You obtain an SpO2 reading of 100 on a patient receiving O2 ...

[nevelica]

You obtain an SpO2 reading of 100 on a patient receiving O2 through a nonrebreathing mask. What range of PaO2 levels is possible in this patient?
 
  a. 60 to 90 mm Hg
  b. 90 to 100 mm Hg
  c. 100 to 200 mm Hg
  d. 100 to 600 mm Hg

Question 2

You obtain an SpO2 reading of 90 using an oximeter with an approximate accuracy of 5. This could indicate a PO2 as low as what level?
 
  a. 55 mm Hg
  b. 60 mm Hg
  c. 65 mm Hg
  d. 70 mm Hg

[momo1250]

Answer to Question 1

ANS: D
At the high end, oximetry data can be even less meaningful. Because of the characteristics of the oxyhemoglobin dissociation curve (see Chapter 11), a patient with an SpO2 reading of 100 could represent a PaO2 level anywhere between 100 and 600 mm Hg.

Answer to Question 2

ANS: A
However, with the accuracy of some oximeters being only 4, an SpO2 reading of 90 could mean an actual SaO2 reading as low as 86, corresponding to a PO2 level of 55 mm Hg or less