Sun17October0936AM 1

Which of the following causes of hypoxic hypoxia is least likely to be improved by administering 100% oxygen?

(Please select 1 option)

Reduced alveolar oxygen partial pressure

Ventilation perfusion mismatch

Hypoventilation

Diffusion defects

True shunt Correct

Explanation

A true shunt is sometimes called an anatomical or extra-pulmonary shunt. Blood enters the arterial system without passing through ventilated areas of the lungs.

Physiological shunt: normally 2-4% of the cardiac output bypasses the lungs.

Coronary arterial blood empties directly into the left ventricle via the thebesian veins

Some bronchial arterial blood empties directly into the pulmonary veins.

Pathological shunt:

Congenital heart disease with right to left shunt

Perfusion of non-ventilated areas of lung (V/Q ratio = zero). For example, areas of atelectasis or bronchial obstruction

Pulmonary arterio-venous shunts.

Answer Statistics

1

15%

2

7%

3

7%

4

5%

5

68%

Times answered: 220