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

Abstract

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 (PaO2 FiO2 −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 PaO2 FiO2 −1 quotient and CO2 removal by the PaCO2 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) PaO2 FiO2 −1; P = 0.027] and CO2 removal [PaCO2 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)