Hindman B J, Dexter F, Smith T, Cutkomp J
Department of Anesthesia, University of Iowa, College of Medicine, Iowa City 52242.
Anesthesiology. 1995 Jan;82(1):241-50. doi: 10.1097/00000542-199501000-00029.
Although pulsatile and nonpulsatile cardiopulmonary bypass (CPB) do not differentially affect cerebral blood flow (CBF) or metabolism during hypothermia, studies suggest pulsatile CPB may result in greater CBF than nonpulsatile CPB under normothermic conditions. Consequently, nonpulsatile flow may contribute to poorer neurologic outcome observed in some studies of normothermic CPB. This study compared CBF and cerebral metabolic rate for oxygen (CMRO2) between pulsatile and nonpulsatile CPB at 37 degrees C.
In experiment A, 16 anesthetized New Zealand white rabbits were randomized to one of two pulsatile CPB groups based on pump systolic ejection period (100 and 140 ms, respectively). Each animal was perfused at 37 degrees C for 30 min at each of two pulse rates (150 and 250 pulse/min, respectively). This scheme created four different arterial pressure waveforms. At the end of each perfusion period, arterial pressure waveform, arterial and cerebral venous oxygen content, CBF (microspheres), and CMRO2 (Fick) were measured. In experiment B, 22 rabbits were randomized to pulsatile (100-ms ejection period, 250 pulse/min) or nonpulsatile CPB at 37 degrees C. At 30 and 60 min of CPB, physiologic measurements were made as before.
In experiment A, CBF and CMRO2 were independent of ejection period and pulse rate. Thus, all four waveforms were physiologically equivalent. In experiment B, CBF did not differ between pulsatile and nonpulsatile CPB (72 +/- 6 vs. 77 +/- 9 ml.100 g-1.min-1, respectively (median +/- quartile deviation)). CMRO2 did not differ between pulsatile and nonpulsatile CPB (4.7 +/- 0.5 vs. 4.1 +/- 0.6 ml O2.100 g-1.min-1, respectively) and decreased slightly (0.4 +/- 0.4 ml O2.100 g-1.min-1) between measurements.
During CPB in rabbits at 37 degrees C, neither CBF nor CMRO2 is affected by arterial pulsation. The absence of pulsation per se is not responsible for the small decreases in CMRO2 observed during CPB.
尽管搏动性和非搏动性体外循环（CPB）在低温期间对脑血流量（CBF）或代谢没有差异影响，但研究表明，在常温条件下，搏动性CPB可能比非搏动性CPB导致更高的CBF。因此，在一些常温CPB研究中观察到的较差神经学结果可能与非搏动性血流有关。本研究比较了37℃时搏动性和非搏动性CPB之间的CBF和脑氧代谢率（CMRO2）。
在实验A中，16只麻醉的新西兰白兔根据泵的收缩射血期（分别为100和140毫秒）随机分为两个搏动性CPB组之一。每只动物在37℃下以两种脉搏率（分别为150和250次/分钟）各灌注30分钟。该方案产生了四种不同的动脉压波形。在每个灌注期结束时，测量动脉压波形、动脉和脑静脉氧含量、CBF（微球法）和CMRO2（Fick法）。在实验B中，22只兔子随机分为37℃下的搏动性（射血期100毫秒，脉搏率250次/分钟）或非搏动性CPB组。在CPB的30和60分钟时，如前所述进行生理测量。
在实验A中，CBF和CMRO2与射血期和脉搏率无关。因此，所有四种波形在生理上是等效的。在实验B中，搏动性和非搏动性CPB之间的CBF没有差异（分别为72±6和77±9毫升·100克-1·分钟-1（中位数±四分位数偏差））。搏动性和非搏动性CPB之间的CMRO2没有差异（分别为4.7±0.5和4.1±0.6毫升O2·100克-1·分钟-1），并且在测量之间略有下降（0.4±0.4毫升O2·100克-1·分钟-1）。
在37℃的兔CPB期间，CBF和CMRO2均不受动脉搏动的影响。搏动的缺失本身并不是CPB期间观察到的CMRO2小幅下降的原因。
