Purpose

The Patient State Index (PSI) is a newly introduced electroencephalogram-based tool for objective and continuous monitoring of sedation levels of patients under general anesthesia. This study investigated the potential correlation between the PSI and the Richmond Agitation‒Sedation Scale (RASS) score in intensive care unit (ICU) patients and established the utility of the PSI in assessing sedation levels.

Methods

In this prospective observational study, PSI values were continuously monitored via SedLine® (Masimo, Irvine, CA, USA); the RASS score was recorded every 2 h for patients on mechanical ventilation. Physicians and nurses were blinded to the PSI values. Overall, 382 PSI and RASS score sets were recorded for 50 patients.

Results

The PSI score correlated positively with RASS scores, and Spearman’s rank correlation coefficient between the PSI and RASS was 0.79 (95% confidence interval [CI]: 0.75‒0.83). The PSI showed statistically significant difference among the RASS scores (Kruskal‒Wallis chi-square test: 242, df = 6, P < 2.2-e16). The PSI threshold for distinguishing light (RASS score ≥ − 2) sedation from deep sedation (RASS score ≤ − 3) was 54 (95% CI: 50–65; area under the curve, 0.92 [95% CI: 0.89‒0.95]; sensitivity, 0.91 [95% CI: 0.86‒0.95]; specificity, 0.81 [95% CI: 0.77–0.86]).

Conclusions

The PSI correlated positively with RASS scores, which represented a widely used tool for assessing sedation levels, and the values were significantly different among RASS scores. Additionally, the PSI had a high sensitivity and specificity for distinguishing light from deep sedation. The PSI could be useful for assessing sedation levels in ICU patients.

University Hospital Medical Information Network (UMIN000035199, December 10, 2018).

中文翻译：

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用于监测危重患者镇静状态的患者状态指数的验证：一项前瞻性观察研究

目的

患者状态指数 (PSI) 是一种新推出的基于脑电图的工具，用于客观和连续监测全身麻醉下患者的镇静水平。本研究调查了重症监护病房 (ICU) 患者 PSI 与里士满激越-镇静量表 (RASS) 评分之间的潜在相关性，并确定了 PSI 在评估镇静水平方面的效用。

方法

在这项前瞻性观察研究中，PSI 值通过 SedLine®（Masimo，Irvine，CA，USA）持续监测；每 2 小时记录一次机械通气患者的 RASS 评分。医生和护士对 PSI 值视而不见。总体而言，为 50 名患者记录了 382 个 PSI 和 RASS 评分集。

结果

PSI 评分与 RASS 评分呈正相关，PSI 和 RASS 之间的 Spearman 等级相关系数为 0.79（95% 置信区间 [CI]：0.75-0.83）。PSI 在 RASS 评分之间显示出统计学上的显着差异（Kruskal-Wallis 卡方检验：242，df = 6，P < 2.2-e16）。区分轻镇静（RASS 评分 ≥ − 2）和深度镇静（RASS 评分 ≤ − 3）的 PSI 阈值为 54（95% CI：50-65；曲线下面积，0.92 [95% CI：0.89-0.95] ；灵敏度，0.91 [95% CI：0.86-0.95]；特异性，0.81 [95% CI：0.77-0.86]）。

结论

PSI 与 RASS 评分呈正相关，RASS 评分代表了一种广泛使用的评估镇静水平的工具，并且 RASS 评分之间的值显着不同。此外，PSI 在区分轻镇静和深度镇静方面具有很高的灵敏度和特异性。PSI 可用于评估 ICU 患者的镇静水平。

大学医院医学信息网（UMIN000035199，2018年12月10日）。