Labor, Vaginal & Cesarean Delivery Flashcards
Analgesic options for 1st stage labor pain:
-neuraxial block
-paravertebral lumbar sympathetic block
-Paracervical block
Analgesic options for 2nd stage labor pain
Neuraxial block
Pudendal nerve block
Where is pain in the first stage of labor?
Caused mainly from lower uterine contractions
begins in the lower uterine segment and the cervix
Where do pain signals travel in the first stage of labor?
T10-L1 posterior nerve roots
Where do pain signals travel in the 2nd stage of labor?
from perineum to the S2-S4 posterior nerve roots
Where is the pain felt during the 2nd stage of labor?
perineal structures via pudendal nerve
adds in pain impulses from the vagina, perineum and pelvic floor
What are the risks of a paracervical block?
accidental injection into the uterine artery
Fetal local anesthetic toxicity
Nerve injury and/or hematoma
High risk of fetal bradycardia
Afferent pathway of the uterus and cervix:
Visceral C fibers hypogastric plexus
Afferent pathway of the perineum
Pudendal nerve
which local anesthetic reduces the efficacy of epidural morphine?
2-chloroprocaine
(antagonizes mu and kappa receptors)
When administered alone, what are the benefits of neuraxial opioids?
No loss of sensation or proprioception
no sympathectomy (superior hemodynamic stability)
they do not impair mom’s ability to push
What opioid has local anesthetic properties?
Meperidine
What are the most common side effects of neuraxial opioids?
Puritus
N/V
sedation
respiratory depression
They don’t meaningfully depress the fetus
Bupivacaine class and DOA:
Amide
Long duration
Ropivacaine class and DOA
Amide
Long DOA
Levobupivacaine class and DOA
Amide
Long DOA
Lidocaine class and DOA
Amide
Intermediate duration
2-Chloroprocaine class and DOA
Ester
Short duration
What is the risk if lidocaine is given in the subarachnoid space?
Neurotoxicity
Why is lidocaine not popular for labor analgesia?
Strong motor block (better for c-sections)
Tachyphylaxis can occur with continuous infusions and it crosses the placenta to a greater degree than alternatives
15 mins after a pts epidural was dosed, the pt becomes hypotensive and experiences resp. arrest. What is the MOST likely etiology?
A. epidural catheter migration
B. Loss of accessory respiratory muscle strength
C. Subdural injection
D. Eclampsia
C. subdural injection
Ways that a patient can develop a total spinal:
1.) An epidural dose injected into the subarachnoid space
2.) An epidural dose injected into the subdural space (s/Sx may be delayed)
3.) a single shot spinal after a failed epidural block
Treatment for total spinal:
Supportive:
-airway management
-IVF
-Vasopressors
-left uterine displacement
-leg elevation
Presentation of total spinal:
Dyspnea
difficulty phonating
hypotension
LOC d/t hypoperfusion secondary to severe HoTN
Anesthetic implications for Caesarean section under general anesthesia include:
A. administration of a dopamine agonist
B. prolonged neonatal respiratory depression
C. Increased MAC
D. rapid sequence induction
D. RSI
An obstetric pt at 33 weeks gestation requires a laparoscopic appendectomy. Which drug presents the greatest risk to fetal well-being?
A. ketorolac
B. succinylcholine
C. propofol
D. Morphine
A. ketorolac
After the first trimester, NSAIDs can close the ductus arteriosus
while no anesthetic is a proven teratogen in humans, its wise to stay with drugs w a long track record for safety such as propofol, opioids, NMB, and inhalation agents
Most significant fetal risks with maternal nonobstetric procedures:
growth restriction
low birth weight
demise
increased incidence of preterm labor
Highest risk= intraabdominal and pelvic surgery
appendectomy and cholecystectomy most common
How long would be ideal to wait to have a procedure after giving birth?
6 weeks after delivery
If one cannot wait to have a surgical procedure and is pregnant, what trimester is the best time for surgery?
2nd trimester (12-24 wks.)
At how many weeks is the pregnant patient always considered a “full stomach”?
18-20 wks.
May be earlier if pt has symptoms of GERD
Also applies to the immediate postpartum period
Why is hyperventilation bad?
reduces placental blood flow (risk of fetal asphyxia)
Teratogenicity can occur any time during pregnancy but the risk is highest during:
organogenesis (day 13-60)
(3-8 wks)
Aspiration prophylaxis:
-non-particulate antacid (sodium citrate)
-H2 antagonist (ranitidine) 1 hr before induction
-Gastric prokinetic (metoclopramide) 1 hr before induction
Teratogens are:
substances that act to irreversibly alter growth, structure, or function of the developing embryo
a major malformation is defined as:
one that is incompatible with survival (anencephaly), one that requires major surgery for correction (cleft palate, heart disease) or one that causes mental retardation
Fetal pH is lower or higher than maternal pH?
