S29 Cumulative Intra-Abdominal Pressure Exposure and Dynamic Trajectories in ICU-Admitted Patients Reveal Prognostic Determinants of Severe Acute Pancreatitis

Introduction: Intra-abdominal pressure (IAP) critically drives organ failure progression in severe acute pancreatitis (SAP). However, traditional static IAP monitoring inadequately captures dynamic injury evolution. This study aimed to assess the impact of cumulative IAP exposure (CumIAP) and dynamic trajectories on the prognosis of SAP. Methods: This retrospective cohort study analyzed 1,008 intensive care unit-admitted SAP patients from the Jiangxi cohort (2005 to 2023) and 83 from MIMIC-IV (2008 to 2019). CumIAP was quantified via time-weighted integration of serial IAP measurements. Multivariate Cox regression models and restricted cubic splines were established to analyze the dose-response relationships between CumIAP and death, infectious pancreatic necrosis (IPN), and persistent multiple organ failure (PMOF). Mediation analysis evaluated CumIAP's role in albumin- and acute necrotic collection-associated outcomes. Latent class growth mixture model was used to identify dynamic IAP trajectory subtypes, and the associations between each trajectory group and poor prognosis were analyzed. Results: During the median 17-day inpatient follow-up of the subjects in the Jiangxi cohort, 200 individuals (19.8%), 208 individuals (20.6%), and 329 individuals (32.6%) experienced in-hospital death, IPN, and PMOF, respectively. Regression analysis revealed that for each standard deviation increase in CumIAP, the risks of in-hospital death and PMOF increased by 37% and 86%, respectively, and there was a U-shaped association with the risk of IPN occurrence (P for nonlinearity = 0.004). Mediation analysis showed that CumIAP mediated 24.26% and 33.76% of the associations between albumin, acute necrotic collection, and the risk of in-hospital death, respectively. Three IAP trajectories were identified by latent class growth mixture model: the high-pressure rapid decline group, the low-pressure gradual decline group, and the low-pressure progressive increase group. Among them, compared with the high-pressure rapid decline group and the low-pressure gradual decline group, the subjects in the low-pressure progressive increase group had a significantly increased risk of poor prognosis. Conclusion: This study, for the first time, revealed that CumIAP is linearly positively correlated with death and PMOF, while it exhibits a U-shaped association with IPN. Moreover, the risk of poor prognosis in the trajectory group with a low baseline IAP but progressive increase is significantly higher than that in the group with a high baseline IAP but rapid decline.