Ventilatieverhouding

Ventilatieverhouding, often translated as ventilation-perfusion ratio or V/Q ratio, is a physiological concept that describes the relationship between alveolar ventilation (the amount of air that reaches the alveoli) and pulmonary perfusion (the amount of blood that flows through the pulmonary capillaries). In a healthy lung, this ratio is close to 1, meaning that the amount of air reaching the alveoli is well matched to the amount of blood flowing through them. This optimal matching is crucial for efficient gas exchange, where oxygen from the inhaled air is transferred to the blood and carbon dioxide from the blood is transferred to the air to be exhaled.

Deviations from this ideal ratio can occur due to various pulmonary conditions. A high V/Q ratio, meaning ventilation exceeds perfusion, can result from conditions like pulmonary embolism, where a blood clot obstructs blood flow to a portion of the lung, or from certain lung diseases that reduce blood supply to specific areas. In such cases, air reaches the alveoli, but there is insufficient blood to pick up the oxygen. Conversely, a low V/Q ratio, where perfusion exceeds ventilation, can be caused by conditions like pneumonia or pulmonary edema, where fluid fills the alveoli or the air spaces are blocked, hindering airflow. This leads to poor oxygenation of the blood as the available blood encounters less than adequately ventilated alveoli.

The V/Q ratio is a fundamental concept in respiratory physiology and is used to understand and diagnose various lung diseases. Monitoring and understanding these ratios help clinicians assess the severity of respiratory impairment and guide treatment strategies aimed at improving gas exchange and overall lung function. Changes in V/Q can be detected through various diagnostic tools, including blood gas analysis and advanced imaging techniques.