Gas transport Flashcards
What are pathologic shunts defined as?
Diffusion limitations.
What are physiologic shunts consisted of?
Alveolar shunts and V/Q mismatching.
What are the four types of hypoxia?
Stagnant hypoxia, anemic hypoxia, histotoxic hypoxia, and hypoxic hypoxemia (arterial hypoxemia).
What does stagnant (hypoperfusion) hypoxia present with?
Decreased venous PvO2 and CvO2, but no change in the PaO2, CaO2, or PAO2. Thus, the A-a gradient is not effected.
Would 100% oxygen help with stagnant hypoxia?
No, the issue is that there is hypoperfusion, not a transport issue.
What does anemic hypoxia present with?
Decreased PvO2, CvO2. PaO2 would not be affected (no A-a gradient change), but CaO2 (total carried O2) would be lowered due to less hemoglobin.
Would 100% oxygen help with anemic hypoxia?
No (issue is with less hemoglobin) In the case of CO poisoning it might help by competing with CO.
What does histotoxic anemia present with?
Increased PvO2 and CvO2 (cells are not using O2 so venous blood will be more oxygenated). PaO2 and CaO2 are the same or increased (not using O2). A-a gradient is not changed.
Would 100% oxygen help with histotoxic hypoxia?
No. Need to treat the poisoning.
What causes hypoxic hypoxemia?
Low inspired O2 (high altitude, ect).
What does hypoxic hypoxemia present with?
PvO2, CvO2, PaO2, and CaO2 all decrease. However, there is also a corresponding decrease in PAO2 (high altitude), so the A-a gradient is falsely normal.
Would 100% oxygen help with hypoxic hypoxemia?
Yes.
What are the five types of hypoxemia?
Low inspired O2 hypoxemia, hypoventilation hypoxemia, diffusion impairment hypoxemia, ventilation/perfusion mismatch hypoxemia, and shunt.
What does hypoventilation hypoxemia present with?
Like low inspired O2 hypoxemia, PvO2, CvO2, PaO2, CaO2, and PAO2 are all decresed. Since both PAO2 and PaO2 are both decreased the A-a gradient is falsely normal.
Would 100% oxygen help with hypoventilation hypoxemia?
Yes.
