OB Flashcards
How does pregnancy affect minute ventilation? Why? What changes are seen?
It is increased by up to 50% due to increased progesterone
Vt increases by 40%
RR increases by 10%
How does pregnancy affect the mothers blood gas? How does mom compensate for this?
Due to progesterone, she is slightly respiratory alkalotic
Renal eliminates excess bicarb which normalizes the blood’s pH
Moms;
pH?
PaO2?
PaCO2?
HCO3?
pH - no change
PaO2 - increased
PaCO2 - decreased
HCO3 - Decreased
How does pregnancy affect mom’s oxyhemoglobin dissociation curve?
Shifts it to the right - offloads O2 to the fetus
How does pregnancy affect the lung volumes and capacities?
FRC is reduced due to baby pushing up on lungs. ERV decreases more than RV
How does cardiac output change during pregnancy?
Increases by 40% - uterus receives 10% of the cardiac output
How does cardiac output change during the stages of labor?
1st - Increased by 20%
2nd - Increased by 50%
3rd - Increased by 80%
When does CO return to baseline after delivery?
Pre labor values - 24 hours
Pre pregnancy values - 2 weeks
How does BP change during pregnancy?
Net effect due to an increase in blood volume and decrease in SVR
How does SVR change during pregnancy?
Progesterone causes Increased nitric oxide which leads to vasodilation
+
Decreased response to angiotensin and NE
<15% in SVR
<30% in PVR
What is aortocaval compression? Who is at risk?
Gravid uterus compresses the vena cava and aorta in the supine position
This leads to decreased CO and compromises fetal profusion
Sign and symptom - LOC
How is aortocaval compression treated?
Displace the uterus away by elevating the right torso by 15 degrees
How does intravascular fluid volume change during pregnancy?
It increases by 35%
Plasma volume increases by 45% and RBC’s increase by 20%
Which clotting factors are increased during pregnancy?
Increased clotting factors 1, 7, 8, 9, 10, 12
Which clotting factors are decreased during pregnancy ?
11 and 13
What happens to fibrin during pregnancy ?
Decreases
Protein S and C during pregnancy?
Protein S decreaseS
Protein C - no change
What happens to MAC during pregnancy ? Why?
Decreases by 30-40% due to progesterone
How does pregnancy affect gastric volume and pH? Why?
Increases volume and decreases pH (more acidic)
Due to increased gastrin
How does pregnancy affect gastric emptying?
Before labor - no change
After labor - slowed
What is normal uterine blood flow? During pregnancy ?
Normal - 100mL/min
Pregnancy - 700mL/min or 10% of cardiac output
Does the uterus autoregulate?
It does not autoregulate there it is dependent on MAP, CO, and uterine vascular resistance
What conditions can reduce uterine blood flow?
Anything that causes decreased perfusion;
-Sympathectomy
-Hemorrhage
-Aortocaval compression
Anything that causes increased resistance;
-Uterine contraction
-Hypertension that increases UVR
Which law determines which drugs will pass through the placenta?
Ficks Law of diffusion