Abbott i-STAT 1 System Manual page 443

pH
pH is measured by direct potentiometry. In the calculation of results for pH, concen tra tion is related to
potential through the Nernst equation. Results are reported at 37°C.
See below for information on factors affecting results. Certain substances, such as drugs, may affect analyte
levels in vivo.
1
If results appear inconsistent with the clinical assessment, the patient sample should be retested using
another cartridge.
Intended Use
The test for pH, as part of the i-STAT System, is intended for use in the in vitro quantification of pH in
arterial, venous, or capillary whole blood.
pH measurements are used in the diagnosis, monitoring, and treatment of respiratory disturbances and
metabolic and respiratory-based acid-base disturbances.
Contents
Each i-STAT cartridge contains one reference electrode (when potentiometric sensors are included in the
cartridge configuration), sensors for the measurement of specific analytes, and a buffered aqueous calibrant
solution that contains known concentrations of analytes and preservatives. For cartridges that contain a
sensor for the measurement of pH, a list of reactive ingredients is indicated below:
Reactive Ingredient
Hydrogen Ion (H )
+
Metrological Traceability
The i-STAT System test for pH measures the hydrogen ion amount-of-substance concentration in the
plasma fraction of arterial, venous, or capillary whole blood (expressed as the negative logarithm of the
relative molal hydrogen ion activity) for in vitro diagnostic use. pH values assigned to i-STAT's controls and
calibration verification materials are traceable to the U.S. National Institute of Standards and Technology
(NIST) standard reference materials SRMs 186-I, 186-II, 185, and 187. i-STAT System controls and
calibration verification materials are validated for use only with the i-STAT System and assigned values may
not be commutable with other methods. Further information regarding metrological traceability is available
from Abbott Point of Care Inc..
Expected Values
Test/Abbreviation Units
pH
* Calculated from Siggaard-Andersen nomogram.
Venous samples normally measure 0.01 – 0.03 pH units lower than arterial samples.
Rev. Date: 15-Jul-16
Minimum Quantity
6.66 pH
Reportable Reference
Range Range
6.50 – 8.20 7.35 – 7.45
(arterial)
Art: 714181-01N
7.31 – 7.41*
2
(venous)