老年病人冠脉搭桥术中脑氧代谢与术后精神障碍的关系

Relationship between cerebral oxygen metabolism during coronary artery bypass graft and postoperative mental disorders in geriatric patients

目的 观察老年病人体外循环(CPB)冠脉搭桥术(CABG)中脑氧代谢变化与术后精神障碍的关系。方法 年龄≥65岁择期CABG病人30例,取右颈内静脉和桡动脉血进行血气分析,葡萄糖及乳酸测定,并计算脑血流量/脑氧耗比值(CBF/CMRO_2)、脑氧耗/脑糖耗比值(CMRO_2/CMRglu)及乳酸生成量(ADVL);术后用ICU精神错乱评估量表(CAM-ICU)将病人分为精神障碍(POMD)组和无精神障碍(NPMD)组,比较两组术中指标差异。结果 (1)术后7例病人发生POMD,发生率为23.33％;(2)复温期8例病人颈内静脉血氧发生去饱和(颈内静脉血氧饱和度≤50％或颈内静脉血氧分压≤25mmHg),其中POMD组3例(发生率43％),NPMD组5例(发生率22％),两组差异显著(P<0.01);(3)复温期POMD组CBF/CMRO_2显著低于NPMD组(P<0.01);(4)降温期、复温期和停CPB,尤其是复温期,POMD组CMRO_2/CMRglc明显低于NPMD组,P<0.01,而ADVL明显高于后者(P<0.01)。结论老年病人CABG术后精神障碍与CPB期间脑氧代谢失衡有关。

Objective To investigate the relationship between cerebral 0, metabolism during coronary artery bypass graft (CABG) performed with cardiopulmonary bypass (CPB) and postoperative mental disorders (POMD) in the elderly.Methods Thirty patients (13 male,17 female) aged 65-76 yr undergoing CABG performed with CPB were studied. Patients with senile dementia were excluded. The patients were premedicated with scopolamine 0.3 mg and pethidine 50mg. Anesthesia was induced with midazolam 0.05-0.1 mg·kg_(-1), propofol 0.2-0.5 mg·g_(-1), fentanyl 10-15μg·g_(-1) and vecuronium 0.1-0.3 mg·g_(-1) and maintained with isoflurane inhalation and intermittent iv boluses of fentanyl. Nasopharyngeal temperature (T) was maintained at 26℃-28℃) during CPB. Radial artery was cannulated for BP monitoring and blood sampling.Swan-Ganz was placed via right internal jugular vein (UV).Another catheter was inserted into right UV and threaded retrogradely until J point for blood sampling. Blood samples were taken from artery and UV simultaneously for blood gas analyses and determination of blood glucose and lactate concentration before anesthesia (T_1 ),immediately after induction of anesthesia (T_2), during splitting of sternum (T_3) when T was reduced to 28℃ (T_4) and rewarmed to 35℃(T_5 ) and at the end of bypass (T_6 ).Cerebral O2 delivery (CDO2 ),cerebral oxygen consumption (CMRO2),cerebral glucose consumption (CMRglu) and lactic acid production (ADVL) were calculated. POMD was assessed using CAM-ICU chart.Results (1)Seven patients developed POMD (7/30 or 23.3% ).(2) Low jugular bulb 02 saturation (SjO2 ≤50% or PjO2≤25% mm Hg) was observed in 8 patients during rewarming. The incidence was significantly higher in POMD patients (3/7 or 42.96%) than that in non-POMD patients (5/23 or 21.74%). (3) CBF/CMRO2 was significantly lower in POMD patients than in non-POMD patients during rewarming.(4) CMRO2/CMRglu was significantly lower but ADVL was significantly higher in POMD patients than in non-POMD patients during hypothermia, rewarming and at the end of CPB.(P<0.05 or 0.01).Conclusion POMD is closely related to abnormal cerebral O2 metabolism during CABG performed under CPB in the elderly.