Department of Anaesthesiology, Intensive Care Medicine and Pain Therapy, University Medical Centre of Rostock, Schillingallee 35, 18057, Rostock, Germany.
Rudolf-Zenker Institute for Experimental Surgery, University Medical Centre of Rostock, Rostock, Germany.
BMC Anesthesiol. 2023 Sep 19;23(1):320. doi: 10.1186/s12871-023-02273-z.
Pulse pressure variation (PPV) and stroke volume variation (SVV), which are based on the forces caused by controlled mechanical ventilation, are commonly used to predict fluid responsiveness. When PPV and SVV were introduced into clinical practice, volume-controlled ventilation (VCV) with tidal volumes (VT) ≥ 10 ml kg was most commonly used. Nowadays, lower VT and the use of pressure-controlled ventilation (PCV) has widely become the preferred type of ventilation. Due to their specific flow characteristics, VCV and PCV result in different airway pressures at comparable tidal volumes. We hypothesised that higher inspiratory pressures would result in higher PPVs and aimed to determine the impact of VCV and PCV on PPV and SVV.
In this self-controlled animal study, sixteen anaesthetised, paralysed, and mechanically ventilated (goal: VT 8 ml kg) pigs were instrumented with catheters for continuous arterial blood pressure measurement and transpulmonary thermodilution. At four different intravascular fluid states (IVFS; baseline, hypovolaemia, resuscitation I and II), ventilatory and hemodynamic data including PPV and SVV were assessed during VCV and PCV. Statistical analysis was performed using U-test and RM ANOVA on ranks as well as descriptive LDA and GEE analysis.
Complete data sets were available of eight pigs. VT and respiratory rates were similar in both forms. Heart rate, central venous, systolic, diastolic, and mean arterial pressures were not different between VCV and PCV at any IVFS. Peak inspiratory pressure was significantly higher in VCV, while plateau, airway and transpulmonary driving pressures were significantly higher in PCV. However, these higher pressures did not result in different PPVs nor SVVs at any IVFS.
VCV and PCV at similar tidal volumes and respiratory rates produced PPVs and SVVs without clinically meaningful differences in this experimental setting. Further research is needed to transfer these results to humans.
基于控制机械通气产生的力的脉压变化（PPV）和每搏量变化（SVV），通常用于预测液体反应性。当 PPV 和 SVV 引入临床实践时，最常使用潮气量（VT）≥10ml/kg 的容量控制通气（VCV）。如今，较低的 VT 和压力控制通气（PCV）的使用已广泛成为首选的通气类型。由于其特定的流量特性，VCV 和 PCV 在可比潮气量下导致不同的气道压力。我们假设较高的吸气压力会导致较高的 PPV，并旨在确定 VCV 和 PCV 对 PPV 和 SVV 的影响。
在这项自我对照的动物研究中，16 只麻醉、麻痹和机械通气（目标：VT 8ml/kg）的猪接受了用于连续动脉血压测量和经肺热稀释的导管插入术。在四个不同的血管内液体状态（IVFS；基础状态、低血容量、复苏 I 和 II）下，在 VCV 和 PCV 期间评估通气和血流动力学数据，包括 PPV 和 SVV。使用 U 检验和 RM ANOVA 进行统计分析，以及描述性 LDA 和 GEE 分析。
八只猪中有完整的数据集。在两种通气方式下，VT 和呼吸频率相似。在任何 IVFS 下，心率、中心静脉压、收缩压、舒张压和平均动脉压在 VCV 和 PCV 之间均无差异。在 VCV 中，吸气峰压明显较高，而在 PCV 中，平台压、气道压和经肺驱动压明显较高。然而，在任何 IVFS 下，这些较高的压力并没有导致不同的 PPV 或 SVV。
在相似的潮气量和呼吸频率下，VCV 和 PCV 产生的 PPV 和 SVV 在这个实验环境中没有临床意义上的差异。需要进一步的研究将这些结果转移到人类。
