Electrical Impedance Tomography for Positive End-Expiratory Pressure Setting after Bilateral Lung Transplantation

Abstract

Purpose After lung transplantation (LT) the magnitude of graft recruitability is variable, therefore postoperative personalized positive end-expiratory pressure (PEEP) setting is desirable in order to minimize ventilator-induced lung injury and to reduce pulmonary complications [1]. Electrical impedance tomography (EIT) offers this opportunity by bedside estimating both alveolar collapse and overdistension throughout a decremental PEEP trial [2]. This study aims to assess the reliability of EIT-based PEEP selection compared to PEEP titration to the best respiratory system static compliance (Crs) after LT [3]. Methods All patients were deeply sedated without spontaneous breathing efforts and ventilated in volume control mode with lung-protective settings [1]. At Intensive Care Unit admission after LT, PEEP was adjusted to best Crs (PEEPCrs). Subsequently, an EIT-based decremental PEEP trial was performed through a dedicated device (Pulmovista500, Drӓger-Medical, Germany). EIT optimal PEEP (PEEPEIT) was defined as the best compromise between lung collapse and overdistension [2]. PEEPEIT was compared with PEEPCrs using Mann-Whitney test. Data are expressed as median and interquartile ranges. Results Six bilateral LT patients were enrolled (4 pulmonary fibrosis, 1 bronchiectasis and 1 bronchiolitis obliterans syndrome). Age was 57 (52-63) years and body mass index was 23.3 (20.0-25.6) kg/m2. PEEPEIT was 9 (8-13) cmH2O, not significantly different from PEEPCrs [9 (7-9) cmH2O, p = 0.413]. The loss of lung compliance due to lung collapse observed with PEEPEIT [4.8% (4.1-7.3%)] was comparable to that obtained with PEEPCrs [8.0% (6.5-12.3%) (p = 0.195)]. The loss of lung compliance consequent to lung overdistension was similar between PEEPEIT and PEEPCrs [4.0% (2.5-5.0%) vs. 1.8% (1.1-2.4%) (p = 0.134)]. Conclusion After LT, EIT is a reliable tool for individualized PEEP setting, with analogous performances to PEEP titration to the best Crs. Whether EIT is to be preferred for this purpose and the overall clinical influence of personalizing PEEP based on EIT after LT remain to be determined.