Impact of Continuous Renal Replacement Therapy on Outcomes in Septic Shock Patients Receiving Polymyxin B Hemoperfusion: A Retrospective Cohort Study

Background: Polymyxin B hemoperfusion (PMX-HP) is increasingly used as an adjunctive therapy for severe sepsis and septic shock, yet the prognostic significance of continuous renal replacement therapy (CRRT) and vasoactive-inotropic score (VIS) dynamics under real-world ICU practice remains unclear. This study aimed to evaluate whether CRRT requirement and hemodynamic responses to PMX-HP influence short-term mortality among critically ill patients. Methods: We conducted a retrospective cohort study of 64 ICU patients in Taiwan with severe sepsis or septic shock who received PMX-HP. Clinical characteristics, illness severity, VIS measurements before and after PMX-HP, organ-support therapies, and outcomes—including 28-day mortality, ICU and hospital mortality, and lengths of stay—were analyzed. Patients were stratified by CRRT use, and multivariate logistic regression was performed to identify independent predictors of 28-day mortality. Results: Among 64 patients (mean age 66 years; 67% male), 67.2% received CRRT and the overall 28-day mortality was 46.9%. CRRT users exhibited higher crude mortality and higher APACHE II scores. Survivors were younger and had lower baseline severity. Hemodynamic trajectories differed substantially: VIS increased after PMX-HP more frequently in non-survivors than survivors. In multivariate analysis, post-PMX-HP VIS elevation and higher APACHE II were independent predictors of 28-day mortality, whereas CRRT requirement was not an independent determinant. Conclusions: In this real-world cohort, PMX-HP did not significantly reduce mortality. Illness severity and inadequate vasopressor improvement, rather than CRRT use, primarily determined outcomes. VIS elevation following PMX-HP may serve as an early indicator of poor hemodynamic recovery in septic shock.