Causes and Evaluation of Hypoxemia

Question 1

If you compare two VA/Q ratio, A=0,63, B=0,73 representing lung units, which of them have less PCO2, PO2 and pH alveolar and end capillary?

Answer 1

• ⬇️ PCO2: B
• ⬇️ PO2: A
• ⬇️ pH: A

Question 2

Which is the result of blocking the airway

Answer 2

• “shunt” ▶️ ratio VA/Q low

- PCO2⬆️, PO2⬇️, pH⬇️,

Question 3

What is the result of a thrombus in a pulmonary artery

Answer 3

• lung unit affected act as a “dead space” ▶️ ratio VA/Q high
• PO2 ⬆️, PCO2 ⬇️, pH ⬆️

Question 4

Why does the gradient A-a change with age?

Answer 4

Result of anatomic shunts

*⬆️ with age ventilation-perfusion matching become less ideal (increase number of shunts)

Question 5

What is the difference between some causes of hypoxemia and high altitude?

Answer 5

• high altitude ▶️ ⬇️PO2 but PCO2 ⬇️ too because subjects hyperventilate
• others conditions (COPD, neuromuscular disorders, kyphoscoliosis, narcotics, etc) PCO2⬆️⬆️

Question 6

Cause of hypoxemia with normal A-a gradient

Answer 6

Hypoventilation

Question 7

Cause of hypoxemia that doesn’t correct with supplemental oxygen

Answer 7

Right to left shunt (pulmonary)

Question 8

Under normal conditions, what limits the amount of oxygen uptake in the lungs?

Answer 8

Cardiac output

Question 9

In case of hypoxemia and hypercapnia, perfusion studies ot the lungs show normal distribution of blood flow and there is no evidence of fluid accumulation. What is the most likely cause of the disorder?

Answer 9

Diffusion impairment

Question 10

Under normal conditions, what limits the amount of oxygen uptake in the lungs?

Answer 10

Cardiac output

Question 11

In case of hypoxemia and hypercapnia, perfusion studies ot the lungs show normal distribution of blood flow and there is no evidence of fluid accumulation. What is the most likely cause of the disorder?

Answer 11

Diffusion impairment