What is the normal relationship between the partial pressure of ...

[storky111]

What is the normal relationship between the partial pressure of arterial carbon dioxide (PaCO2) and partial pressure of end-tidal CO2 (PETCO2)?
 
  a. PaCO2 and PETCO2 are equal.
  b. PaCO2 is 10 mm Hg more than PETCO2.
  c. PaCO2 is 4 to 6 mm Hg less than PETCO2.
  d. PaCO2 is 4 to 6 mm Hg more than PETCO2.

Question 2

A 24-year-old skier with a broken femur has been in the postanesthesia care unit for 24 hours and is 12 hours post-extubation with no supplemental oxygen.
 
  He is awake, alert, and oriented, and he reports shortness of breath. A capnograph shows de-creased PETCO2. This patient's current status could be caused by which of the following?
  a. Respiratory center depression c. Muscular paralysis
  b. Pulmonary embo-lism d. Alveolar shunt

[Sweetkitty24130]

Answer to Question 1

ANS: D
Although the partial pressure of end-tidal CO2 (PETCO2) should equal the partial pressure of arte-rial carbon dioxide (PaCO2), the PETCO2 is actually 4 to 6 mm Hg lower than the PaCO2.

Answer to Question 2

ANS: B
Long-bone fractures put a patient at risk for the development of pulmonary emboli. The de-creased PETCO2 is showing that physiologic dead space has increased because of the blockage of pulmonary arterioles.