Roche OMNI C, Инструкция по эксплуатации

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1 Introduction
Instructions for Use, Roche OMNI C, Rev. 4.0, December 2002
1-5
1.2 Measurement and calibration procedure
1.2.1 Measurement procedure
Use the following procedures to calculate the various measurement variables:
P O
2
: Use of the Clark measurement principle: measurement of current generated by the
reduction of oxygen
P CO
2
: Use of the Severinghouse principle: potentiometric measurement of the pH change
in the electrode caused by CO
2
.
pH-, Na
+
-, K
+
-, Ca
2+
- and Cl
–
are potentiometric electrodes. Special glasses are used as the
sensitive element for pH and Na
+
. The potassium and calcium membranes contain special
neutral carriers. A special ion exchanger is used for chloride membranes. Calculation of
these variables also requires the use of a reference electrode—a permanently contacted chlo-
ride electrode in the Roche OMNI C.
tHb / S O
2
: Light absorption in whole blood is measured at four different wavelengths,
whereby on one hand the sample is subjected to light radiation and on the other hand the
dispersed light is also evaluated.
Hematocrit : Measurement of the sample's conductivity
1.2.2 Calibration procedure
tHb and S O
2
are calibrated when the instrument is calibrated. Ambient air and a zero point
solution are used to calibrate oxygen. The remaining parameters are calibrated with the help
of two solutions, which are mixed in various ratios. Gas containers are not used. The use of
at least two calibration points for each measurement variable and constant internal moni-
toring of the calibrations ensures the accuracy and precision of the measurement values.
1.3 Measurement evaluation
The validity of the test results from the Roche OMNI C must be carefully examined by a clin-
ical-medical specialist who will take the patient's clinical condition into consideration
before any clinical decisions are reached based on the test results.
To ensure the quality of the measurement results, a quality control must be performed on
3 levels (low, normal, high) at least once daily, or more frequently depending on local reg-
ulations, after each electrode exchange and after the startup of the instrument (for detailed
information see chapter 5 "Quality Control").