Mutch W A, Warrian R K, Eschun G M, Girling L G, Doiron L, Cheang M S, Lefevre G R
Department of Anesthesia, University of Manitoba, Winnipeg, Canada.
Ann Thorac Surg. 2000 Feb;69(2):491-7. doi: 10.1016/s0003-4975(99)01077-2.
Conventional pulsatile (CP) roller pump cardiopulmonary bypass (CPB) was compared to computer controlled biologically variable pulsatile (BVP) bypass designed to return beat-to-beat variability in rate and pressure with superimposed respiratory rhythms. Jugular venous O2 saturation (SjvO2) below 50% during rewarming from hypothermia was compared for the two bypass techniques. A SjvO2 less than 50% during rewarming is correlated with cognitive dysfunction in humans.
Pigs were placed on CPB for 3 hours using a membrane oxygenator with alpha-stat acid base management and arterial filtration. After apulsatile normothermic CPB was initiated, animals were randomized to CP (n = 8) or BVP (roller pump speed adjusted by an average of 2.9 voltage output modulations/second; n = 8), then cooled to a nasopharyngeal temperature of 28 degrees C. During rewarming to stable normothermia, SjvO2 was measured at 5 minute intervals. The mean and cumulative area for SjvO2 less than 50% was determined.
No between group difference in temperature existed during hypothermic CPB or during rewarming. Mean arterial pressure, arterial partial pressure O2, and arterial partial pressure CO2 did not differ between groups. The hemoglobin concentration was within 0.4 g/dL between groups at all time periods. The range of systolic pressure was greater with BVP (41 +/- 18 mm Hg) than with CP (12 +/- 4 mm Hg). A greater mean and cumulative area under the curve for SjvO2 less than 50% was seen with CP (82 +/- 96 versus 3.6% +/- 7.3% x min, p = 0.004; and 983 +/- 1158 versus 42% +/- 87% x min; p = 0.004, Wilcoxon 2-sample test).
Computer-controlled BVP resulted in significantly greater SjvO2 during rewarming from hypothermic CPB. Both mean and cumulative area under the curve for SjvO2 less than 50% exceeded a ratio of 20 to 1 for CP versus BVP. Cerebral oxygenation is better preserved during rewarming from moderate hypothermia with bypass that returns biological variability to the flow pattern.
将传统的搏动性（CP）滚压泵体外循环（CPB）与计算机控制的生物可变搏动性（BVP）体外循环进行比较，后者旨在恢复心率和压力逐搏变化并叠加呼吸节律。比较了两种体外循环技术在低温复温期间颈静脉血氧饱和度（SjvO2）低于50%的情况。复温期间SjvO2低于50%与人类认知功能障碍相关。
使用带有α-稳态酸碱管理和动脉滤过的膜式氧合器对猪进行3小时的体外循环。在开始无搏动常温体外循环后，将动物随机分为CP组（n = 8）或BVP组（滚压泵速度平均每秒调整2.9次电压输出调制；n = 8），然后冷却至鼻咽温度28摄氏度。在复温至稳定常温期间，每隔5分钟测量一次SjvO2。确定SjvO2低于50%的平均值和累积面积。
在低温体外循环或复温期间，两组之间的体温无差异。两组之间的平均动脉压、动脉血氧分压和动脉血二氧化碳分压无差异。在所有时间段，两组之间的血红蛋白浓度相差不超过0.4 g/dL。BVP组的收缩压范围（41±18 mmHg）大于CP组（12±4 mmHg）。CP组SjvO2低于50%的曲线下平均面积和累积面积更大（82±96对3.6%±7.3%×分钟，p = 0.004；983±1158对42%±87%×分钟；p = 0.004，Wilcoxon双样本检验）。
计算机控制的BVP在低温CPB复温期间导致SjvO2显著更高。CP组与BVP组相比，SjvO2低于50%的曲线下平均面积和累积面积均超过20比1的比例。在中度低温复温期间，通过使血流模式恢复生物变异性的体外循环能更好地保存脑氧合。
