Medica EasyStat, Руководство оператора

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/
t h e o r y
r
PCO
2
Electrode
1
The PCO2 electrode is a modified pH electrode, using Severinghaus
electrode technology. The sample is introduced to a CO2 permeable
membrane surrounding internal fill solution (bicarbonate solution)
which is in direct contact with pH-sensitive glass and a silver/silver
chloride electrode terminal (an internal reference electrode). A chemi-
cal reaction takes place in the bicarbonate solution after CO2 has
permeated the membrane. This reaction produces hydrogen ions and
a change in the pH of the bicarbonate solution. The change in pH is
in proportion to the PCO2, creating a voltage change which is then
converted into PCO2 units.
PO
2
Electrode 1
The PO2 electrode uses Clark electrode technology. A positively
charged silver/silver chloride electrode acts as an anode, and a
negatively charged platinum electrode acts as a cathode. Oxygen
measurement begins when a voltage is supplied between the anode
and the cathode through the internal fill solution. When a sample is
introduced to the oxygen permeable membrane, the oxygen passes
through the membrane to the electrode (cathode). This causes a reac-
tion which produces a current that is directly proportional to the PO2
in the sample. The final calculation uses the electrode slope and mea-
surements of Calibrant A and sample.