Konishi H, Antaki J F, Boston J R, Kerrigan J P, Mandarino W A, Yamazaki K, Oe M, Litwak P, Borovetz H S, Butler K C
University of Pittsburgh, Artificial Heart and Lung Program, School of Medicine, PA, USA.
ASAIO J. 1994 Jul-Sep;40(3):M299-302. doi: 10.1097/00002480-199407000-00012.
Changes in systemic vascular resistance (SVR) in response to diminished pulse perfusion were analyzed over a dynamic range of flow conditions. An axial flow LVAD (Nimbus AxiPump, Rancho Cordova, CA) was implanted in a sheep for 28 days, during which time SVR was determined over several conditions of posture and excitability. Total arterial resistance (TR) was calculated dynamically as an index of SVR by analysis of pump flow in diastole, and systemic pressure estimated from the characteristic pressure-flow-speed relation of the AxiPump. TR was evaluated over a range of flow rates, including maximum flow--for which the pressures and flows were essentially nonpulsatile. Throughout the course of support, and independent of pulsatility, TR dropped when the sheep stood and was significantly lower than that in the sitting position (P < 0.01). Response to excitement followed the same trend: TR was significantly higher during agitation than during normal temper (P < 0.01). In spite of changes in pulse pressure and flow rate, SVR changes occurred according to expected physiologic responses for pulsatile perfusion. Because pump flow and pressure are sensitive to afterload, the results of these studies suggest that pump speed control must compensate for changes in SVR to maintain acceptable perfusion.
在一系列动态血流条件下，分析了因脉冲灌注减少而导致的全身血管阻力（SVR）变化。将一台轴流左心室辅助装置（Nimbus AxiPump，加利福尼亚州兰乔科尔多瓦）植入一只绵羊体内28天，在此期间，在几种姿势和兴奋状态条件下测定SVR。通过分析舒张期泵血流量，并根据AxiPump的特征压力-流量-速度关系估算全身压力，动态计算总动脉阻力（TR）作为SVR的指标。在一系列流速范围内评估TR，包括最大流速——此时压力和流量基本无脉动。在整个支持过程中，与搏动性无关，当绵羊站立时TR下降，且显著低于坐姿时的TR（P < 0.01）。对兴奋的反应遵循相同趋势：激动时的TR显著高于正常状态时的TR（P < 0.01）。尽管脉压和流速发生了变化，但SVR的变化符合搏动灌注预期的生理反应。由于泵血流量和压力对后负荷敏感，这些研究结果表明，泵速控制必须补偿SVR的变化，以维持可接受的灌注。
