Bispectral index for improving anaesthetic delivery and postoperative recovery

 

Abstract

Background

The use of clinical signs may not be reliable in measuring the hypnotic component of anaesthesia. The use of bispectral index to guide the dose of anaesthetics may have certain advantages over clinical signs. This is an update of a review originally published in 2007.

Objectives

The objective of this review was to assess whether bispectral index (BIS) reduced intraoperative recall awareness, anaesthetic use, recovery times and cost.

Search methods

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, Issue 2), MEDLINE (1990 to 21 May, 2009), EMBASE (1990 to 14 May, 2009) and reference lists of articles. The original search was performed in May 2007.

Selection criteria

We included randomized controlled trials comparing BIS with standard practice criteria for titration of anaesthetic agents.

Data collection and analysis

Two authors independently assessed trial quality, extracted data and analysed the data. We contacted study authors for further details.

Main results

We included 31 trials. In studies using clinical signs as control, the results demonstrated a significant effect of the BIS-guided anaesthesia in reducing the risk of intraoperative recall awareness among surgical patients with high risk of awareness (2493 participants; OR 0.24, 95% CI 0.08 to 0.69). This effect was not demonstrated in studies using end tidal anaesthetic gas monitoring as standard practice (1981 participants; OR 1.01, 95% CI 0.14 to 7.16). BIS-guided anaesthesia reduced the requirement for propofol by 1.44 mg/kg/hr (662 participants; 95% CI -1.95 to -0.93), and for volatile anaesthetics (desflurane, sevoflurane, isoflurane) by 0.14 minimal alveolar concentration equivalents (MAC) (95% CI -0.22 to -0.05) in 928 participants. Irrespective of the anaesthetics used, BIS reduced the following recovery times: time for eye opening (2446 participants; by 2.14 min, 95% CI -2.99 to -1.29), response to verbal command (777 participants; by 2.73 min, 95% CI -3.92 to -1.54), time to extubation (1488 participants; by 2.87 min, 95% CI -3.74 to -1.99), and orientation (316 participants; by 2.57 min, 95% CI -3.30 to -1.85). BIS shortened the duration of postanaesthesia care unit stay by 7.63 min (95% CI -12.50 to -2.76) in 1940 participants but did not significantly reduce time to home readiness (329 participants; -7.01 min, 95% CI -30.11 to 16.09).

Authors' conclusions

BIS-guided anaesthesia could reduce the risk of intraoperative recall in surgical patients with high risk of awareness in studies using clinical signs as a guide to anaesthetic practice but not in studies using end tidal anaesthetic gases as a guide. In addition, anaesthesia guided by the BIS within the recommended range could improve anaesthetic delivery and postoperative recovery from relatively deep anaesthesia.

 

Plain language summary

Monitoring the bispectral index (BIS) to improve anaesthetic delivery and patient recovery from anaesthesia

The results from this updated review indicate that BIS could be useful in guiding the anaesthetic dose to avoid the risk of intraoperative recall in surgical patients with high risk of awareness.  Furthermore, anaesthesia guided by BIS could improve anaesthetic delivery and recovery from anaesthesia.

General anaesthesia requires multiple agent administration to achieve unconsciousness (hypnotics), muscle relaxation, analgesia and haemodynamic control. Many anaesthesiologists rely on clinical signs alone to guide anaesthetic management. Bispectral index (BIS) is a scale derived from the measurement of cerebral electrical activity in anaesthetized patients so that the level of anaesthesia and drug delivery can be optimized. We systematically reviewed 31 randomized controlled studies to find out whether BIS can reduce the risk of intraoperative recall and reduce anaesthetic use and recovery times in adult surgical patients. The risk of intraoperative recall awareness was determined in selected patients who were at potentially high risk of awareness. Two studies (2493 patients) that used clinical signs as a guide to anaesthetic administration in the control group demonstrated a significant reduction in the risk of awareness with BIS monitoring. Two studies (1981 patients) compared BIS monitoring with end tidal anaesthetic gas monitoring as a guide to management of anaesthesia and this did not demonstrate any difference. No intraoperative recall awareness was reported in the trials in surgical patients with low risk of awareness. There was an overall reduction in volatile anaesthetic dose and the dose of propofol. Recovery from anaesthesia was quicker and post-anaesthesia recovery care unit stay was shorter. The limitations of some of the clinical trials on BIS are discussed.

