Seasonal variations and clinical influencing factors in the volume of emergency department in-hospital cardiac arrest: a retrospective observational study

Emergency Department In-Hospital Cardiac Arrest (EDIHCA) constitutes a critical and life-threatening clinical event, characterized by notable seasonal variation in its incidence. This study seeks to identify the peak seasonal distribution of EDIHCA cases within a temperate climate zone and to investigate the clinically relevant factors associated with these events. A retrospective observational study was conducted involving patients who experienced EDIHCA at the Second Affiliated Hospital of Kunming Medical University between March 2021 and February 2025. Patients were divided into peak season and non-peak seasons groups based on the distribution of EDIHCA cases. Clinical influencing factors contributing to the increased volume of EDIHCA during the peak season were assessed using multivariable logistic regression after an assessment of collinearity. During the study period, 246 EDIHCA cases were recorded during the peak season (winter), compared to 422 cases in other seasons. Univariate and multivariate logistic regression analyses identified severe pneumonia (OR = 6.53, 95% CI:3.59–11.86, p < 0.001), acute coronary syndrome (ACS) (OR = 2.33, 95% CI:1.10–4.94, p = 0.027), hemorrhagic shock (OR = 1.92, 95% CI:1.14–3.23, p = 0.014), and admission pulse oxygen saturation (SpO 2 ) < 90% (OR = 1.83, 95% CI:1.26–2.64, p = 0.001) as significant independent influencing factors associated with increased EDIHCA patient volume in winter. This study identified a potential peak season for EDIHCA patient volumes in a moderate climate, along with its associated clinical influencing factors. These findings warrant further validation through larger-scale, multicenter studies. ChiCTR2500110602. Registered on 16 October 2025.