Abstract
Background Septic patients with heart failure may be more sensitive to intravenous fluid infusion and are at risk for fluid overload. Methods to assess fluid overload status and how fluid accumulation relates to prognosis in these patients remain unknown. Based on these results, we aimed to explore how cumulative fluid balances during the initial three days in the ICU affect the prognosis of septic patients with heart failure . Methods Data for this retrospective study were obtained from the MIMIC IV2.2 database. According to the daily cumulative fluid balance status, patients were divided into negative fluid balance group (CFB < 0%) and positive fluid balance group (CFB ≥ 0%). The main outcome of this study was all-cause in-hospital mortality. Cox regression analysis was conducted to investigate the association between the daily CFB and the risk of mortality. Subgroup analyses were conducted to investigate the consistency of the prognostic value of the daily CFB status (day1-day3) in septic patients with reduced ejection fraction (HFrEF,LVEF < 50%) and preserved ejection fraction ( HFpEF,LVEF ≥ 50%). Results A total of 1150 patients were included in this study, including 776 survivors and 374 deaths.The median age was 65 ± 12 years, with males comprising 58.0% of the sample. CFB-day3 (AUC = 0.765) had a better predictive ability for mortality than CFB-day2(AUC = 0.727) or CFB-day1 (AUC = 0.530). Similar results were observed in the HFrEF and HFpEF population. Subgroup analysis showed that a positive fluid balance of CFB-day1 was associated with a 78% increased risk of mortality among patients with HFrEF(LVEF < 50%). However, a positive fluid balance of CFB-day1 was associated with a 52% reduced risk among patients with HFpEF(LVEF ≥ 50%). In exploratory analyses, the proportional effect of a positive fluid balance of CFB-day2 or CFB-day3 on mortality was consistent across all eight pre-specified subgroups, regardless of whether the patient had a preserved ejection fraction or a reduced ejection fraction (all P for interaction > 0.05). Conclusions In septic patients with HFpEF, positive fluid balance of CFB-day1 might improve the prognosis of patients. However, from the second day, fluid overload was associated with poor prognosis. Therefor, we propose that on the first day of fluid resuscitation, the therapy should be considered according to the LVEF level. Furthermore, diuretics or CRRT should be utilized as much as possible on the second or third day to achieve a negative fluid balance.