Part 5: Maternal CardioPulm Changes

Question 1

Effect of pregnancy on maternal intravascular volume:

Answer 1

30-40% increase.

Question 2

Effect of pregnancy on maternal RBC volume:

Answer 2

• 30% increase.
• Progesterone stimulates erythropoiesis.

Question 3

What hormone is responsible for the rise in maternal RBC volume during pregnancy?

Answer 3

• Progesterone; stimulates erythropoiesis.

Question 4

Effect of pregnancy on maternal heart rate/cardiac output:

Answer 4

• HR: 10 BPM increase.
• CO: 40% increase due to increased HR.

Question 5

The 4 things that increase in the maternal cardiovascular system during pregnancy:

Answer 5

1. intravascular volume.
2. RBC volume.
3. Heart rate/cardiac output.
4. Vasodilation.

Question 6

Maternal vasodilation occurs during pregnancy due to progesterone.

What is the function of this vasodilation?

Answer 6

• maintain proper placental perfusion.

Question 7

What hormone triggers the RAAS system to become active during pregnancy in order to increase intravascular volume?

Answer 7

placental E2.

Question 8

BP = CO X TPR.

BP remains relatively constant during pregnancy despite increased cardiac output due to:

Answer 8

progesterone-mediated vasodilation.

Question 9

Signs of progesterone-mediated vasodilation on physical exam of a pregnant woman:

Answer 9

• widened pulse pressure.
  
  • progesterone-mediated vasodilation causes decline in diastolic pressure.

Question 10

What lung volumes decrease in a pregnant woman, and why?

Answer 10

1. FRC
2. ERV

• growing fetus pushes up on diaphragm.
• decreased chest wall compliance.

Question 11

Effect of progesterone on ventilation:

Answer 11

• directly effects medullary respiratory centers.
• increases respiratory rate by 30-50%.
• increases tidal volume.

Question 12

The increased respiratory rate in a pregnant women is due to (3):

Answer 12

1. increased progesterone.
2. diaphragm being pushed upward.
3. increased pCO2.

Question 13

Increased minute ventilation lowers maternal PaCO2. What effect does this have on maternal and fetal respiration?

Answer 13

• favors fetal CO2 off-loading.
• increased PAO2 and PaO2.

Question 14

Acid-base status in a pregnant woman:

Answer 14

• PaCO2 low (increased RR).
• HCO3- low (kidney compensation).
• Blood pH high.

Question 15

What two acid-base disorders are normal for pregnant women?

Answer 15

1. compensated chronic respiratory alkalosis.
2. mixed respiratory alkalosis + metabolic acidosis.