Venn G E, Sherry K, Klinger L, Newman S, Treasure T, Harrison M, Ell P J
Department of Cardio-thoracic Surgery, Middlesex Hospital, London, UK.
Eur J Cardiothorac Surg. 1988;2(5):360-3. doi: 10.1016/1010-7940(88)90012-7.
In a study of the cerebral consequences of cardiopulmonary bypass (CPB), we have assessed cerebral blood flow (CBF) by intra-arterial Xenon 133 clearance, utilising a Novocerebrograph 10a, before, during and immediately following CPB. All patients (n = 51), under the care of a single surgical team underwent elective coronary revascularisation using a standardised anaesthetic and surgical protocol. CBF, measured as the initial slope index (ISI), fell significantly from before (median 22.5) to on bypass (median 20) (Wilcoxon P less than 0.005) and was significantly increased in the immediate post-bypass period (median 28) compared with pre-bypass (Wilcoxon P less than 0.001). Scattergrams reveal CBF to be independent of arterial pressure (BP) but show an important relationship between arterial PaCO2 and CBF. The correlations between PaCO2 and CBF prior to bypass (r = 0.46 P less than 0.005) and post-bypass (r = 0.46 P less than 0.001) are very similar, whilst on bypass, the correlation, although remaining significant, is reduced (r = 0.31 P less than 0.02). The median values for arterial PaCO2 are low throughout the study (pre-bypass median 33 mmHg, on bypass median 28 mm Hg and post-bypass median 36 mm Hg). The maintenance of PaCO2 within the normal range of 35-45 mm Hg may minimise the risk of low CBF due to hypocarbia which could theoretically be harmful in patients known to be at risk of both short term and long term cerebral dysfunction.
在一项关于体外循环（CPB）对大脑影响的研究中，我们使用诺沃脑血流图10a，通过动脉内氙133清除率，在CPB前、CPB期间和CPB后即刻评估脑血流量（CBF）。所有患者（n = 51）均在同一个手术团队的护理下，采用标准化的麻醉和手术方案接受择期冠状动脉血运重建术。以初始斜率指数（ISI）衡量的CBF，从CPB前（中位数22.5）显著下降至CPB期间（中位数20）（Wilcoxon检验P < 0.005），并且与CPB前相比，在CPB后即刻显著增加（中位数28）（Wilcoxon检验P < 0.001）。散点图显示CBF与动脉压（BP）无关，但显示动脉血二氧化碳分压（PaCO2）与CBF之间存在重要关系。CPB前（r = 0.46，P < 0.005）和CPB后（r = 0.46，P < 0.001）PaCO2与CBF之间的相关性非常相似，而在CPB期间，尽管相关性仍然显著，但有所降低（r = 0.31，P < 0.02）。在整个研究过程中，动脉PaCO2的中位数均较低（CPB前中位数33 mmHg，CPB期间中位数28 mmHg，CPB后中位数36 mmHg）。将PaCO2维持在35 - 45 mmHg的正常范围内，可能会将因低碳酸血症导致的低CBF风险降至最低，理论上这对已知有短期和长期脑功能障碍风险的患者可能有害。