LOWER
Whats the risk with fetal acidosis?
it can significantly increase the fetal concentration of drugs such as local anesthetics
On average, women take ____ drugs during pregnancy
4
The US Food and Drug Administration has implemented the:
The pregnancy and lactation labeling rule
Which two drug categories have a high risk for adverse fetal effects?
Anticonvulsants and antidepressants
what is the safest analgesic in pregnancy?
Acetaminophen (NSAIDs should be avoided)
Which 2 cardiac drug classes should be avoided during pregnancy?
ACEIs and ARBs
What is an up-to-date resource for the safety of drugs during breast feeding?
LactMed
What class of meds is not recommended during breast-feeding?
oral opioids- codeine and tramadol
Which anesthetics may interfere with reproductive physiology in vitro?
Local anesthetics
nitrous oxide
volatile halogenated agents
what are some of the symptoms that can occur during ovarian hyperstimulation syndrome?
ascites
pleural effusion
hemoconcentration
oliguria
thromboembolic events
problems of early pregnancy:
ectopic pregnancy
cerclage
molar pregnancy
dilation and curettage
dilation and evacuation
what is cervical insufficiency?
the inability of the cervix to hold a pregnancy in the uterus through the 2nd trimester in the absence of labor
Most common cerclage procedures:
Shirodkar cerclage
McDonald cerclage
What is a molar pregnancy?
an abnormality of the placenta caused by a problem when the egg and sperm join together at fertilization
also called gestational trophoblastic disease (GTD), hydatidiform mole
Anesthetic considerations for GTD
Normal GA
2 PIV
immediate availability of blood
etomidate if unstable
Oxytocin infusion 6-15IU per hr after dilation.
Abortion:
pregnancy loss or termination before 20 wks gestation or when fetus weighs less than 500g
Anesthetic considerations for D&C/D&E
-MAC
-1 PIV
-if more than 15 wks gestation w large fetal size/fetal ossification GA
-Oxytocin available / ergot alkaloid
-observe for HoTN for 5 mins after legs down
-TYPE AND SCREEN
Anesthetic agents deemed safe:
thiopental
morphine
meperidine
fentanyl
succinylcholine
NDMRs
What class of medications have been linked to congenital abnormalities (especially in wks 3-8?)
Benzodiazepines
Nitrous oxide should be avoided in the 1st and 2nd trimesters d/t potential teratogenic effects and its interference with:
B12 metabolism
volatile anesthetics may suppress:
preterm labor
Also decrease uterine tone
TRUE OF FALSE:
nearly all opioids cross placenta and depress fetus?
TRUE
loss of beat-to-beat variability and decreased movement complicate evaluation
TRUE OF FALSE:
nearly all opioids cross placenta and depress fetus?
TRUE
loss of beat-to-beat variability and decreased movement complicate evaluation
Why isn’t morphine used often?
The immature blood brain barrier of the neonate causes resp. depression
Meperidine (Demerol)
Dose 25-50 mg IV.
Onset 5 min.
Kinetics Half-life 18-23 hrs. in neonate, also has active metabolites.
Causes frequent N/V.
Neonatal respiratory depression unlikely if given less than 1 hour prior to delivery.
Contraindicated in pt. with seizure or renal failure diagnosis
Fentanyl
50-100 mcg/hr (100x more potent than morphine!).
Onset 3-5 min after IV dose.
Kinetics rapid transfer across placenta.
Respiratory depression may outlast analgesia.
PCA recipe: loading dose 1-2 mcg/kg; dose 50 mcg with 10 min lockout; if persistent pain decrease lockout interval. Use pulse oximetry.
Nalbuphine (Nubain)
Mu opioid antagonist, kappa agonist.
Has ceiling effect on resp depression but no real large difference in side effects.
Dysphoria common.
Used to treat opioid induced pruritis (5-10 mg iv q 6 H prn).
Nalbuphine (Nubain)
Mu opioid antagonist, kappa agonist.
Has ceiling effect on resp depression but no real large difference in side effects.
Dysphoria common.
Used to treat opioid induced pruritis (5-10 mg iv q 6 H prn).
Butorphanol (Stadol)
Dose 1-2 mg.
