Ventilation-Perfusion Mismatch
If the V/Q ratio reduces due to inadequate ventilation, gas exchange within the affected alveoli will be impaired. ... A mismatch in ventilation and perfusion can arise due to either reduced ventilation of part of the lung or reduced perfusion.
What factors affect pulmonary perfusion?
Factors which affect regional pulmonary blood flow:
- Lung volume (atelectasis increases pulmonary vascular resistance)
- Hypoxic pulmonary vasoconstriction.
- Gravity (affects the direction of the hydrostatic gradient)
- Pulmonary vascular architecture (some lung units are structurally advantaged)
What decreases ventilation perfusion?
The low V/Q ratio may occur either from a decrease in ventilation secondary to airway or interstitial lung disease or from overperfusion in the presence of normal ventilation.
