D-RSBI Versus RSBI for Predicting Weaning Success in COPD Patients

Inclusion Criteria: * Mechanically ventilated COPD patients fulfilling standard weaning readiness criteria. * Invasive mechanical ventilation for more than 24 hours before spontaneous breathing trial. * Hemodynamically stable without significant vasopressor support. * Adequate oxygenation with FiO2 ≤ 0.5 and PEEP ≤ 8 cmH2O . * Preserved mental status and ability to initiate spontaneous breathing. * Successful tolerance of spontaneous breathing trial conducted on CPAP mode with pressure support ≤ 8 cmH2O. Exclusion Criteria: * Refusal of consent * Neuromuscular disease, phrenic nerve palsy, or diaphragmatic paralysis. * Large pneumothorax or pathology interfering with ultrasound assessment. * Terminal extubation. * Recent major thoracic surgery. * Poor sonographic window despite repeated attempts.