Question

If blood flow is completely blocked by an embolism in the left pulmonary artery, which of the following will occur?

1. Ventilation/perfusion (V/Q) ratio in the left lung will be zero
2. Systemic arterial PaO₂ will be elevated
3. V/Q ratio in the left lung will be lower than in the right lung
4. Alveolar PO₂ in the left lung will be approximately equal to the PO₂ in the inspired air
5. Alveolar PO₂ in the right lung will be approximately equal to the PaO₂ in the venous blood

Answer 1

Option a,c and d are the correct answer as when pulmonary emboli block the blood flow to left lung completely then it will lead to no perfusion of air into lungs so ventilation / perfusion ratio will be zero

Option c is correct as the v/q of left lung will be zero which is less than that of right lung

Option d is correct as no perfusion is occuring so the atmospheric air pressure if po2 will be there in alveoli

Option b and e are wrong as systemic arterial pao2 will not increase and pao2 of left lung will not be equal to venous blood

So Option a,c and d are correct

:)