OB Flashcards
What is the risk of placenta accreta in women with placenta previa?
3% for first repeat C-section
up to 67% for fifth repeat C-section
When should elective delivery take place for placenta previa?
36-37 weeks
What is Sheehan syndrome?
pituitary failure after severe obstetric hemorrhage
When is magnesium used for neuroprotection?
threatened preterm delivery between 24-28 weeks
When should steroids be given to promote fetal lung maturity?
threatened preterm delivery between 24-34 weeks
What are the respiratory changes associated with pregnancy?
increased minute ventiltion due to increased tidal volume (respiratory alkalosis)
decreased FRC
capillary engorgement causing airway swelling
What are the cardiovascular changes associated with pregnancy?
increased cardiac output (up to 80% increase immediately post-partum)
decreased SVR
aortocaval compression (after 20 weeks)
What are the GI changes associated with pregnancy?
decreased LES tone
decreased gastric motility during labor
What are the hematological changes associated with pregnancy?
physiologic anemia (greater increase in plasma volume than RBC volume)
increased fibrinogen and clotting factors (except II, V, XI, and XIII)
decreased ATIII
What is the anesthetic of choid for placenta accreta?
neuraxial has better post-op hematocrit
**unless percreta suspected, then GA**
What are the primary causes of post-partum hemorrhage?
ATONY!
retained placenta
uterine inversion
surgical trauma
What are the undesirable effects of oxytocin?
decreased SVR
anti-diurectic effect (homology to ADH)
What is the risk of blood salvage during C-section?
amniotic fluid embolus
What are the causes of DIC in an obstetric patient?
hemorrhagic shock
AFE
placental abruption
IUFD
sepsis
What are the major components of AFE syndrome?
hypoxemia
hypotension
seizures
hemorrhage
cardiopulmonary arrest
What are the major complications associated with pre-eclampsia?
CHF
pulmonary edema
acute renal failure
liver rupture
intracerebral hemmorhage
post-partum hemmorhage
DIC
How is magnesium given for seizure prophylaxis in pre-eclampsia?
4-6 g bolus dose
1-2 g/hr infusion until 24 h post-partum
**therapeutic range, 4-6 mEq/L, DTRs lost at 10 mEq/L**
What is the minimum platelet count for epidural placement in a pre-eclamptic patient?
about 80,000
**trend is important**
When should ECV be considered?
a breech presentation recognized prior to labor at 36 weeks or later
What improves the success rate of ECV?
neuraxial anesthesia
tocolytics (terbutaline more than NTG)
What are the mainstays of mitral stenosis treatment during pregnancy?
heart rate reduction (beta blockers)
cautious use of diuretics
What is the normal fetal heart rate?
120-160 bpm with variability
What causes early decelerations? Lates? Variables?
early decelerations: vagal response to fetal head compression
late decelerations: uteroplacental insufficiency
variable decelerations: umbilical cord compression
What are the hemodynamic goals for intra-operative management of the pregnant patient with mitral stenosis?
avoid tachycardia
maintain sinus rhythm (for atrial kick)
avoid marked decreass in SVR (causes reflex tachycardia)
avoid increases in PVR (hypoxia, hypercarbia, acidosis)
avoid volume overload
What normal parts of a GA C-section should be avoided in a patient with mitral stenosis?
ephedrine (tachycardia)
nitrous oxide (increased PVR)
bolus dosing of pitocin (increased PVR, infusion OK)
methergine and hemabate (increased PVR)
What is the dose of epinephrine for neonatal resuscitation?
0.01 - 0.03 mg/kg
What does the umbilical artery blood gas represent? Umbilical vein?
umbilical artery: fetal conditions
umbilical vein: maternal and uteroplacental conditions
Should ephedrine or phenyephrine be used to treat maternal hypotension during anesthesia?
both are fine, outcomes are similar, but ephedrine shows more fetal acidosis
