CLEAR Model for Predicting Ventilatory Liberation in Severe COPD

Inclusion Criteria: * Age ≥40 years * Confirmed or clinically diagnosed chronic obstructive pulmonary disease (COPD) based on prior spirometry or consistent clinical history * Admission to the intensive care unit (ICU) with acute respiratory failure requiring ventilatory support * Receiving either: Invasive mechanical ventilation (MV), or Non-invasive ventilation (NIV) -Considered clinically ready for ventilatory withdrawal: Undergoing spontaneous breathing trial (SBT) in the MV cohort Undergoing structured withdrawal or low-support trial in the NIV cohort Exclusion Criteria: * Age \<40 years * Primary diagnosis other than COPD driving respiratory failure (e.g., isolated pneumonia, cardiogenic pulmonary edema without COPD exacerbation) * Known neuromuscular disease affecting respiratory muscle function * Significant chest wall deformity or restrictive thoracic disorder affecting ventilatory mechanics * Presence of tracheostomy at baseline * Hemodynamic instability requiring high-dose vasopressors at the time of assessment * Inability to perform a diaphragm or muscle ultrasound (e.g., poor acoustic window, extensive dressings) * Reduced level of consciousness precluding valid clinical assessment (outside expected NIV cohort context) * Refusal of consent by patient or legal representative