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THE LABOUR IS REPORTED TO BE ONE OF
THE MOST PAINFUL EXPERIENCES IN A
First stage of labour- uterine contraction + cervical
Afferent- visceral afferent from uterus (symathetic)
T 10, 11, 12, L 1 posterior segments.
Second stage- distension of pelvic floor, vagina and
perineum by descending head
Afferent- sensory fibres of S 2, 3, 4 (pudendal nerve)
EFFECTS OF PAIN AND STRESS
release of adrenocorticotropic
hormone, cortisol, catecholamines, and b-endorphins.
b-adrenergic agents have uterine relaxant effects and
higher epinephrine levels are associated with anxiety
and prolonged labour.
animal studies indicate that both epinephrine and
nor-epinephrine can decrease uterine blood flow in
the absence of maternal heart rate and blood pressure
changes, contributing to occult fetal asphyxia.
Maternal psychological stress (induced by bright lights
or toe clamp) can detrimentally affect uterine blood
flow and fetal acid-base status (animal studies)
Postpartum women suffer objective deficits in
cognitive and memory function when compared with
Analgesia for Labor and Delivery
“Birth is a natural process”
Women should suffer!!
Concerns for mother’s safety
Concerns for baby
Concerns for effects on labor
ANALGESIA FOR LABOUR
Relaxation, concentration on
breathing, acupuncture, gentle massage, and partner
may be used alone, or in conjunction with parenteral
or regional techniques.
efficacy of these techniques is largely unproven
because of a lack of randomized clinical trials.
there are no serious safety concerns with any of these
Acupuncture alleviates labour pain and reduces use of
both epidural analgesia and parenteral opioids.
Arranging to have a qualified provider available at the
time of delivery may be challenging.
Under Water Delivery
No advantage in labour outcome or in reducing the
need for analgesia.
The request for epidural analgesia was delayed by
about 30 minutes.
Lack of trials demonstrating safety and the rare but
reported unusual complications such as fetal infection
Intracutaneous sterile water injections- similar gating
mechanism as acupuncture.
transcutaneous electrical nerve stimulation during
labour- made the pain less disturbing, doesn’t decrease
Placental Transfer of Drugs:
Maternal, Drug, Placental and Fetal Factors
Total dose of drug
Maternal metabolism and excretion
Degree of ionization
pKa of drug, maternal and fetal pH
Protein binding - mother and fetus
Uterine blood flow
Do not possess analgesic qualities.
Used early in labour to relieve anxiety or to aid in
Cross the placenta freely.
Barbiturates, Phenothiazines, and Benzodiazepines.
Barbiturate and benzodiazepines are not used
routinely in obstetrics.
Dose- 25 mg
Antagonists are not available.
Routine use of promethazine is unnecessary.
Systemic Opioid Analgesia
Morphine-like pharmacological activity.
Natural- morphine and codeine
Semisynthetic- hydromorphone and heroine
Synthetic- meperidine and fentanyl
Provide sedation and a sense of euphoria.
Analgesic effect in labour is limited.
Primary mechanism of action is sedation.
Avoids complications of regional block.
Does not require skilled personnel.
Few serious maternal complications.
All drugs easily cross placenta.
Pain relief inadequate in most cases
Nausea, vomiting, gastric stasis
Fetal heart rate effects:
Loss of beat-to-beat variability
Dose-related maternal / neonatal depression
Newborn neurobehavioral depression
Centrally acting opioid analgesic used in treating severe
Route- IV or IM
Dose- 50 mg
Should be given with antiemetic.
Maximum respiratory depression and low apgar score
occur in newborns that are delivered within-
3 hours after an IM administration
2 hours after an IV administration.
Meperidine 100 mg is roughly equi-analgesic to
morphine 10 mg.
Side effects- tachycardia, nausea and vomiting, and a
delay in gastric emptying.
Normeperidine - active metabolite of
meperidine, potentiating meperidine's depressant
effects in the newborn. Concentrations increase
slowly, therefore, exerts its effect on the newborn
during the second hour after administration.
Multiple doses of meperidine = greater accumulation
of both meperidine and normeperidine in fetal tissues.
Fast-onset, short-acting synthetic opioid.
Requires frequent redosing or the use of a patient-
controlled intravenous infusion pump.
Fewer neonatal effects and less maternal sedation and
Other opioids are
nalbuphine, pentazocine, buprenorphine and
Easy to administer (no needles)
Nitrous oxide is administered in subanaesthetic
concentrations. (N2O 30-50%)
Analgesia without loss of consciousness.
Crosses the placenta but is eliminated efficiently, no
untoward neonatal effects.
No effects on uterine contractions.
Most effective for short term (1-2 hrs) pain relief
Most beneficial in late first stage of labour.
Local and regional techniques
Paravertebral (lumbar sympathetic block)
Epidural - lumbar (caudal)
Combined spinal-epidural (CSE)
Direct infiltration of 1% lignocaine is used for perineal
and lower vaginal lacerations.
Advance the needle and inject and aspirate to avoid
Dose of lignocaine is 3-4 mg/kg plain solution, and 7-8
mg/kg with added epinephrine.
1% solution = 10 mg/ml
For 6O kg woman total dose should not exceed 200 mg
or 20 ml.
