User's Manual

i15 Blood Gas and Chemistry Analysis System User Manual Parameters
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refers to the standard error of estimate.
Parameter N Slope Intercept
Correlation
Coefficient
Sy.x Range
Na
+
15 0.98 1.30 0.99999 0.1924 102.6 – 180.3
In the comparison study, samples were analyzed in parallel on the i15 Blood Gas and Chemistry
Analysis System and the Rapidpoint 400 system. Two replicates of each sample were analyzed
on each system.
Parameter N Slope Intercept
Correlation
Coefficient
Sy.x Range
Na
+
215 0.9813 2.3952 0.9961 1.1661 102.3 – 164.9
12.4.4 Interfering Substances
Aqueous sample was spiked by addition of a potentially interfering substance to the following
test concentration to test for interferences. Twelve replicates of both the spiked sample and the
unspiked sample were tested on two i15 Blood Gas and Chemistry Analysis Systems with one lot
of test cartridges. The interference was computed using the difference between the mean of the
spiked sample and the unspiked sample.
The substances that interfere with the Na
+
measurement are listed below:
37.5mmol/L bromide will increase Na
+
results by 5.5mmol/L.
The following substances were tested and found not to be clinically significant for the Na
+
measurement: 24mmol/L hydroxyurea, 1.0mmol/L magnesium, 20mmol/L lactate, 4.00mmol/L
salicyte, 12.5mmol/L bromide, and 20mmol/L β-hydroxybutyrate.
NOTE:
It is possible that there are other substances interfering with the Na
+
measurement.
12.5 Potassium (K
+
)
Potassium is measured by potentiometry with an ion-selective electrode. The concentration of
potassium ions is determined by the measured potential through the Nernst equation. The system
uses a direct (undiluted) method to measure potassium and the obtained values may differ from
those obtained by an indirect (diluted) method.