2. PAIN PATHWAYS IN LABOUR AND
CAESAREAN SECTION
• The afferent nerve supply of the
uterus and cervix is via A8 and C
fibers that accompany the
thoraco-lumbar and sacral
sympathetic outflows.
• First stage of labor = uterus and
the cervix = T10, 11, 12 and LI.
• Pain of distension of the birth
canal and perineum = S2-S4
nerves.
• Caesarean section = block T4 +
the sacral roots (S1-S5).
3. Pain
↓ Placental blood flow.
less effective uterine
contractions
↑ Catecholamine ↑
myocardial work and arterial
pressure + peripheral VC.
↑ adreno-cortical
hormones electrolyte,
carbohydrate and protein
metabolism.
The ideal analgesic
The ideal analgesic
Rapid-onset
Effective pain relief in 1st and
2nd stages
No side-effects to mother or
fetus
Preserve mother's ability to
strain.
4. LABOUR ANALGESIA
• non-pharmacological
• Parenteral
• inhalation
• Regional.
Non-pharmacological analgesia
• Birth preparation classes
• Environment and the management of labor
• Transcutaneous electrical nerve stimulation (TENS)
• Hypnosis
5. Parenteral (systemic) analgesia pethidine
• Many opioids pethidine, morphine …..
Pethidine
• Two doses of 100 mg.
• Intramuscular injection maximum effect after 1 h.
• The analgesic effects are variable
Adverse effects on mother
Maternal sedation
Nausea and vomiting
Dysphoria
Inhibition of gastric
emptying.
Adverse effects on the fetus as it
freely crosses the placenta
CTG abnormalities and
Respiratory depression
Neurobehavioural
depression
6. Inhalation analgesia Nitrous oxide
• The ideal inhalation agent
• Good analgesic in sub-anesthetic doses.
• Rapid onset of action and recovery and not accumulate.
• Nitrous oxide is relatively insoluble in blood and has
these properties.
• Isonox 50% nitrous oxide and 50% oxygen with 0.2%
isoflurane.
• Entonox 50% nitrous oxide and 50% oxygen under
pressure in a cylinder
• Entonox on-demand valve with a face mask or
mouthpiece.
• Although Entonox is a reasonably effective analgesic,
many women feel faint and nauseated and may vomit or
become out of control.
7. Regional analgesia for labor
• The most effective form of analgesia in labor.
• 90% women complete or near-complete pain relief.
• it is invasive and require careful monitoring.
Contraindications to epidural
analgesia in labor
Maternal refusal
Bleeding disorders
Sepsis in the lumbar area and
systemic sepsis
Local infection epidural
abscess.
systemic infection or systemic
inflammatory response syndrome
(SIRS)
Indications for epidural analgesia
Maternal request
Occipitoposterior presentation
pre-eclampsia
Prematurity or IUGR
Intrauterine death
Induction of labor
Instrumental or caesarean delivery likely
Previous caesarean delivery
Presence of significant concurrent disease
(e.g. heart disease,diabetes, hypertension)
Twin pregnancy
8. Dose
1 - Test dose+ maintenance
test dose small dose of local anesthetic 2 ml 2% lidocaine or 3 ml
0.5% bupivacaine to check for inadvertent intrathecal or vascular
placement Hypotension or profound motor block
Maintenance 0.1% bupivacaine/fentanyl 2 ug /ml may be used.
2- Boluses from the start
A 15 ml bolus 0.1% bupivacaine/fentanyl 2 ug /ml 15 mg bupivacaine
in total.
Bupivacaine 0.25% given in 10 ml boluses has been standard practice
10-15 ml boluses 0.1% bupivacaine/fentanyl 2 ug /ml in
The lower concentration ↓hypotension + ↑ ability to walk.
The disadvantage of boluses is the possibility of intermittent pain if
top-ups are not administered at appropriate intervals.
9. 3 - Continuous infusion by syringe pump. 0.1%
bupivacaine/fentanyl 2 ug /ml a rate of 10 ml/ h.
4 - Patient-controlled epidural analgesia (PCEA).
Initial bolus dose 0.1% bupivacaine/fentanyl 2 ug /ml
and maintaining analgesia by allowing the patient to
self-administer boluses of analgesic solution as
required by depressing a button on a special
computer-controlled volumetric syringe. There may or
may not be a low-dose background infusion.
The advantage more control to the patient and
reduced total analgesic consumption
10. Problems maintaining epidural analgesia
• Epidural is not effective.
• If the epidural is not providing good analgesia within 15-20 min
with 15 ml 0.1% bupivacaine/fentanyl 2 ug /ml or 10 ml of 0.25%
bupivacaine, the catheter is probably not in the epidural space
and it should be withdrawn and re-sited.
• Missed segment or unilateral block. Groin pain is
the most common manifestation small bolus,
e.g. 5 ml of 0.25% bupivacaine.
• Hypotension. exclude aortocaval compression+
Intravenous fluids + ephedrine
11. CSE for labour and the 'walking' epidural
• intrathecal injection of 1 ml 0.25% bupivacaine with 25
ug fentanyl is given.
• rapid-onset analgesia (< 5 min) and approximately 70%
of patients
• have normal or near-normal leg power such that they
may walk.
• commencing with a 15 ml bolus of bupivacaine 0.1%
bupivacaine/fentanyl 2 ug /ml without a test dose, as
described above. potentially making walking hazardous.
• The medicolegal position of the anesthetist in the
event of a fall of a parturient during a walking epidural
is unclear.
