From the Department of Anaesthesiology and Pain Medicine, Inselspital, Bern University Hospital, University of Bern, Bern (DH, CS, MH, FS, HAK) and Department of General Internal Medicine, Canton Hospital Frauenfeld, Frauenfeld, Switzerland (CS).
Eur J Anaesthesiol. 2022 Apr 1;39(4):305-314. doi: 10.1097/EJA.0000000000001576.
With an ageing global population, it is important to individualise titration of anaesthetics according to age and by measuring their effect on the brain. A recent study reported that during general surgery, the given concentration of volatile anaesthetics, expressed as a fraction of the minimum alveolar concentration (MAC fraction), decreases by around only 3% per age-decade, which is less than the 6% expected from age-adjusted MAC. Paradoxically, despite the excessive dosing, Bispectral index (BIS) values also increased.
We planned to investigate the paradox of age when using the Narcotrend depth of anaesthesia monitor.
Secondary analyses of a prospective observational study.
Tertiary hospital in Switzerland, recordings took place during 2016 and 2017.
One thousand and seventy-two patients undergoing cardiac surgery entered the study, and 909 with noise-free recordings and isoflurane anaesthesia were included in this analysis.
We calculated mean end-tidal MAC fraction and mean index value of the Narcotrend depth of sedation monitor used in the study during the prebypass period. Statistical associations were modelled using linear regression, local weighted regression (LOESS) and a generalised additive model (GAM).
Primary endpoints in this study were the change in end-tidal MAC fraction and mean Narcotrend index values, both measured per age-decade.
We observed a linear decrease in end-tidal MAC fraction of 3.2% per age-decade [95% confidence interval (CI) -3.97% to -2.38%, P < 0.001], consistent with previous findings. In contrast to the BIS, mean Narcotrend index values decreased with age at 3.0 index points per age-decade (95% CI, -3.55 points to -2.36 points, P < 0.001), a direction of change commensurate with the increasing age-adjusted MAC fraction with patient age. These relationships were consistent regardless of whether age-adjusted MAC was displayed on the anaesthetic machine.
We caution that the 'paradox of age' may in part depend on the choice of depth of sedation monitor.
ClinicalTrials.gov Identifier: NCT02976584.
随着全球人口老龄化，根据年龄个体化调整麻醉药物的滴定并测量其对大脑的影响非常重要。最近的一项研究报告称，在全身手术中，挥发性麻醉药物的给予浓度（以最低肺泡浓度（MAC）的分数表示）每 10 年仅降低约 3%，低于年龄调整 MAC 所预期的 6%。矛盾的是，尽管给予了过量的药物，双频谱指数（BIS）值也升高了。
我们计划研究使用麻醉深度监测仪时年龄的矛盾现象。
前瞻性观察研究的二次分析。
瑞士的一家三级医院，记录于 2016 年和 2017 年进行。
1072 名接受心脏手术的患者进入研究，其中 909 名患者具有无噪声记录和异氟醚麻醉，包括在本分析中。
我们计算了预体外循环期间使用的研究中呼气末 MAC 分数和麻醉深度监测仪的平均指数值。使用线性回归、局部加权回归（LOESS）和广义相加模型（GAM）对统计关联进行建模。
本研究的主要终点是每 10 年测量的呼气末 MAC 分数和平均麻醉深度监测仪指数值的变化。
我们观察到呼气末 MAC 分数线性下降 3.2%/10 年[-3.97%至-2.38%，P<0.001]，与之前的发现一致。与 BIS 相反，平均麻醉深度监测仪指数值随年龄增加而降低，每 10 年降低 3.0 个指数点（95%置信区间，-3.55 点至-2.36 点，P<0.001），这一变化方向与患者年龄增加时的年龄调整 MAC 分数增加一致。这些关系在是否显示年龄调整 MAC 分数的麻醉机上都是一致的。
我们警告说，“年龄悖论”可能部分取决于镇静深度监测仪的选择。
ClinicalTrials.gov 标识符：NCT02976584。
