PN 177196BB
4-19
QUALITY ASSURANCE
SETTING UP XB/XM
4
4. When using XB/XM, you can elect to have the instrument stop analyzing patient samples
when a XB/XM Failed message (alarm) is generated.
a. Selecting Auto-Stop for a XB/XM Failed message is covered under Heading 3.1,
MISCELLANEOUS (OPERATIONAL) SETUP OPTIONS, in this Training Guide.
b. Click tt tt
General tab to see the current setting for this option.
Establishing Target Values and Ranges for the XB/XM Analysis
1. Once an XM/XB option is enabled, the laboratory must establish their own mean values
(XB/XM limits).
2. The XB/XM mean values should reflect the entire patient population of the laboratory:
a. Patient population of a general hospital usually includes samples from all patient
age groups, disease states and many hematologically “normal” samples.
b. A patient population that includes only one age group or only one disease state will
yield different target values than a patient population that includes all groups.
3. For the Three-Parameter XB/XM analysis (MCV, MCH, and MCHC):
a. You may want to start with the following target values and the 5% limit range
suggested by Dr. Brian Bull for his X
B
Analysis.
r MCV = 89.5
r MCH = 30.5
r MCHC = 34.0
b. To calculate the ± range, multiply the target value by the percentage variation.
For example:
1) If for MCV you use Dr. Bull’s suggested mean of 89.5 and a 5% limit.
XM mean value x percentage = ± value (89.5 x 0.05 = 4.5)
2) You would enter the 89.5 as the mean value and 4.5 as the limit. The
Workstation calculates the upper and lower limits and displays them as a whole
number.
3) In this case, the upper limit would be 94 and the lower limit, 85. The upper
and lower limits are displayed in whole numbers.
c. If you begin with Dr. Bull’s values, your laboratory must then evaluate and adjust
the values for your own patient population.
1) Collect results from at least 250, but ideally 1000 blood samples to find your
laboratory’s XM mean values.
2) Include all types of patients (oncology, presurgical, OB, dialysis, out patients,
and so forth).
d. As long as the patient population remains constant, the XM mean values of each
index also remain constant.
e. If the patient population changes, the mean of an index may also change and need
to be reevaluated.
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