OB Anesthesia

Question 1

Normal umbilical artery blood gas

Answer 1

pH 7.2-7.3
PaCO2 50-55
PaO2 18-25
bicarb 22-25
BE -2.7 to -4.7

Question 2

PaO2: nonpregnant, 1st, 2nd, 3rd trimester

Answer 2

100, 107, 105, 103

Question 3

PaCO2: nonpregnant, 1st, 2nd, 3rd trimester

Answer 3

40, 30, 30, 30

Question 4

HCO3: nonpregnant, 1st, 2nd, 3rd trimester

Answer 4

24, 21, 20, 20

Question 5

pH: nonpregnant, 1st, 2nd, 3rd trimester

Answer 5

7.40, 7.44, 7.44, 7.44

Question 6

Effect of pregnancy on O2-Hgb dissociation curve

Answer 6

Right shift (increased p50) -> greater O2 unloading to tissues/fetus

Question 7

Factors affecting placental transfer of drugs

Answer 7

Size: >1000 Da do not cross readily (insulin, heparin, protamine)
Lipid solubility: highly ionized don’t readily cross (succ, NDNMBDs), lipophilic do (fentanyl)
Protein binding: mother has 50% more plasma proteins compared to fetus and will maintain better (bupi, ropi)
Maternal drug concentration: higher in mom = higher rate of transfer

Question 8

Changes in clotting factors in pregnancy

Answer 8

Unchanged: II and V
Slight decrease: XI, XIII
Decreased 20-30%: Protein C & S (& increased resistance to activated Prot C)
Increased 20-200%: I (fibrinogen - doubles), VII, VIII, X, XII

Question 9

Changes in blood during pregnancy

Answer 9

Platelets: decreased 10-20%
RBC mass: increased 15-30%
Plasma: increased 40-50%
WBC: increased 10%
Erythropoetin: increased 50-200%
Total blood volume: increased 25-40%

Question 10

Changes in hemodynamics during pregnancy

Answer 10

CVP: unchanged
SVR: slight decrease
CO: increased 30-50%
HR: increased 15-25%
SV: increased 20-30%

Question 11

How does cardiac output change surrounding delivery?

Answer 11

Increases significantly throughout pregnancy due to increased HR (1st trim) and SV (trim 2/3, 50% increase in CO from baseline)
Onset of labor: 110% above prepregnant state d/t SV
Immediately after delivery: SV increases d/t loss of IVC compression, >150% above prepregnant state
1 hr postpartum: 100% above pre-pregnancy
2 days postpartum: 10% above pre-preg
2-24w postpartum: return to prepregnant state

Question 12

APGAR scoring: skin color

Answer 12

0: cyanotic
1: acrocyanotic
2: pink

Question 13

APGAR scoring: HR

Answer 13

0: absent
1: <100 bpm
2: >100 bpm

Question 14

APGAR scoring: reflexes

Answer 14

0: no response to stimulation
1: grimace and/or feeble cry
2: active, strong response

Question 15

APGAR scoring: muscle tone

Answer 15

0: absent, limp
1: some extremity flexion
2: active movement

Question 16

APGAR scoring: breathing

Answer 16

0: absent
1: weak, irregular, slow, shallow, or gasping
2: strong, regular, crying