PHYSIOLOGY OF LABOUR PAIN AND LABOUR ANALGESIA [Autosaved] [Autosaved].pptx

PHYSIOLOGY OF LABOUR
PAIN AND LABOUR
ANALGESIA
MODERATOR:DR.CHANDRASHEKAR DANDI
PRESENTER:DR.KEERTHY UNNIKRISHNAN

LABOUR PAIN
 Labour pain is ranked one of the highest on
the pain rating scale.

COMPONENTS OF LABOR PAIN
 Visceral pain:
 Occurs during early first stage and second stage of labor.
 Mainly due to dilatation of:
-Cervix.
-Lower uterine segment.
 Transmitted by small unmyelinated C fibres.
 Pain is dull in character and not easily localized.
 Pain is referred to T10-T12 dermatomes such as:
-Lower abdomen
-Sacrum
-Back.

 Somatic pain:
 Occurs during late first stage and second stage
of labor.
 Due to distention of:
-Pelvic floor.
-Perineum.
-Vagina.
 Transmitted by fine myelinated A-delta fibres.
 Pain is sharp in character and easily localized.
 Occurs closer to delivery.
 Radiates to adjacent T10 to L1 dermatomes.
 More resistant to opioids.

LABOR PAIN PATHWAYS
 Visceral pain:
 Transmitted via small unmyelinated c fibres.
 These travel along the sympathetic fibres to:
-Uterine plexus.
-Cervical plexus.
-Hypogastric plexus.
 Fibres from sympathetic chain enter white
rami communicantes with T10-L1.

 They synapse in dorsal horn of spinal cord via posterior
nerve roots.
 Some fibres cross over at the dorsal horn level with multiple
extensions.
 This leads to poor localization of pain.
 From dorsal horn cells,they are transmitted via
spinothalamic tract to brain.
 Chemical mediators involved in this pathway:
-Bradykinin.
-Leukotrienes.
-Prostaglandins.
-Serotonin.
-Substance P.
-Lactic acid.

 Somatic pain:
 Transmitted by fine,myelinated,rapidly transmitting A
delta fibres.
 Transmission occurs to S2-S4 nerve roots via:
-Pudendal nerves.
-Perineal branches of posterior cutaneous nerve of thigh.
 Afferent fibres are also carried to L1 and L2 roots via:
-Ilioinguinal nerve.
-Genitofemoral nerve.
 From dorsal horn cells,they are transmitted via spino-
thalamic tract to brain.

FACTORS AFFECTING SEVERITY OF LABOR PAIN
 Parity:
 Severity of pain varies between nulliparous and multiparous
women.
 Nulliparous women experience more severe pain.
 Prior education:
 Prior education about the process of labor reduces intensity
of pain.
 This may also explain cultural differences in perception of
labor pain.
 Severity of labor pain increases with progression of
labor due to:
 Cervical distension (primarily).
 Increase in uterine pressure during contractions.

TECHNIQUES
NONPHARMACOLOGICAL
 Low resource methods:
 Psychoprophylaxis:
-Education program
-Strong focus of attention.
-Human support, hand holding.
-Relaxation techniques of voluntary muscles.
-Breathing techniques:
*Slow breathing.
*Counting breaths.
*Reciting mantras in rhythm with breathing .

 Acupuncture.
 Application of hot or cold packs.
 Music and audioanalgesia.

 Moderate resource methods:
 Hypnosis.
 Yoga.
 Acupuncture.
 TENS.
 Sterile water injection.
 Biofeedback.
 Water immersion.
 The Bradley method.
 Lamaze approach.
 High resource methods:Includes pharmacological
interventions like opioids.

PHARMACOLOGICAL
 Opioids:
 Meperidine.
 Remifentanyl.
 Butorphanol.
 Fentanyl.
 Nalbuphine.
 Tramadol.

 Sedative tranquilizers:
 Benzodiazepines.
 Hydroxyzine.
 Barbiturates.
 Phenothiazines.
 Others:Ketamine.

INHALATIONAL ANALGESIA
 Entonox.
 Sevoflurane(0.8%).
 Isoflurane.
 Enflurane(0.25%).
 Desflurane.

REGIONAL ANALGESIA
 Epidural analgesia.
 Subarachnoid block.
 Combined spinal epidural analgesia.
 Paracervical block.
 Pudendal block.
 Lumbar sympathetic block.
 Caudal block.

