Original Article

The Effect of Extracorporeal Circulation Time and Patient Age on Platelet Retention During Cardiopulmonary Bypass: A Comparison of Roller and Centrifugal Pumps

Medical Perfusion Department, Schumpert Medical Center and Department of Medicine (Critical Care), Louisiana State University Medical Center, Shreveport, Louisiana

^* Address correspondence to: Beverly Parault, RN, CCP, Director, Medical Perfusion Department, Schumpert Medical Center, P.O. Box 21976, Shreveport, LA 71120-1976

Abstract

Preservation of platelet count during cardiopulmonary bypass (CPB) was retrospectively studied in 784 consecutive adult patients undergoing cardiac surgery, including high-risk “special case” patients. The extracorporeal circuit included a closed membrane oxygenator system for all patients. A roller pump (Co be Laboratories or Stockert-Shiley) was used for bypass in one group of 564 patients, while a centrifugal pump (BioPump, BioMedicus) was used in a second group of 220 patients. There was no difference between the roller and centrifugal pump groups with respect to age, sex, total bypass time, and pre-bypass platelet count. For purposes of this study, retention refers to the patient's last platelet count on CPB expressed as a fraction of the pre-CPB platelet count. The centrifugal pump group had a higher platelet retention than the roller pump group (.619 vs .595, p<.05). Patients with prolonged bypass times (> 120 min) had a lower platelet retention in the roller pump group (.568 vs .610, p<.05), but no significant decrease was seen in the centrifugal pump group (.617 vs .621, p>.05). Patients OVer the age of 70 had a lower retention than those under 70 in the roller pump group (.576 VS .604, p<.05), but there was no difference in the centrifugal pump group (.600 vs .628, p>.05). The special case patients had a lower retention when the roller pump was used (.563 vs .607, p<.05), while platelet retention was not affected in the centrifugal pump group (.603 vs .625, p>.05), however bypass time was also prolonged in the special case group. The centrifugal pump results in improved platelet retention on cardiopulmonary bypass. This improvement is most notable in prolonged cases(> 120 min), in older patients(> 70 yrs), and in special cases.