Obstetrics 2 Flashcards
All of the following are appropriate for pain relief during the first stages of labor EXCEPT a/an:
a. paracervical block
b. pudendal block
c. paravertebral sympathetic lumbar block
d. epidural block
b. pudendal block
the first stage of labor should seek to anesthetize T10-L1; Pudendal nerve derives from S2-S4- this would be more appropriate during the second stage
The first stage of labor pain originates from
T10-L1
The second stage of labor pain originates from
T10-S4
Analgesic options that target the first stage of labor pain includes
neuraxial blockade, paravertebral lumbar sympathetic block, and paracervical block
Analgesic options that target the second stage of labor pain include
neuraxial blockade and pudendal nerve block
______________ has made a resurgence as a non-invasive alternative for labor analgesia
Inhaled nitrous oxide
The ______ technique provides the dual benefit of a rapid onset of spinal anesthesia and the ability to prolong the duration of anesthesia with an indwelling epidural catheter
CSE
Pin in the first stage of labor begins in the
lower uterine segment and the cervix
The second stage of labor adds in pain impulses from the
vagina, perineum, and pelvic floor
Describe the quality of perineum pain in the second stage of labor.
sharp, well-localized
Describe the afferent pathway of perineum pain.
pudendal nerve
Describe the afferent pathway of the uterus and cervix.
visceral C fibers hypogastric plexus
Describe the quality of pain originating form the uterus and cervix.
Dull
diffuse
cramping
Describe two consequences of uncontrolled pain.
increased maternal catecholamines
maternal hyperventilation
What is the downslope effect of increased maternal catecholamines?
Hypertension and reduced uterine blood flow
What is the downslope effect of maternal hyperventilation?
leftward shift of oxyhemoglobin curve–> reduced delivery of oxygen to the fetus
How does a 50/50 N2O + O2 mixture affect uterine contractility?
it does not impair uterine contractility
What is the epidural extension technique?
Injection of saline into the epidural space immediately after the local anesthetic is administered into the subarachnoid space; allows for rostral spread of local anesthetic
Which local anesthetic reduces the efficacy of epidural morphine?
a. etidocaine
b. ropivacaine
c. levobupivacaine
d. 2-chloroprocaine
d.- 2- chloroprocaine antagonizes mu and kappa receptors in the spinal cord; this reduces the efficacy of epidural morphine
No other local anesthetics do this
Common local anesthetics used in obstetrics include
bupivacaine
ropivacaine
lidocaine
2-chloroprocaine
_________ is contraindicated via epidural due to the risk of toxicity with IV injection.
0.75% bupivacaine
Compared to bupivacaine, _______ has a lower risk of CV toxicity.
ropivacaine
When administered alone, neuraxial opioids confer the following benefits:
- no loss of sensation or proprioception
-no sympathectomy (i.e. superior hemodynamic stability)
-they do not impair mom’s ability to push
Meperidine has ______ properties
local anesthetic
Side effects of neuraxial opioids include
pruritus (most common)
N/V
sedation
respiratory depression
they do not meaningfully depress the fetus
Which local anesthetics that are used for neuraxial technique have a long duration?
bupivacaine
ropivacaine
levobupivacaine
Which local anesthetics that are used for neuraxial technique have an intermediate duration of action?
lidocaine
Which local anesthetics that are used for neuraxial technique have a short duration of action?
2-chloroprocaine
Which local anesthetic is not popular for labor analgesia due to strong motor block (which makes it good for C-section)?
lidocaine
risk of neurotoxicity if given in the SAH
Levobupivacaine has ________ compared to bupivacaine but is
less CV toxicity but is not available in the US
Ropivacaine when compared to bupivacaine has
less risk of CV toxicity
less potency
less motor block
This medication is useful for emergency C-section when epidural is already in place due to its very fast onset
2-chloroprocaine
2-chloroprocaine has a risk of ______ when used for spinal anesthesia due to preservatives
arachnoiditis
2-chloroprocaine solutions without ______ and ________ do not cause neurotoxicity
methylparaben and metabisulfite
Bupivacaine has _____ placental transfer
low placental transfer due to increased protein binding and ionization
Bupivacaine has _____ sensory block relative to other LAs
greater
Cardiac toxicity with bupivacaine is more common with
R-enantiomer
______ occurs before seizures
cardiac toxicity
Lidocaine is not typically used for continuous infusion because _______ is more likely to develop, and it crosses the placenta to a greater degree than the alternatives.
tachyphylaxis
What is the spinal bolus for bupivacaine?
1.25-2.5 mg
What is the spinal bolus for ropivacaine?
2-3.5 mg
What is the spinal bolus for levobupivacaine?
2-3.5 mg
What is the epidural bolus for bupivacaine?
0.0625-0.125%
What is the epidural bolus for ropivacaine?
0.08-0.2%
What is the epidural bolus for levobupivacaine?
0.0625-0.125% (same as for bupivacaine!)
What is the epidural bolus dose for lidocaine?
0.75-1%
The loading volume for an epidural bolus is
10-15 mL in divided doses
What is the epidural continuous infusion rate for both bupivacaine and levobupivacaine?
0.05-0.125%
What is the epidural continuous infusion for ropivacaine?
0.08-0.2%
What is the epidural continuous infusion for lidocaine?
0.5-1%
What is the lumbar infusion rate for continuous epidural infusion?
8-15 mL/hr.
Describe the spinal bolus, epidural bolus, and epidural continuous infusion for fentanyl?
spinal: 15-25 mcg
Epidural: 50-100 mcg
Epidural continuous: 1.5-3mcg/mL
Describe the spinal bolus, epidural bolus, and epidural continuous infusion for morphine.
spinal: 125-250 mcg
epidural: NA
Epidural continuous: NA
