From the Department of Anesthesiology and Perioperative Medicine, School of Medicine.
Clinical and Translational Science Institute.
Anesth Analg. 2024 Mar 1;138(3):635-644. doi: 10.1213/ANE.0000000000006633. Epub 2023 Aug 15.
Although patients are commonly monitored for depth of anesthesia, it is unclear to what extent administration of intravenous anesthetic medications may affect calculated bispectral (BIS) index values under general anesthesia.
In a retrospective analysis of electronic anesthesia records from an academic medical center, we examined BIS index changes associated with 14 different intravenous medications, as administered in routine practice, during volatile-based anesthesia using a novel screening approach. Discrete-time windows were identified in which only a single drug bolus was administered, and subsequent changes in the BIS index, concentration of volatile anesthetic, and arterial pressure were analyzed. Our primary outcome was change in BIS index, following drug administration. Adjusted 95% confidence intervals were compared to predetermined thresholds for clinical significance. Secondary sensitivity analyses examined the same outcomes, with available data separated according to differences in baseline volatile anesthetic concentrations, doses of the administered medications, and length of time window.
The study cohort was comprised of data from 20,170 distinct cases, 54.7% of patients were men, with a median age of 55. In the primary analysis, ketamine at a median dose of 20 mg was associated with a median (confidence limits) increase in BIS index of 3.8 (2.5-5.0). Midazolam (median dose 2 mg) was associated with a median decrease in BIS index of 3.0 (1.5-4.5). Neither of these drug administrations occurred during time periods associated with changes in volatile anesthetic concentration. Analysis for dexmedetomidine was confounded by concomitant decreases in volatile anesthetic concentration. No other medication analyzed, including propofol and common opioids, was associated with a significant change in BIS index. Secondary analyses revealed that similar BIS index changes occurred when midazolam and ketamine were administered at different volatile anesthetic concentrations and different doses, and these changes persisted 11 to 20 minutes postadministration.
Modest, but persistent changes in BIS index occurred following doses of ketamine (increase) and midazolam (decrease) during periods of stable volatile anesthetic administration.
尽管患者通常会接受麻醉深度监测，但静脉麻醉药物的给予在多大程度上会影响全身麻醉下计算出的双频谱指数（BIS）值尚不清楚。
我们通过一种新的筛选方法，对某学术医疗中心的电子麻醉记录进行回顾性分析，以检查在使用挥发性麻醉剂的基础麻醉期间，常规给予的 14 种不同静脉内药物与 BIS 指数变化的关系。确定了仅给予单次药物推注的离散时间窗口，并分析了随后 BIS 指数、挥发性麻醉剂浓度和动脉压的变化。我们的主要结局是药物给予后 BIS 指数的变化。比较了调整后的 95%置信区间与临床意义的预定阈值。二次敏感性分析检查了相同的结局，根据基线挥发性麻醉剂浓度、给予的药物剂量和时间窗口长度的差异，对可用数据进行了分离。
研究队列由 20170 个不同病例的数据组成，其中 54.7%的患者为男性，中位年龄为 55 岁。在主要分析中，中位数（置信区间）剂量为 20mg 的氯胺酮与 BIS 指数中位数增加 3.8（2.5-5.0）相关。中位数剂量为 2mg 的咪达唑仑与 BIS 指数中位数降低 3.0（1.5-4.5）相关。这两种药物的给予均未发生在挥发性麻醉剂浓度变化的时间段内。右美托咪定的分析因挥发性麻醉剂浓度同时降低而受到干扰。分析的其他药物，包括丙泊酚和常用阿片类药物，与 BIS 指数的显著变化无关。二次分析显示，当咪达唑仑和氯胺酮在不同的挥发性麻醉剂浓度和剂量下给予时，BIS 指数发生了类似的变化，并且这些变化在给药后 11 至 20 分钟持续存在。
在稳定给予挥发性麻醉剂期间，给予氯胺酮（增加）和咪达唑仑（减少）剂量后，BIS 指数会出现适度但持续的变化。
