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.
