No abstract

European Society of Anaesthesiology.

Rationale: Obesity is characterized by elevated pleural pressure (P PL) and worsening atelectasis during mechanical ventilation in patients with acute respiratory distress syndrome (ARDS). Objectives: To determine the effects of lung recruitment maneuver (LRM) in the presence of elevated P PL on hemodynamics, left and right ventricular pressures and pulmonary vascular resistance. We hypothesized that elevated P PL protects the cardiovascular system against high airway pressures and prevents lung overdistension. Methods: First, an interventional crossover trial in adult subjects with ARDS and BMI≥35 kg/m 2 (n=21) was performed to explore the hemodynamic consequences of LRM. Second, cardiovascular function was studied during low/high PEEPs in a model of swine with ARDS and high P PL (n=9) versus healthy swine with normal P PL (n=6). Measurements and Main Results: Subjects with ARDS and obesity (BMI=57±12 kg/m 2) following LRM, required an increase in PEEP of 8[7, 10] cmH 2 O above traditional ARDSnet settings to improve lung function, oxygenation and ventilation/perfusion matching, without impairment of hemodynamics or right heart function. ARDS swine with high P PL demonstrated unchanged transmural left ventricle pressure and systemic blood pressure after LRM protocol. Pulmonary artery hypertension decreased 8[13, 4] mmHg, as did vascular resistance 1.5[2.2, 0.9] WU, and transmural right ventricle pressure 10[15, 6] mmHg during exhalation. LRM and PEEP decreased pulmonary vascular resistance and normalized ventilation/perfusion ratio.