Question

In a patient with pulmonary embolism causing complete obstruction of blood flow, which point on the V/Q graph indicates the effect of pulmonary embolism?

• A. A
• B. B
• C. C
• D. D

Hint:

Pulmonary embolism = ventilation without perfusion = dead space = high V/Q ratio.

Answer 1

The Correct Option is D

Concept: Pulmonary embolism blocks blood flow to a ventilated part of the lung. Ventilation is present but perfusion is absent, producing increased V/Q ratio and dead space ventilation.

Step 1: Understand V/Q ratio.
The V/Q ratio is: \[ \frac{\text{Ventilation}}{\text{Perfusion}} \]

Step 2: Effect of pulmonary embolism.
In pulmonary embolism: \[ \text{Ventilation is present, but perfusion decreases or becomes absent} \] So: \[ V/Q \rightarrow \infty \]

Step 3: Match with graph point.
The graph point representing very high V/Q or dead space effect is marked as: \[ D \] Therefore, the correct answer is D.