Hettrick D A, Pagel P S, Warltier D C
Department of Anesthesiology, Medical College of Wisconsin, Milwaukee 53226, USA.
Anesthesiology. 1996 Aug;85(2):403-13. doi: 10.1097/00000542-199608000-00023.
The effects of desflurane, sevoflurane, and isoflurane on left ventricular-arterial coupling and mechanical efficiency were examined and compared in acutely instrumented dogs.
Twenty-four open-chest, barbiturate-anesthetized dogs were instrumented for measurement of aortic and left ventricular (LV) pressure (micromanometer-tipped catheter), dP/dtmax, and LV volume (conductance catheter). Myocardial contractility was assessed with the end-systolic pressure-volume relation (Ees) and preload recruitable stroke work (Msw) generated from a series of LV pressure-volume diagrams. Left ventricular-arterial coupling and mechanical efficiency were determined by the ratio of Ees to effective arterial elastance (Ea; the ratio of end-systolic arterial pressure to stroke volume) and the ratio of stroke work (SW) to pressure-volume area (PVA), respectively.
Desflurane, sevoflurane, and isoflurane reduced heart rate, mean arterial pressure, and left ventricular systolic pressure. All three anesthetics caused similar decreases in myocardial contractility and left ventricular afterload, as indicated by reductions in Ees, Msw, and dP/dtmax and Ea, respectively. Despite causing simultaneous declines in Ees and Ea, desflurane decreased Ees/Ea (1.02 +/- 0.16 during control to 0.62 +/- 0.14 at 1.2 minimum alveolar concentration) and SW/PVA (0.51 +/- 0.04 during control to 0.43 +/- 0.05 at 1.2 minimum alveolar concentration). Similar results were observed with sevoflurane and isoflurane.
The present findings indicate that volatile anesthetics preserve optimum left ventricular-arterial coupling and efficiency at low anesthetic concentrations (< 0.9 minimum alveolar concentration); however, mechanical matching of energy transfer from the left ventricle to the arterial circulation degenerates at higher end-tidal concentrations. These detrimental alterations in left ventricular-arterial coupling produced by desflurane, sevoflurane, and isoflurane contribute to reductions in overall cardiac performance observed with these agents in vivo.
在急性插管的犬中，研究并比较了地氟烷、七氟烷和异氟烷对左心室 - 动脉耦合及机械效率的影响。
对24只开胸、巴比妥类麻醉的犬进行插管，以测量主动脉和左心室（LV）压力（微测压头导管）、dP/dtmax和LV容积（电导导管）。通过一系列左心室压力 - 容积图得出的收缩末期压力 - 容积关系（Ees）和预负荷可募集搏功（Msw）评估心肌收缩力。左心室 - 动脉耦合和机械效率分别由Ees与有效动脉弹性（Ea；收缩末期动脉压与搏出量之比）的比值以及搏功（SW）与压力 - 容积面积（PVA）的比值确定。
地氟烷、七氟烷和异氟烷降低了心率、平均动脉压和左心室收缩压。所有三种麻醉药均使心肌收缩力和左心室后负荷出现相似程度的降低，分别表现为Ees、Msw、dP/dtmax和Ea降低。尽管地氟烷使Ees和Ea同时下降，但它降低了Ees/Ea（对照时为1.02±0.16，在1.2倍最低肺泡浓度时为0.62±0.14）以及SW/PVA（对照时为0.51±0.04，在1.2倍最低肺泡浓度时为0.43±0.05）。七氟烷和异氟烷也观察到类似结果。
目前的研究结果表明，挥发性麻醉药在低麻醉浓度（<0.9倍最低肺泡浓度）时可保持最佳的左心室 - 动脉耦合和效率；然而，在较高的呼气末浓度时，从左心室到动脉循环的能量传递的机械匹配会退化。地氟烷、七氟烷和异氟烷引起的左心室 - 动脉耦合的这些有害改变导致了在体内观察到的这些药物所致的整体心脏功能下降。
