After a red blood cell product has been collected it is centrifuged and plasma removed, resulting in a "packed" unit. The volume of plasma to remove depends on the donor's hematocrit and the final hematocrit desired.



(1) initial volume of red blood cell product in mL

(2) original hematocrit of product in percent, as determined from the segment (this would allow for any dilution due to anticoagulant and preservative in the collection bag)

(3) target or final hematocrit for product in percent (usually in range of 70-80%)


red blood cell volume in mL =

= (original hematocrit) / 100 * (initial product volume in mL)


final volume for product =

= (red blood cell volume in mL) / (target hematocrit) * 100 =

= (original hematocrit) / (target hematocrit) * (initial product volume in mL)


volume of plasma to remove =

= (initial product volume in mL) - (final product volume in mL)

= (initial product volume in mL) * (1 - ((original hematocrit) / (target hematocrit)))


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