 

摘要

背景

畢斯腦波指數(bispectral index, BIS)增進麻醉藥物給予和術後恢復

利用臨床徵象來評估達到意識喪失的程度並不是一個完全可以信賴的方式，使用畢斯腦波指數可以引導我們給予準確的麻醉劑量，與單用臨床徵象相比有其優勢存在。

目標

本篇回顧性文章的目標是要評估使用畢斯腦波指數是否可以減少麻醉劑的使用，恢復時間，術中甦醒，以及成本。

搜尋策略

我們搜尋了Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 2), MEDLINE (1990to May 2007), EMBASE (1990 to May 2007)以及文章中的引用清單。

選擇標準

我們參考了比較畢斯腦波指數和臨床徵象來滴定麻醉藥物的臨床試驗。

資料收集與分析

兩位獨立的作者分別評估臨床試驗品質，擷取數據，並分析數據。我們還向文章作者請教臨床試驗的細節。

主要結論

我們採納了20個臨床試驗，當中包含4056位參與者，其中有7個近期的試驗仍待評估。使用畢斯腦波指數來引導麻醉可以減少異丙酚(propofol)的需求量達1.30 mg/kg/hr (578位參與者; 95% confidence interval (CI) −1.97to −0.62)，減少吸入性麻醉氣體[輸活能(desflurane), 安汝達(sevoflurane), 愛氟寧(isoflurane)]達0.17 最小肺泡濃度(MAC)(689位參與者; 95% CI −0.27 to −0.07)。不論使用之麻醉劑為何，畢斯腦波指數可以減少麻醉回復時間(參與者可以張開眼睛)達2.43分鐘(996位參與者; 95% CI −3.60 to −1.27)，減少參與者對口頭命令有反應的時間達2.28分鐘(717位參與者; 95% CI −3.47 to −1.09)，減少拔管時間達3.05分鐘(1057位參與者; 95% CI −3.98 to −2.11)，減少可認知自己身在何處的時間達2.46分鐘(316位參與者; 95% CI −3.21 to −1.71)。使用畢斯腦波指數可減少恢復室停留時間達6.83分鐘(584位參與者; 95% CI −12.08 to −1.58)，但是無法減少達到可返家狀態的時間(329位參與者; 95% CI −30.11 to 16.09)。使用畢斯腦波指數可顯著減少術中甦醒高危險群發生術中甦醒的發生率(OR 0.20, 95% CI 0.05 to 0.79)。

作者結論

使用建議的畢斯腦波指數值(40至60)來引導麻醉可以增進麻醉藥物給予和由相當程度的麻醉中回復。此外，畢斯腦波指數對於減少術中甦醒高危險群發生術中甦醒的發生率有顯著程度的影響。

翻譯人

本摘要由慈濟醫院黃佳君翻譯。

此翻譯計畫由臺灣國家衛生研究院(National Health Research Institutes, Taiwan)統籌。

總結

畢斯腦波指數已經被報告可增進麻醉藥物傳送，術後恢復，以及減低術中甦醒高危險群發生術中甦醒的發生率。利用臨床徵象如血壓及心跳來引導麻醉藥物的給予可能會造成劑量過多或劑量不足的情形。畢斯腦波指數是利用偵測腦部電氣活動來評量麻醉藥物對大腦所產生的效果，且經過度量化的儀器，它可以幫助精確地給予麻醉劑量以達到適宜的麻醉深度。本篇包含20個臨床試驗的回顧性論文發現，使用建議的畢斯腦波指數值(40至60)來引導麻醉可以減少麻醉藥物的使用量並增進由相當程度的麻醉中回復。再者，使用畢斯腦波指數可減少術中甦醒高危險群發生術中甦醒的發生率。