gas exchange Flashcards
hypoxemia
reduction in PaO2
causes of hypoxemia (5)
- ventilation-perfusion mismatch
- shunt
- diffusion abnormality
- hypoventilation
- reduced FiO2
what happens if there is hypoxemia and PaCO2 is reduced ?
A-a gradient is wide
The percentage of ____________ is a major
determinant (99%) of the O2 carrying
capacity of blood (CaO2).
The percentage of hemoglobin
saturated with oxygen is a major
determinant (99%) of the O2 carrying
capacity of blood (CaO2).
hyperventilation causes PaO2 to ______ and PaCO2 to ______
PaO2 increases and PaCO2 decreases
Widened A-a gradient PaCO2 variable Hyperventilation helps a little Improves with increased FiO2 100% PaO2 > 500 mmHG Most common cause of hypoxemia
ventilation-perfusion mismatch
Widened A-a gradient PaCO2 usually decreased Magnitude of hypoxemia depends (shunt blood flow, mixed venous O2 content) No or minimal hPaO2 with h FiO2
shunt
Widened A-a gradient
Worse with exercise
Improves with hFiO2
PaCO2 usually i
Not a common cause of hypoxemia
abnormal diffusion
Normal A-a gradient
Improves with hFiO2
PaCO2 h
Can’t breathe or Won’t Breathe
global hypoventilation
excess CO2 production is sufficient to cause hypercapnia
false; there also must be a problem with ventilation or excess dead space
which gas is more soluble? which one has the greater driving force for diffusion?
CO2 more soluble but O2 has a greater driving force
what does the driving force for O2 affected with high altitude?
not enough time to load the blood during transit time
3 forms of CO2 transport
- dissolved CO2
- bicarbonate
- carbamino compounds
which has greater absorbtion: oxyHb or deoxyHb
OxyHb has greater absorption at 940 whie deoxyHb has greater absorption at 660
capnography
measures CO2 in exhaled gas
