Which of the following statements is true concerning the ...

[maychende]

Which of the following statements is true concerning the operation of a transcutaneous carbon dioxide electrode?
 
  a. PtcCO2 readings are slightly lower than the PaCO2 value.
  b. Electrodes should be calibrated when they are repositioned.
  c. Heating the transcutaneous PCO2 (PtcCO2) to 43C will adversely affect its operation.
  d. Before its use, the electrode should be calibrated to 20 and 40 CO2.

Question 2

The standard transcutaneous carbon dioxide electrode is which of the following?
 
  a. Clark c. Spectrophotometer
  b. Levy-Jennings d. Modified Stow-Severinghaus

[zogaridan]

Answer to Question 1

ANS: B
Manufacturers typically suggest calibration of an electrode each time it is repositioned. PtcCO2 readings are slightly higher than the PaCO2 value because of the higher metabolic rate at the site of the electrode caused by heating the skin. The PtcCO2 electrode must be heated to 42 C to 44 C. The PtcCO2 electrodes are calibrated with a two-point calibration procedure by using 5 CO2 and 10 calibration gases.

Answer to Question 2

ANS: D
The standard transcutaneous carbon dioxide electrode is a modified Stow-Severinghaus blood gas electrode composed of pH-sensitive glass with a silversilver chloride (Ag/AgCl) electrode. The Clark electrode measures oxygen. Levy-Jennings is a chart that allows the operator of blood gas analyzers to detect trends and shifts in electrode performance. A spectrophotometer is a de-vice for measuring light that can measure intensity as a function of the wavelength of light. It is used in pulse oximeters.