Enhanced hemolysis in pediatric patients requiring extracorporeal membrane oxygenation and continuous renal replacement therapy

PURPOSE: Hemolysis during extracorporeal membrane oxygenation (ECMO) may be associated with the development of hemoglobinuria (Hb) nephropathy and acute renal failure. For patients requiring ECMO, continuous renal replacement therapy (CRRT) can be simultaneously performed by attaching a hemofilter to the ECMO circuit, thereby shunting part of the ECMO blood flow through the hemofilter. However, the possibility that CRRT may further enhance hemolysis (and the risk of Hb nephropathy) in patients on ECMO has not been previously investigated. METHODS: Medical records of 42 children (1 day-12 years old) who required ECMO (ECMO group, n=25) or ECMO and CRRT (ECMO+CRRT group, n=17) after cardiac surgery were reviewed. RESULTS: Forty-one out of 42 patients had elevated plasma-free hemoglobin (FHb) on the first day of ECMO. For all subjects, peak change (mean+/-SD) in FHb (Peak%C-FHb, 83.6+/-183%) correlated with serum lactic dehydrogenase (150+/-324%, r=0.49, p<0.05) and marginally with ECMO blood flow rate (BFR) (Peak%C-BFR, 36.8+/-51.0%, r=0.29, p=0.06). Compared with the ECMO group, the ECMO+CRRT group had a higher Peak%C-FHb (160+/-259%, p<0.05) and Peak%C-BFR (62+/-64%, p<0.05). Also, there was a significant increase in FHb one day after the initiation of CRRT compared with the level prior to CRRT (73.3+/-49.2 vs. 50.0+/-30.3 mg/dL, respectively, p=0.012). Serum creatinine (but not blood urea nitrogen) was significantly higher in the ECMO+CRRT group compared with the ECMO group. The percent change in serum creatinine during ECMO did not correlate with Peak%C-FHb in the ECMO group. CONCLUSION: Our findings suggest that there is enhanced hemolysis during combined ECMO and CRRT compared with ECMO alone. However, the clinical impact of increased hemolysis on renal function in patients receiving ECMO with or without CRRT remains to be determined.