Respiratory

Question 1

A-a Gradient Equation =

Answer 1

A= [FiO2 x (elevation - barometric pressure) - (PaCO2/0.8)

Question 2

Definition of A-a Gradient

Answer 2

The difference between the Alveolar and Arterial oxygen concentrations

Question 3

Normal A-a Gradient value

Answer 3

Less than 15 mm Hg

Question 4

True or false: The A-a gradient is beneficial as a one-off value.

Answer 4

False: It’s the most useful when used for trending.

Question 5

Using the P:F ratio, what would an expected arterial PaO2 be on a patient breathing 100% oxygen?

Answer 5

PaO2= ~500 mm Hg

Question 6

Define the P:F ratio

Answer 6

PaO2:FiO2 ratio is the arterial PaO2 should = ~5x the FiO2

Question 7

Define the 120 rule

Answer 7

Essentially PaO2 + PaCO2 should be equal to or greater than 120 in an animal with normal pulmonary function. It’s an easier version of the A-a gradient.

Question 8

Define a V/Q mismatch.

Answer 8

Blood that has traveled through the lungs without becoming properly oxygenated resulting in venous admixture.

Question 9

What are some causes of a low V/Q?

Answer 9

Pneumonia, PTE, pulmonary edema, asthma

Question 10

What would cause no
V/Q?

Answer 10

Atalectasis, severe pleural effusion, collapsed alveoli

Question 11

When can the 120 rule be applied?

Answer 11

It only applies to patients breathing room air at sea level.