Abbott i-STAT 1 System Manual page 428

To convert a result from %PCV to fraction packed cell volume, divide the %PCV result by 100. For the
measurement of hematocrit, the i-STAT System can be customized to agree with methods calibrated by
the microhematocrit reference method using either K
of K EDTA anticoagulated blood are approximately 2-4% less than K
3
the choice of anticoagulant affects the microhematocrit method to which all hematocrit methods are
calibrated, results from routine samples on hematology analyzers are independent of the anticoagulant
used. Since most clinical hematology analyzers are calibrated by the microhematocrit method using K
anticoagulant, the i-STAT System default customization is K
The reference range programmed into the analyzer and shown above is intended to be used as a guide
for the interpretation of results. Since reference ranges may vary with demographic factors such as
age, gender and heritage, it is recommended that reference ranges be determined for the population
being tested.
Clinical Significance
Hematocrit is a measurement of the fractional volume of red blood cells. This is a key indicator of the
body's state of hydration, anemia or severe blood loss, as well as the blood's ability to transport oxygen.
A decreased hematocrit can be due to either overhydration, which increases the plasma volume, or a
decrease in the number of red blood cells caused by anemias or blood loss. An increased hematocrit can be
due to loss of fluids, such as in dehydration, diuretic therapy, and burns, or an increase in red blood cells,
such as in cardiovascular and renal disorders, polycythemia vera, and impaired ventilation.
Performance Characteristics
The typical performance data summarized below were collected in health care facilities by health care
professionals trained in the use of the i-STAT System and comparative methods.
Precision data were collected in multiple sites as follows: Duplicates of each control fluid were tested in the
morning and in the afternoon on five days for a total of 20 replicates. The averaged statistics are presented
below.
Method comparison data were collected using CLSI guideline EP9-A.
lithium heparin Vacutainer
methods for hematocrit within 20 minutes of collection.
Deming regression analysis
table, n is the number of specimens in the data set, Sxx and Syy refer to estimates of imprecision based
on the duplicates of the comparative and the i-STAT methods respectively, Sy.x is the standard error of the
estimate, and r is the correlation coefficient.*
Method comparisons will vary from site to site due to differences in sample handling, comparative method
calibration and other site specific variables.
Interference studies were based on CLSI guideline EP7-P.
*The usual warning relating to the use of regression analysis is summarized here as a reminder: For any analyte, "if the data is collected over a narrow
range, the estimate of the regression parameters are relatively imprecise and may be biased. Therefore, predictions made from these estimates may be
invalid". The correlation coefficient, r, can be used as a guide to assess the adequacy of the comparative method range in overcoming this problem.
5
As a guide, the range of data can be considered adequate if r>0.975.
Precision Data (%PCV)
Whole Blood Control
Low
High
Hct - 2
tubes, were analyzed in duplicate on the i-STAT System and on the comparative
®
was performed on the first replicate of each sample. In the method comparison
5
Mean SD
30.0 0.44
49.0 0.50
Art: 714178-01O
EDTA or K EDTA anticoagulant. Mean cell volumes
3 2
EDTA anticoagulated blood.
2
EDTA.
3
Venous blood samples, collected in
4
6
%CV
1.5
1.0
While
2
EDTA
3
Rev. Date: 15-Aug-16