Clinical Research Directory

Inclusion Criteria: * Age 18 years or older. * Undergoing non-traumatic emergency major abdominal surgery performed through an open laparotomy. * Direct admission to the intensive care unit following surgery. * Receiving invasive mechanical ventilation through an endotracheal tube or tracheostomy at the time of postoperative ICU admission. * Primary abdominal fascial closure performed at the end of surgery. * Presence of an indwelling urinary catheter allowing intra-abdominal pressure measurement using the intravesical technique. * Availability of simultaneous intra-abdominal pressure and respiratory mechanics measurements at the initial assessment after ICU admission. * Written informed consent obtained from the patient or, when the patient lacks decision-making capacity, from a legally authorized representative or an eligible relative in accordance with applicable regulations and ethics committee requirements. * Additional written consent obtained from the patient for continued participation if decision-making capacity is regained during the study. Exclusion Criteria * Age younger than 18 years. * Elective abdominal surgery. * Abdominal surgery completed laparoscopically without an open laparotomy. * Laparotomy performed for traumatic injury. * Open abdomen or temporary abdominal closure at the end of surgery. * Planned second-look laparotomy or planned surgical reintervention within the first 48 hours. * Absence of invasive mechanical ventilation at postoperative ICU admission. * Bladder injury, previous bladder surgery, neurogenic bladder, or other urinary tract conditions that may compromise the reliability of intravesical pressure measurements. * Contraindication to urinary catheterization or inability to obtain reliable intra-abdominal pressure measurements through the urinary catheter. * Bronchopleural fistula, significant endotracheal tube or ventilator circuit leakage, or other mechanical problems preventing reliable measurement of plateau pressure and static respiratory system compliance. * Extracorporeal membrane oxygenation (ECMO) support. * Pre-existing dependence on chronic invasive mechanical ventilation. * Advanced neuromuscular disease, high-level spinal cord injury, or known diaphragmatic paralysis directly affecting ventilator liberation. * Pregnancy. * A decision for exclusively palliative care or limitation of life-sustaining treatment at ICU admission. * Refusal to participate by the patient or legally authorized representative, or inability to obtain written informed consent. * Inability to obtain simultaneous baseline intra-abdominal pressure and respiratory mechanics measurements at ICU admission.