Viability and validity of the bispectral index to measure sleep in patients in the intensive care unit

Abstract Objective: To investigate the viability of the bispectral index in the sleep evaluation of critically ill patients and to quantify the associations of sleep parameters measured by this index with the Richards-Campbell Sleep Questionnaire and environmental noise. Methods: This was a cross-sectional observational study that evaluated critically ill adults with diseases of low or moderate severity. The following were measured: total sleep volume and time, deep sleep volume and time, continuous sleep volume and time, sleep onset latency, and environmental sound pressure level. The subjective perception of sleep was evaluated with the Richards-Campbell Sleep Questionnaire the morning after each night of observation. Results: Patients had a low total sleep time (234 minutes), a predominance of superficial sleep stages, and little deep sleep (1.7 minutes). The total, deep, and continuous sleep volumes were 3,679, 9.4, and 3,143 (bispectral index units × minutes), respectively. The sleep latency was 94 minutes. The mean score of the Richards-Campbell Sleep Questionnaire was 57.9. Total sleep volume, total sleep time, and continuous sleep volume were weakly correlated with the Richards-Campbell Sleep Questionnaire depth of sleep domain score, overall sleep quality domain score, and total score. Total volume, total time, and continuous volume were moderately correlated with the occurrence of awakenings domain score. Conclusion: The bispectral index is an instrument with limited viability to monitor the sleep of lucid patients and patients with low to moderate disease severity in the intensive care unit. Patients with higher total sleep volume, total sleep time, and continuous sleep volume had better overall sleep perception.

摘要 研究目的：探讨脑电双频指数（bispectral index）用于重症患者睡眠评估的可行性，并量化该指标所测得的睡眠参数与理查兹-坎贝尔睡眠问卷（Richards-Campbell Sleep Questionnaire）及环境噪声的关联。研究方法：本研究为一项横断面观察性研究，纳入病情轻中度的成年重症患者进行评估。测量指标包括：总睡眠量与总睡眠时间、深睡眠量与深睡眠时间、连续睡眠量与连续睡眠时间、睡眠潜伏期以及环境声压级。于每夜观察结束次日清晨，采用理查兹-坎贝尔睡眠问卷评估患者的睡眠主观感知情况。研究结果：患者总睡眠时间偏短（234分钟），以浅睡眠阶段为主，深睡眠时间极少（仅1.7分钟）。总睡眠量、深睡眠量与连续睡眠量分别为3679、9.4与3143（脑电双频指数单位×分钟）。患者睡眠潜伏期为94分钟，理查兹-坎贝尔睡眠问卷平均得分为57.9。总睡眠量、总睡眠时间与连续睡眠量与理查兹-坎贝尔睡眠问卷的睡眠深度维度得分、整体睡眠质量维度得分及总得分呈弱相关；上述三项指标与觉醒次数维度得分呈中度相关。研究结论：脑电双频指数用于监测重症监护室内意识清醒及病情轻中度患者的睡眠情况时，可行性有限。总睡眠量、总睡眠时间与连续睡眠量更高的患者，其整体睡眠感知更佳。