DSA: Respiratory adaptation in health and Dz

Question 1

Ideally, what would we want out alveolar oxygen (P_AO₂) and arterial oxygen (P_aO₂) to be?

Answer 1

the whole point of the alveolus is to bring the blood and the air together in such a way that the alveolar oxygen and the arterial oxygen come to equilibrium with each other.

In other words, in an ideal world, the PAO2 should be the same as the PaO2.

If there is a large difference between the PAO2 and the PaO2, there is a problem with gas exchange

Question 2

How can we calculate our alveolar P_AO_2?

Answer 2

P_AO₂₌ oxygen inspired- oxygen consumed.

But this is not solvable.

Solvable equation is:

P_AO₂= [(Patm-47)FiO2]-[PaCO2/RQ]

Question 3

[(Patm-47)FiO2] can also be referred to as what?

Answer 3

P_IO₂

_{=oxygen inspired}

_{=inspired partial pressure of oxygen}

Question 4

What is FiO2?

Answer 4

fraction of inspired oxygen (which is 21% or 0.21 if we are breathing room air) =149.7 mm Hg

Question 5

How do we solvefor the amount of O2 consumed?

Answer 5

we get it indirectly by measuring CO2!

In the tissue, O2 and CO2 are tied together.

RMBR in the lungs O2 and CO2 are independent of one another.

Question 6

What is the RQ?

Answer 6

Oxygen consumed and CO2 being used made by metabolism IN THE TISSUE.

RQ = V(dot)CO2/V(dot)O2. No math for this eqn bc only three options depending on the fuel source you are using:

Burning primarily glucose, the RQ –> 1.0
Burning fats, the RQ –> 0.7
Since we usually burn a mix of fuels, the measured RQ –> 0.8

Question 7

For those of you who are wondering how I would indicate to you what RQ to use:

How do we know when to use a RQ of 0.8?

How do we know when to use a RQ of 1.0?

How do we know when do to use a RQ of 0.7?

Answer 7

RQ= 0.8= if Dr. Karius says NOTHING, assume this.

RQ= 1= IV glucose soluation

RQ= 0.7= Pt is hypoglycemic or a diabetic and relying on FA metabolism

Question 8

all of the CO2 dissolved in our blood is the result of _________

Answer 8

Cellular metabolism. We do not breathe any in.

Question 9

What is the alveolar-arterial (A-a)-o2 gradient?

Answer 9

The alveolar-arterial (A-a)-o2 gradient is the difference between PAO2 and PaO2.

Ideally, we want this to be 0: we want them to be in equillbrium.

Question 10

What is the . A-a O2 gradient?

Answer 10

3.7 mm Hg.

This is normal, as opposed to it being 0.

Question 11

3.7 mmHg alveolar-arterial O2 gradient tells us what?

Answer 11

Gas exchage is occuring normally.

Question 12

If our alveolar-a O2 gradient is higher than 3.7 mmHg, then what?

Answer 12

If the number had been high, blood is not coming into equilibrium with alveolar gases. It would indicate that the process of gas exchange has been impaired by some disease process