Vortex pumping for routine cardiac surgery: a comparative study

Abstract

Vortex pumping has become popular for mechanical assist applications, but has only recently received serious consideration for use as the arterial pump of choice for routine open-heart surgery. We report on a prospective randomized study designed to evaluate this pump in routine use. Sixteen patients undergoing routine coronary artery surgery were randomized into two groups in which the only difference in equipment and technique was the use of a Stockert roller pump in group S and a Biomedicus vortex pump in group B. The groups were compared with respect to haematology, perioperative fluid balance, transfusion requirements, complement activation, haemolysis and microbubble transmission. The groups were reasonably well matched, with slightly longer mean bypass and ischaemic times in group S (94.8 vs 105.5 minutes and 75.7 and 83.8 minutes respectively). Group B patients showed significant improvements over group S patients with respect to preservation of platelet numbers, decreased complement activation and reduced microbubble transmission. The afterload sensitivity of the vortex pump did not present the perfusionist with any practical problems although a different technique is required for initiating and terminating bypass. We conclude that vortex pumping would seem to offer better blood handling for routine use. More extensive testing is required to establish whether or not this would be reflected in clinically measurable improved patient outcome.

A comparison of gaseous emboli release in five membrane oxygenators

“…While perhaps not completely effective in stopping the passage of microair and boluses of air less than the priming volume of the device, they have been shown to deprime and stop blood flow following large air volume entry. [23][24][25] Devices, therefore, exist which limit the amount of air emboli released to the membrane oxygenator (for example, closed reservoir systems, level detectors and centrifugal pumps) and other devices exist which limit the amount of air emboli released to the distal arterial line (for example, arterial line filters, bubble traps and air bubble detectors). The question arises whether or not the membrane oxygenator itself may have certain design features which limit the amount of air emboli released into the outlet.…”

Centrifugal and roller pumps — are there differences in coagulation and fibrinolysis during and after cardiopulmonary bypass?

“…Two major types of nonpulsatile blood pumps are currently in use: the conventional roller pump and the centrifugal pump, which employs a method known as the constrained force vortex principle. The latter was shown to have advantages in preservation of platelet count [7] and in the reduction of platelet [8] and complement [9] activation as well as in the reduction of hemolysis [10]. No difference between red and white blood cell levels could be demonstrated [11].…”

Detection and Elimination of Microemboli Related to Cardiopulmonary Bypass

“…In a small trial by Wheeldon and colleagues, significantly less microemboli generation, less complement activation, and better preservation of platelet count was observed in patients randomized to a centrifugal pump. 30 Scott identified more neurobehavioral test deficits among the roller pump group, however this difference did not reach statistical significance. 34 A study of 3438 consecutive patients revealed that the use of the centrifugal pump showed a trend toward risk reduction for adverse neurological events.…”