BACKGROUND: Chronic obstructive pulmonary disease (COPD) and acute exacerbation of chronic obstructive pulmonary disease (AECOPD) pose global challenges, with oxygen saturation (SpO METHODS: This study involved 996 AECOPD patients sourced from the Medical Information Mart for Intensive Care (MIMIC) III database (version 1.3), with 134 fatalities. Patients were categorized into a death group (n=134) and a survival group (n=862). The average admission SpO RESULTS: The GAM curve demonstrated a non-linear, U-shaped relationship between admission SpO CONCLUSIONS: Admission SpO