The method for keeping low perfusion flow weaning from centrifugal pumps: an evaluation of hemolysis in the...

Currently, the clinical application of extracorporeal and assisted circulation using centrifugal pumps is becoming popular. However, a problem in the use of centrifugal pumps is the difficulty in controlling the flow rate when it is a low range. Although we have been controlling the flow rate with a control unit that simply squeezes the blood outlet tube from the outside, hemolysis resulting from turbulent flow in the tube was discovered. Therefore, this control procedure was evaluated experimentally. Two groups were tested as follows: in Group A (n = 10), the tube was squeezed from the outside using the control unit, and in Group B (n = 10), no control unit was used. Blood in each circuit was circulated at 1,500 rpm, and the flow rate was controlled to 250 ml/min using the control unit for Group A. Time-course changes of lactate dehydrogenase (LDH) and free hemoglobin in the blood were measured during 8 h of circulation. There were no significant differences between the 2 groups in the mean values of LDH and free hemoglobin. Therefore, the present low flow rate control provided by the control unit makes it appear to be a simple and useful apparatus for controlling blood circulation using centrifugal pumps.