Some reports suggest better analgesic profile than fentanyl.
Sedation common.
Ceiling effect on resp depression.
Butorphanol (Stadol)
Dose 1-2 mg.
Some reports suggest better analgesic profile than fentanyl.
Sedation common.
Ceiling effect on resp depression.
What dose should MAC be limited to when using volatile anesthetics?
0.5 MAC
Side effect of volatile agents
decreased uterine tone
Technique for pudendal block:
Technique: Needle is placed bilaterally via transvaginal approach under the ischial spines.
Risks of pudendal block
fetal injury
infection
hematoma
order of ligaments needle will go through to get to epidural /subarachnoid space
Suprasinous ligament
interspinous ligament
ligamentum flavum
posterior longitudinal ligament
anterior longitudinal ligament
Ligamentum flavum
epidural space
dura mater “pop”
subdural space (potential space)
arachnoid mater
subarachnoid space (contains CSF- target for spinal)
What level does the spinal cord end in adults?
L1
5% L2-L3
Spinals should be placed below L3 if possible
What dermatomes do you want your spinal to cover?
T10-S4
What should you do if pt complains of paresthesia while spinal is being dosed?
remove the needle
Tuffier’s Line:
L4/L5
Transverse line passing across the lumbar spine btwn the posterior iliac crests
Safe injection would be considered below what level?
L2/L3
On average how deep is the epidural space?
4.75cm deep
After space identified- thread catheter until how deep at the skin?
10-15 cm mark
What should you not do to prevent shearing?
do not pull the catheter back through the needle
Activating dose or bupiv/ropiv for epidural:
10cc 0.15% bupiv/ropiv + 50-100 mcg of fentanyl
How should you set your infusion for epidural?
8cc/hr of 0.1% bupiv/ropiv +2-4 mcg of fentanyl
PCEA bolus:
4cc
locals and opioids are _____ in nature
synergistic
are drugs more potent delivered through the spinal or epidural route?
spinal route
10x more potent and much smaller needles are used
22-27 g for spinal
17-18ga for epidural
What are subarachnoid blocks used for?
c-sections
sufenta 5-10mcg or 15-20mcg fent + 2mg bupiv (1.4-1.8 ml typically)
Good for cases where delivery expected soon and not enough time available to place epidural.
Physiologic changes of pregnancy that alter neuraxial anatomy:
accentuation of lumbar lordosis
softer ligamentum flavum
decreased space in the spinal canal (caused by vascular engorgement of epidural veins
what kind of needle for spinal anesthesia can reduce the incidence of post-dural puncture headache?
noncutting (pencil-point)
How much less local is required for epidural and spinal in pregnant women than in nonpregnant pts?
20-30%
How much less local is required for epidural and spinal in pregnant women than in nonpregnant pts?
20-30%
How are amino esters metabolized?
plasma cholinesterase
What is the metabolite that causes allergies with esters
Para-aminobenzoic acid (PABA)
how are amides metabolized?
Liver
what characteristic of locals influences onset the most?
pKa
dose and concentration secondary
what characteristics of locals influences potency the most?
Lipid solubility
intrinsic vasodilating ability
what characteristic of locals influences DOA the most?
protein binding
lipid solubility
vasodilating effects
addition of vasoconstrictors
high protein binding decreases:
placental transfer
high protein binding decreases:
placental transfer
A I-acid glycoprotein
high affinity, low capacity
albumin:
low affinity, high capacity
site of action for LAs
neuronal cell membrane sodium channel in the active/inactivated state
the closer pKa is to physiological pH = more LA in nonpolar form=
faster onset
once across the membrane, polar molecule is responsible for:
receptor binding and blocking channel
Volume and concentration of LA (total dose) will dictate:
onset, quality and duration
increasing doses = faster onset and longer duration
warmed LA will reduce:
onset time (faster onset)
Which fibers are blocked 1st?
B- preganglioninc ANS fibers
Which fibers are blocked last?
