What does "ventilation-perfusion mismatch" mean?

Ventilation-perfusion mismatch refers to a condition where the air that reaches the alveoli (ventilation) does not adequately match the blood flow (perfusion) in the surrounding capillaries. This imbalance can lead to inefficient gas exchange in the lungs, resulting in inadequate oxygenation of the blood and the buildup of carbon dioxide in certain areas.

In a healthy respiratory system, ventilation and perfusion are closely matched to ensure optimal gas exchange. However, in conditions such as pulmonary embolism, chronic obstructive pulmonary disease (COPD), or pneumonia, this balance can be disrupted. When airflow is available but not matched with blood flow—or vice versa—certain regions of the lung are ventilated without being adequately perfused, leading to decreased oxygenation and possibly hypoxemia.

Understanding this concept is crucial for identifying and managing respiratory and cardiovascular conditions effectively.