Ob Anesthesia Module C, Part Ii

Front 1

What types of non-ob surgery does pregnant pt's undergo?

Back 1

trauma, cervical cerclage, appy, biliary, breast, ovarian, cystectomy

Front 2

List special concerns for surgery in the pregnant patient:

Back 2

physiological changes, teratogenicity of drugs, urteroplacental blood flow, increased risk for PTL, IUGR, fetal demise

Front 3

List characteristics of drugs that cross the placenta:

Back 3

high lipophilicity, low ionization, low maternal protein binding, low molecular weight

Front 4

How are placental transfer and fetal uptake of a drug measured?

Back 4

ratio of umbilical vein to maternal venous concentration (UV/MV) = degree of transfer of drug;
ratio of umbilical artery to umbilical vein (UA/UV) = fetal uptake of drug

Front 5

Is the timing of exposure to a drug important?

Back 5

Yes, risk is highest during organogensesis (2-8weeks gestation); drugs prior to implantation <1week gestation insignificant; exposure late in pregnancy =functional/behavioral changes

Front 6

When should non-ob surgery be done on the pregnant patient?

Back 6

second trimester; cervical cerclage is usually done at 12-16weeks gestation

Front 7

Name 8 concerns when planning surgery for an OB patient:

Back 7

1. Decreased MAC
2. Decreased FRC
3. Increased metabolic rate
4. Slowed GI emptying
5. Teratogenicity
6. Maintenance of uteroplacental circulation
7. Increased Risk Preterm Labor
8. Need to monitor FHR

Front 8

How would you premedicate a pregnant patient for non-ob surgery?

Back 8

Bicitra, H2 antagonist, metoclopramide, barbiturate, glycopyrrolate

Front 9

Misc. perioperative concerns:

Back 9

Keep maternal PaCO2 at 30torr (the PaCO2-EtCO2 gradient is reduced d/t decreased dead space ventilation-perfusion from increased CO); Avoid alpha agonists, high levels of LA, & catecholamines, avoid hypoglycemia

Front 10

Special considerations appendectomy:

Back 10

increased incidence pulmonary edema-careful fluid management

Front 11

Special considerations Neurosurgery:

Back 11

induced hypotension = decreased UPP; hyperventilation shifts dissociation curve to the left and decreeases O2 released to fetus, high dose mannitol can cause fetal dehydration

Front 12

Special considerations laparoscopic surgery:

Back 12

keep intraabdominal pressure <15torr, elevated paCO2 = fetal acidosis; on Varess needle

Front 13

Special considerations cardiac surgery:

Back 13

usually for valvular dx, avoid high dose vasopressors = decreased UPP

Front 14

Special considerations for trauma:

Back 14

Increased maternal CO may lead to underestimation of hemorrhage; preterm labor, premature rupture of membranes, uterine rupture, placental abruption, spontanous AB

Front 15

How is cardiac arrest managed in the parturient?

Back 15

Standard BLS/ACLS guidelines with avoidance of aortocaval compression, emergency c-section at >24-25weeks gestation

Front 16

Indications for emergent c-section in traumatic event:

Back 16

stable mother with viable fetus in distress; traumatic uterine rupture; gravid uterus interfering with intraabdominal repair; unsalvageable mother with viable fetus

Front 17

What are the relative advantages of GA vs. regional in traumatic/non-ob surgery?

Back 17

GA: inhalation agents are tocolytics
Regional: decreased risk of aspiration, possible increased risk of hypotension
**Priority is to maintain maternal oxygenation & UPP

Front 18

Is N20 safe in pregnant patients?

Back 18

N2O shown in animals to vasoconstrict the uterine arteries when not administered with volatile agent (not shown in humans)

Front 19

Does N2O increase the risk of congenital defects?

Back 19

In rats shown, not in humans; inactivates Vit. B12, inhibits methionine synthetase & potentially interfers with DNA synthesis; Conservative approach-use 50% N2O during organogenesis, limit use in longer cases

Front 20

Can benzodiazapines be used in pregnant patients?

Back 20

Case reports of cleft palates in children, but failed to find in studies

Front 21

Are there special considerations in patient monitoring of non-ob surgery, pregnant patients?

Back 21

FHR, uterine activity pre, intra, & post-op; Loss of beat to beat variability is normal after anesthetic medications, but decelerations are NOT expected; atropine can cause decreased beat to beat variability and fetal tachycardia

Front 22

Which medications are most likely to pass into breast milk?

Back 22

Highly lipid soluble
Poorly protein bound