The Bohr equation applies to ventilationperfusion ratios that ...

[Metfan725]

The Bohr equation applies to ventilationperfusio n ratios that have which of the following characteristics?
 
  A. having a ventilationperfusio n value of zero
  B. having perfusion in excess of ventilation
  C. having ventilation in excess of perfusion
  D. having a ventilationperfusio n value of

Question 2

Calculate the VD/VT ratio for a patient who has a PaCO2 of 40 mm Hg and a PECO2 of 30 mm Hg.
 
  A. 1.0
  B. 0.75
  C. 0.5
  D. 0.25

[LP]

Answer to Question 1

ANS: D
A. Incorrect response: Alveoli having a ventilationperfusio n value of zero are defined as capillary shunt units.
B. Incorrect response: Alveoli characterized as having perfusion in excess of ventilation are called low ventilationperfusio n units.
C. Incorrect response: Alveoli experiencing ventilation in excess of perfusion are defined as high ventilationperfusio n units.
D. Correct response: Alveoli having a ventilationperfusio n value of  are defined as alveolar dead space units.

Answer to Question 2

ANS: D
A. Incorrect response: See explanation D.
B. Incorrect response: See explanation D.
C. Incorrect response: See explanation D.
D. Correct response: To calculate the VD/VT ratio knowing the PaCO2 and the PCO2, one needs to use the modified Bohr equation, which is
VD/VT = (PaCO2  PCO2)  PaCO2
Therefore, based on a PaCO2 of 40 mm Hg and a PECO2 of 30 mm Hg:
VD/VT = (40 mm Hg  30 mm Hg)  40 mm Hg
= 0.25
A normal VD/VT ratio is about 0.30.

[Metfan725]

Thank you

[LP]

Happy to help you