NEWER ADVANCES
 Patient controlled analgesia:
 PCIVA:Patient Controlled IV Analgesia with
remifentanil.
 PCIA:Patient controlled Inhalation Analgesia with
Sevoflurane.
 PCEA:Patient Controlled Epidural Analgesia.
 CI-PCEA:Computer Integrated PCEA.
 CI-AMB:Computer Integrated Automated
Mandatory Boluses.

 Acoustic Puncture Assisted Devices for
identifying epidural space.
 Ultrasound guided epidural anaesthesia.
 Transverse abdomen plane block(TAP block).
 EREM:Extended Release Epidural Morphine.

WATER IMMERSION
 Involves immersing the parturient in warm water deep
enough to cover the abdomen.
 This is thought to enhance relaxation and reduce
labor pain.
 Parturient may remain in the bath for a few minutes to
hours during first stage of labor.
 Water is kept at or slightly above the body
temperature.
 This is done to avoid increasing the mothers core
temperature.
 Analgesia is provided due to the warmth,influencing
nociceptive input to brain.

 Validation:
-Water immersion may be offered during first stage
of labor to:
-Healthy parturients.
-Uncomplicated pregnancies.
-Between 37-41 weeks gestation.
-Hydrotherapy is usually safe,but used cautiously
due to risk of infection.

HYPNOSIS
 Technique aims at the attainment of an altered state
of consciousness.
 This prevents normal feelings such as pain from
reaching the conscious mind.
 Induction of altered state is through the patient itself
or the partner.
 Methods used to induce hypnosis include:
-Guided imagery.
-Relaxation audio tapes.
 Modulates pain via suppression of neural activity in
the anterior cingulate gyrus.
 This method is contraindicated in patients with
previous history of psychosis.

 Validation:
-It can be used as an adjunct to pharmacological or
epidural analgesia.
-Patients using hypnosis usually donot require
pharmacological analgesia.

ACUPUNCTURE
 Form of traditional medicine which deals with a specific
type of energy,Qi.
 Involves placementof needles at specific points on
body,called acupuncture points.
 Placement of these needles at specific points on body
depends on:
-Degree and location of pain.
-Stage of labor.
-Level of maternal fatigue.
 Validity:
-Acupuncture was associated with superior pain relief.
-Acupuncture also reduces the requirement for
pharmacological analgesia.

BIOFEEDBACK
 Trains the patient to gain control over physiological
responses.
 This is done using electronic instruments.
 This enables patient to consciously regulate both
psychological and physical processes.
 Validation:
-Doesnot appear to be effective in reducing labor pain.
-Most patients treated with biofeedback require
additional analgesia.
-Thus,it may be attempted as an analgesic adjuvant.
-At present,there is insufficient evidence that
biofeedback is effective.

TRANSCUTANEOUS ELECTRICAL NERVE
STIMULATION(TENS)
 Involves transmission of low-voltage
electrical impulses to skin via surface
electrodes.
 Impulses are generated with the help of a
hand held battery powered generator.
 Parturient is allowed to adjust the
frequency,intensity and waveform of
impulses.

 Mechanism of action:
-Relieves pain through gate-control theory.
-Nociceptive inhibition at presynaptic level in
dorsal horn.
-Inhibits propagation of nociception along
unmyelinated small fibres.
-Blocks impulses to target cells in sustantia
gelatinosa.
-Stimulates release of endorphins in the brain.

 Method:
 One pair of electrodes is placed paravertebrally between
T10-L1.
 The second pair is placed at the level of S2-S4.
 The parturient controls the intensity of current using a dial.
 Continuous stimulation is self-applied during contractions.
 Intermittent,pulsing stimulation is used in between
contractions.
 Stimulation causes a buzzing or pricking sensation.
 This reduces the awareness of contraction pain,thus
providing analgesia.

 Validity:
 May provide analgesia during 1st stage of labor.
 Traditionally used as an analgesic adjuvant,not a
sole analgesic.
 Found to have no benefit when used as an
adjuvant to epidural analgesia.

