Labor analgesia Labor causes severe pain for many women There is no other circumstance where it is considered acceptable for an individual to experience untreated severe pain amenable to safe intervention while under a physicians care In the absence of a medical contraindication maternal r ID: 914339
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Slide1
Labor Analgesia
Katy Kemnetz
Slide2Labor analgesia
“Labor causes severe pain for many women. There is no other circumstance where it is considered acceptable for an individual to experience untreated severe pain, amenable to safe intervention, while under a physician's care. In the absence of a medical contraindication, maternal request is a sufficient medical indication for pain relief during labor.... None of the techniques appears to be associated with an increased risk of cesarean delivery.”
-ACOG committee opinion 339
Slide3Patient education
A woman's satisfaction with her labor and delivery are less dependent on the amount of pain and more dependent on her involvement in the decision-making process
Obstetricians should educate their patients early in pregnancy about their options
Slide4Stages of labor
First stage
Visceral pain caused by contractions, stretching of cervix and uterus, ischemia
Fibers from uterine body and
fundus
enter spinal cord at T10-L1 with
sympathetics
Fibers from cervix and upper vagina enter cord at S2-S4 with
parasympathetics
Second
stage
Add somatic pain from stretching of vaginal, perineum, and pelvic ligaments
Travels to spinal cord in S2-S4 via
pudendal
nerve
Slide5Slide6Distribution/intensity of labor pain
T11/T12 dermatomes
T10/L1 dermatomes
Perineum
Lower back and perineum
Slide7Adverse consequences of pain
Stress
Release of
catecholamines
can reduce placental blood flow
Hyperventilation
Impaired transfer of oxygen to fetus
Impaired maternal hemoglobin dissociation
Placental vasoconstriction
Psychological
PTSD and postpartum depression
Slide8Systemic labor analgesics
Options
Opioids
Morphine,
fentanyl
,
meperidine
,
hydromorphone
Mixed
opioid
agonist-antagonists
Nalbuphine
,
butorphanol
Dose ceiling effect for respiratory depression
PCA
Cons
Less
effective analgesia
Risk of respiratory depression, nausea, vomiting, sedation, decrease in FHR variability
Pros
Result
in shorter duration of labor and less
oxytocin
augmentation
Slide9Local blocks
Pudendal
block
Somatic pain of stretching of vagina/cervix/perineum
Ineffective for pain of contractions
Para cervical block
Blocks some uterine, cervical sensory fibers
Somewhat effective for contractions
?Effect on fetus
Slide10Contraindications to neuraxial analgesia
Patient refusal
Uncorrected
coagulopathy
Infection of the lower back
Uncorrected
hypovolemia
Increased intracranial pressure
Slide11Epidural analgesia
The epidural space is bounded
anteriorly
by the posterior longitudinal ligaments, laterally by the pedicles and
intervertebral
foramina, and
posteriorly
by the
ligamentum
flavum
. Contents of the epidural space include the nerve roots that traverse it from foramina to peripheral locations, fat,
areolar
tissue,
lymphatics
, and blood vessels
Slide12Epidural
anesthesia
A catheter is placed in the epidural space and left there for the duration of labor
Slower onset of anesthesia (5-10 minutes) but longer duration
Dosing regimens:
Intermittent dosing
Breakthrough pain
Continuous infusion
Increased risk of motor blockade
PCEA
Lower total dose of analgesics used during labor and lower incidence of motor block
Usually
an epidural includes a
combination of
opioid
(
fentanyl
/
sufentanyl
) and
local anesthetic
(
bupivicaine
/
ropivacaine
)
Ephinephrine
and
opioids
reduce concentration of local
anesthesia required
A
lower concentration of local anesthetic reduces the
motor blockade
(“walking epidural”)
Slide13Spinal and
Combined Spinal-Epidural (CSE)
Spinal analgesia has quicker onset (within 5 minutes) but shorter duration (90 minutes)
Catheter is not left in
intrathecal
space
More useful for planned c-section, less useful for labor
Combined spinal epidural
is best for quick onset and long duration
Greater risk of
pruritis
, fetal
bradycardia
, maternal hypotension with higher doses
Minimized by using
lipophilic
opioids
like
fentanyl
in
intrathecal
space
No change in rate of cesarean section
Slide14Second stage of labor
May have to discontinue epidural if motor block is preventing
pushing
Slide15Third stage of labor
If there is a complication with delivery and patient does not have
neuraxial
analgesia, may have to administer general anesthesia
Shoulder
dystocia
Emergent cesarean section
Considerations for general anesthesia
More difficult intubation
Higher aspiration risk
Shorter lasting
preoxygenation
Risk of fetal depression
Slide16Adverse effects of labor analgesia
Systemic toxicity (inadvertent injection into blood vessel)
CNS (tinnitus, seizures) and cardiovascular
High spinal
Aspiration,
dyspnea
, hypotension
Hypotension (w/ decreased placental perfusion)
Failed block
Pruritis
, nausea,
vomting
, backache, urinary retention
Postdural
puncture headache (decreased with pencil point spinal needles)
Respiratory depression, epidural hematoma, infection
Effects on fetus: hypotension; if not, then increased placental flow, improved fetal acid/base status. Fetal
bradycardia
2/2 uterine
hypertonus
2/2
opioids
Association with cesarean delivery and instrumental delivery but no causation
Slide17Slide18