Ventilation Perfusion Mismatch Flashcards
1
Q
What is ventilation?
A
Amount of air to enter the lungs
2
Q
What is perfusion?
A
Amount of blood flowing to lungs
3
Q
What is the normal V/Q ratio?
A
1
4
Q
What happens with inadequate ventilation?
A
PaCO2 rises
PaO2 falls
New steady state established
Blood equilibriates
5
Q
What happens when alveolar PaO2 falls?
A
Hypoxic vasoconstriction - diverts blood to ventilated alveoli
6
Q
What can cause a V/Q <1 ?
A
Asthma - airway narrowing COPD - airway collapse Pneumonia - exudate in alveoli NRDS - collapse alveoli Pulmonary oedema - fluid in alveoli
7
Q
What is the effect of hyperventilation?
A
PCO2 decreases
PO2 normal
8
Q
What occurs when V/Q <1?
A
Low pO2
High pCO2
9
Q
What occurs when V/Q >1?
A
High pO2
Low pCO2
