Abbott i-STAT 1 System Manual page 449

Temperature "Correction" Algorithm
PCO is a temperature-dependent quantity and is measured at 37°C. The PCO
2
temperature other than 37°C can be 'corrected' by entering the patient's temperature on the chart page of
the analyzer. See section 12 'Procedure for Cartridge Testing' in the i-STAT 1 System Manual or section 11
'Patient and Control Sample Testing' in the i-STAT System Manual for details. In this case, blood gas results
will be displayed at both 37°C and the patient's temperature. The PCO
calculated as follows:
1
Note: Patient temperature corrected results are available only on cartridges containing pH, PCO
PO
sensors.
2
Performance Characteristics
The performance characteristics of the sensors are equivalent in all cartridge configurations.
The typical performance data summarized below were collected in a health care facility 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.
collected in blood gas syringes. All samples were analyzed in duplicate on the i-STAT System and on
the comparative methods within 10 minutes of each other. Arterial blood samples were collected from
hospital patients in 3 cc blood gas syringes and were analyzed in duplicate on the i-STAT System and
the comparative method within 5 minutes of each other.
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.
* 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". 7 The correlation coefficient, r, can be used as a guide to assess the adequacy of the comparative method range in overcoming this problem.
As a guide, the range of data can be considered adequate if r>0.975.
Precision Data (mmHg)
Aqueous Control
Level 1
Level 3
Rev. Date: 01-Jul-13
was performed on the first replicate of each sample. In the method comparison
6
Mean SD
63.8 1.57
19.6 0.40
Art: 714182-01R
2
at the patient's temperature (T
2
Venous blood samples were
5
%CV
2.5
2.0
reading at a body
) is
p
, and
2
PCO2 - 3