BACKGROUND Ketamine administration during stable propofol anesthesia is known to be associated with an increase in bispectral index (BIS) but a "deepening" in the level of hypnosis. This study aimed to evaluate the association between the effect-site concentration of ketamine (CeK) and 2 electroencephalogram (EEG)-derived parameters, the BIS and spectral edge frequency (SEF95), after the administration of a ketamine bolus. Secondary aims included investigating the BIS and SEF95 variations with time and changes in the surgical pleth index (SPI). METHODS We conducted an observational, prospective, single-center study analyzing intraoperative data from 14 adult female patients undergoing breast oncologic surgery. During stable propofol-remifentanil target-controlled infusion (TCI) anesthesia, a ketamine analgesic bolus was delivered with the target CeK set to 1 μg.mL-1 (Domino model) corresponding to a dose of 0.57 mg.kg-1 (interquartile range [IQR] 0.56-0.57 mg.kg-1). Once the CeK reached a value of 1 μg.mL-1, the target CeK was set to 0 μg.mL-1. We determined the median BIS, SEF95, and SPI trends with time and as a function of the modeled CeK. RESULTS BIS and SEF95 showed no significant change from when ketamine was administered to when CeK=1 μg.mL-1, but a significant increase was observed at lower CeKs. The maximum BIS was reached at 16.0 minutes [10.2-22.7 minutes] after CeK=1 μg.mL-1, at CeK=0.22 μg.mL-1 [0.12-0.41 μg.mL-1]. The peak SEF95 value was observed at 10.0 minutes [8.62-14.1 minutes] after CeK=1 μg.mL-1, at CeK=0.43 μg.mL-1 [0.25-0.50 μg.mL-1]. No significant association was found between CeK and the registered SPI values. CONCLUSIONS Our results show that BIS and SEF95, but not SPI, follow a CeK-dependent trend after administering a ketamine bolus. Interestingly, their peak values were not reached at CeK=1 μg.mL-1, but after several minutes after the drug infusion at CeKs in the 0.2 to 0.5 μg.mL-1 range. This may be explained by the specific pharmacodynamics of ketamine and its varying effects at different concentrations, as well as by the time delay associated with the calculation of the BIS.

中文翻译：

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氯胺酮对异丙酚-瑞芬太尼麻醉期间双频指数、光谱边缘频率和手术注射量指数的影响：一项观察性前瞻性试验。


背景已知在稳定的异丙酚麻醉期间施用氯胺酮与双频指数 （BIS） 的增加有关，但与催眠水平的“加深”有关。本研究旨在评估氯胺酮推注后氯胺酮效应位点浓度 （CeK） 与 2 个脑电图 （EEG） 衍生参数 BIS 和频谱边缘频率 （SEF95） 之间的关联。次要目标包括研究 BIS 和 SEF95 随时间的变化以及手术注射液指数 （SPI） 的变化。方法 我们进行了一项观察性、前瞻性、单中心研究，分析了 14 名接受乳腺肿瘤手术的成年女性患者的术中数据。在稳定的异丙酚-瑞芬太尼目标对照输注 （TCI） 麻醉期间，给予氯胺酮镇痛药推注，目标 CeK 设置为 1 μg.mL-1（Domino 模型），对应于 0.57 mg.kg-1 的剂量（四分位距 [IQR] 0.56-0.57 mg.kg-1）。当 CeK 达到 1 μg.mL-1 值时，目标 CeK 设置为 0 μg.mL-1。我们确定了 BIS 、 SEF95 和 SPI 趋势随时间的变化以及作为建模 CeK 的函数。结果 BIS 和 SEF95 显示从氯胺酮给药到 CeK=1 μg.mL-1 时没有显着变化，但在较低的 CeK 下观察到显着增加。在 CeK=1 μg.mL-1 后 16.0 分钟 [10.2-22.7 分钟] 达到最大 BIS，CeK=0.22 μg.mL-1 [0.12-0.41 μg.mL-1]。在 CeK=1 μg.mL-1 后 10.0 分钟 [8.62-14.1 分钟] 观察到 SEF95 峰值，CeK=0.43 μg.mL-1 [0.25-0.50 μg.mL-1]。在 CeK 和注册的 SPI 值之间没有发现显着关联。结论 我们的结果表明，BIS 和 SEF95，而不是 SPI，在推注氯胺酮后遵循 CeK 依赖性趋势。 有趣的是，它们在 CeK=1 μg.mL-1 时未达到峰值，但在 CeKs 输注后几分钟后，在 0.2 至 0.5 μg.mL-1 范围内。这可以通过氯胺酮的特定药效学及其在不同浓度下的不同作用以及与 BIS 计算相关的时间延迟来解释。