A- alpha (skeletal muscle, motor, proprioception)
A-Beta (touch, pressure)
_____ and _____ myelinated neurons are more rapidly susceptible to blockade
small and poorly myelinated
(C fibers)
____ myelinated fibers require higher LA concentration for blockade
Larger (type A fibers)
differential blockade
prevents pain w/o eliminating awareness/ pressure of labor
A- gamma
skeletal muscle tone
blocked 3rd
A-delta
fast pain, temperature, touch
blocked 3rd
C sympathetic
postganglionic ANS fibers
blocked 2nd
C -dorsal root
slow pain
temperature
touch
blocked 2nd
C -dorsal root
slow pain
temperature
touch
blocked 2nd
Locals for labor epidural analgesia:
bupivacaine
ropivacaine
lidocaine
Locals for operative epidural anesthesia
Lidocaine
2-chloroprocaine
Locals for spinal anesthesia
tetracaine
Bupivacaine
What is a risk of using bupivacaine?
highly cardiotoxic - can cause v.tach/v.fib
CNS symptoms of LAST
Tinnitus
Light-headedness
Metallic taste
circumoral numbness
convulsions
LOC
resp. arrest
increased paco2 and acidosis lower seizure threshold
CNS symptoms of LAST
Tinnitus
Light-headedness
Metallic taste
circumoral numbness
convulsions
LOC
resp. arrest
increased paco2 and acidosis lower seizure threshold
effects of LAST on CV system
inhibition of cardiac sodium channels
Decrease rate of depolarization in Purkinje fibers and ventricular muscle
Decreased duration of action potential and effective refractory period
Increased toxicity to bupivacaine and cocaine w preganancy
effects of LAST on CV system
inhibition of cardiac sodium channels
Decrease rate of depolarization in Purkinje fibers and ventricular muscle
Decreased duration of action potential and effective refractory period
Increased toxicity to bupivacaine and cocaine w preganancy
LAST treatment:
20% intralipid
1.5 mL/kg as initial bolus followed by 0.25 ml/kg for 30-60 mins
bolus can be repeated 1-2 times for persistent asystole
fetal acidosis results in greater accumulation of which class of local in the fetus?
amide
fetal acidosis results in greater accumulation of which class of local in the fetus?
amide
American Society of Regional Anesthesia (ASRA) guidelines for the treatment of local anesthetic systemic toxicity (LAST) for cardiac arrhythmias include the use of Intralipid and the AVOIDANCE of all of the following drugs EXCEPT
A. Vasopressin
B. β-Blockers
C. Calcium channel blockers
D. Low-dose epinephrine (<1 μg/kg)
D. Low-dose epinephrine (<1 μg/kg)
Factors associated with advanced molar pregnancy (i.e., >14- to 16-week size uterus) include all of the following EXCEPT
A. Hypertensive disorders of pregnancy
B. Hypothyroidism
C. Acute cardiopulmonary distress
D. Hyperemesis gravidarum
B. Hypothyroidism
A woman has been admitted for a dilation and evacuation (D&E) at 10 weeks’ EGA. She has some persistent bleeding and cramping after the expulsion of some tissue. Her obstetric condition is called
A. A threatened abortion
B. An inevitable abortion
C. A complete abortion
D. An incomplete abortion
D. An incomplete abortion
Agents that are useful for decreasing the incidence of shivering during cesarean section under regional anesthesia or for treating shivering include all of the following EXCEPT
A. Administration of intrathecal local anesthetic with fentanyl and/or morphine
B. Intravenous magnesium sulfate
C. Administration of epidural local anesthetic solu-
tions with epinephrine
D. Intravenous meperidine
C. Administration of epidural local anesthetic solu-
tions with epinephrine
Which agent is the MOST useful for raising the gastric pH just before induction of general anesthesia for emergency cesarean section?
A. Ranitidine
B. Sodium citrate
C. Metoclopramide
D. Magnesium hydroxide and aluminum hydroxide
B. Sodium citrate
While moving a parturient from the birthing room to the operating room for an emergency cesarean section for a prolapsed umbilical cord, the patient develops cough, wheezing, and stridor and becomes cyanotic. The trachea is intubated, and food is noted in the pharynx. Appropriate treatment in this patient should consist of
A. Intravenous lidocaine to suppress the cough
B. Glucocorticoids
C. 100% oxygen and positive end-expiratory pressure
(PEEP)
D. Saline lavage
C. 100% oxygen and positive end-expiratory pressure
(PEEP)
During the second stage of labor, complete pain relief can be obtained with
A. Paracervical block
B. Neuraxial block with fentanyl and morphine
C. Pudendal nerve block
D. Lumbar epidural block with bupivacaine and no
narcotic
D. Lumbar epidural block with bupivacaine and no
narcotic
Which inhalation anesthetic does NOT produce uterine relaxation?
A. Isoflurane
B. Sevoflurane
C. Nitrous oxide
D. All produce uterine relaxation
C. Nitrous oxide
Which of the following narcotics has the LONGEST duration of action when added during a cesarean section under epidural anesthesia?
