V/Q mismatch

Question 1

V/Q mismatch

Answer 1

Ideally,

ventilation matched to perfusion (V/Q=1) for adequate gas exchange to occur.

Question 2

Lung zones

Answer 2

Apex: V/Q= 3 (wasted ventilation)
Base: V/Q= 0.6 (wasted perfusion)

Question 3

Ventilation and perfusion along the lung

Answer 3

Both ventilation AND perfusion are greater at the base of the lung than at the apex of the lung.

Question 4

Zone 1: apex

Answer 4

PA > Pa > Pv

Question 5

Zone 2: middle

Answer 5

Pa> PA > Pv

Question 6

Zone3: bottom

Answer 6

Pa > Pv > PA

Question 7

With exercise

Answer 7

Exercise (high cardiac output)

Vasodilation of apical capillaries, resulting in V/Q ~1

Question 8

V/Q=0

Answer 8

Shunt: airway obstruction

In shunt, 100% O2 does NOT improve PO2

Question 9

V/Q=infinity

Answer 9

Physiologic dead space: blood flow obstruction

Assuming <100% is dead space, 100% O2 improves PO2