LAMAZE PHILOSOPHY
 Developed by French obstetrician Dr.Fernand Lamaze.
 This is a technique of psychoprophylaxis.
 Follows the philosophy that child-birth is a normal,natural and
healthy process.
 Breathing and relaxation techniques are employed by
parturients.
 Health practices adopted during labor include:
-Labor is allowed to begin on its own.
-Walking,moving around and changing positions is
recommended.
-Interventions that are not medically necessary are avoided.
-Rooming in of mother and baby is an important part of the
Lamaze philosophy.

THE BRADLEY METHOD
 Described by Dr. Robert Bradley, an obstetrician in 1965.
 Focuses on methods to achieve natural birth without the use of:
- Surgery
-Medication
-Medical intervention
 Revolves around the principle that birth is a natural process.
 Advocates that babies should be brought into the world in an ideal state.
 Husbands play an important part in this technique .
 Husbands are taught to coach their partner in:
- Deep breathing and concentrated awareness during labor.
-Ensuring a distraction free environment during childbirth.
 Does not support the use of labor analgesia or any other medications during
labor.

PHARMACOLOGICAL ANALGESIA
MEPERIDINE:
 Most commonly used parenteral opioid.
 Dose:
-Intermittent boluses:
.50-100 mg IM given Q4H.
.Onset of action 30-45 minutes.
.Duration of action 2-3 hours.
-IV-PCA:
.Bolus dose 15 mg.
.Lockout interval 10 minutes.

 Clinical utility:
-Less than 20% parturients experience effective
analgesia.
-Other opioids may provide better relief compared with
meperidine.
-Still remains the most commonly used opioid for labor
analgesia worldwide.
-Associated with significant maternal and fetal side
effects:
Maternal side effects:
.Seizures.
.Drug interactions.

 Fetal side effects:
.Associated with prolonged fetal side effects.
.This is due to generation of nor-meperidine.
.Greatest risk if meperidine is given 3-5 hours prior to
delivery.
.Least risk if administered 1 hour before delivery.
.Side effects may be seen up to 72 hours after
delivery.
.Fetal side effects include:
-Low APGAR scores.
-Reduced fetal aortic flow.
-Reduced fetal muscular activity.
-Loss of beat-to-beat variability in FHR tracings.

FENTANYL
 Analgesic efficacy:
-100 times that of morphine.
-800 times that of meperidine.
 Dosage:
.50-100 microgram IV once every hour or 1 microgram/kg.
.Onset of action 3-5 minutes.
.Duration of action:30-60 minutes.
-PCA regimen:
.Loading dose of 50-100 microgram.
.Patient controlled dose of 10-25 microgram.
.Lockout interval of 10-12 minutes.

 Can be given IV,SC,orally or transdermally.
 Preferably used as PCIA due to:
-Rapid onset.
-High potency.
-Good analgesia.
-Short duration of action.
-Absence of active metabolites.
-Provides an attractive alternative due to pharmacokinetic profile.
-Effectively used in IV-PCAs for analgesia.
-Less effective when used as intermittent boluses.
 Provides reasonable analgesia with:
-Minimal neonatal depression.
-Minimal maternal sedation.
-Reduced vomiting.

MORPHINE
 Twilight sleep:
-Refers to historical use of morphine with
scopolamine during labor.
-Good analgesia is seen in the presence of maternal
and fetal depression.
-Technique is associated with:
.Delirium,extreme agitation.
.Sedation,amnesia.

 Dosage:
-5-10 mg IM:
.Time of onset 20-40 minutes.
-2-5 mg IV:
.Time of onset 3-5 minutes.

-Good analgesia with morphine is usually obtained
only at higher doses.
-There is a lack of analgesic efficacy seen at non-
sedating doses.
-Therefore,not very commonly used for labor
analgesia.

 Morphine administration is associated with
neonatal and maternal side effects.
 Morphine is not routinely used as an infusion in
PCA’s for labor analgesia.
 This is because of morphine-6-glucuronide
accumulation.
 M-6-G can inturn cause maternal and fetal
respiratory depression.

REMIFENTANYL
 Ultra short acting opioid with rapid onset and
offset of action.
 Rapid metabolism occurs by maternal non-
specific esterases.
 This accounts for the ultra short duration of
action.
 Mostly used in IV-PCA regimens.

 Dose:
-Bolus dose 15-50 microgram (0.3- 0.5 microgram/kg).
-Lock out interval of 3-5 minutes.
-Onset of action 30-60 seconds.
-Peak action:2.5 minutes.

