Severe adverse clinical impacts are predicted by an early high positive fluid balance in patients with severe acute pancreatitis.

Fluid balance in the early stages of severe acute pancreatitis (SAP) significantly impacts patient outcomes. This study aimed to identify the optimal fluid balance value affecting adverse outcomes in SAP patients to enhance fluid management. The study comprised two parts. Part 1 involved a retrospective review of 560 SAP patients at Ruijin Hospital (1996–2008) to determine the optimal fluid balance for in-hospital mortality using multivariable regression and ROC curve analysis. Part 2 prospectively examined 343 SAP patients in Emergency Intensive Care Unit at Ruijin Hospital (2020–2023) to validate findings regarding 30-day mortality and organ support. In Part 1, key independent risk factors for in-hospital mortality included age, weight, hypertension, APACHE II score, D0-D2/kg fluid balance, sugery and necrosis. The optimal predictive D0-D2/kg fluid balance value was found to be 48.4 ml/kg. In Part 2, exceeding this value indicated a higher risk for 30-day mortality (HR = 3.477) and increased need for mechanical ventilation (OR = 4.741) and blood purification (OR = 3.685). A D0-D2/kg fluid balance above 48.4 ml/kg correlates with poorer outcomes in SAP patients, providing guidance for clinicians in fluid management to improve prognosis.