Which of the following statements about Ventilation/Perfusion ratio is true:
V/Q ratio of infinity indicates Zero perfusion. This creates &;Dead space&; where no Gas exchange occurs since pulmonary blood flow (perfusion) is blocked. Option A: In a complete airway obstruction, the ventilation is Zero hence V/Q ratio approaches Zero (not infinity) Option B: In complete pulmonary embolism, the perfusion is zero and hence the V/Q ratio approaches Infinity (not Zero) Option C: V/Q ratio of Zero a shunt (Not dead space) where perfused blood is shunted without oxygenation. V/Q ratio is defined as the ratio of ventilation (the amount of air reaching the alveoli) to perfusion (the amount of bloof reaching the alveoli) "V"- Ventilation- The air which reaches the alveoli "Q"- Perfusion- The blood which reaches the alveoli An area with No ventilation (V=0) Has a V/Q ratio of zero An area with No perfusion (Q=0) has a V/Q Ratio of infinity An area where ventilation is perfectly matched to perfusion (V=Q) Has a V/Q Ratio of 1.0 Shunt Dead space Adequate Gas exchange This is also termed as a shunt since deoxygenated blood is shunted without oxygenation due to lack of any ventilation Perfusion is Wasted This is also termed a dead space since the Ventilation is wasted This represents Ideal/Adequate Gas Exchange Ref: Pathophysiology: The essentials 4th edition Pgno: 22
In a complete airway obstruction, the ventilation/Perfusion ratio approaches Infinity
In complete Pulmonary Embolism, the ventilation/perfusion ratio approaches Zero
Ventilation Perfusion Ratio of Zero indicates Dead space
Ventilation perfusion ratio of infinity indicates no gas exchange
Respiratory system