Department of Perioperative Medicine and Intensive Care, Karolinska University Hospital, Stockholm, Sweden.
Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
Acta Anaesthesiol Scand. 2020 May;64(5):670-676. doi: 10.1111/aas.13552. Epub 2020 Jan 30.
Lung protective ventilation can decrease post-operative pulmonary complications. The aim of this study was to evaluate a capnodynamic method estimating effective lung volume (ELV) as a proxy for end-expiratory lung volume in response to PEEP changes in patients, healthy subjects and a porcine model.
Agreement and trending ability for ELV in anaesthetized patients and agreement in awake subjects were evaluated using nitrogen multiple breath wash-out/in and plethysmography as a reference respectively. Agreement and trending ability were evaluated in pigs during PEEP elevations with inert gas wash-out as reference.
In anaesthetized patients bias (95% limits of agreement [LoA]) and percentage error (PE) at PEEP 0 cm H O were 133 mL (-1049 to 1315) and 71%, at PEEP 5 cm H O 161 mL (-1291 to 1613 mL) and 66%. In healthy subjects: 21 mL (-755 to 796 mL) and 26%. In porcines, at PEEP 5-20 cm H O bias decreased from 223 mL to 136 mL LoA (34-412) to (-30 to 902) and PE 29%-49%. Trending abilities in anaesthetized patients and porcines were 100% concordant.
The ELV-method showed low bias but high PE in anaesthetized patients. Agreement was good in awake subjects. In porcines, agreement was good at lower PEEP levels. Concordance related to PEEP changes reached 100% in all settings. This method may become a useful trending tool for monitoring lung function during mechanical ventilation, if findings are confirmed in other clinical contexts.
肺保护性通气可以降低术后肺部并发症。本研究旨在评估一种基于二氧化碳动力学的有效肺容量（ELV）估计方法，作为反映患者、健康受试者和猪模型中呼气末肺容量对 PEEP 变化反应的替代指标。
使用氮多次呼吸冲洗/清除和体描法分别作为参考，评估麻醉患者的 ELV 一致性和趋势能力，以及清醒受试者的一致性。使用惰性气体冲洗作为参考，评估猪在 PEEP 升高期间的一致性和趋势能力。
在麻醉患者中，PEEP 为 0 cm H2O 时的偏倚（95%一致性界限[LoA]）和百分比误差（PE）分别为 133 mL（-1049 至 1315）和 71%，PEEP 为 5 cm H2O 时分别为 161 mL（-1291 至 1613 mL）和 66%。在健康受试者中，分别为 21 mL（-755 至 796 mL）和 26%。在猪中，PEEP 从 5 到 20 cm H2O 时，偏倚从 223 mL 降低到 136 mL 的 LoA（34 至 412）到（-30 至 902），PE 从 29%降至 49%。麻醉患者和猪的趋势能力完全一致。
ELV 方法在麻醉患者中表现出低偏倚但高 PE。在清醒受试者中，一致性良好。在猪中，在较低的 PEEP 水平下，一致性良好。在所有设置中，与 PEEP 变化相关的一致性达到 100%。如果在其他临床环境中得到证实，该方法可能成为监测机械通气期间肺功能的有用趋势工具。
