Venn G E, Patel R L, Chambers D J
Cardiac Surgical Research, Rayne Institute, London, United Kingdom.
Ann Thorac Surg. 1995 May;59(5):1331-5. doi: 10.1016/0003-4975(95)00096-4.
Increased cerebral blood flow occurring during cardiopulmonary bypass as a result of changes in arterial carbon dioxide tension during acid-base regulation is thought to increase postoperative cognitive dysfunction. We studied 70 patients undergoing coronary artery bypass procedures who were randomized to two different acid-base protocols: pH-stat or alpha-stat regulation. Cerebral blood flow, cerebral blood flow velocity, and cerebral oxygen metabolism were measured before bypass, during bypass (hypothermic [28 degrees C] and normothermic phases), and after bypass. Detailed cognitive tests were conducted before operation and 6 weeks after operation. During 28 degrees C bypass, cerebral blood flow was significantly (p < 0.05) higher in the pH-stat group than in the alpha-stat group (41 +/- 2 versus 24 +/- 2 mL.100 g-1.min-1), and cerebral blood flow velocity was significantly increased in the pH-stat group and significantly decreased in the alpha-stat group (152% +/- 10% versus 78% +/- 7%). Cerebral extraction ratio of oxygen demonstrated a relatively greater disruption of autoregulation in the pH-stat group than in the alpha-stat group with relative hyperemia of 0.12 +/- 0.02 versus 0.26 +/- 0.03, respectively, during 28 degrees C bypass. Using the criterion of deterioration in three or more neuropsychologic tests, a significantly higher proportion of patients in the pH-stat group fared less well than in the alpha-stat group (49% +/- 17% versus 20% +/- 13%). Patients in the alpha-stat group experienced less disruption of cerebral autoregulation during hypothermic cardiopulmonary bypass, and this was accompanied by a reduction in postoperative cognitive dysfunction.
在心肺转流期间，由于酸碱调节过程中动脉二氧化碳张力的变化而导致的脑血流量增加被认为会增加术后认知功能障碍。我们研究了70例行冠状动脉搭桥手术的患者，他们被随机分为两种不同的酸碱方案：pH稳态或α稳态调节。在体外循环前、体外循环期间（低温[28℃]和常温阶段）以及体外循环后测量脑血流量、脑血流速度和脑氧代谢。在手术前和手术后6周进行详细的认知测试。在28℃体外循环期间，pH稳态组的脑血流量显著高于α稳态组（p < 0.05）（41±2对24±2 mL·100 g-1·min-1），pH稳态组的脑血流速度显著增加，而α稳态组显著降低（152%±10%对78%±7%）。在28℃体外循环期间，pH稳态组的脑氧摄取率显示出自主调节的破坏相对大于α稳态组，相对充血分别为0.12±0.02对0.26±0.03。以三项或更多神经心理学测试恶化作为标准，pH稳态组中情况较差的患者比例显著高于α稳态组（49%±17%对20%±13%）。α稳态组的患者在低温心肺转流期间脑自主调节的破坏较少，并且这伴随着术后认知功能障碍的减少。
