This document provides an overview of obstetric anaesthesia and analgesia. It describes the pain pathways of labour and delivery, including that the first stage is visceral pain conducted by C fibers, while the second stage is somatic pain conducted by A-delta fibers. It discusses various techniques for labour analgesia including non-pharmacological methods, pharmacological methods like nitrous oxide and narcotics, and regional techniques like epidural, spinal, combined spinal-epidural and continuous spinal analgesia. The advantages, disadvantages and complications of different analgesic methods are outlined.

1. OBSTETRIC ANAESTHESIA
AND ANALGESIA
Dr. Ayesha Sherzada
FCPS Resident – OBGYN
THE INDUS HOSPITAL.
Karachi, Pakistan.

2. OBJECTIVES
 Describe the pain pathways of labour and delivery.
 Describe labour analgesic techniques.
 Describe the advantages, disadvantages and
complications of regional analgesia.
 Describe the advantages, disadvantages and
complications of epidural, spinal, CSE and general
anaesthesia.

3. Does Labor Pain
Need Analgesia?

4. Analgesia for Labor and
Delivery
Always controversial!
• “Birth is a natural process”
• Concerns for mother’s safety
• Concerns for baby
• Concerns for effects on labor

5. The Physiology of Pain in Labor
 1st stage of labor – mostly visceral
◦ Dilation of the cervix and distention of the
lower uterine segment
◦ Dull, aching and poorly localized
◦ Slow conducting, visceral C fibers, enter
spinal cord at T10 to L1
 2nd stage of labor – mostly somatic
◦ Distention of the pelvic floor, vagina and
perineum
◦ Sharp, severe and well localized
◦ Rapidly conducting A-delta fibers, enter
spinal cord at S2 to S4

6. Pain Pathways of Labor

7. Labor
Respirat
ory &
Cardiova
scular
Gastro-
intestina
l &
Urinary
Neuro-
endorcin
e
Post-
traumati
c Stress
Syndro
me

8. Potential effects of maternal hyperventilation and subsequent
hypocarbia on oxygen delivery to the fetus

9. Effects of labor pains
Severe and prolonged pain is associated with
sympathetic autonomic hyperactivity, increased
maternal heart rate and blood pressure,
vasoconstriction, increased oxygen consumption and
reduced fetal oxygenation.
Dewhurst's textbook of OBGYN

10. Pain relief in labor
Uterine contractions in labour are associated with
pain. Professionals can help to reduce women’s
fears by giving precise, accurate and relevant
information antenatally including the types of
analgesia available in their unit.
oxford handbook of OBGYN.

11. Ideal pain relief in labor
SHOULD:
• Provide good analgesia.
• Be safe for mother and baby.
• Be predictable and constant in its effects.
• Be reversible if necessary.
• Be easy to administer.
• Be under the control of the mother.
SHOULD NOT:
• Interfere with uterine contractions.
• Interfere with mobility.
oxford handbook of OBGYN.

12. What Are the Types of
Labor Analgesia?

13. Types of labor analgesia
1. Non-pharmacological analgesia
2. Pharmacological analgesia
3. Regional analgesia

14. Non-pharmacological analgesia
• Transcutaneous electrical nerve
stimulation (TENS)
• Relaxation/breathing techniques
• Temperature modulation: hot or cold
packs, water immersion
• Hypnosis
• Massage
• Acupuncture
• Aromatherapy
EVIDENCE-BASED TEXT FOR THE MRCOG

15. Pharmacological analgesia
• Nitrous oxide (Entonox):
Entonox is premixed NO and O2 as a 50:50 mixture. It is self-
administered and has quick onset of action and a short half-life.
Side effects include feeling faint, nausea and vomiting.
• Narcotic agents:
o Pethidine is administered at a dose of 50-150mg, onset of action
is 15-20mins, lasts for 3-4 hrs, usually given with an antiemetic.
If given within 2 hrs of delivery, can cause neonatal respiratory
depression and naloxone may be needed.
o Diamorphine is also used in some units at a dose of 2.5-5mg.
There is controversy about the extent and timing od neonatal
respiratory depression, but it may be up to 3-4 hrs after last
dose.
o Meptazinol, opioid, has onset of action in 15 mins and lasts for2-
7 hrs.
EVIDENCE-BASED TEXT FOR THE MRCOG

16. Regional analgesia and anesthesia
 Epidural
 Spinal
 Combined Spinal Epidural (CSE)
 Continuous spinal analgesia
 Paracervical block
 Lumbar sympathetic block
 Pudendal block
 Perineal infiltration
EVIDENCE-BASED TEXT FOR THE MRCOG

17. Epidural Analgesia
• Provides excellent pain relief
reducing maternal
catecholamines.
• Ability to extend the duration
of block to match the
duration of labor
• Blunts hemodynamic effects
of uterine contractions:
beneficial for patients with
preeclampsia.

