Short-term Modification of Postoperative Ventilation Phenotypes With Electrical Impedance Tomography-guided Positive End-expiratory Pressure Titration

BACKGROUND: Postoperative ventilation inhomogeneity is common after major surgery and has been associated with adverse outcomes. Whether these ventilation phenotypes can be acutely modified remains unknown. We investigated whether electrical impedance tomography (EIT)-guided PEEP titration can improve ventilation homogeneity and cardiopulmonary function. METHODS: This prospective, single-center, non-randomized feasibility study was conducted from August 2024 to June 2025. Sixty mechanically ventilated adults admitted to the ICU after surgery at high risk of postoperative pulmonary complications (PPCs) underwent EIT assessment. 30 with heterogeneous ventilation patterns (15 phenotype 1: ventral-dominant; 15 phenotype 3: dorsal-dominant) received individualized PEEP titration guided by dorsal fraction of ventilation (DFV) to achieve a homogeneous pattern (phenotype 2: DFV 50-59%), whereas 30 with homogeneous ventilation received no protocolized intervention. The primary endpoint was feasibility of achieving homogenization. RESULTS: Immediate phenotype conversion was achieved in 29 of 30 patients (96.7%; 95% CI, 82.8-99.9%). At 4 h, 28 of 30 patients (93.3%; 95% CI, 77.9-99.2%) remained within the target DFV range. In ventral-dominant patterns (n=15), PEEP increased from 5 to 9 cm H₂O; respiratory system compliance increased by 9.2 mL/cm H₂O (95% CI, 6.1-12.3), and PaO₂/FIO₂ increased by 61.9 mm Hg (95% CI, 8.6-115.2). In dorsal-dominant patterns (n=15), PEEP decreased from 7 to 3 cm H₂O; ventral compliance increased by 3.4 mL/cm H₂O (95% CI, 1.1-5.8), without changes in global respiratory system compliance or oxygenation. Individualized PEEP reduced mean pulmonary artery pressure and increased cardiac index. Exploratory comparison showed severe PPCs occurred in 25% of the interventional cohort and 41% of the historical cohort (absolute risk difference, -15.8 % [95% CI, -38.8 to 2.2]; P = 0.17). CONCLUSIONS: Short-term modification of postoperative ventilation phenotypes is feasible with EIT-guided phenotype-directed PEEP titration. This strategy is associated with improved homogeneity and cardiopulmonary function, supporting regional ventilation as a therapeutic target.