41 - 45 Physiology SBAs for the Primary FRCA
Question 41
You've just placed a Venturi mask onto a patient with COPD, when someone asks you about hypoxic pulmonary vasoconstriction.
A decrease in which of the following would be most likely to induce hypoxic pulmonary vasoconstriction?
- Partial pressure of oxygen in the pulmonary artery
- Partial pressure of oxygen in the pulmonary veins
- Partial pressure of oxygen in the alveoli
- Oxygen saturation of haemoglobin in the pulmonary artery
- Oxygen saturation of haemoglobin in the pulmonary veins
Answer
- Partial pressure of oxygen in the alveoli
Hypoxic pulmonary vasoconstriction sends blood to better ventilated areas of the lung.
The primary determinant of which pre-capillary arterioles vasoconstrict to make this happen is the alveolar partial pressure of oxygen.