A. 50 to 100 μg fentanyl
B. 10 to 20 μg sufentanil
C. 3 to 4 mg morphine
D. 50 to 75 mg meperidine
C. 3 to 4 mg morphine
The MOST common side effect of intraspinal narcotics in the obstetric population is
A. Pruritus
B. Nausea and vomiting
C. Respiratory depression
D. Urinary retention
A. Pruritus
True statements regarding inclusion of intrathecal morphine, fentanyl, or sufentanil in obstetric anesthesia practice include each of the following EXCEPT
A. The chief site of action is the substantia gelatinosa
of the dorsal horn of the spinal column
B. There is no motor and no sympathetic blockade
C. Pain relief is adequate for the second stage of labor
D. Lipophilic narcotics are associated with less
respiratory depression than nonlipophilic narcotics
C. Pain relief is adequate for the second stage of labor
A 23-year-old parturient in the first trimester is brought to the operating room for emergency appendectomy. General anesthesia is planned. Which drug has a U.S. Food and Drug Administration (FDA) Use-In-Pregnancy rating of D (studies in humans and in investigational or postmarketing data demonstrate fetal risk; nevertheless, potential benefits may outweigh potential risk)?
A. Nitrous oxide
B. Isoflurane
C. Midazolam
D. None of the above
C. Midazolam
Which intrathecal narcotic can be used as a sole agent for cesarean section (i.e., without an ester or amide local anesthetic)?
A. Morphine
B. Fentanyl
C. Meperidine
D. None of the above; a local anesthetic is needed
C. Meperidine
Which of the following properties of epidurally administered local anesthetics determines the extent to which epinephrine will prolong the duration of blockade?
A. Molecular weight
B. Lipid solubility
C. pKa
D. Concentration
B. Lipid solubility
General anesthesia is induced in a 35-year-old patient for elective cesarean section. No part of the glottic apparatus is visible after two unsuccessful attempts to intubate, but mask ventilation is adequate. The most appropriate step at this point would be to
A. Wake up the patient
B. Attempt a blind nasal intubation
C. Continue mask ventilation and cricoid pressure D. Use a laryngeal mask airway
A. Wake up the patient
A 38-year-old primiparous patient with placenta pre- via and active vaginal bleeding arrives in the operating room with a systolic blood pressure of 85 mm Hg. A cesarean section is planned. The patient is lightheaded and scared. Which of the following anesthetic induction plans would be most appropriate for this patient?
A. Spinal anesthetic with 12 to 15 mg bupivacaine
B. General anesthetic induction with 2 to 2.8 mg/kg propofol and paralysis with 1 to 1.5 mg/kg succinylcholine
C. General anesthesia induction with 0.75 to 1 mg/kg ketamine and paralysis with 1 to 1.5 mg/kg succinylcholine
D. Replace lost blood volume first, then use any anesthetic the patient wishes
C. General anesthesia induction with 0.75 to 1 mg/kg ketamine and paralysis with 1 to 1.5 mg/kg succinylcholine
The MOST common injury recorded in the American Society of Anesthesiologists’ (ASA’s) Closed Claim Project regarding obstetric anesthetic claims is
A. Pain during anesthesia
B. Maternal nerve damage
C. Headache
D. Aspiration pneumonitis
B. Maternal nerve damage
A 29-year-old gravida 1, para 0 parturient at 8 weeks of gestation is to undergo an emergency appendectomy under general anesthesia with isoflurane, N2O, and oxygen. Which of the following is a proven untoward consequence of general anesthesia in the unborn fetus?
A. Congenital heart disease
B. Cleft palate
C. Behavioral defects
D. None of the above
D. None of the above
Which of the following drugs should NOT be used during transvaginal oocyte retrieval (TVOR) for assisted reproductive technology (ART)?
A. Propofol
B. Ketamine
C. Midazolam
D. All are safe and can be used
D. All are safe and can be used
When is the fetus most susceptible to the effects of teratogenic agents?
A. 1 to 2 weeks of gestation
B. 3 to 8 weeks of gestation
C. 9 to 14 weeks of gestation
D. 15 to 20 weeks of gestation
B. 3 to 8 weeks of gestation
A32-year-old parturient with a history of spinal fusion, severe asthma, and hypertension (blood pressure 180/110) is brought to the operating room wheezing. She needs an emergency cesarean section under general anesthesia for a prolapsed umbilical cord. Which of the following induction agents would be MOST appropriate for her induction?
A. Sevoflurane
B. Midazolam
C. Ketamine
D. Propofol
D. Propofol