-Bolus dose is self administered at the beginning of
one contraction.
-Effect of this dose usually lasts during the
subsequent contraction.
-However,it remains an inferior alternative to epidural
analgesia.
-May be used in patients whom epidural is
contraindicated.

 Side effects:
-Major adverse effects are rare due to short duration
of action.
-Respiratory depression is possible due to frequent
boluses.
-Overall,fetal side effects are lesser as compared
with meperidine.

NALBUPHINE
 Mixed agonist-antagonist opioid analgesic.
 Agonist-antagonist:
-Partial κ agonist.
-μ antagonist.
-Minimal affinity.
 Analgesic potency of nalbuphine is comparable with morphine.
 However,the respiratory depressant effect shows a ceiling effect.
 Nalbuphine dose beyond 0.5mg/kg fails to increase respiratory
depression.
 This is due to the mixed receptor affinity of nalbuphine.

 Dosage:
.10-20mg IV /IM/SC Q4-6H.
.Onset of action 2-3 minutes following IV
injection.
.Onset of action 15 minutes following IM/SC
injection.
.Duration of action up to 3-6 hours.
-IV-PCA:
.Bolus dose 1mg.
.Lockout interval 6-10 minute.

-Analgesia is comparable to that produced by
meperidine.
-Associated with lesser nausea and
vomiting,compared with meperidine.
-It is not routinely used for labor analgesia.
-Intermittent nalbuphine boluses is used when
epidural and PCA are not options.

BOTORPHANOL
 Agonist:antagonist:
-Partial κ agonist.
-μ antagonist.
-Minimal alpha affinity.
 Pharmacodynamic properties resemble that of nalbuphine.
 Similar to nalbuphine,respiratory depressant effect has ceiling
effect.
 Beyond a 2mg dose,respiratory depression action of
butorphanol plateaus.
 Analgesic potency:
-5 times as potent as morphine.
-40 times as potent as meperidine.

 Dosage:
-1-2 mg IM/IV.
-Duration of action 4 hours.
-Produces analgesic effect comparable to
meperidine.
-However,adverse effects are fewer compared with
meperidine.
-Not routinely used for labor analgesia.

PHENOTHIAZINES
 Most commonly used phenothiazine is
promethazine.
 25-50 mg IV/IM promethazine is used
clinically.
 This dose results in profound sedation and
respiratory stimulation.
 The respiratory stimulation is useful to
counter opioid induced depression.

Clinical utility:
 Rarely used nowadays as the sole analgesic.
 Used most commonly in combination with opioids
for:
-Additive sedation.
-Prevention of nausea and vomiting.
-Respiratory stimulation.
 Disadvantages:
-Produces profound maternal sedation.
-Can cause variation in FHR.

KETAMINE
 Potent analgesic which preserves airway reflexes.
 However,increase in airway secretions may cause laryngospasm.
 Dosage:
-Intermittent boluses;
.0.2 -0.5 mg/kg IV.
.Can be repeated every 2-5 minutes up to total of 1mg/kg in 30 minutes.
-Continuous infusion:
.Bolus dose 0.1mg/kg.
.Followed by infusion of 0.2mg/kg/hour titrated to effect.
-Rarely used as the sole analgesic agent.
-Usually used to supplement incomplete neuraxial block.
-Causes hypertension and psychomimetic effects.
-Therefore,it is not routinely used for labor analgesia.

TRAMADOL
 It is an atypical weak synthetic opioid.
 Has a low μ receptor affinity.
 10% as potent as morphine.
 Dosage:
-1-2mg/kg IV/IM
-Onset of action within 10 minutes of IV
administration.
-Duration of action 2-3 hours.

-Not very useful for labor analgesia.
-Analgesic profile is inferior to meperidine.
-Causes more nausea and vomiting
compared with meperidine.
 Causes no clinically significant respiratory
depression at normal doses.

BENZODIAZEPINES
 Clinical utility:Not routinely used as:
-High incidence of maternal and fetal side effects.
-Non-preference for a sedated parturient in active labor.
 Maternal side effects:
-Sedation,hypnosis.
-Cyanosis and amnesia.
 Fetal side effects:
-Neonatal hypotonicity.
-Respiratory depression.
-Impaired thermoregulation.

