Zitzmann Amelie, Müller-Graf Fabian, Bandorf Tim, Reuter Susanne, Merz Jonas, Frenkel Paul, Vollmar Brigitte, Böhm Stephan H, Reuter Daniel A
Department of Anaesthesiology, Intensive Care Medicine and Pain Therapy, University Medical Centre of Rostock, Schillingallee 35, 18057, Rostock, Germany.
Rudolph-Zenker-Institute for Experimental Surgery, University Medical Centre of Rostock, Rostock, Germany.
Anaesthesiologie. 2025 Sep 1. doi: 10.1007/s00101-025-01575-w.
To reliably assess fluid responsiveness using pulse pressure variation (PPV), tidal volumes (VT) of at least 8 ml/kg of ideal bodyweight are recommended. This contrasts with the current recommendations for lung-protective mechanical ventilation, which advocate VTs between 6 and 8 ml/kg to minimize ventilator-induced lung injury.
The aim of this study was to analyze whether indexing PPV to certain ventilatory parameters can be a possibility for VT-independent assessment of fluid responsiveness during mechanical ventilation with lower tidal volumes.
Hemodynamic and ventilatory data were collected from eight anesthetized, paralyzed, intubated and mechanically ventilated pigs. Each animal was ventilated with four different VTs (4, 6, 8, and 12 ml/kg) during volume-controlled ventilation, across four intravascular fluid states: normovolemia; hypovolemia induced by bleeding and two stages of fluid resuscitation induced by retransfusion and additional fluid administration. The PPV values were indexed to various ventilatory parameters including VT, plateau pressure (Pplat) and driving pressure (∆P), as well as transpulmonary pressures and composite parameters, such as minute ventilation (MV), mechanical power and mechanical energy.
Indexing PPV to MV (PPV/MV) resulted in values with the smallest variation across different VTs, followed by PPV/VT, PPV/Pplat and PPV/∆P. These indexed parameters exhibited high ratios of explained variance (R) to regression slope (β), indicating reduced VT dependency. In each case, higher values reflected a greater calculated fluid deficit.
Indexing PPV to MV can be a feasible way to use dynamic parameters of fluid responsiveness across a wide spectrum of ventilator settings, such as during lung protective ventilation strategies involving lower tidal volumes. Future studies should evaluate the performance of the indexed parameters in guiding fluid therapy in the clinical setting and define thresholds.
为了使用脉压变异度（PPV）可靠地评估液体反应性，建议理想体重下的潮气量（VT）至少为8 ml/kg。这与当前肺保护性机械通气的建议形成对比，后者提倡采用6至8 ml/kg的潮气量以尽量减少呼吸机诱发的肺损伤。
本研究的目的是分析将PPV与某些通气参数进行指数化是否有可能在低潮气量机械通气期间独立于VT评估液体反应性。
收集了8只麻醉、瘫痪、插管并接受机械通气的猪的血流动力学和通气数据。在容量控制通气期间，每只动物使用四种不同的VT（4、6、8和12 ml/kg）进行通气，涵盖四种血管内液体状态：血容量正常；出血诱发的低血容量以及再输血和额外补液诱发的两个液体复苏阶段。PPV值与包括VT、平台压（Pplat）和驱动压（∆P）在内的各种通气参数以及跨肺压和复合参数（如分钟通气量（MV）、机械功率和机械能）进行指数化。
将PPV与MV进行指数化（PPV/MV）得出的值在不同VT之间的变化最小，其次是PPV/VT、PPV/Pplat和PPV/∆P。这些指数化参数显示出较高的可解释方差（R）与回归斜率（β）之比，表明对VT的依赖性降低。在每种情况下，较高的值反映出计算出的液体亏缺更大。
将PPV与MV进行指数化可以作为一种可行的方法，在广泛的通气设置中使用液体反应性的动态参数，例如在涉及低潮气量的肺保护性通气策略期间。未来的研究应评估指数化参数在临床环境中指导液体治疗的性能并确定阈值。
