Scharf S M, Brown R, Saunders N, Green L H
J Appl Physiol Respir Environ Exerc Physiol. 1979 Sep;47(3):582-90. doi: 10.1152/jappl.1979.47.3.582.
To assess the hemodynamic effects of spontaneous inspiration, we studied 12 anesthetized mongrel dogs during normal and loaded inspiration, before and after bilateral cervical vagotomy. Peak aortic flow fell (15--20%) whereas peak pulmonary artery flow rose (15--20%) under all conditions. When aortic flow fell, left ventricular diastolic size decreased whereas aortic and left atrial transmural pressures increased slightly. Right ventricular diastolic size and right atrial transmural pressure increased. During inspiratory loading transmural pressures rose more, but the fall in aortic flow remained the same. After vagotomy, inspiration was prolonged, allowing aortic flow to return to preinspiratory levels. At this time left ventricular diastolic size was increased compared to preinspiratory levels and there were further increases in left atrial and aortic transmural pressures. We have concluded that at least two factors affect aortic flow during inspiration: 1) a decrease in left ventricular preload that is associated with decreased left ventricular compliance, and 2) increased impedance to left ventricular emptying as reflected by the increase in aortic transmural pressure. This may play a greater role during inspiratory loading and when inspiration is prolonged.
为评估自主吸气的血流动力学效应，我们在双侧颈迷走神经切断术前、后，对12只麻醉的杂种犬在正常吸气和负荷吸气时进行了研究。在所有情况下，主动脉血流峰值下降（15%-20%），而肺动脉血流峰值上升（15%-20%）。当主动脉血流下降时，左心室舒张期大小减小，而主动脉和左心房跨壁压略有增加。右心室舒张期大小和右心房跨壁压增加。在吸气负荷时，跨壁压上升更多，但主动脉血流的下降保持不变。迷走神经切断术后，吸气延长，使主动脉血流恢复到吸气前水平。此时，与吸气前水平相比，左心室舒张期大小增加，左心房和主动脉跨壁压进一步升高。我们得出结论，至少有两个因素影响吸气时的主动脉血流：1）左心室前负荷降低，这与左心室顺应性降低有关；2）主动脉跨壁压升高所反映的左心室排空阻抗增加。这在吸气负荷时和吸气延长时可能起更大作用。
