Individualised flow-controlled versus pressure-controlled ventilation in a porcine oleic acid-induced acute respiratory distress syndrome model

BACKGROUND: A continuous gas flow provided by flow-controlled ventilation (FCV) facilitates accurate dynamic compliance measurement and allows the clinician to individually optimise positive end-expiratory and peak pressure settings accordingly. OBJECTIVE: The aim of this study was to compare the efficiency of gas exchange and impact on haemodynamics between individualised FCV and pressure-controlled ventilation (PCV) in a porcine model of oleic acid-induced acute respiratory distress syndrome (ARDS). DESIGN: Randomised controlled interventional trial conducted on 16 pigs. SETTING: Animal operating facility at the Medical University Innsbruck. INTERVENTIONS: ARDS was induced in lung healthy pigs by intravenous infusion of oleic acid until moderate-to-severe ARDS at a stable Horowitz quotient (PaO(2) FiO(2)(−1)) of 80 to 120 over a period of 30 min was obtained. Ventilation was then either performed with individualised FCV (n = 8) established by compliance-guided pressure titration or PCV (n = 8) with compliance-guided titration of the positive end-expiratory pressure and peak pressure set to achieve a tidal volume of 6 ml kg(−1) over a period of 2 h. MAIN OUTCOME MEASURES: Gas exchange parameters were assessed by the PaO(2) FiO(2)(−1) quotient and CO(2) removal by the PaCO(2) value in relation to required respiratory minute volume. Required catecholamine support for haemodynamic stabilisation was measured. RESULTS: The FCV group showed significantly improved oxygenation [149.2 vs. 110.4, median difference (MD) 38.7 (8.0 to 69.5) PaO(2) FiO(2)(−1); P = 0.027] and CO(2) removal [PaCO(2) 7.25 vs. 9.05, MD −1.8 (−2.87 to −0.72) kPa; P = 0.006] at a significantly lower respiratory minute volume [8.4 vs. 11.9, MD −3.6 (−5.6 to −1.5) l min(−1); P = 0.005] compared with PCV. In addition, in FCV-pigs, haemodynamic stabilisation occurred with a significant reduction of required catecholamine support [norepinephrine 0.26 vs. 0.86, MD −0.61 (−1.12 to −0.09) μg kg(−1) min(−1); P = 0.037] during 2 ventilation hours. CONCLUSION: In this oleic acid-induced porcine ARDS model, individualised FCV significantly improved gas exchange and haemodynamic stability compared with PCV. TRIAL REGISTRATION: Protocol no.: BMBWF-66.011/0105-V/3b/2019)