Croughwell N, Lyth M, Quill T J, Newman M, Greeley W J, Smith L R, Reves J G
Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710.
Circulation. 1990 Nov;82(5 Suppl):IV407-12.
We tested the hypothesis that insulin-dependent diabetic patients with coronary artery bypass graft surgery experience altered coupling of cerebral blood flow and oxygen consumption. In a study of 23 patients (11 diabetics and 12 age-matched controls), cerebral blood flow was measured using 133Xe clearance during nonpulsatile, alpha-stat blood gas managed cardiopulmonary bypass at the conditions of hypothermia and normothermia. In diabetic patients, the cerebral blood flow at 26.6 +/- 2.42 degrees C was 25.3 +/- 14.34 ml/100 g/min and at 36.9 +/- 0.58 degrees C it was 27.3 +/- 7.40 ml/100 g/min (p = NS). The control patients increased cerebral blood flow from 20.7 +/- 6.78 ml/100 g/min at 28.4 +/- 2.81 degrees C to 37.6 +/- 8.81 ml/100 g/min at 36.5 +/- 0.45 degrees C (p less than or equal to 0.005). The oxygen consumption was calculated from jugular bulb effluent and increased from hypothermic values of 0.52 +/- 0.20 ml/100 g/min in diabetics to 1.26 +/- 0.28 ml/100 g/min (p = 0.001) at normothermia and rose from 0.60 +/- 0.27 to 1.49 +/- 0.35 ml/100 g/min (p = 0.0005) in the controls. Thus, despite temperature-mediated changes in oxygen consumption, diabetic patients did not increase cerebral blood flow as metabolism increased. Arteriovenous oxygen saturation gradients and oxygen extraction across the brain were calculated from arterial and jugular bulb blood samples. The increase in arteriovenous oxygen difference between temperature conditions in diabetic patients and controls was significantly different (p = 0.01). These data reveal that diabetic patients lose cerebral autoregulation during cardiopulmonary bypass and compensate for an imbalance in adequate oxygen delivery by increasing oxygen extraction.
接受冠状动脉搭桥手术的胰岛素依赖型糖尿病患者会出现脑血流与氧消耗耦合的改变。在一项针对23名患者（11名糖尿病患者和12名年龄匹配的对照组患者）的研究中，在低温和常温条件下，于非搏动性、α稳态血气管理的体外循环期间，使用氙133清除法测量脑血流。糖尿病患者在26.6±2.42℃时脑血流为25.3±14.34毫升/100克/分钟，在36.9±0.58℃时为27.3±7.40毫升/100克/分钟（p值无统计学意义）。对照组患者的脑血流从28.4±2.81℃时的20.7±6.78毫升/100克/分钟增加到36.5±0.45℃时的37.6±8.81毫升/100克/分钟（p≤0.005）。氧消耗通过颈静脉球流出液计算得出，在糖尿病患者中，从低温时的0.52±0.20毫升/100克/分钟增加到常温时的1.26±0.28毫升/100克/分钟（p = 0.001），在对照组中从0.60±0.27增加到1.49±0.35毫升/100克/分钟（p = 0.0005）。因此，尽管氧消耗随温度变化，但随着代谢增加，糖尿病患者并未增加脑血流。根据动脉血和颈静脉球血样本计算动静脉氧饱和度梯度和全脑氧摄取率。糖尿病患者和对照组在不同温度条件下动静脉氧差的增加存在显著差异（p = 0.01）。这些数据表明，糖尿病患者在体外循环期间失去了脑自动调节能力，并通过增加氧摄取来补偿充足氧输送的失衡。
