(1571) Influence of Intravascular Hemolysis on Sepsis Outcomes

Introduction: Sepsis is a major cause of morbidity and mortality in hospitalized patients and remains difficult to treat due to its heterogeneity. Hemolysis is a phenomenon often seen in critically ill patients with sepsis. This study seeks to evaluate potential correlation between degree of hemolysis and mortality in a group of adult sepsis patients.

Methods: Patients > 18 years were consented and enrolled based on SEPSIS-3 definition in a single ICU as part of multicenter SEPSIS immune endotyping - SPIES - study. Plasma isolated from fresh samples was cryopreserved for future analysis. Patients excluded with chronic immunosuppressive or infectious diseases, recent steroids or chemotherapy. Serial samples collected throughout hospitalization. Plasma from 16 adult ICU sepsis patients were analyzed for markers of hemolysis. Haptoglobin and hemopexin ELISAs, Drabkin’s test to measure cell-free hemoglobin (CFH), and a novel heme assay to measure total and free heme were performed. Statistics performed using Graphpad v.10. ANOVA used between groups, T-test performed to compare two groups.

Results: Patients that survived (n=13) trended towards increased hemopexin (0.75 +/- 0.1mg/mL vs 0.3 +/- 0.2mg/mL on day 1, p>0.05) and higher haptoglobin (2.4 +/- 0.4mg/mL vs 1.1 +/- 0.9mg/mL on day 1, p>0.05) than the nonsurviving group (n=3). Total and unbound heme tended to be lower compared with nonsurvivors (total 15.8 +/- 5.7uM vs 45.4 +/- 35.5uM on day 1, p>0.05; unbound 2.2 +/- 0.6uM vs 4.8 +/- 1.8uM on day 1, p>0.05). There was no significant difference in cell-free hemoglobin between groups. There was a slight increase in haptoglobin and free heme levels from day 1 to 4. CFH levels remain stable throughout, and total heme levels trended upwards over time.

Conclusions: Haptoglobin and hemopexin levels are weakly suggestive of increased hemolysis in sepsis correlates with higher mortality. Measures of total and free heme also weakly suggest increased hemolysis is seen in non-surviving sepsis patients. None of the findings were statistically significant, likely due to high intragroup variability and small sample size resulting in low power. Future directions seek to increase sample size, as well as to compare markers of hemolysis with functional immune studies performed as primary outcome for this multicenter study.