Grubb T L, Constable P D, Benson G J, Foreman J H, Olson W O, Thurmon J C, Tranquilli W J, Davis L E
Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana 61801, USA.
Am J Vet Res. 1999 Jul;60(7):872-9.
To determine the most repeatable method for evaluating right ventricular relaxation rate in horses and to determine and compare effects of isoflurane or halothane with and without the added influence of intravenously administered calcium gluconate on right ventricular relaxation rates in horses.
6 Thoroughbred horses from 2 to 4 years old.
6 models (2 for monoexponential decay with zero asymptote, 3 for monoexponential decay with variable asymptote, and 1 for biexponential decay) for determining right ventricular relaxation rate were assessed in conscious and anesthetized horses. The 2 methods yielding the most repeatable results then were used to determine right ventricular relaxation rates in horses anesthetized with isoflurane or halothane before, during, and after i.v. administration of calcium gluconate. Right ventricular pressure was measured, using a catheter-tip high-fidelity pressure transducer, and results were digitized at 500 Hz from minimum rate of change in ventricular pressure.
2 models that used monoexponential decay with zero asymptote repeatedly produced an estimate for relaxation rate and were used to analyze effects of anesthesia and calcium gluconate administration on relaxation rate. Isoflurane and halothane each prolonged right ventricular relaxation rate, with greater prolongation evident in halothane-anesthetized horses. Calcium gluconate attenuated the anesthesia-induced prolongation in right ventricular relaxation rate, with greater response obtained in isoflurane-anesthetized horses.
Right ventricular relaxation rate in horses is assessed best by use of a monoexponential decay model with zero asymptote and nonlinear regression. Intravenous administration of calcium gluconate to isoflurane-anesthetized horses best preserves myocardial relaxant function.
确定评估马右心室舒张速率的最可重复方法，并确定和比较异氟烷或氟烷在静脉注射葡萄糖酸钙与否的情况下对马右心室舒张速率的影响。
6匹2至4岁的纯种马。
在清醒和麻醉的马中评估6种用于确定右心室舒张速率的模型（2种零渐近线单指数衰减模型、3种可变渐近线单指数衰减模型和1种双指数衰减模型）。然后使用产生最可重复结果的2种方法来确定在用异氟烷或氟烷麻醉的马在静脉注射葡萄糖酸钙之前、期间和之后的右心室舒张速率。使用导管尖端高保真压力传感器测量右心室压力，并从心室压力的最小变化率以500 Hz对结果进行数字化处理。
2种使用零渐近线单指数衰减的模型反复产生舒张速率估计值，并用于分析麻醉和葡萄糖酸钙给药对舒张速率的影响。异氟烷和氟烷均延长了右心室舒张速率，在氟烷麻醉的马中延长更明显。葡萄糖酸钙减弱了麻醉引起的右心室舒张速率延长，在异氟烷麻醉的马中获得了更大的反应。
马的右心室舒张速率最好通过使用零渐近线单指数衰减模型和非线性回归进行评估。向异氟烷麻醉的马静脉注射葡萄糖酸钙能最好地保留心肌舒张功能。
