The effect of bispectral index monitoring on cognitive performance following sedation for outpatient colonoscopy: a randomized controlled trial

ABSTRACT BACKGROUND: Bispectral index (BIS) monitoring can positively affect cognitive performance through decreasing the use of sedative agents. We aimed to evaluate the effect of BIS monitoring on early cognitive performance among patients undergoing sedation for colonoscopy. DESIGN AND SETTING: Randomized, controlled trial in a university hospital. METHODS: 100 patients were randomized into two groups. In the monitored group (n = 50), the depth of anesthesia was monitored using the BIS, and BIS scores were maintained between 60 and 80. In the usual care group (n = 50), BIS monitoring was not performed. To determine the patients’ baseline cognitive performance levels, the mini-mental state examination (MMSE), Trieger dot test (TDT) and clock drawing test (CDT) were used. The patients’ post-procedure cognitive performance levels were determined when they were classified as ready for discharge. RESULTS: The total volume (mg) of propofol used [median (range) IQR] in the sedation procedure was lower in the monitored group [100 (50-200) 100-140] than in the usual care group [150 (75-200) 100-200] (P < 0.001). The discharge scores [mean (SD)] using MMSE and CDT were higher in the monitored group [26 (3) and 3 (1), respectively] than in the usual care group [23 (3) and 2 (1), respectively] (P = 0.002 and P = 0.002, respectively). The discharge scores using TDT [mean (SD)] were lower in the monitored group [11 (7)] than in the usual care group [15 (11)] (P = 0.033). CONCLUSION: BIS monitoring among sedated patients was associated with lower propofol use and smaller decline in cognitive performance. CLINICAL TRIAL REGISTRATION: This trial was registered in the Australian New Zealand Clinical Trial Registry (ACTRN12617000134325).

研究背景：脑电双频指数（Bispectral index, BIS）监测可通过减少镇静药物用量，对患者的认知功能产生积极影响。本研究旨在评估接受结肠镜检查镇静治疗的患者中，BIS监测对其早期认知功能的影响。

研究设计与开展场所：本研究为某大学医院开展的随机对照试验。

研究方法：本研究共纳入100例患者，按随机原则分为两组。监测组（n=50）采用BIS监测麻醉深度，维持BIS值在60~80范围内；常规护理组（n=50）未实施BIS监测。为评估患者的基线认知功能水平，本研究采用简易精神状态检查表（mini-mental state examination, MMSE）、特里格点试验（Trieger dot test, TDT）及画钟试验（clock drawing test, CDT）进行测评。在患者被评定为可出院时，对其术后认知功能水平进行检测。

研究结果：镇静操作中使用的丙泊酚总剂量（mg）[中位数（极差），四分位间距（Interquartile Range, IQR）]，监测组为100（50~200），四分位间距100~140，显著低于常规护理组的150（75~200），四分位间距100~200（P<0.001）。出院时采用MMSE与CDT测评的评分[均值（标准差（standard deviation, SD））]，监测组分别为26（3）与3（1），均高于常规护理组的23（3）与2（1）（P分别为0.002和0.002）。采用TDT测评的出院评分[均值（SD）]，监测组为11（7），低于常规护理组的15（11）（P=0.033）。

研究结论：对接受镇静治疗的患者实施BIS监测，可降低丙泊酚的使用量，并减轻认知功能的下降程度。

临床试验注册：本试验已在澳大利亚新西兰临床试验注册中心（Australian New Zealand Clinical Trial Registry）注册，注册号为ACTRN12617000134325。