MEPTAZINOL
 Mixed agonist-antagonist activity.
 Partial opioid agonist at μ receptors.
 Dosage:
-100 mg IM.
-Onset of action 15 minutes after IM
administration.
-Duration of action 2-3 hours.

-Produces less neonatal depression
compared with meperidine.
-Analgesic profile is also better than
meperidine.
-However,it is neither widely available nor
used for labor analgesia.

INHALATIONAL ANALGESIA
ENTONOX:
 50% N20:O2 mixture.
 Was used both as sole analgesic and as adjuvant earlier.
 Maximal effect after 45-60 mins.
 Important to use Entonox at early onset of contraction.
 Use discontinued after peak of contraction.
 Causes nausea,dizziness,dysphoria,lack of cooperation.
 OT pollution.
 Not routinely used.
 Used now as adjuvant or when regional analgesia not
possible.

VOLATILE ANAESTHETICS:
 Not routinely used.
 Sevoflurane 0.8% most commonly used.
 Isoflurane and enflurane(0.2-0.25%) and
desflurane(0.2%).
 Causes more intense sedation,unpleasant smell,OT
pollution.
 Unconsciousness and loss of airway reflexes occur if
accidental overdose.
 PCIA uses sevoflurane and special vapourizes.

REGIONAL ANAESTHESIA
EPIDURAL ANALGESIA
 Indicated when patient is in active labor:
 Cervix 5-6cm dilated in primigravida.
 Cervix 3-4 cm in multigravida.
 Required level of analgesia:
 T10-L1 level required for 1st stage of labor.
 S2-S3 level required in 2nd stage of labor.

 Advantages:
 Good analgesia.
 Stable therapeutic analgesic level without
fluctuations in pain relief.
 Minimizes motor block:allows greater patient
mobility.
 Minimizes hypotensive episodes.
 Reduces stress response.
 Avoids parenteral drug therapy.

 Disadvantages:
 Subarachnoid puncture or migration of
catheter.
 Longer time for onset of analgesia.
 Catheter related infections.

EPIDURAL ANALGESIA REGIMEN
 INITIAL BOLUS:
-10-15 ml bupivacaine 0.0625-0.125% with 50-100
microgram fentanyl.
-10-15 ml ropivacaine 0.1 -0.2% with 50-100
microgram fentanyl.
 MAINTAINENANCE DOSE:
-Bupivacaine 0.0625 -0.125%with fentanyl 1-
2microgram/ml at 10-15 ml/hour.
-Alternatively,intermittent boluses may be injected as
per requirement.

PAIN CONTROLLED EPIDURAL ANALGESIA
REGIMEN
 INITIAL BOLUS:
-10-15 ml bupivacaine 0.0625-0.125% with 50-100microgram
fentanyl.
-10-15 ml ropivacaine 0.1 -0.2% with 50-100 microgram fentanyl.
 MAINTENANCE:
-Basal infusion of 5-10 ml/hour 0.0625%-0.125% bupivacaine.
-Demand bolus of 5-10 ml 0.0625 -0.125% bupivacaine.
-Lockout interval of 5-15 minutes.
-Total 1 hour lockout of 20-25 ml 0.0625-0.125% bupivacaine.

SUBARACHNOID BLOCK
 Clinical utility:
 Useful as it provides immediate analgesia of a wider
dermatome(T10-S5).
 Effective alternative when placement of epidural catheter
is not feasible.
 Single shot spinal analgesia is rarely indicated.
 Continuous spinal analgesia is avoided due to high risk
of complications.
 Therefore,SAB is rarely used outside the premise of
operative delivery.

 Spinal analgesia is useful for:
 Multiparous women in rapidly progressing labor.
 Primipara in advanced labor(fully dilated and
significant pain).
 High likelihood of emergent operative delivery.
 Following accidental dural puncture during
epidural analgesia.
 When epidural catheter placement is technically
difficult;
-Patients with abnormal anatomy.
-Post extensive spine surgery.

 Saddle block(sacral-only anaesthesia):
 Indications:
-Forceps delivery.
-Repair of vaginal/rectal tears postpartum.
-Removal of placenta.
 Regimen used for saddle block;
-Hyperbaric bupivacaine 4-5 mg.
-Hyperbaric lidocaine 15-20 mg.
-Hyperbaric tetracaine 3mg.
-Opioid additive can be used with the local anesthetic:
.Fentanyl 10-25 microgram.
.Sufentanil 2.5-5 microgram.
 Injection of the drug is followed by the patient sitting up to establish block.
 This allows accomplishment of sacral-only anaesthesia.

