Association between plasma-free hemoglobin levels, lactate dehydrogenase and hemolysis-index in patients with and without mechanical circuit support - a retrospective data analysis

Abstract Purpose Hemolysis is a frequent problem in patients with mechanical circulatory support (MCS) that can indicate device malfunctions or pump thrombosis. In this retrospective cohort study, we assessed whether hemolysis index (HI) can replace plasma free hemoglobin (fHb) and lactate dehydrogenase (LDH) to guide anticoagulation and performed a cost analysis to combine medical with economical efficacy. Methods We correlated simultaneously obtained HI, fHb, LDH measures of venous blood samples in a cohort of 96 ICU patients. 429 datasets (40.7%) were collected from patients with and 556 datasets (52.8%) without extracorporeal life support (ECLS). 68 (6.5%) from a cohort of 51 outpatients on LVAD support. A cost analysis of all three hemolysis monitoring options was performed. Results Correlation of HI and fHb values was highly significant (r = 0.968, p < 0.01) overall and equally significant (r = 0.949, p < 0.01) in samples with clinically significant hemolysis (HI ≥ 20). Correlation of fHb and LDH was low (r = 0.192, p < 0.01) in all patients. Estimated cost per ICU patient on ECLS was 0 USD if HI, 4.347.25 (794.21-5350.46) USD if fHb, 383.29 (70.02-471.74) USD if serial measurements of LDH were used for hemolysis monitoring. Conclusions HI represents a cost-efficient, accurate and easily obtainable alternative to fHb measurements for clinicians treating patients with and without MCS, whereas LDH is significantly less specific. Further clinical studies on major cohorts of short and long-term MCS patients are needed to assess the optimal HI target with minimal thromboembolic as well as bleeding events.