ATC vs PSV for Weaning in Patients With Respiratory Failure

Inclusion Criteria: * Age ≥18 years. * Admitted with acute respiratory failure (ARF). * On mechanical ventilation with Puritan-Bennett 840 ventilator for ≥24 hours. * Considered for weaning after improvement or resolution of underlying cause. * Fully conscious. * Minimal or no requirement for vasoactive drugs or sedation. * Adequate gas exchange (PaO₂/FiO₂ \>200 at PEEP 5 cmH₂O and FiO₂ \<0.5) Rapid shallow breathing index (RSBI) \<105 breaths/min/L. Exclusion Criteria: * Age \<18 years. * Pre-existing chronic obstructive pulmonary disease (COPD). * Neuromuscular disorders. * Hemodynamic instability requiring high-dose vasoactive support. * Persistent altered level of consciousness. * Ongoing sedation. * Severe metabolic or electrolyte disturbances. * Morbid obesity (BMI ≥40 kg/m²). * Tracheostomy. * Pregnancy. * Refusal to participate by patient or legal guardian.