ITE OB 2 Flashcards
Bupivacaine has (high/low) placental transfer
low
- bc it is highly protein bound
Determinants of local anesthetic placental transfer (2)
- degree of ionization at physiological pH
2. amt of protein binding
Protein bound drugs are (readily/unable) to cross the uteroplacental barrier
unable to cross
the ___ is the pH at which a drug has equal [ ] of ionized (protonated) and nonionized (nonprotonated) forms
pKa
drugs can freely pass the placenta in the (ionized/nonionized) state
nonionized
____ fetal drug accumulation d/t pH differences btwn maternal and fetal blood, esp in fetal acidosis
ion trapping
Bupivacaine has a pKa of ___, so at physiological pH of ___ (lower than the drugs pKa), there is more drug in the (ionized/unionized) state
8.1, 7.4
ionized form
- unable to cross placenta
Most amide local anesthetics are (highly/poorly) lipid soluble
highly
Why is lidocaine and 2-chloroprocaine not used for maintenance of epidural anesthesia?
tachyphylaxis
- rapidly diminishing response to successive doses, making it less effective
*use bupi and ropi instead
Preeclampsia is associated with (increase/decrease) thromboxane A2 levels and (increase/decrease) prostacyclin levels
increase
- hypercoagulability
decrease
- vasoconstricted state
Preeclampsia is characterized by global vascular hyperreactivity leading to ___ (4)
- intravascular volume depletion
- high systemic vascular resistance
- uterine vasoconstriction
- decreased uterine and placental blood flow
amniotic fluid embolism leads to pulmonary (vasoconstriction/vasodilation) and generally causes ____ shock
intense pulmonary vasoconstriction
cardiogenic from RHF
Two stages of amniotic fluid embolism
- pulmonary vasospasm and RHF
2. pulmonary edema and LHF
a healthy fetus has a relatively (high/low) pH when compared to its mother
low (7.35) vs 7.43
a (acidic/basic) drug (ie. local anesthetic) that crosses the placenta in the unionized form accepts a H+ and becomes ionized and trapped
basic
- ie: lidocaine as pKa of 7.8 and more will exist in its ionized (charged, non-lipophilic) fraction as pH decreases below 7.8
Drugs that do not cross the placenta
He Is Going Nowhere Soon
- Heparin
- Insulin
- Glycopyrrolate
- Nondepolarizing muscle relaxants
- Succinylcholine
(Glycopyrrolate/Neostigmine) does not cross the placenta
Glycopyrrolate
- neostigmine will and fetus can become bradycardic
- use atropine instead
Loss of fetal heart rate variability is an early sign of _____
fetal hypoxia
Head compression can ppt _______, which require which type of intervention?
early decels
none
what FHT is a response to hypoxemia?
late decels
- lag 10-30 sec behind uterin contractions
DIC is associated with elevated ____ with decreased _____ and ____
PTT
platelets, fibrinogen
*other factors like fibrin, fibrinogen are already elevated in pregnancy
Most common causes of DIC
preeclampsia placental abruption sepsis postpartum hemorrhage Amniotic fluid embolism
Most likely cause of shivering after epidural infusion?
redistribution of core heat to the periphery
fetal scalp pH of ___ is suggestive of fetal acidosis and distress
< 7.20
- fetus cannot compensate when uteroplacental blood flow is reduced and will become acidotic