Intra-abdominal hypertension (IAH) is a life-threatening complication of early-onset severe acute pancreatitis (SAP) and a direct driver of multiple organ dysfunction. Bedside percutaneous catheter drainage has limited applicability, and CT-guided drainage is generally feasible only after two weeks. We aimed to explore whether OXIRIS CRRT improves IAH and systemic inflammation in early SAP patients.

This pilot, real-world, multicenter, retrospective cohort study enrolled 36 adults with early-onset SAP and IAP >= 12 mmHg treated with CRRT at 8 Chinese hospitals between 2021 and 2025. Twenty patients received OXIRIS (AN69-PEI) and 16 received standard CRRT (AN69ST150); filter selection was at the treating physician's discretion. The primary endpoint was the 72-hour reduction in intra-abdominal pressure (ΔIAP = IAP_D0 − IAP_D3). Secondary endpoints were pre-post changes in APACHE-II, IL-6, lactate, norepinephrine dose, and PaO2/FiO2 at 72 hours. Within-group comparisons used paired t-test or Wilcoxon signed-rank test; between-group comparisons used Mann-Whitney U test and ANCOVA adjusting for baseline IAP.

In the OXIRIS group (n = 20, mean age 49.4 ± 19.4 years, 90% male; biliary 50%, hypertriglyceridemia 45%), 72-hour treatment reduced IAP from 21.9 ± 6.3 to 17.2 ± 7.1 mmHg (paired t P = 0.0006), APACHE-II from 21.6 ± 9.1 to 14.4 ± 6.9 (P < 0.0001), lactate from 3.8 ± 4.9 to 2.4 ± 4.9 mmol/L (P = 0.0015), median IL-6 from 449 to 125 pg/mL (Wilcoxon P = 0.007), and median norepinephrine dose from 0.22 to 0.00 μg/kg/min (P = 0.05). In the standard CRRT group (n = 16), none of these indices changed significantly (all P > 0.05). The between-group ΔIAP difference was +2.96 mmHg favoring OXIRIS (95% CI −0.62 to +6.54, P = 0.18). Twenty-eight-day mortality was 5.0% vs 6.2%; no filter-related adverse events occurred.

In this pilot multicenter cohort, 72-hour OXIRIS-based CRRT achieved significant within-patient reductions in IAP, organ-dysfunction scores, lactate, norepinephrine requirement, and IL-6 in early-onset SAP with IAH—a pattern absent in standard CRRT. These mechanistic findings warrant confirmation in a randomized controlled trial with IAP as the primary outcome.