Abstract: Objective  To explore the relationship between cumulative fluid balance (CFB) and prognosis after continuous renal replacement therapy (CRRT) in patients with severe acute pancreatitis (SAP).  Methods  A total of 248 SAP patients treated in our hospital from March 2020 to March 2023 were selected as the research subjects. Computer-generated random number method was used to divide them into a training set (n=165) and a validation set (n=83) in a 2:1 ratio. According to the prognosis of CRRT patients in the training set, they were divided into a survival group (n=113) and a death group (n=52). General information and CFB within 7 days after treatment were compared between the two groups. The influencing factors for mortality in SAP patients after CRRT treatment and the dose relationship between CFB3 and patient survival after treatment were analyzed.  Results  After 7 days of treatment, the death group had higher levels of CFB3 (t=126.906, P=0.263), CFB4 (t=149.141, P=0.409), CFB5 (t=163.673, P＜0.001), CFB6 (t=158.426, P＜0.001), and CFB7 (t=373.539, P＜0.001) compared to the survival group. Multivariate Cox regression analysis showed that total duration of CRRT during hospitalization (HR=2.864, 95% CI:1.042～4.057, P=0.034), procalcitonin (PCT) (HR=3.628, 95% CI:2.605～5.231, P=0.016), and CFB3 (HR=2.743, 95% CI:1.536～3.967, P=0.008) were the independent risk factors for mortality in SAP patients after CRRT treatment, while albumin (ALB) (HR=0.726, 95% CI:0.532～0.965, P=0.024) was a protective factor. The top 4 factors that affect the prognosis of SAP patients were CFB3, total duration of CRRT during hospitalization, ALB and PCT. Restrictive cubic spline model analysis showed that there was no non-linear dose-response relationship between CFB3 and the risk of death after CRRT treatment in SAP patients, regardless of gender.  Conclusion  Excessive CFB after CRRT in SAP patients can increase the risk of death, and CFB3 is an independent risk factor for poor prognosis. 

Key words: Severe acute pancreatitis, Continuous renal replacement therapy, Cumulative fluid balance, Prognosis