Department of Anesthesiology and Critical Care, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA.
J Clin Monit Comput. 2021 Apr;35(2):343-354. doi: 10.1007/s10877-020-00477-z. Epub 2020 Feb 17.
Anesthesia care providers and anesthesia decision support tools use mathematical pharmacokinetic models to control delivery and especially removal of anesthetics from the patient's body. However, these models are not able to reflect alterations in pharmacokinetics of volatile anesthetics caused by obesity. The primary aim of this study was to refine those models for obese patients. To investigate the effects of obesity on the elimination of desflurane, isoflurane and sevoflurane for various anesthesia durations, the Gas Man® computer simulation software was used. Four different models simulating patients with weights of 70 kg, 100 kg, 125 kg and 150 kg were constructed by increasing fat weight to the standard 70 kg model. For each modelled patient condition, the vaporizer was set to reach quickly and then maintain an alveolar concentration of 1.0 minimum alveolar concentration (MAC). Subsequently, the circuit was switched to an open (non-rebreathing) circuit model, the inspiratory anesthetic concentration was set to 0 and the time to the anesthetic decrements by 67% (awakening times), 90% (recovery times) and 95% (resolution times) in the vessel-rich tissue compartment including highly perfused tissue of the central nervous system were determined. Awakening times did not differ greatly between the simulation models. After volatile anesthesia with sevoflurane and isoflurane, awakening times were lower in the more obese simulation models. With increasing obesity, recovery and resolution times were higher. The additional adipose tissue in obese simulation models did not prolong awakening times and thus may act more like a sink for volatile anesthetics. The results of these simulations should be validated by comparing the elimination of volatile anesthetics in obese patients with data from our simulation models.
麻醉护理提供者和麻醉决策支持工具使用数学药代动力学模型来控制麻醉剂从患者体内的输送，尤其是清除。然而，这些模型无法反映肥胖对挥发性麻醉剂药代动力学的改变。本研究的主要目的是为肥胖患者改进这些模型。为了研究肥胖对不同麻醉持续时间下地氟烷、异氟烷和七氟烷消除的影响，使用了 Gas Man®计算机模拟软件。通过向标准 70kg 模型增加脂肪重量，构建了模拟体重为 70kg、100kg、125kg 和 150kg 的四个不同模型。对于每个模拟患者情况，将蒸发器设置为快速达到并然后维持肺泡浓度 1.0 最小肺泡浓度（MAC）。随后，将回路切换到开放（非再呼吸）回路模型，将吸气麻醉浓度设置为 0，并确定麻醉剂减少 67%（苏醒时间）、90%（恢复时间）和 95%（分辨率时间）所需的时间在富含血管的组织腔室中，包括中枢神经系统的高灌注组织。苏醒时间在模拟模型之间差异不大。在接受七氟烷和异氟烷的挥发性麻醉后，在更肥胖的模拟模型中苏醒时间更低。随着肥胖的增加，恢复和分辨率时间更高。肥胖模拟模型中额外的脂肪组织并没有延长苏醒时间，因此可能更像是挥发性麻醉剂的汇。这些模拟的结果应该通过将肥胖患者中挥发性麻醉剂的消除与我们的模拟模型的数据进行比较来验证。