 Continuous spinal analgesia:
 Rarely used due to high incidence of
complications.
 Usually performed using 19-20 G epidural
catheters.
 The placement of these catheters requires 17-18
G spinal needles.
 But the risk of PDPH is increased in this case due
to larger dural rent.
 28-32 G microcatheters are rarely used due to risk
of cauda equina syndrome.

 Regimen:
-Induction of analgesia is with hyperbaric bupivacaine 2.5-7.5 mg.
-Maintenance:
.Intermittent boluses:
-0.5-1.5 ml 0.1-0.25% bupivacaine.
-10-20 microgram fentanyl may be added to the injection.
.Continuous infusion:
-0.0625-0.125% bupivacaine with 2 microgram/ml fentanyl.
-Continuous infusion given at 1-5ml/hour.

 Advantages:
-Provision of rapid analgesia.
-Allows flexibility in dosing.
-Limits degree of sympathectomy and hypotension.
 Disadvantages:
-Risk of PDPH as large needles are used for insertion of the
catheter.
-Cauda equina syndrome: more common with:
.Use of intrathecal lidocaine.
.Use of high concentrations of lidocaine.
.Use of finer gauge microcatheters(28-32 G).
.Continuous infusions(rather than intermittent boluses).
.This causes drug pooling around nerves of the cauda equina.

COMBINED SPINAL EPIDURAL
 Includes intrathecal injection of drugs to
initiate spinal analgesia.
 This is followed by insertion of epidural
catheter to allow:
 Maintenance of analgesia.
 Conversion to surgical anaesthesia.

 CSE regimens commonly used:
 Initial spinal injection:
-2.5-10 microgram sufentanyl or 10-25 microgram fentanyl
alone or combined with 1-2.5 mg plain bupivacaine.
-This provides initial analgesia for approximately 60-90
minutes.
 Maintenance analgesia:
-Usually 0.0625-0.125% bupivacaine with 2 microgram/ml
fentanyl used.
-Alternatively 0.08-0.1% ropivacaine with 2g/ml fentanyl can
be used.
-Alternatively,continuous infusion at 8-15 ml/hour can be used.

 Indicated in:
 Very early stage of labor when local anaesthetics are
avoided.
 Advanced stage when rapid analgesia is required.
 Difficult epidural as it reduces failure rate of epidural.
 Methods of CSE:
 Epidural catheter followed by SAB at lower interspace.
 Epidural needle besides spinal needle at same
interspace.
 Needle through needle technique at same interspace.

 Advantages:
 Rapid onset of analgesia within 5 minutes.
 Duration of action of subarachnoid block 2-3 hours.
 Absence of significant motor block in most of the cases.
 Makes ambulation possible due to limited motor block.
 Reduces complications of epidural anaesthesia:
-Patchy block.
-Poor sacral spread.
 Reduces duration of 1st stage of labor.
 Same catheter can be used for operative anaesthesia if
required.

 Disadvantages:
 Potential for complications arising due to deliberate dural
puncture.
 Risk of total spinal:
-Epidural catheter remains untested at the time of insertion.
-This is because spinal injection during insertion precludes
testing.
-Thus,subsequent epidural injection has to be done
cautiously.
 Inadvertent spread of local anaesthetic through dural rent into
CSF fluid.
 Complications due to intrathecal administration of opioids.
 Increased risk of maternal respiratory depression.
 Increased incidence of fetal bradycardia.

CAUDAL ANESTHESIA
 Rarely used,unless lumbar epidural is
contraindicated or technically difficult.
 However,it remains a useful option for
analgesia once labor is established.

 Double catheter technique:
 Used in the past.
 Lumbar epidural catheter was placed for early
labor analgesia.
 Caudal epidural was placed to ensure
analgesia at the time of delivery.
 This allowed higher dermatomal analgesia(T10-
L1) during early labor.
 During later stages caudal activation permits
parturient to feel contractions.
 At the same time,profound perineal analgesia is
provided.

