If the PCO2 of an arterial blood sample is 60 mm Hg, the expected ...

[fnuegbu]

If the PCO2 of an arterial blood sample is 60 mm Hg, the expected pH is:
 
  a. 7.20. c. 7.50.
  b. 7.30. d. 7.60.

Question 2

Erroneous PCO2 measurements can be caused by which of the following?
 
  1. A worn electrode
  2. A cracked electrode
  3. Wearing out of the silver anode
  4. Increased temperature of the patient
  5. Dehydration of bicarbonate solution
  a. 1 and 5 c. 3 and 4
  b. 2 and 3 d. 1, 2, and 5

[blakeserpa]

Answer to Question 1

ANS: A
The pH changes by 0.1 unit for every 10-mm Hg increase in PCO2. Therefore, a PCO2 of 60 mm Hg is 20 mm Hg higher than normal, which equates to 2  0.1 = 0.2 decrease in pH from normal, or 7.40  0.2 = 7.20.

Answer to Question 2

ANS: D
The most common problems encountered with a PCO2 electrode involve interference with the diffusion of CO2 across the Teflon membrane and the H+ ions across the glass membrane from either worn or cracked electrodes or protein deposits. If the bicarbonate solution dehydrates be-tween the Teflon membrane and the pH glass electrode, erroneous data can result.

[fnuegbu]

TYSM

[sultana.d]

Excellent