Pagel P S, Kampine J P, Schmeling W T, Warltier D C
Department of Anesthesiology, Medical College of Wisconsin, Milwaukee.
Acta Anaesthesiol Scand. 1993 Feb;37(2):203-10. doi: 10.1111/j.1399-6576.1993.tb03702.x.
Characterization of changes in myocardial contractility using indices derived from ventricular pressure-segment length loops in animals with intact autonomic nervous system (ANS) function is complicated by alterations in systemic hemodynamics mediated by baroreceptor reflexes and by spontaneous respiration and its effects on ventricular pressure and filling. This investigation examined and compared the effects of desflurane and isoflurane on myocardial contractility in dogs with intact ANS reflexes using techniques designed to overcome these potential difficulties. Two groups comprising 18 experiments were performed using nine dogs chronically instrumented for measurement of aortic and left ventricular pressure, the maximum rate of increase of left ventricular pressure (dP/dt), subendocardial segment length, cardiac output and intrathoracic pressure. A brief occlusion of the inferior vena cava was used to alter preload to generate pressure-length loops prior to onset of baroreceptor reflex-mediated increases in heart rate. Respiratory variation in ventricular pressure was negated by calculation of "transmural pressure" via instantaneous subtraction of intrathoracic pressure from corresponding left ventricular pressure. Contractility was then evaluated in the conscious and anesthetized states using transmural pressure-length loops and calculation of the preload recruitable stroke work (PRSW) relationship. Dogs were anesthetized with 1.25, 1.5, or 1.75 MAC desflurane or isoflurane and measurements were repeated after 30 min of equilibration at each anesthetic concentration. Desflurane and isoflurane produced similar declines in PRSW slope [Mw; 41 +/- 6 (5.5 +/- 0.8) during 1.75 MAC desflurane compared to 43 +/- 5 mmHg (5.7 +/- 0.7 kPa) during 1.75 MAC isoflurane], indicating that these agents cause similar depression of contractile state at equivalent MAC.(ABSTRACT TRUNCATED AT 250 WORDS)
在具有完整自主神经系统（ANS）功能的动物中，使用源自心室压力 - 节段长度环的指标来表征心肌收缩力的变化很复杂，这是因为压力感受器反射介导的全身血流动力学改变，以及自主呼吸及其对心室压力和充盈的影响。本研究使用旨在克服这些潜在困难的技术，研究并比较了地氟烷和异氟烷对具有完整ANS反射的犬心肌收缩力的影响。使用九只长期植入用于测量主动脉和左心室压力、左心室压力最大上升速率（dP/dt）、心内膜下节段长度、心输出量和胸内压力的犬，进行了两组共18次实验。在下腔静脉短暂闭塞以改变前负荷，从而在压力感受器反射介导的心率增加开始之前生成压力 - 长度环。通过从相应的左心室压力中瞬时减去胸内压力来计算“跨壁压力”，从而消除心室压力的呼吸变化。然后使用跨壁压力 - 长度环并计算前负荷可募集搏功（PRSW）关系，在清醒和麻醉状态下评估收缩力。犬用1.25、1.5或1.75 MAC的地氟烷或异氟烷麻醉，在每个麻醉浓度平衡30分钟后重复测量。地氟烷和异氟烷使PRSW斜率产生相似的下降[Mw；1.75 MAC地氟烷时为41±6（5.5±0.8），而1.75 MAC异氟烷时为43±5 mmHg（5.7±0.7 kPa）]，表明这些药物在等效MAC下引起相似程度的收缩状态抑制。（摘要截断于250字）
