Clinical Research Directory

Inclusion Criteria: * Hospitalized patients with a documented diagnosis of acute exacerbation of chronic obstructive pulmonary disease. * Patients identified retrospectively from hospital records during the predefined study period. * Patients who received at least one form of respiratory support during the index hospitalization, including conventional oxygen therapy, high-flow nasal cannula oxygen therapy, noninvasive ventilation, or invasive mechanical ventilation. * Patients with available clinical records containing sufficient dynamic physiological, laboratory, and treatment-related data for retrospective analysis. Exclusion Criteria: • Patients whose hospitalization was not primarily due to acute exacerbation of COPD, even if COPD was documented as a comorbidity. Patients with stable COPD and no evidence of acute exacerbation during the index hospitalization. * Patients admitted primarily for other acute conditions, including but not limited to pneumonia without documented AECOPD, acute heart failure, pulmonary embolism, pneumothorax, asthma exacerbation, trauma, or postoperative care. * Patients with insufficient documentation to confirm AECOPD as the primary reason for admission. * Patients with incomplete clinical records preventing retrospective analysis. * Repeated hospitalizations of the same patient during the study period, with only the first eligible admission included.