新西兰奥克兰城市医院Timothy G Short课题组的一项最新研究探讨了麻醉深度和大手术后并发症的关系。相关论文在线发表于10月20日的《柳叶刀》杂志。

研究组在7个国家的73个中心进行了一项国际随机对照试验，招募60岁及以上、并发症严重、手术时间超过2小时、预计住院时间至少2天的患者。2012年12月19日至2017年12月12日，研究组共招募了6644名大手术后并发症风险增加的患者，并将其随机分组，其中3316名接受轻度全身麻醉，即脑电双频指数（BIS）目标为50，3328名接受深度全身麻醉，即BIS目标为35。

BIS 50组的平均动脉压比BIS 35组高3.5 mmHg，挥发性麻醉剂用量比BIS 35组低0.26最低肺泡有效浓度（30%）。BIS 50组和BIS 35组的1年死亡率分别为6.5%和7.2%，3级不良事件的发生率分别为29%和27%，4级不良事件的发生率则均为8%。最常见的不良事件主要包括感染、血管疾病、心脏疾病和肿瘤。

研究表明，在大手术后并发症风险增加的患者中，轻度全身麻醉与深度全身麻醉相比，1年死亡率并无显著差异。研究组定义了一个广泛的麻醉深度范围，在此范围内，对挥发性麻醉剂浓度进行监测，麻醉可安全进行。

据悉，一些观察性研究证实增加麻醉深度可能会降低术后生存率，但缺乏随机对照试验的数据。

附：英文原文

Title: Anaesthetic depth and complications after major surgery: an international, randomised controlled trial

Author: Timothy G Short, Douglas Campbell, Christopher Frampton, Matthew T V Chan, Paul S Myles, Tomás B Corcoran, Daniel I Sessler, Gary H Mills, Juan P Cata, Thomas Painter, Kelly Byrne, Ruquan Han, Mandy H M Chu, Davina J McAllister, Kate Leslie, M Shulman, S Wallace, C Farrington, W Gallagher, A Ditoro, P Peyton, S Baulch, A Dalyell, S Sidiropoulos, J Reynolds, J Rowley, N Tan, D McCallum, E OLoughlin, S Wong, K Owen, I-K Sim, L Glazov, P Coutts, M Pushpanathan, V Findlay, M Paech, D Cavill, A Chuan, L Pope, J Lucas, B Robinson, A Millard, S Allen, M Allen, S McKeown, P Sivalingam, T Wilkes, C Jowett, A Kearney, M Bennett, J-P Favero, S Sawhney, K Drummond, S Osborn, A Wing, J Taylor, M Edwards, H Reynolds, C Town, N Terblanche, M Challis, R Seale, K Button, R Cotter, M Stewart, N Zingerle, S Hannon, D Middleton, C Edgley, S March, T McCulloch, G Wong, S Jeong, K Connell, K Kramer, G Henderson, V Ward, Y Buller, N Hird, D Scott, L Evered, G Snyder, B Silbert, P Corcoran, E Fitzgerald, S Said, A Watson, D Baby, S Bolsin, A Marriott, K Ives, B-J Wakefeld, A Jeffreys, S Bates, R Halliwell, D Elliott, L Cope, R Paranthoiene, P Peng, X Liu, X Zhou, X Jin, H Liu, L An, W Cui, L Zhang, B Jia, J Fang, E Koo, E Lo, B Fung, M Tsang, L Lam, E Pang, V Lau, G Choi, M Tsang, B Fung, R Kwok, K Yau, B Cheng, C Lam, E Lee, D Buggy, H Keane, K Byrne, C Connolly, M Ali

Issue&Volume: 2019-10-20

Abstract: 

Background

An association between increasing anaesthetic depth and decreased postoperative survival has been shown in observational studies; however, evidence from randomised controlled trials is lacking. Our aim was to compare all-cause 1-year mortality in older patients having major surgery and randomly assigned to light or deep general anaesthesia.
Methods

In an international trial, we recruited patients from 73 centres in seven countries who were aged 60 years and older, with significant comorbidity, having surgery with expected duration of more than 2 h, and an anticipated hospital stay of at least 2 days. We randomly assigned patients who had increased risk of complications after major surgery to receive light general anaesthesia (bispectral index [BIS] target 50) or deep general anaesthesia (BIS target 35). Anaesthetists also nominated an appropriate range for mean arterial pressure for each patient during surgery. Patients were randomly assigned in permuted blocks by region immediately before surgery, with the patient and assessors masked to group allocation. The primary outcome was 1-year all-cause mortality. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12612000632897, and is closed to accrual.
Findings

Patients were enrolled between Dec 19, 2012, and Dec 12, 2017. Of the 18?026 patients screened as eligible, 6644 were enrolled, randomly assigned to treatment or control, and formed the intention-to-treat population (3316 in the BIS 50 group and 3328 in the BIS 35 group). The median BIS was 47·2 (IQR 43·7 to 50·5) in the BIS 50 group and 38·8 (36·3 to 42·4) in the BIS 35 group. Mean arterial pressure was 3·5 mm Hg (4%) higher (median 84·5 [IQR 78·0 to 91·3] and 81·0 [75·4 to 87·6], respectively) and volatile anaesthetic use was 0·26 minimum alveolar concentration (30%) lower (0·62 [0·52 to 0·73] and 0·88 [0·74 to 1·04], respectively) in the BIS 50 than the BIS 35 group. 1-year mortality was 6·5% (212 patients) in the BIS 50 group and 7·2% (238 patients) in the BIS 35 group (hazard ratio 0·88, 95% CI 0·73 to 1·07, absolute risk reduction 0·8%, 95% CI −0·5 to 2·0). Grade 3 adverse events occurred in 954 (29%) patients in the BIS 50 group and 909 (27%) patients in the BIS 35 group; and grade 4 adverse events in 265 (8%) and 259 (8%) patients, respectively. The most commonly reported adverse events were infections, vascular disorders, cardiac disorders, and neoplasms.
Interpretation

Among patients at increased risk of complications after major surgery, light general anaesthesia was not associated with lower 1-year mortality than deep general anaesthesia. Our trial defines a broad range of anaesthetic depth over which anaesthesia may be safely delivered when titrating volatile anaesthetic concentrations using a processed electroencephalographic monitor.

DOI: 10.1016/S0140-6736(19)32315-3

Source: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(19)32315-3/fulltext