Calibration
Procedure:
(The actual calibration procedure
is performed in two stages. Always begin with the RBC and/or HCT
values when control readings indicate that these parameters require
calibration. The first stage involves entering the calibration specimen
values into the instrument and activating the calibration mode.
The second stage consists of running the calibration specimen.)
1. From
the assay sheet that corresponds to the normal control you have
previously equilibrated at room temperature, obtain the mean value
for RBC shown in the column for Cell Dyn 300/400/500 systems.
2. Using
the numerical keypad, press “Code Select”, then “2”. Either “ECA”
or a value will be displayed. Enter the mean RBC value obtained
from the control assay sheet. This entry requires 3 digits. Once
entered, the indicator on the front panel adjacent to the letters
“RBC” as well as the “Cal/Disc” indicator will automatically begin
to flash.
3. Prepare
two separate red cell dilutions as you would for a patient sample
(1:62,500) using the normal control material. Be sure to thoroughly
mix the control sample beforehand and carefully mix dilutions as
they are being made. Pour the two separate dilutions into a single
cup and place under the transducer.
4. Press
“RBC/HCT” button. The instrument will count the sample 3 times and
if all 3 values are within tolerance will recover and display the
control assay value that was input at the beginning of the procedure.
(A similar process is used to calibrate the hematocrit; however,
a “live” blood sample should be used for this portion of the calibration
procedure.)
5. Obtain
a blood sample drawn and properly diluted in EDTA from a normal
patient and measure the hematocrit value manually using a microhematocrit
centrifuge. Values between 40% and 45% are acceptable and will yield
the best results. Do not use heparinized hematocrit tubes.
6. Press
“Code Select” and then “4”. “ECA” or a number will be displayed.
Enter the spun hematocrit value for the previously obtained “live”
sample. Remember to enter 3 digits, even if one of them is zero.
7. As
with the RBC calibration, prepare two separate RBC/HCT dilutions
using the patient sample. Pour the two separate dilutions into a
single cup and place under the transducer. Press RBC/HCT button.
Verify that the input hematocrit value has been recovered.
8. The
WBC and Hgb parameters can be calibrated simultaneously. As with
the RBC calibration, obtain the Cell-Dyn WBC and Hgb assay target
values from the control assay sheet. Press “Code Select” then “1”
to enter the assay value for the WBC count. Press “Code Select”,
then “3” to enter the value for Hgb.
9. Prepare
two separate (1:250) dilutions of the control adding the appropriate
amount of lysing reagent to each sample and pour both samples
together into a single cup. Mix well. Place the cup under the transducer
and press the “WBC/Hgb” button. Verify that the values previously
input for both WBC and Hgb are recovered and displayed.
Troubleshooting
Tips:
1. If
the letters “CE” are displayed at any time during the calibration
cycle, restart that sequence of steps. Clogs can also cause a calibration
error (CE).
2. When performing
the hematocrit calibration, measure the spun hematocrit carefully.
If an attempt is made to calibrate with an erroneous value, the
procedure will be aborted.
3. Since
calibration determines the overall accuracy and precision of every
patient measurement that follows, good laboratory practices should
be adhered to. Be sure that all samples and dilutions are well mixed
before processing.
