Hypoxemia and Shunt concept

Question 1

fick equation for CO?

Answer 1

fick equation for CO?

Question 2

equation of O2 consumption?

Answer 2

o2 extraction x C.O x 10

Question 3

normal Co2 production

Answer 3

200 ml co2/min

Question 4

normal O2 consumption ? (VO2)

Answer 4

250-300 ml o2/min @ normal resting metabolic rate

Question 5

definition of o2 consumption?

Answer 5

difference between O2 inspired and co2 exhaled , over 1 minute

Question 6

the effect of increase C.O.(how does cardiac compensate?) in O2 extraction ? and why?

Answer 6

1. via increase HR or SV or both
2. increase CO–>blood moves quicker in system capillaries–>less time for o2 to be pick up by the tissue –> CvO2 increases –>decrease Ca-vO2

*Because Cvo2 is higher, lung doesnt’ have to work as hard to increase CaO2

Question 7

the effect of decrease C.O. in O2 extraction ? and why?

Answer 7

->decrease CO means less blood going via capillary per minute–>more time for o2 to be picked up by tissue –>decrease CvO2–>increase CavO2

• more work for lung to increase CaO2
• Assuming O2 consumption stays the same

Question 8

What is the equation of O2 extraction ?

Answer 8

CaO2 - CvO2 = vol% OR ml O2/dl

Normal is 5 vol% (20-15 vol%)

Question 9

definition of O2 extraction?

Answer 9

the volume of O2 in mls, extracted by tissue ,

from each 100 ml or capillary blood