A patient is being treated with dapsone, an antibiotic, for P. ...

[olgavictoria]

A patient is being treated with dapsone, an antibiotic, for P. carinii infection. Which of the fol-lowing ways of measuring oxygen saturation would be most appropriate?
 
  a. In vivo blood gas monitoring c. Pulse oximetry
  b. In vitro blood gas monitoring d. CO-oximetry

Question 2

Fractional hemoglobin saturation is calculated from values measured by which of the following?
 
  a. Pulse oximeter c. Clark electrode
  b. CO-oximeter d. Severinghaus elec-trode

[kingfahad97]

Answer to Question 1

ANS: D
The use of dapsone causes an increase in metHb, which will interfere with the accuracy of a pulse oximeter. The presence of metHb will decrease the actual saturation of Hb. Therefore, direct measurement of O2Hb is most appropriate in this case. A CO-oximeter will not only measure the O2Hb, but it will also measure the metHb level.

Answer to Question 2

ANS: B
The fractional hemoglobin saturation is calculated by dividing the amount of O2Hb by the sum of HHb + O2Hb + HbCO + metHb. All four hemoglobin can be measured by a CO-oximeter. A pulse oximeter noninvasively measures oxygen saturation and heart rate only. A Clark electrode measures only the PO2, and a Severinghaus electrode measures the PCO2.