The Impact of Low Versus High Positive End-expiratory Pressure on Diaphragm Function, Ventilation Efficiency, and Lung Mechanics

Inclusion Criteria: * Mechanical ventilation with pressure support or mechanical ventilation with possibility to transition to pressure support * Oxygen requirement ≤ 50% * Pressure support ≤ 12 cmH2O * PEEP ≤ 12 cmH2O * Age ≥ 18 years * Adequate intravascular volume status Exclusion Criteria: * Circulatory instability * Brain death diagnosis/brain death evaluation * Norepinephrine dose \> 0.4 µg/kg/min * Muscle relaxation administered within 2 hours * Pregnancy * Contraindication to esophageal catheterization (e.g., esophageal varices) * Conditions with increased risk of pneumothorax (such as severe COPD (Chronic Obstructive Pulmonary Disease) or extensive emphysema) * Untreated pneumothorax * Symptomatic airway obstruction Discontinuation criteria during ongoing study intervention: * Heart rate \> 120 beats/min * Systolic blood pressure \> 180 mmHg * Inspired oxygen fraction \> 70% * Respiratory rate \> 35/min * RASS (Richmond Agitation Sedation Scale) ≥ 2 * Doubling of norepinephrine dose or increase of norepinephrine dose to \> 0.5 µg/kg/min to maintain mean arterial pressure * Bradycardia \< 45 beats/min