Residual Platelet Counts in Plasma Prepared for Routine Coagulation Testing with the Beckman Coulter Power Processor
P. W. BARNES, C. S. EBY, M. LUKOSZYK
Laboratory Hematology 8:205-209
© 2002 Carden Jennings Publishing Co., Ltd.
ABSTRACT:
Our laboratory has recently installed a Beckman Coulter
Power Processor as part of a custom solution to fully automate
our routine coagulation testing process. As part of the
validation for this new system, we undertook a series of
studies to assess the minimum centrifugation time required
to prepare platelet-poor plasma using the National Committee
for Clinical Laboratory Standards (NCCLS) guideline
(H21-A3) of <10 x 109/L platelets. First, residual
platelet counts were measured after centrifuging 1 set each
of 20 randomly selected patient plasma samples for 5, 6, 7,
8, 9, and 10 minutes. Results showed that 10 minutes was
the minimum centrifugation time necessary to consistently
meet the NCCLS standard. The next study was designed to
evaluate the effect of elevated whole blood platelet counts
(300-800 x 109/L), on minimum centrifugation time. The
results again supported a minimum centrifugation time of
10 minutes. Additional studies were performed to determine
if elevated residual platelet counts after centrifugation
for 5 minutes in the Power Processor affected the results of
routine coagulation tests (prothrombin time, activated partial
thromboplastin time, and fibrinogen) when compared
with centrifugation for 10 minutes. Results of these studies
demonstrated that centrifugation of citrated whole blood
samples for 5 minutes, despite residual platelet counts >10
x 109/L, produce routine coagulation results equivalent to those from samples centrifuged for 10 minutes.
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