The investigators investigated the efficacy and safety of High Flow Nasal Cannula (HFNC) at different flow rates compared to non-invasive ventilation (NIV) in patients presenting to the emergency department (ED) with acute exacerbations of Chronic obstructive pulmonary disease (COPD) who did not respond adequately to bronchodilator therapy and continued to exhibit hypercapnic respiratory failure. Specifically, the investigators tested the hypothesis that HFNC would be more effective at reducing partial pressure of carbon dioxide (PaCO2) levels and hospital stay duration and would be associated with greater patient comfort than NIV.

The patients were divided randomly into one of three study groups: NIV, HFNC-30, and HFNC-50. The investigators collected patient data, including demographic characteristics (age and sex), vital signs upon admission (systolic blood pressure [SBP], respiratory rate [RR], and heart rate [HR]), complaints and symptoms upon admission, initial arterial blood gas parameters (e.g., pH, PaCO2, lactate, and bicarbonate), length of stay, ED revisits, patient satisfaction, intubation status, and clinical outcomes (hospitalization, admission to the intensive care unit [ICU], or 28-day mortality). Changes in arterial blood gas parameters (e.g., ΔpH, ΔPaCO2, Δlactate, and Δbicarbonate) before treatment vs. 30, 60, and 120 minutes after treatment were recorded using a pre-prepared case data form.

Inclusion Criteria:

- patients age ≥18 years with a confirmed diagnosis of COPD who presented to the ED with exacerbations that did not respond to bronchodilator therapy

Exclusion Criteria:

• patients aged younger than 18 years
• patients had an arterial pH ≤ 7.25;
• patients were in cardiopulmonary arrest;
• patients had unstable cardiac arrhythmias or hemodynamic instability;
• patients showed persistent hypoxemia despite supplemental oxygen therapy;
• patients were unconscious or uncooperative;
• patients could not protect their airway or manage secretions;
• patients had cardiogenic pulmonary edema, active hemoptysis, pneumothorax, recent upper respiratory tract/esophagus surgery, significant airway obstruction (e.g., laryngeal mass or tracheal tumor), active upper gastrointestinal bleeding, or facial trauma or deformities

Stored in non-publicly available Available on request

In this single-blind study, we assigned the participants randomly to one of three treatment groups using a computer-generated randomization program (SAS Institute, 1990). Each participant was assigned an identification number indicating their treatment group. An experienced clinician, who was blinded to the null hypothesis and did not participate in the evaluation of results, administered the treatments and recorded patient data on a pre-prepared case data form.