Background The challenge of non-cardiac, neonatal extracorporal membrane oxygenation (ECMO) is the need for miniaturised circuits, small cannulas and low flow rates. Novel small rotating pump devices with diagonal blood flow have a reduced priming volume and circuit surface area. Bench studies in different in-vitro models are encouraging. However, little data exist on hemolysis, coagulation and fibrinolysis in defined in-vivo models.
Setting Twelve newborn piglets were randomly assigned to receive either veno-arterial ECMO with a novel diagonal pump system or to serve as controls. The ECMO circuit was prefilled with 70 ml packed red blood cells from adult swine. Blood was drained through 8 Fr venous and reinfused through 6 Fr arterial cannulas. ECMO was applied on 75% total cardiac output (80–100 ml/kg). The effect of the diagonal pump system on required circuit settings, heparin-use, plasma-free haemoglobin (fHb), lactatdehydrogenase and coagulation/fibsinolysis were studied.
Results Mild hemolysis was diagnosed within the first hour in all ECMO-piglets [mean fHb 49.7 mg/dl [9.0; 90.3; 95% CI]. After 8 hrs on ECMO mean fHb decreased, but was still significantly higher as compared to controls (25.5 mg/dl [8.7; 42.5] vs 4.7 mg/dl [0.8; 8.6], p = 0.02). Median mean flow rate, venous inlet pressure, and revolutions per hour were 222 ml/min (197; 313, Range), -20 cm H2O (-36; -6), and 5295 rpm (4906; 6816) respectively. Fibrin degradation products and fibrinogen levels remained normal in ECMO and control piglets throughout the study period.
Conclusion The use of a novel diagonal pump system for ECMO in our in-vivo model generates a comparable amount of fHb as previously observed under in-vitro conditions.