V/Q ratio

(noun)

The ratio of ventilation and blood perfusion of the lungs. Its balance is an important indicator of lung function and efficiency.

Related Terms

Examples of V/Q ratio in the following topics:

  • Lungs

    • The ratio of ventilation in the lungs and perfusion of the lungs (the air and blood supply of the alveoli respectively) is called the V/Q ratio (with Q being perfusion); it is an important indicator of efficiency in the lungs.
    • The V/Q in a healthy individual is variable but balanced, usually around .8, but can be higher or lower depending on the region of the lung sampled.
    • An imbalance in V/Q ratio is called a mismatch, and indicates a severe problem.
    • Too low perfusion (and a higher ratio) indicates alveolar dead space, while too low ventilation (and a lower ratio) indicates a shunt, which is a lack of air supply relative to perfusion.
    • V/Q mismatches occur during many different kinds of lung failure, and have many different causes.