AEMCA Practice Exam

What is the normal V/Q ratio?

1. 1:1

2. 0.5

3. 0.8

4. 1.2

The correct answer is: 0.8

The normal ventilation-perfusion (V/Q) ratio is approximately 0.8. This ratio represents the relationship between the amount of air reaching the alveoli (ventilation) and the amount of blood flow in the pulmonary capillaries (perfusion). In a healthy individual, the average V/Q ratio indicates that there is slightly more blood flow than ventilation, which supports efficient gas exchange in the lungs. The ideal V/Q ratio allows for optimal oxygenation of the blood and removal of carbon dioxide, highlighting the importance of both ventilation and blood flow in lung function. In contrast, a V/Q ratio of 1:1 would imply equal ventilation and perfusion, which is not typically the case in the lungs due to physiological variations in both airflow and blood supply. A ratio of 0.5 suggests that ventilation is significantly lower than perfusion, which can lead to inadequate oxygenation. A ratio of 1.2 reflects a condition where ventilation exceeds blood flow, potentially leading to wasted ventilation in areas of the lung where there is insufficient blood flow for gas exchange. Understanding the normal V/Q ratio helps in diagnosing various respiratory and cardiac conditions, making it essential knowledge for healthcare professionals.