A novel insight in exploring the positive end expiratory pressure for sustained ventilation after lung recruitment in a porcine model of acute respiratory distress syndrome.

The aim of the present study was to explore a novel insight to determine the positive end expiratory pressure (PEEP) for sustained ventilation after lung recruitment in an acute respiratory distress syndrome (ARDS) model. Continuous infusion of oleic acid was performed to establish a ARDS model. Pressure control ventilation (PCV) was applied for lung recruitment with PEEP of 20 cm H2O. After lung recruitment, maneuver was changed to volume-controlled ventilation and PEEP titration were performed by decreasing PEEP gradually starting from the level of 20 cm H2O. The optimal level of PEEP for sustained ventilation was set as the lowest PEEP until oxygen partial pressure (PaO2) plus carbon dioxide partial pressure (PaCO2) ≥400 mmHg. Hemodynamic and respiratory parameters at basal level, ARDS state and different levels of PEEP around the optimal PEEP were recorded. The defined optimal PEEP was 13.14 ± 1.35 cm H2O. Respiratory parameters including intrapulmonary shunt (Qs/Qt) and arterial oxygen saturation (SaO2) were significantly improved by various levels of PEEP for sustained ventilation after lung recruitment (P<0.05). Static compliance (Cst) and dynamic compliance (Cdyn) were also significantly increased after application of different levels of PEEP ventilation after lung recruitment (P<0.05). There was no significant statistic difference on most hemodynamic parameters (P>0.05) between various levels of PEEP. The application of different PEEP levels around the defined optimal PEEP had an obvious improvement on respiratory mechanics and gas exchange for collapsed lung tissue without influencing the hemodynamics.