Prone Positioning and Thoracoabdominal Binding on Lung and Muscle Protection in ARDS Patients During Spontaneous Breathing

Ventilator-induced diaphragmatic dysfunction and intensive care unit (ICU)-acquired weakness are two consequences of prolonged mechanical ventilation and critical illness in patients with acute respiratory distress syndrome (ARDS). Both complicate the process of withdrawing mechanical ventilation, increase hospital mortality and cause chronic disability in survivors. During transition from controlled to spontaneous breathing, these complications of critical illness favor an abnormal respiratory pattern and recruit accessory respiratory muscles which may promote additional lung and muscle injury. The type of ventilatory support and positioning may affect the muscle dysfunction and patient-self-inflicted lung injury at spontaneous breathing onset. In that regard, ARDS patients with ventilator-induced diaphragmatic dysfunction and ICU-acquired weakness who are transitioning from controlled to partial ventilatory support probably present an abnormal respiratory pattern which exacerbates lung and muscle injury. Physiological-oriented ventilatory approaches based on prone positioning or semi recumbent positioning with abdominal binding at spontaneous breathing onset, could decrease lung and muscle injury by favoring a better neuromuscular efficiency, and preventing intense inspiratory efforts and high transpulmonary driving pressures, as well as high-magnitude pendelluft. In the current project, in addition to perform a multimodal description of the severity of ventilator-induced diaphragmatic dysfunction and ICU-acquired weakness in prolonged mechanically ventilated ARDS patients, prone positioning and supine plus thoracoabdominal binding at spontaneous breathing onset will be evaluated.

Inclusion Criteria: * Adult ARDS patients with moderate-severe ARDS on controlled protective mechanical ventilation for more than 2 days (modified from "more than 3 days" by the protocol amendment approved in May 2024) * Stable hemodynamics * Level of consciousness enough to initiate spontaneous breathing Exclusion Criteria: * Unstable hemodynamics * Tracheostomy * Abnormal level of consciousness * Central nervous system injury * Esophageal varices * Pregnancy * Contraindications for installation of electrical impedance tomography or nasogastric catheter placement * Contraindications for prone positioning and thoracoabdominal binding * Chronic neuromuscular disorders * Obstructive lung disease; intrinsic positive end-expiratory pressure (PEEP) ≥3 cmH₂O (measured without inspiratory effort); * Recent-onset sepsis and moderate-to-severe metabolic acidosis; * Multi-organ failure with high short-term mortality risk * Clinical evidence of respiratory or hemodynamic instability