Nutritional Risk Assessment and Diaphragmatic Thickness for Predicting Outcome in Elderly Mechanically Ventilated COPD Patients

Malnutrition and muscle wasting are frequent complications in patients with chronic obstructive pulmonary disease (COPD) experiencing acute exacerbations. In critically ill patients who require invasive mechanical ventilation, nutritional depletion and ventilator-induced diaphragmatic dysfunction can complicate recovery and prolong intensive care unit (ICU) stays. The purpose of this prospective observational cohort study is to evaluate nutritional status and diaphragmatic structure in elderly patients (aged 60 years and older) with COPD who require invasive mechanical ventilation for at least 48 hours. Participants will undergo bedside assessments, including: * Calculation of clinical risk scores within the first 24 hours of ICU admission: modified Nutrition Risk in the Critically Ill (mNUTRIC), Sequential Organ Failure Assessment (SOFA), and Acute Physiology and Chronic Health Evaluation II (APACHE II). * Anthropometric measurements: mid-upper arm circumference (MUAC) and calf circumference (CC) measured at baseline, day 7, and the day of weaning. * Diaphragmatic ultrasonography: point-of-care ultrasound to measure diaphragm thickness at end-expiration and end-inspiration at baseline, day 7, and during weaning trials. The main goal is to evaluate the relationship between nutritional risk (assessed by the mNUTRIC score) and diaphragmatic thickness, and to determine how these parameters correlate with clinical outcomes such as weaning success, total duration of mechanical ventilation, ICU length of stay, and ICU mortality.