OB/GYN

Question 1

Describe normal respiratory physiologic changes expected in pregnancy (mechanics of ventilation)

Answer 1

Increased minute ventilation from:
Increased tidal volume
Decreased residual volume

*Respiratory rate stays the same

Question 2

What O2 saturation should be maintained during pregnancy? What blood gas findings are expected during pregnancy? (PaCO2, PaO2)

Answer 2

Baby needs mom to have a PaO2 > 70mmHg (normal in pregnancy 100mmHg) and therefore O2 sats should be kept >95%

PaCO2 is expected to rise during pregnancy to 28-32mmHg

Question 3

How is asthma managed in pregnancy?

Answer 3

Same as out of pregnancy. The risk of poorly controlled asthma is worse for mom and baby than the medications used to treat.

Question 4

Why are pregnant patients more prone to pulmonary edema and what are common triggers?

Answer 4

Pregnancy => decreased oncotic pressure predisposing to edema

Pyelonephritis, tocolytics and preeclampsia are common triggers

Question 5

How is pulmonary edema treated in pregnancy?

Answer 5

Treat the underlying cause first and then give small dose of diuretic. Response is usually dramatic.

Question 6

How does the heart adapt to increased blood volume in pregnancy?

Answer 6

LV increases compliance and end diastolic volume leading to increased stroke volume, but relatively unchanged EF. Heart enlarges showing a larger silhouette on CXR.
After 5weeks gestation heart rate increases

Question 7

What factors allow for increased cardiac output during pregnancy?

Answer 7

Decreased vascular resistance, increased stroke volume, increased heart rate

Question 8

How does cardiac output change during labor and what valve condition can lead to pulmonary edema?

Answer 8

Labor leads to increased venous return from the uterus and placenta from contractions. This causes a large increase in cardiac output as long as the heart can keep up.
Mitral stenosis limits the heart’s ability to adapt to the increased volume and can lead to pulmonary edema.

Question 9

What causes the decreased vascular resistance in pregnancy?

Answer 9

The low-resistance flow to the uterus and placenta

Question 10

What should be remembered regarding respiratory changes in pregnancy when considering intubation?

Answer 10

Decreased reserve capacity leads to decreased O2 reserve and less time to desaturation

Question 11

How does the renal system change in pregnancy?

Answer 11

Increased urine volume output which also leads to a progressively lower Creatinine level meaning that in later pregnancy a normal creatinine is around 0.5 making otherwise normal levels of 0.8-1.0 abnormal in pregnancy

Question 12

What is the most important valvular issue in pregnancy?

Answer 12

Mitral stenosis which inhibits the heart’s ability to accommodate increased blood volume and can lead to pulmonary edema

Question 13

How are mitral and aortic insufficiencies affected by pregnancy?

Answer 13

Hemodynamics in these conditions are improved because of decreased vascular resistance that is common in pregnancy. This allows for more forward movement of blood flow and less regurgitation.
Left-Right intracardiac shunts are also improved.

Question 14

How is coronary filling affected by pregnancy?

Answer 14

Decreased coronary artery filling from decreased vascular resistance.

Question 15

What is an essential and unique task when performing CPR on a pregnant patient?

Answer 15

Shifting the patient’s abdomen to the left

Question 16

At what point is perimortem C-Section considered in a mother with cardiac arrest?

Answer 16

When no improvement within 4-5 minutes of cardiac arrest, the c-section must be done. Survival of the infant after 5 minutes drops rapidly. Performing the section also gives the mother an increased chance of survival.
Uterine fundus must exceed the umbilicus.

Question 17

How is perimortem C-Section performed?

Answer 17

Vertical incision from the epigastrum to the symphisis pubis, then vertical incision through the uterus and through the placenta, if needed. Baby is removed and the cord is clamped and cut.

Question 18

Beyond what time is there virtually no survival of a mother or fetus after maternal cardiac arrest?

Answer 18

Beyond 20 minutes

Question 19

Describe features of peripartum cardiomyopathy

Answer 19

Idiopathic disorder occurring in last 1 month of pregnancy to 6 months postpartum
Left ventricular failure
Higher risk of embolization to lungs and body
High risk of death!

Question 20

What are the risk factors for peripartum cardiomyopathy?

Answer 20

Increased maternal age
Multiple gestation
Preeclampsia
African

Question 21

Are ACE inhibitors ok in pregnancy?

Answer 21

No

ACE inhibitors are contraindicated in pregnancy

Question 22

What is the vasodilator of choice in pregnancy when treating heart failure?

Answer 22

Hydralazine

Question 23

What is the difference between heparin vs LMWH in terms of mechanism of action?

Answer 23

LMWH is a small part of the larger heparin molecule and only has effects on antithrombin III whereas heparin also has a site for thrombin giving it a faster onset of action

MOA: activate antithrombin ii which stops Xa which stops prothrombin which prevents forming fibrin