of Cervical Vagotomy on Pulmonary Ventilation and Mechanics

Abstract

The ventilatory function and mechanical properties of the respiratory pump were studied before and after cervical vagotomy in anesthetized dogs. Vagotomy reduced the frequency and increased the amplitude of breathing without producing a significant change in total ventilation. Alveolar ventilation, however, increased approximately 40% and this produced a respiratory alkalosis. Flow patterns, analyzed by pneumotachograph, showed a longer flow duration and a reduced peak velocity during inspiration following vagotomy. Expiratory peak flow velocity was increased without marked changes in form or duration of flow, but the end-expiratory pause was greatly prolonged. Vagotomy increased both lung compliance and functional residual capacity in such a way that ‘specific compliance’ remained constant. No change in lung tissue-airway resistance was observed after vagotomy. Mechanical work done on the lungs and respiratory gases per liter total ventilation increased 45% following vagal denervation due exclusively to an increase in the elastic component. Submitted on May 7, 1958