Takahashi Kazuhiro, Toyama Hiroaki, Funahashi Yutaro, Kawana Shin, Ejima Yutaka, Kikuchi Kenji, Ishikawa Takuji, Yamauchi Masanori
Department of Anesthesiology and Perioperative Medicine, Tohoku University Graduate School of Medicine.
Department of Anesthesiology, Miyagi Children's Hospital.
Tohoku J Exp Med. 2022 Apr 19;256(4):271-281. doi: 10.1620/tjem.2022.J003. Epub 2022 Mar 17.
Fluid mechanics show that high-density gases need more energy while flowing through a tube. Thus, high-density anesthetic gases consume more energy to flow and less energy for lung inflation during general anesthesia. However, its impact has not been studied. Therefore, this study aimed to investigate the effects of high-density anesthetic gases on tidal volume in laboratory and clinical settings. In the laboratory study, a test lung was ventilated at the same pressure-controlled ventilation with 22 different gas compositions (density range, 1.22-2.27 kg/m) using an anesthesia machine. A pneumotachometer was used to record the tidal volume of the test lung and the respiratory gas composition; it showed that the tidal volume of the test lung decreased as the respiratory gas density increased. In the clinical study, the change in tidal volume per body weight, accompanied by gas composition change (2% sevoflurane in oxygen and with 0-30-60% of NO), was recorded in 30 pediatric patients. The median tidal volume per body weight decreased by 10% when the respiratory gas density increased from 1.41 kg/m to 1.70 kg/m, indicating a significant between-group difference (P < 0.0001). In both settings, an increase in respiratory gas density decreased the tidal volume during pressure-controlled ventilation, which could be explained by the fluid dynamics theory. This study clarified the detailed mechanism of high-density anesthetic gas reduced the tidal volume during mechanical ventilation and revealed that this phenomenon occurs during pediatric anesthesia, which facilitates further understanding of the mechanics of ventilation during anesthesia practice and respiratory physiology.
流体力学表明，高密度气体在流经管道时需要更多能量。因此，在全身麻醉期间，高密度麻醉气体在流动时消耗更多能量，而在肺膨胀时消耗较少能量。然而，其影响尚未得到研究。因此，本研究旨在探讨高密度麻醉气体在实验室和临床环境中对潮气量的影响。在实验室研究中，使用麻醉机以相同的压力控制通气对一个测试肺进行通气，通气气体有22种不同的气体成分（密度范围为1.22 - 2.27 kg/m³）。使用呼吸流速计记录测试肺的潮气量和呼吸气体成分；结果显示，随着呼吸气体密度增加，测试肺的潮气量减少。在临床研究中，记录了30例儿科患者在气体成分变化（氧气中2%七氟醚以及0 - 30 - 60%一氧化氮）时每体重的潮气量变化。当呼吸气体密度从1.41 kg/m³增加到1.70 kg/m³时，每体重的潮气量中位数下降了10%，表明组间差异有统计学意义（P < 0.0001）。在两种环境中，呼吸气体密度增加均会使压力控制通气期间的潮气量减少，这可以用流体动力学理论来解释。本研究阐明了高密度麻醉气体在机械通气期间降低潮气量的详细机制，并揭示了这种现象在儿科麻醉期间会发生，这有助于进一步理解麻醉实践中的通气力学和呼吸生理学。
