Hemolysis. A comparative study of four nonpulsatile pumps.

Hemolysis is one of the important performance parameters of blood pumps. However, comparisons of published data are compromised by the different test methods used. This article reports the results obtained when testing four nonpulsatile blood pumps (Roller pump, Biopump Model 600, Biopump BP-80, Hemadyne pump) in the identical test circuit under the same hemodynamic conditions. A closed test circuit was composed of a flexible bag reservoir and two short tubes for connection to the pump head. The priming volume was 1 L, and the total surface area was 950 cm2. Fresh blood from a fasted calf was directly primed into the circuit and maintained at 37 degrees C. It was pumped at 6 L/min for 12 hr against a 100 mmHg afterload. The hemolysis index (HI), defined as grams of hemoglobin released per 100 L pumped, was calculated from a curve fit to the hourly data. Each pump was tested five times. The mean HI obtained ranged from 0.0467 for the roller pump to 0.0076 for the Biopump BP-80. There was no statistically significant difference among the three centrifugal pumps tested.