B-Aware试验中BIS监测对远期生存率的影响

背景当使用脑电双频指数（bispectral index，Bis）监测指导麻醉药用量时，通常仅需要较低剂量的镇静药，如果用较低剂量的麻醉药，术中低血压和器官毒性作用也许能避免。然而，这是否能减少严重并发症和术后死亡率还存争议。B．Aware试验将2463例术中知晓高危的患者随机分为BIS指导麻醉组和常规麻醉组。我们假设使用BIS指导麻醉组患者死亡、心肌梗死（myocardial infarction，MI）和卒中的风险都低于常规麻醉组患者。方法对术后30天尚存活的所有患者的医疗记录进行回顾，记录他们的死亡日期、死亡原因以及心肌梗死或卒中的发生情况．然后对所有存活的点者主牛行由话随访．本研究的主要终点是存活。结果随访时间中位值4．1年（全距：0－6．5年），参加试验的患者中有548例（22．2％）术后死亡，220例（8．9％）发生了心肌梗死，115例（4．7％）发生卒中。BIS监测组与常规麻醉组的死亡风险没有显著差异{危害比=0．86[95％可信区间（CI）：0．72-1．01]；P=0．07]。但是，倾向性评分分析显示，BIS值〈40、持续时间〉5分钟的患者与其他BIS监测组的患者相比，死亡的危害比为1．41（95％CI：1．02-1．95；P=0．039），并且心肌梗死的优势比（OR）为1．94（95％CI：1．12-3．35；P=0．01），卒中的优势比为3．24（95％CI：1.29-8．07；P=0．01）。结论在B-Aware试验患者中，采用了BIS指导麻醉且从未出现BIS值低于40并持续超过5分钟，与存活率的增加及并发症的减少相关。

BACKGROUND： When anesthesia is fitrated using bispectral index （BIS） monitoring, patients generally re- ceive lower doses of hypnotic drugs. Intraoperative hypotension and organ toxicity might be avoided if lower doses of anes- thetics are administered, but whether this translates into a reduction in serious morbidity or mortality remains controversial. The B-Aware Trial randomly allocated 2463 patients at high risk of awareness to BIS-guided anesthesia or routine care. We tested the hypothesis that the risks of death, myocardial infarction （MI）, and stroke would be lower in patients allocated toBIS-guided management than in those allocated to routine care. METHODS： The medical records of all patients who had not died within 30 days of surgery were reviewed. The date and cause of death and occurrence of MI or stroke were recorded. A telephone interview was then conducted with all surviving patients. The primary end point of the study was survival. RE- SUITS： The median follow-up time was 4. 1 （range： 0 -6.5） years. Five hundred forty-eightpatients （22.2%） had died since the index surgery, 220 patients （8.9%） had an MI, and 115patients （4.7%） had a stroke. The risk of death in BIS patients was not significantly different thanin routine care patients （hazard ratio = 0. 86 [95% confidence interval {CI}： 0. 72 - 1.01 ] ; P =0.07）. However, propensity score analysis indicated that the hazard ratio for death in patientswho recorded BIS values 〈40 for 〉5 min compared with other BIS-monitored patients was 1.41 （95% CI： 1.02 - 1.95; P = 0. 039）. In addi- tion, the odds ratios for MI in patients who recorded BISvalues 〈40 for 〉5 min compared with other BIS-monitored pa- tients was 1.94 （95% CI： 1. 12 - 3.35; P = 0.02） and the odds ratio for stroke was 3.23 （95% CI： 1.29 - 8.07; P = 0.01 ）.