 Regimen:
 10-15 ml bupivacaine 0.0625-0.125% with
50-100 microgram fentanyl.
 10-15 ml ropivacaine 0.1-0.2% with 50-100
microgram fentanyl.
 15-20 ml local anaesthetic volume is
required to ensure a block level upto T10.

 Advantages:
 Onset of perineal analgesia is more
rapid,compared with lumbar epidural.
 Allows parturient to feel uterine contractions.
 At the same time it provides dense perineal
analgesia.
 Disadvantages:
 Associated with higher incidence of CNS
toxicity.
 Inadequate during early phases of labor.

PARACERVICAL BLOCK
 Can be used as an alternative when neuraxial blockade
contraindicated.
 Technique:
-Local anaesthetic injected submucosally into fornix for
vagina,lateral to cervix.
 Injections are carried out at 3 and 9 o’clock positions.
 5-10 ml of 1.5% chloroprocaine or 1% mepivacaine is
used.
 Bupivacaine is avoided due to high incidence of maternal
systemic absorption.

 Blocks transmission through the paracervical ganglion.
 This is also called frankenhauser’s ganglion.
 This ganglion carries visceral nerve fibres from;
-Uterus,cervix.
-Upper vagina.
 Thus,it is very effective during the first stage of labor.
 However,somatic sensory fibres from the perineum are not
blocked.
 Thus,it is ineffective during the second stage of labor.
 Rarely used nowadays due to fetal bradycardia.

 Advantages:
 Provides good analgesia during 1st stage of labor.
 Simple to perform,doesnot affect progress of labor.
 Disadvantages:
 No pain relief offered during 2nd stage of labor.
 Close proximity of injection site to uterine artery
makes it technically difficult.
 Relatively high incidence of fetal bradycardia.

 Complications;
 Profound fetal bradycardia.
 Local anaesthetic systemic toxicity.
 Postpartum neuropathy.
 Infection.

PUDENDAL NERVE BLOCK
 Usually administered during second stage of labor.
 Alleviates pain from lower vagina and perineum.
 However,clinical efficacy is limited compared to neuraxial
analgesia.
 Thus,rarely used for labor analgesia nowadays.
 However,it also causes motor blockade of:
-Perineal muscles.
-External anal sphincter.

 Technique:
 Through transvaginal approach in lithotomy position.
 Ischial spine is palpated transvaginally/transrectally.
 Needle guide is placed under ischial spine.
 20G needle is passed through the guide until tip lies on the
vaginal mucosa.
 Needle is advanced 1-1.5 cm,piercing the sacrospinous
ligament.
 10 ml of 1% lidocaine or mepivacaine,or 2%
chloroprocaine is injected.
 Local anaesthetic is therefore deposited behind
sacrospinous ligament.
 The procedure is repeated on the opposite side.

 Satisfactory analgesia for:
 Spontaneous vaginal delivery.
 Outlet forceps delivery.
 Vaccum delivery.
 Not useful for:
 Mild-pelvic forceps delivery.
 Repair of cervical or upper vaginal laceration.
 Manual removal of retained placenta.
 Complications:
 LAST
 Infection
 Hematoma
 Sciatic nerve block.

LUMBAR SYMPATHETIC BLOCK
 Bilateral lumbar sympathetic block may be used
during first stage of labor.
 This must be supplemented during second stage of
labor with:
-Pudendal nerve block.
-Spinal analgesia.
 Rarely used nowadays unless epidural analgesia is
contraindicated.

 Technique:
 Technically difficult to perform.
 Performed at the level of L2, using 22G,10 cm
needle.
 Transverse spinous process is used as the
landmark to guide needle placement.
 Injection is performed anterior to medial attachment
of psoas muscle.
 Injection is performed on both sides.
 Total of 20 ml 0.0625-0.125% bupivacaine is divided
between the 2 sides.

 Advantages
 Fewer complications than paracervical block.
 Useful when epidural analgesia has failed due
to prior spine surgery.
 Disadvantages:
 Technically more difficult to perform.
 More painful needle placement.
 Doesnot provide second stage analgesia.
 Accelerates first stage of labor.
 Thus,it should be used cautiously in rapidly
progressive labor.

REFERENCES
 Morgan and mikhail,s clinical
anaesthesiology.
 Kaushik Jothinath Anaesthesia Review.

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