and there are indications that the post-thaw stability is
improved in comparison to units that were volume-reduced
before freezing [32, 36].
5. Filters have to be tested in the right order. If tested in the
incorrect order, power the machine off and back on. The
Line Sensor Calibration Check can now be repeated.
6. Because the used freezing bag has a greater volume (1000 mL)
than programmed in the ACP215, the machine can erroneously conclude that the sterile connection is not intact. To
prevent false-negative result, at the start of the test, a Kocher
clamp can be placed on the line between the weld and the RBC
bag. Do not forget to remove the clamp after the test is
finished.
7. In the rare event that the color of the supernatant is not
acceptable (too red), or when the printout indicates that the
hemoglobin content of the final wash step was above 50 mg%, a
manual washing step could be performed:
(a) Sterilely connect a 500 mL transfer bag to the RBC bag.
(b) Centrifuge to unit at 3200 Â g in a 22
C centrifuge for
5 min.
(c) Place the RBC unit in a plasma extractor and express the
supernatant fluid. Check if supernatant is now colorless; if
not, the unit should be discarded.
(d) Add an equal volume of SAGM to the RBC unit.
(e) The shelf life of a washed unit is limited to 24 h.
8. To take a representative RBC sample, the RBC bag should be
thoroughly mixed. After connection of the sample bag, the
RBC should be mixed between the RBC bag and the sample
bag at least three times before the final sample is taken.
9. The freezing and thawing process results in increased permeability of the RBC membrane. Because of this, hematology
analyzers could give wrong values for mean corpuscular volume
and hematocrit. For a correct determination of the hematocrit,
the spun hematocrit should be determined.
10. The supernatant should have an osmolality comparable with
that of the additive solution used. In general, an osmolality
value below 400 mOsm/kg indicates a residual glycerol level of
less than 1 g% [19]. An alternative method to determine the
efficient removal of glycerol is the measurement of the glycerol
concentration in the supernatant by the use of a plasma triglycerides test [27].
11. A major quality parameter in determining the post-thaw storage time is hemolysis. According to European guidelines [12],
this should be below 0.8% at the end of the storage period
Cryopreservation of Red Blood Cells
535
improved in comparison to units that were volume-reduced
before freezing [32, 36].
5. Filters have to be tested in the right order. If tested in the
incorrect order, power the machine off and back on. The
Line Sensor Calibration Check can now be repeated.
6. Because the used freezing bag has a greater volume (1000 mL)
than programmed in the ACP215, the machine can erroneously conclude that the sterile connection is not intact. To
prevent false-negative result, at the start of the test, a Kocher
clamp can be placed on the line between the weld and the RBC
bag. Do not forget to remove the clamp after the test is
finished.
7. In the rare event that the color of the supernatant is not
acceptable (too red), or when the printout indicates that the
hemoglobin content of the final wash step was above 50 mg%, a
manual washing step could be performed:
(a) Sterilely connect a 500 mL transfer bag to the RBC bag.
(b) Centrifuge to unit at 3200 Â g in a 22
C centrifuge for
5 min.
(c) Place the RBC unit in a plasma extractor and express the
supernatant fluid. Check if supernatant is now colorless; if
not, the unit should be discarded.
(d) Add an equal volume of SAGM to the RBC unit.
(e) The shelf life of a washed unit is limited to 24 h.
8. To take a representative RBC sample, the RBC bag should be
thoroughly mixed. After connection of the sample bag, the
RBC should be mixed between the RBC bag and the sample
bag at least three times before the final sample is taken.
9. The freezing and thawing process results in increased permeability of the RBC membrane. Because of this, hematology
analyzers could give wrong values for mean corpuscular volume
and hematocrit. For a correct determination of the hematocrit,
the spun hematocrit should be determined.
10. The supernatant should have an osmolality comparable with
that of the additive solution used. In general, an osmolality
value below 400 mOsm/kg indicates a residual glycerol level of
less than 1 g% [19]. An alternative method to determine the
efficient removal of glycerol is the measurement of the glycerol
concentration in the supernatant by the use of a plasma triglycerides test [27].
11. A major quality parameter in determining the post-thaw storage time is hemolysis. According to European guidelines [12],
this should be below 0.8% at the end of the storage period
Cryopreservation of Red Blood Cells
535