Oxygen Transport Flashcards
What is the formula that relates O2 consumption by the tissues to flow?
VO2= Q (CaO2 - CvO2).
What does the plateau of the O2 dissociation curve permit?
Toleration to hypoxemia
What does the sigmoid shape facilitate?
The unloading of O2 in tissue. This favors O2 delivery to tissues where O2 is low.
What happens to the volume of O2 in patients with anemia? What about polycythemia?
Anemia is a lower volume %. Polycythemia is a higher volume % of O2.
What causes a right shift in the O2 binding curve resulting in more oxygen being unloaded?
An increase in P CO2, decrease in pH, increase in Temperature, increase in 2,3-DPG (happens in high altitude and is slower)
What is the total amount of O2 in the blood? What percent comes from dissolved oxygen?
20% by volume. Only .3% vol is dissolved in the plasma. The O2 in the alveoli first equilibrates wight he plasma and then is bound to Hb.
What is the formula for extraction?
E = Ca O2 - Cv O2 E = V O2/ CO
How is hypoxic hypoxia characterized?
Low PaO2 (hypoxemia) and low CaO2 with normal extraction and therefore low PvO2 and CvO2. Causes include high altitude, diffusion problems, and hypoventilation.
What characterizes stagnant hypoxia?
Normal PaO2 and CaO2, increased extraction and therefore low PvO2 and CvO2. Causes include a sluggish circulation due to low cardiac output as occurs during CHF.
What characterizes histotoxic hypoxia?
Normal PaO2 and CaO2 with reduced extraction and elevated PvO2 and CvO2. Causes include poisoning of the tissue metabolism by heavy metals, cyanide or other toxins.
What characterizes anemic hypoxia?
Normal PaO2 but low CaO2 with normal extraction and therefore low PvO2 and CvO2. Causes include iron deficiency anemia or congenital hemolytic anemias such as sickle cell anemia
What does CO poisoning due to the O2 dissociation curve?
It causes it to shift left. The O2 binding capacity is reduced by CO.
