Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.
J Neurosurg Anesthesiol. 2013 Jan;25(1):33-42. doi: 10.1097/ANA.0b013e3182712fba.
Previous clinical trials and animal experiments have suggested that long-lasting neurotoxicity of general anesthetics may lead to postoperative cognitive dysfunction (POCD). Brain function monitoring such as the bispectral index (BIS) facilitates anesthetic titration and has been shown to reduce anesthetic exposure. In a randomized controlled trial, we tested the effect of BIS monitoring on POCD in 921 elderly patients undergoing major noncardiac surgery.
Patients were randomly assigned to receive either BIS-guided anesthesia or routine care. The BIS group had anesthesia adjusted to maintain a BIS value between 40 and 60 during maintenance of anesthesia. Routine care group had BIS measured but not revealed to attending anesthesiologists. Anesthesia was adjusted according to traditional clinical signs and hemodynamic parameters. A neuropsychology battery of tests was administered before and at 1 week and 3 months after surgery. Results were compared with matched control patients who did not have surgery during the same period. Delirium was measured using the confusion assessment method criteria.
The median (interquartile range) BIS values during the maintenance period of anesthesia were significantly lower in the control group, 36 (31 to 49), compared with the BIS-guided group, 53 (48 to 57), P<0.001. BIS-guided anesthesia reduced propofol delivery by 21% and that for volatile anesthetics by 30%. There were fewer patients with delirium in the BIS group compared with routine care (15.6% vs. 24.1%, P=0.01). Although cognitive performance was similar between groups at 1 week after surgery, patients in the BIS group had a lower rate of POCD at 3 months compared with routine care (10.2% vs. 14.7%; adjusted odds ratio 0.67; 95% confidence interval, 0.32-0.98; P=0.025).
BIS-guided anesthesia reduced anesthetic exposure and decreased the risk of POCD at 3 months after surgery. For every 1000 elderly patients undergoing major surgery, anesthetic delivery titrated to a range of BIS between 40 and 60 would prevent 23 patients from POCD and 83 patients from delirium.
先前的临床试验和动物实验表明，全身麻醉的长期神经毒性可能导致术后认知功能障碍（POCD）。脑功能监测，如双频谱指数（BIS），有助于麻醉滴定，并已被证明可减少麻醉暴露。在一项随机对照试验中，我们测试了在 921 名接受非心脏大手术的老年患者中，BIS 监测对 POCD 的影响。
患者被随机分配接受 BIS 引导麻醉或常规护理。BIS 组将麻醉调整为维持麻醉维持期间 BIS 值在 40 至 60 之间。常规护理组测量了 BIS，但未向主治麻醉师透露。根据传统的临床体征和血流动力学参数调整麻醉。手术前后 1 周和 3 个月进行神经心理学测试。结果与同期未手术的匹配对照患者进行比较。使用混乱评估方法标准测量谵妄。
对照组麻醉维持期的中位数（四分位距）BIS 值明显低于 BIS 引导组，分别为 36（31 至 49）和 53（48 至 57），P<0.001。BIS 引导麻醉减少了 21%的异丙酚输注和 30%的挥发性麻醉剂输注。与常规护理组相比，BIS 组的谵妄患者更少（15.6%比 24.1%，P=0.01）。尽管手术后 1 周两组的认知表现相似，但 BIS 组在 3 个月时 POCD 的发生率低于常规护理组（10.2%比 14.7%；调整后的比值比 0.67；95%置信区间，0.32-0.98；P=0.025）。
BIS 引导麻醉减少了麻醉暴露，并降低了术后 3 个月 POCD 的风险。对于每 1000 名接受大手术的老年患者，将麻醉滴定至 BIS 40 至 60 范围内，可预防 23 名患者发生 POCD 和 83 名患者发生谵妄。
