# [Whole Blood Mixing]{.smallcaps}

# 

# A Synopsis of an Evaluation Performed by

The Montreal Centre of Canadian Blood Transfusion,

Dr. Gilles Roy, Dr. Mindy Goldman, and Suzanne Remy-Prince,

July, 1992

submitted to the CBER Blood Products Advisory Committee, August 31, 2001
(reschedule meeting December 13-14, 2001)

principally prepared by Loren Acker and Jim Herzfeld, SEBRA

[Background]{.underline}:

Canadian blood collection centers were interested in evaluating
automated blood collection systems to provide enhanced mixing to prevent
micro-clotting. A testing method was developed to evaluate the mixing of
anticoagulant and whole blood from actual donors during the donation
process. The hypothesis was that SEBRA's new proprietary mixing action
would yield better anticoagulant-to-blood mix.

[Materials and Methods]{.underline}:

Units of whole blood (n=21) were used. Prior to the donation, 3 ml of
anticoagulant (CPDA) was replaced with 3 ml of trypan blue, a dye of the
same specific gravity of the CPDA. Three separate studies were
conducted: ten of the recipient bags were collected using a "standard"
SEBRA Shaker (Model 1020), five of which had samples extracted directly
after collection, while five had additional manual mixing provided prior
to the sample collection; eleven bags were collected using the enhanced
digital SEBRA Shaker (Model 1040) with no manual mixing. (Note: the
Model 1020 is at least comparable in capability to other international
mixing devices.)

After the donation, seven samples were drawn from each unit; the first
samples were 10 cc (as per standard specimen tube) of unmixed blood
directly from the tubing between the needle and the blood bag; the
second samples were 10 cc of mixed blood from the donor bag ; the next
four samples were 2.5 cc each of mixed blood from the blood bag; the
last sample was 10 cc, and was collected only after additional manual
mixing to represent maximal mixing.

Mixing was measured by allowing the plasma to separate in the sample
tubes after collection. The amount of trypan blue mixed into the plasma
was determined by measuring the Optical Density (OD) of the plasma at
580 nm. The higher the OD, the greater the mixing. An OD of 0.8 was
determined to represent complete, optimal mixing (100% mixing of
anticoagulant and blood). Unmixed blood, having no dye added, has an OD
of 0.0 and 0% mixing.

[Results]{.underline}:

As demonstrated on the following graph, the Model 1040 Shaker provided a
higher amount of mixing, approximately 75%, compared to the Model 1020
Shaker level of mixing, approximately 25%. Vigorous manual mixing after
collection provided the greatest mixing, typically in the high 90%
range.

[Conclusion]{.underline}:

Automated blood collection devices provide varying degrees of mixing
capability. The results demonstrate the SEBRA Model 1040 Shaker provides
a greater level of mixing than do predecessor devices.

Anecdotal and empirical evidence of both Canadian Blood Services and the
Southern Arizona Chapter of the American Red Cross indicates that
clotting can be avoided and the viability of blood components enhanced
by providing automated mixing throughout the blood collection process.
Both organizations are processing 100% leukocyte reduced blood, both
organizations have a lower than 0.3% loss due to clogged filters, and
both organizations use only automated mixers for whole blood collection.

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