麻醉深度与术后远期死亡率

Anesthesia Depth and Postoperative Long-term Mortality

近来研究认为术后死亡率与累计低BIS值(脑电双频谱指数)麻醉持续时间有关。2005年,Monk等人首先指出累计深睡眠持续时间(累计低BIS值持续时间)是进行非心脏大手术术后1年死亡率的独立预测因子。此后一些关于BIS监测预防术中知晓的临床研究,根据随访和对资料的二次分析,也证实死亡率与深睡眠存在相关性。在这些数据追加分析中,Lindholm等人发现BIS值小于45的累计时间与术后2年死亡风险增加有关。在B-Aware研究,研究者对远期死亡率的二次分析认为,非低BIS组的死亡率及发病率(心肌梗死及中风)与低BIS组相比明显降低。Kertai等人的B-Unware数据追加分析同样证实了累计低BIS持续时间与术后死亡率相关。在这项研究中,17.8%的患者在进行心脏手术后3年内死亡,术中BIS值低于45的持续时间每增加1小时死亡风险增加29%。此外,Watson等人又发现ICU患者在使用镇静剂后,经历爆发性抑制的患者与没有经历爆发性抑制的患者相比6个月死亡率明显升高(59%vs.33%)。认识到深睡眠与死亡率之间存在一定相关性,需要我们更深一步研究这一问题。

Recently postoperative mortality has been associated with cumulative anesthetic duration of low BIS(bispectral index). Monk et al. was the first to suggest that cumulative deep hypnotic time (cumulative duration of low BIS) was an independent predictor of 1-yr mortality after major noncardiac surgery in 2005. After that a few previously published reports confirming the mortality– hypnosis association were all derived from secondary analyses of data collected prospectively for other purposes, which were to evaluate the effect of BIS monitoring on the incidence of intraoperative awareness. In these substudies, Lindholm et al. found that cumulative time at BIS less than 45 was associated with an increased risk of death for up to 2 yr after surgery. The investigators in the B-Aware Trial reported their secondary analysis of long-term mortality and found that the absence of low BIS values was associated with improved survival and reduced morbidity (myocardial infarction and stroke). The report by Kertai et al. in the substudy of the B-Unaware Trial added the evidence confirming the association between cumulative duration of low BIS and postoperative mortality. In this investigation, 17.8% of patients died in the first 3 yr after cardiac surgery, with the risk of death increasing by 29% for every cumulative hour for which the BIS was less than 45 during surgery. These three studies along with the report by Watson et al. from the ICU patients who experienced burst suppression had a significantly higher 6-month mortality rate compared with patients who did not have burst suppression when sedated (59 vs. 33%). Recognizing that the hypnosis-mortality association exists is time to understand this phenomenon.