Abstract
An in vitro experiment was designed to examine and compare pump durability and stability, and hematologic derangements induced by four centrifugal pumps and one roller pump on fresh, unpooled citrated bovine blood. Pumps tested included St. Jude Medical Lifestream (n = 7), Medtronic Bio-Pump® (n = 7) and Carmeda Bio-Pump® (n = 7), Sarns (n = 7) centrifugal pump, and Sarns roller pump (n = 7). Identical circuits consisted of equal inflow and outflow lengths of 3/8″ tubing connecting a 1 liter (L) reservoir to a pump head or roller region. Pump flow was controlled at 4.5 ± 0.3 L/min. All circuits (0.1 L lactated Ringer's solution prime + 1 L blood) were tested for 24 h. Blood samples were drawn hourly for hours 1–6, every other hour for hours 8–12, and then at hour 24. Parameters monitored included pH, fibrinogen, plasma free hemoglobin (free Hb), lactate dehydrogenase (LDH), and platelet counts. Over the 24-h period, platelet counts decreased similarly among the perfusion systems. Free Hb and LDH rose significantly with the Sarns roller and centrifugal pumps after five hours of pumping. No significant changes in fibrinogen or pH were detected. Pump speed required to maintain flow with the Bio-pumps was significantly faster than with the Sarns and St. Jude Medical pumps.
The authors conclude that these perfusion systems function reliably and satisfactorily during the first 4 h in an in vitro circuit. All centrifugal pumps were less hostile to red blood cells than the roller pump. Under these experimental conditions, the Sarns centrifugal pump caused more hemolysis than the other three centrifugal systems tested. There was no apparent advantage to the Carmeda Bio-Pump (heparin bonded) circuit in this trial.
