Affiliation:
1. Department of Medicine, University of Wisconsin-Madison 53705, USA.
Abstract
Respiratory sinus arrhythmia (RSA) is used as a noninvasive measure of vagal cardiac input, but its causative mechanisms in humans remain undetermined. We compared the RSA of five lung-denervated double-lung transplant patients with intact hearts to six normal (N) control subjects, five heart-denervated patients, and two liver transplant patients at matched tidal volumes (VT's) and breathing frequencies. In N and liver transplant subjects, RSA was significant during eupnea and increased two- to threefold with increasing VT and inspiratory effort. In heart- and lung-denervated subjects, RSA at eupnea was significant but was only 53% of that in N subjects and was not respondent to changing VT, inspiratory effort, or breathing frequency. We also compared the RSA of N subjects during voluntary (active) and passive positive pressure ventilation at normocapnia. RSA was reduced from 11 +/- 2.2 beats/min during active ventilation to 5.4 +/- 0.8 beats/min during PPV. We conclude that vagal feedback from pulmonary stretch receptors is obligatory for the generation of a neurally mediated RSA in awake humans at normal and raised levels of VT and respiratory motor output. In intact humans, we also hypothesize an important effect for nonpulmonary central and/or peripheral modulation of RSA. It is likely that the key mechanisms for neurally mediated RSA in unanesthetized humans are mutually dependent.
Publisher
American Physiological Society
Subject
Physiology (medical),Physiology
Cited by
141 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献