Maternal Fetal Physiology Flashcards
M&M Chapter 40
What happens to MAC in pregnancy? Why?
The minimum alveolar concentration (MAC) progressively decreases during pregnancy—at term, by as much as 40%—for all general anesthetic agents; MAC returns to normal by the third day after delivery. Changes in maternal hormonal and endogenous opioid levels have been implicated. Progesterone, which is sedating when given in pharmacological doses, increases up to 20 times normal at term and is at least partly responsible for this observation.
T/F; pregnant women need less local anesthesia
True
Obstruction of the inferior vena cava by the enlarging uterus distends the epidural venous plexus and increases epidural blood volume. What 3 effects does this have?
1) decreased spinal cerebrospinal fluid volume, (2) decreased potential volume of the epidural space, and (3) increased epidural (space) pressure. The first two effects enhance the cephalad spread of local anesthetic solutions during spinal and epidural anesthesia, respectively, whereas the last may complicate identification of the epidural space
What happens to oxygen consumption and minute ventilation in pregnancy?
They both increase
What happens to TV in pregnancy? What about respiratory rate? Inspiration reserve volume?
They all increase. TV more so than the others.
How is resp alkalosis prevented in preggo patients?
By a decrease in serum bicarbonate
What offsets the affinity for oxygen in the presence of hyperventilation?
Increased 2,3 DPG in preggo patients.
What happens to the P50 in pregnancy? And what is P50, and why does it matter?
It increases from 27-30. It is the point at which hemoglobin is 50% saturated. If it increases, that means that the affinity is decreased, and that o2 is unloaded.
