<unk>  or V/Q defects are defects in the total lung ventilation/perfusion ratio (V/Q ratio). It is a condition in which one or more areas of the lung receive oxygen but no blood flow, or they receive blood flow but no oxygen. In a healthy lung, the rate of alveolar ventilation to the rate of pulmonary blood flow is roughly equal; more precisely, because normal lungs are not perfectly matched, the V/Q ratio of a healthy lung is approximately 0.8.
Ventilation perfusion mismatch
Right-to-left shunt
Hypoxic pulmonary vasoconstriction
Silent hypoxia
Histotoxic hypoxia
Central neurogenic hyperventilation
Cerebral hypoxia
Pulmonary-to-systemic shunt