A patient has a whole-body O2 consumption of 320 ml/min and a ...

[james0929]

A patient has a whole-body O2 consumption of 320 ml/min and a measured CaO2  CO2 of 8 ml/dl. What is the cardiac output?
 
  a. 3.2 L/min
  b. 4.0 L/min
  c. 5.0 L/min
  d. 7.0 L/min

Question 2

According to the Fick principle, if O2 consumption remains constant, an increase in cardiac out-put will manifest itself as which of the following?
 
  a. Decrease in the CaO2  CO2.
  b. Increase in the CaO2.
  c. Increase in the CaO2  CO2.
  d. Decrease in the CO2.

[mathjasmine]

Answer to Question 1

ANS: B
Fick equation:
t = O2  C(av)O2  10
In this equation, t is cardiac output (L/min), O2 is the whole-body O2 consumption (ml/min), and C(a)O2 is the arteriovenous O2 contents difference (ml/dl). The factor of 10 converts ml/dl to ml/L. Given a normal O2 of 250 ml/min and a normal C(a)O2 of 5 ml/dl, a normal cardiac output is calculated as follows:
t = 200 ml/min  5 ml/dl  10
t = 250 ml/min  5 ml/L
t = 5.0 L/min

Answer to Question 2

ANS: A
If the cardiac output rises and O2 consumption remains constant, the C(a)O2 will fall propor-tionately.