Early Cumulative Fluid Balance Trajectories and Mortality in Sepsis with Reduced Right Ventricular Systolic Function: A Retrospective Cohort Study

Abstract Background Patients with sepsis and reduced right ventricular (RV) systolic function present particular challenges for fluid management. We investigated early cumulative fluid balance trajectories and their associations with mortality and ventilator-free days in this population. Methods This retrospective cohort study used MIMIC-IV version 3.1. Adults with sepsis and echocardiographically documented reduced RV systolic function who remained alive and in the ICU for 72 hours after sepsis onset were included. Group-based trajectory modelling identified patterns of weight-normalised cumulative fluid balance measured at 6-hour intervals during these 72 hours. The primary outcome was 28-day all-cause mortality; secondary outcomes were ICU mortality, in-hospital mortality, and 28-day ventilator-free days. Cox models evaluated mortality from the 72-hour landmark, adjusting for demographic characteristics, comorbidities, initial severity, cardiac and renal function, haemodynamics, and initial ventilation. Results Among 1,042 patients, five trajectories were identified: persistent negative (T1), mild negative (T2), mild positive (T3), moderate positive (T4), and high positive (T5) balance. Overall, 338 patients (32.4%) died within 28 days. Twenty-eight-day mortality ranged from 25.9% in T1 to 43.0% in T5. Compared with T1, T5 was associated with higher 28-day mortality after full adjustment (HR 2.01, 95% CI 1.34–3.02; P < 0.001). Corresponding adjusted HRs were 1.97 (95% CI 1.19–3.27) for ICU mortality and 2.25 (95% CI 1.45–3.48) for in-hospital mortality. Median 28-day ventilator-free days decreased across T1–T5, from 25.75 to 10.59 days (global P < 0.001). Conclusions Early cumulative fluid balance trajectories were associated with outcomes in patients with sepsis and reduced RV systolic function. High positive balance identified a pattern associated with greater mortality and fewer ventilator-free days, highlighting the prognostic relevance of longitudinal fluid balance assessment in this population.