After local infiltration one should wait 3 minutes
5 to 6 ml of a dilute solution of local anesthetic
without epinephrine (e.g., 1 percent lidocaine or 1 or 2
percent 2-chloroprocaine) is injected into the mucosa
of the cervix at the 3- and 9-o'clock positions
fetal bradycardia that follows in 2 to 70 percent of
fetal acidosis and death have been reported
Paracervical block should be used cautiously at all
times and should not be used at all in mothers with
fetuses in either acute or chronic distress.
mechanism of postparacervical block bradycardia-
local anesthetic injected close to the uterine artery
passed to the fetus
uterine artery vasoconstriction secondary to a direct
effect of the local anesthetic on the uterine artery
local anesthetic injected directly into the uterine
musculature increases uterine tone
Pudendal nerve block
minor regional block, effective and very safe.
Using a 20-gauge needle, inject 5 to 10 ml of local
anesthetic just below the ischial spine.
Because the hemorrhoidal nerve may be aberrant in 50
percent of patients, some prefer to inject a portion of
the local anesthetic somewhat posterior to the spine.
Although a transperineal approach to the ischial spine
is possible, most prefer the transvaginal approach.
One-percent lidocaine or 2-percent 2-chloroprocaine
can be used
satisfactory for all spontaneous vaginal deliveries and
episiotomies, and for some outlet or low operative
The potential for local anesthetic toxicity is higher
with pudendal block compared with perineal
infiltration because of large vessels proximal to the
injection site. Aspiration before injection is
Regional Analgesia for Labor
Epidural (LA or opioids)
Spinal (LA ± opioids)
CSE- combined spinal epidural (opioids ± LA)
Fetal / Neonatal Effects of Regional
Analgesia in Labor
Uterine perfusion maintained.
Profound hypotension & possible fetal compromise.
LA toxicity - extremely rare.
periodic decelerations (due to maternal
Neurobehavioral effects absent with current agents.
Epidural block is the most effective and least
depressant (pharmacologic option) allowing for an
alert, participating mother.
(guidelines American College of Obs & gynae)
Primary indication is the patient's desire for pain
Medical indications during labor- selected forms of
cardiovascular and respiratory disease, and prevention
or treatment of autonomic hyperreflexia in parturients
with a high spinal cord lesion.
Epidural analgesia prevents increases in both cortisol
and 11-hydroxycorticosteroid levels during labor, but
systemically administered opioids do not.
Epidural analgesia also attenuates elevations of
epinephrine, norepinephrine, and endorphin levels.
Fixed cardiac output disease
History of allergy to local anaesthetics
Lumbar- routinely done
Caudal- not favoured
Low concentrations of local anesthetic are injected at
Affecting the small easily blocked sympathetic nerves
that mediate early labour pain.
Sparing the sensation of pressure and motor function
of the perineum and lower extremities.
Dose can be adjusted according to patient’s response.
Choice of epidural local anaesthetic
Lignocaine- rapid onset, dense motor block, risk of
cumulative toxicity with repeated doses.
Bupivacaine- good sensory block with minimal motor
No adverse effect on labour with 0.0625%
Highly protein bound, fetal blood concentrations are
lower than with other local anaesthetics.
Epidural Opioids in Labour
Inadequate analgesics used alone
Synergistic with local anesthetics
Speedy onset of analgesia
Improves quality of analgesia
Permits use of very dilute LA solutions
Help relieve persistent perineal pain and unblocked
Fentanyl and Sufentanil
Rapid onset, few side effects
Sufentanil slightly more effective
No significant fetal drug accumulation
No serious adverse neonatal effects with either
Side effects of epidural-
local anesthetic toxicity
high or total spinal anesthesia
The effect of epidural analgesia on labour
progression, fetal position, and risk of cesarean
delivery is controversial.
Randomized studies support the conclusion that
epidural analgesia results in a modest prolongation of
both the first and second stages of labour.
Significant increase in the use of oxytocin for labour
Increased rate of instrumental delivery.
Several well-designed randomized studies suggest
that, in settings with baseline low rates of caesarean
delivery, epidural analgesia does not increase the risk
of caesarean delivery.
Epidural analgesia during labor is associated with an
increase in maternal temperature.
Dependent on the duration of exposure.
Possible mechanisms- noninfectious inflammatory
activation, changes in thermoregulation, and acquired
Combined spinal epidural
Opioids ± LA
Rapid onset of intense analgesia.
Ideal in late or rapidly progressing labour.
Very low failure rate.
Less need for supplemental boluses.
Minimal motor block (“walking epidural”)
Walking epidural- Use of opioid only to allow
parturients to ambulate during labour because there is
little or no interference with motor function.
Early intrathecal opioids followed by continuous
epidural infusion in active labour may be a good
option for women desiring regional analgesia, offering
superior pain control until active labour has been
One randomized study found that use of intrathecal
opioids increased speed of cervical dilatation and
decreased length of labour when compared with
The use of intrathecal opioids improved pain control in
early labor without increasing the risk of caesarean
avoids maternal sedation , decreases nausea and vomiting.
comparisons of intrathecal opioid analgesia versus epidural
or parenteral opioids in labour found the use of intrathecal
opioids significantly increases the risk of fetal bradycardia .
Fetal heart rate should be monitored during and after
the administration of either epidural or intrathecal
medications to allow for timely intrauterine
No increase in emergency caesarean delivery.
Individualize technique to patient’s goals and stage of
Optimize management for spontaneous delivery.
Provide safe, cost-effective analgesia.