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
Preeclampsia is d/t (paternal/maternal) factors
both
two ways to provide uterine relaxation
- volatile anesthetics via GA
2. IV or sublingual nitroglycerin
How long can you wait after delivery of baby for the delivery of the placenta?
60 min in absence of hemorrhage
30 min with manual extraction with severe hemorrhage
The _______ block is effective regional anesthesia for first stage analgesia, by blocking lower uterine and cervical visceral afferent sensory fibers that join L2 and L3
lumbar sympathetic
The second stage of labor begins with ____ and ends with ______
complete dilation of the cervix
birth of baby
The _______ is effective regional anesthesia for the first and second stage of labor.
epidural analgesia
spinal analgesia
___ to ____ spinal segment coverage is needed to relieve pain of contractions and cervical dilation
T10-L1
___ to ___ spinal segment coverage is needed to relieve pain of vaginal and perineal distention
S2-S4
*second stage of labor
_____ nerve block helps relieve the pain during second stage of labor by covering somatic nerve fibers from ___ to ___
pudendal
S2-S4
Dose of nitroglycerin if shoulder dystocia leading to fetal life threatening emergency requiring uterine relaxation
0.4 mg sublingual
50-200 mcg IV
_____ can help with postpartum hemorrhage, but can cause severe bronchospasm and should be avoided in asthmatics
carboprost (aka hemabate)
- prostaglandin analogue
______can help with postpartum hemorrhage, but can cause significant HBP and pulmonary vascular resistance
Methergine
- ergot alkaloid
Why is oxytocin used after the baby is delivered?
hormone derived in posterior pituitary
- increases uterine muscle tone
What is preeclampsia?
multi-organ syndrome with new onset HTN occurring after 20 weeks
can include
- proteinuria
- thrombocytopenia
- hepatic dysfunction
What is severe preeclampsia?
HTN above systolic 160
- worsening thrombocytopenia
- impaired liver function
- renal insufficiency
- pulmonary edema
- new onset visual disturbances
_____ decelerations are the most common type of decelerations and are transient decreases in FHR. This is most commonly a result of ______.
Variable decelerations,
umbilical cord compression -> decreased umbilical blood flow
Pregnancy (does/does not) significantly alter the rate of gastric emptying
Does not, maayyybe in advanced labor.
Pregnant women are more likely to have a difficult airway than nonpregnant women. The best way to optimize pregnant pts for GA would be to:
Avoid solid foods, antacids, H2 receptor antagonists, metoclopramide before C/S
Timing of PDPH is _____ after a dural puncture
usually 6-72 hours
up to 5 days
After a dural puncture with an epidural needle, the risk for PDPH is ~ __%, whereas after puncture with a spinal needle, the risk is __%
50%,
1-10%
Other sx assoc with PDPH (6)
Tinnitus, hearing loss, photophobia, diplopia (traction on 6th CN), nausea, neck pain
Pencil point needles such as ____ and ____ have less risk at causing a PDPH than a cutting needle such as ____.
Sprotte, Whitacre. Quincke
Beat to beat variability in FHR is indicative of ______
Normal finding, healthy ANS, cardiac responsiveness
*Beat to beat variability AKA short term variability (variation from one beat to another from 5-25 bpm)
Pregnancy can exacerbate these 3 physiologic derangements in pts with SCD
- Physiologic anemia intensified d/t hemolysis
- Increased risk for sickling d/t increased oxygen demand and low oxygen tension
- Hypercoagulable state with higher chance of vaso-occlusive crises
Tenants of care for pregnant SCD pts
Avoid:
- Hypercarbia
- Hypoxemia
- Acidosis
- Dehydration
- Hypotension
- Pain
Pt has HTN that developed after 20 weeks gestation, can be _____ or _____
Gestational HTN, preeclampsia
In setting of emergent C/S for terminal decelerations, it is best to perform this type of anesthetic ______
RSI and Intubation with a fast acting antihypertensive (nitroglycerin, esmolol, remifentanil).
Prolonged attempts at neuraxial anesthesia can cause fetal brain hypoxia and brain death.
Nonobstetric surgery in pregnant pts should be done in the _____ trimester to prevent the risk of miscarriage
- Second
Pregnant women with placenta previa (painless vaginal bleeding and nl uterine tone) are at increased risk for ______, especially if there is a h.o previous c/s.
Placenta accrete (>60% if pt had 3/m C/S)
Painful vaginal bleeding and increased uterine tone are classic signs of ______
Placental abruption
Inhaled Nitrous Oxide is (safe/unsafe) in labor analgesia.
Safe, can be delivered up to 50% mixture with oxygen
Because nitrous oxide is 35x more soluble than nitrogen in the blood, it tends to increase the pressure of air containing cavities. Therefore, contraindicated in _____ (4)
VAE, pneumothorax, pneumoperitoneum, pulmonary air cyst
