ABSTRACT
BACKGROUND : Prone positioning has been proposed as a key aspect of care in acute respiratory distress syndrome (ARDS), more than ever with emergence of COVID-19 pandemic, but sometimes at the cost of burdensome procedure and serious adverse events. Bed verticalization (standing upright) could be an efficient alternative to prone position. Semi-seated position (45-degree head-up, 45-degree legs-down) have already been studied and shew promising results, but to our knowledge no study has evaluated the mechanical and physiological impacts of complete patient verticalization during ARDS. The objective was to evaluate the safety and physiological effects of bed verticalization of sedated and ventilated patients with ARDS. METHODS : Patients were gradually verticalized, using a dedicated bed, at 0°, 30°, 60° and 90° by steps of 30 minutes. At each position step, multiparametric measurements were performed, including hemodynamic data with pulmonary artery catheter, ventilatory parameters, arterial and central veinous gasometry, end-expiratory lung volume, esophageal pressures, and electrical impedance tomography. All these measurements were set to assess effects of verticalization on hemodynamics, ventilatory mechanics and hematosis.