V/P Matching And Hypoxemia

Question 1

What are the differences in regional IPP?

Answer 1

1. Apex: IPP is more negative

3. Bases: IPP is less negative (more positive )

Question 2

What alveoli are more compliant, small or big alveoli?

Answer 2

1. Small alveoli

Question 3

Where in the long is blood flow/perfusion higher?

Answer 3

2. Lung bases

Question 4

Where in the lung is the Ventilation (not alveolar size) is higher?

Answer 4

1. Lung bases

Question 5

In the lung bases, what is the relationship between V/Q?

Answer 5

1. Q > V (wasted perfusion )
2. V/Q falls <1.0
3. PO2 ⬇️ PCO ⬆️ pH ⬇️

Question 6

In the lung apex, what is the V/Q relationship?

Answer 6

1. V > Q (Ventilation is wasted )
2. V/Q ⬆️ >1.0
3. ⬆️PO2 ⬇️PCO2 ⬆️pH

Question 7

Relationship between V/Q in a shunt?

Answer 7

1. V/Q= 0
2. 0/1= 0
3. No Ventilation but there’s blood flow

Question 8

What type of shunt is a V/Q shunt?

Answer 8

Right to left

Question 9

Arterial blood changes in V/Q shunts ?

Answer 9

1. ⬇️PaO2

2. ⬆️PaCO2

Question 10

Relationship between V/Q in Alveolar dead space ?

Answer 10

1. V/Q = infinite
2. 1/0 = infinite
3. There’s Ventilation but no perfusion

Question 11

Arterial blood gas relationships in V/Q Alveolar dead space?

Answer 11

1. ⬆️PaO2

2. ⬇️PaCO2 = 0

Question 12

Mechanism of hypoxia vasoconstriction?

Answer 12

1. ⬇️ PAO2 —> vasoconstriction

2. Redistribution of blood to better ventilated areas to maintain PaO2

Question 13

Example of V/Q shunt?

Answer 13

1. Airway blockage

Question 14

Example of Alveolar Dead Space?

Answer 14

1. PE.

Question 15

V/Q changes in exercise?

Answer 15

1. V/Q > 1.

1. ⬆️⬆️V > Q (CO) ⬆️

Question 16

Are O2 and CO2 Diffusion or perfusion-limited?

Answer 16

Perfusion limited

Question 17

Why are O2 and CO2 perfusion limited?

Answer 17

Both substances equilibrate between alveoli and pulmonary end capillary

Question 18

Main cause of an ⬆️A-a gradient ?

Answer 18

1. Anatomical shunts

Question 19

Causes of hypoxemia ?

Answer 19

1. Hypoventilation
2. Diffusion impairment
3. V/Q mismatch
4. Intrapulmonary shunt

Question 20

Gas changes during hypoventilation?

Answer 20

1. A-a gradient is the same
2. All PO2 (A a and v) are ⬇️
3. PCO2 is ⬆️

Question 21

Conditions that cause hypoventilation?

Answer 21

1. Narcotics
2. Anesthetics
3. COPD
4. Neuromuscular disorders (Guillian Barré, Lambert Eaton, Myasthenia Gravis)

Question 22

Gas changes in Diffusion Impairment?

Answer 22

1. A-a gradient ⬆️

2. PaO2 and PvO2 ⬇️

Question 23

Diffusion impairment examples?

Answer 23

1. Pulmonary fibrosis
2. Asbestosis
3. Sarcoidosis
4. Pulmonary edema

Question 24

⬇️ V/Q mismatch gas alterations ?

Answer 24

1. ⬆️A-a gradient
2. ⬇️PaO2 and ⬆️PaCO2

A-a is still elevated because there are areas with normal Ventilation.

Question 25

⬇️V/Q mismatch examples ?

Answer 25

1. Airflow obstruction
2. Pneumonia
3. Chronic bronchitis
4. Cystic fibrosis

Question 26

Examples of true intrapulmonary shunts ?

Answer 26

1. Complete airway obstructions
2. Pneumothorax
3. Atelectatic lung
4. ARDS

Question 27

Difference between intrapulmonary shunts and the rest of hypoxemia causes in terms of treatment?

Answer 27

1. Intrapulmonary shunts don’t respond to supplemental O2