18. Indications of LEA
 PAIN EXPERIENCED BY A WOMAN IN LABOR
 When medically beneficial to reduce the stress of
labor
 ACOG and ASA stated
“ in the absence of a medical contraindication,
maternal request is a sufficient medical indication
for pain relief…”

19. ADVANTAGES OF EPIDURAL ANALGESIA
• It provides effective analgesia in labour.
• Reduced maternal secretion of catecholamines, which
benefits the fetus.
• Can be used when topped up for an operative delivery and
for any complications of the 3rd stage of labour, e.g. retained
placenta or repair of perineal tears.
• Can provide effective postoperative analgesia.
• Can be used as an additional method of controlling blood
pressure in pre-eclampsia.
oxford handbook of OBGYN.

20. Disadvantages and complications of
epidural analgesia
• Failure to site, or a patchy or incomplete block.
• Hypotension from sympathetic blockade.
• Decreased mobility.
• Tenderness over the insertion site; however, there is no
association between epidural analgesia and long-term
backache.
• Inadvertent dural puncture
• Respiratory depression.
• Extremely rare complications resulting in neurological deficits.
• Increased risk of operative delivery
oxford handbook of OBGYN.

21. Contraindications to epidural analgesia
Absolute
• Maternal refusal
• Lack of prsonnel/facilities
• Pre-existing coagulopathy
• Local infection at insertion site.
• Raised intracranial pressure (risk of coning)
• Drug allergy.
Relative
• Haemodynamic instability.
• Anatomical abnormalities.
• Neurological disorders (medicolegal implications)
• Systemic infection.
Dewhurst's textbook of OBGYN

22. Anatomy
• Epidural space lies b/w spinal dura
and vertebral canal.
• Space contain spinal nerve roots,
spinal arteries and extradural veins.
• Usual distance b/w skin and epidural
space in lumbar region in adults is
about 4-5cm.
• Epidural space is continuous the
whole way down the back.
• The lumbar region is chosen for the
provision of labour analgesia.
oxford handbook of OBGYN.

23. Pre-requisites for epidural analgesia
 Obstetrician is consulted and confirmed LEA
 Pre-anesthetic evaluation is performed/verified
 Pt’s (and only patient’s) desire to have LEA is reconfirmed with
informed consent.
 Pt’s understanding of risks of LEA is reconfirmed
 Fetal well-being is assessed and reassured
 Supporting personal is available and present

24. Pre-requisites for epidural analgesia
• Resuscitation equipment and
drugs are immediately available
in the area where LEA placed

25. Standard Technique of LEA
1. Pre epidural check list is completed
2. Aspiration prophylaxis
3. Intravenous hydration (what? When? How?)
4. Monitoring
 BP every 1 to 2 min for 20 min after injection of
drugs
 Continuous maternal HR during induction ( e.g.,
pulse oximetry)
 Continuous FHR monitoring
 Continual verbal communication

26. Standard Technique of LEA
 Maternal position ( sitting or lateral?)

27. Comparison of Sitting and Lateral Positions
for Performing Spinal or Epidural Procedures
Sitting Lying (left lateral)
Advantages
• Midline easier to identify in obese
women
• Obese patients may find this position
more comfortable
• Can be left unattended without risk of
fainting.
• No orthostatic hypotension
• Uteroplacental blood flow not
reduced (particularly important in the
stressed fetus)
Disadvantages
• Uteroplacental blood flow decreased
• Orthostatic hypotension may occur
• Increased risk of orthostatic
hypotension if Entonox and pethidine
have been administered
• Assistant (or partner) needed to
support patient
May be more difficult to find the
midline in obese patient

29. Remifentanil PCA
 An alternate to epidural analgesia, in whom EA is
contraindicated and who are not able to obtain
adequate analgesia from more conventional
mehods such as nitrous oxide.
 Remifantanil is a powerful opiate, rapidly
metabolized and unable to cross the placenta.
 Its administration via a patient-controlled IV sytem
has shown promise in providing analgesia.
OXFORF HANDBOOK OF OBGYN

30. Spinal Anaesthesia/Analgesia
• Used mainly for very late in
labor because it has limited
duration of action
• Faster onset than Epidural
• Amount of local anaesthetic
used is much smaller

31. Searching For Balanced
Labor Analgesia
Ambulatory Labor
Analgesia
CSE

32. Combined spinal epidural (CSE)
• Initial reports: two interspace
technique-epidural followed by spinal
• Later evolution of CSE in the direction
of needle through needle technique
• Postdural puncture headache: 1% or
less incidence for CSE with small bore
atraumatic needles.

33. Advantages of CSE for Labor
Analgesia
 Rapid onset of intense analgesia.
 Ideal in late or rapidly progressing labor.
 Very low failure rate.
 Less need for supplemental boluses.
 Minimal motor block (“walking epidural”)

34. Espocan CSE Needle (B.
Braun)

35. Espocan CSE Needle (B.
Braun)

36. Maintenance of epidural analgesia can be achieved
by:
regular top-ups
an epidural infusion
patient-controlled epidural analgesia (PCEA).

37. Intermittent bolus injections:
• Bupivacaine: 0.125%-0.375%, 5-10 ml,
duration:1-2 hr
• Ropivacaine: 0.125%-0.25%, 5-10 ml, duration:
1-2 hr
• Lidocaine: 0.75%-1.5%, 5-10 ml, duration: 1-1.5
hr

38. Continuous Infusion of Dilute Local
Anesthetic Plus Opioid
• Better pain relief while producing less motor block.
• Maternal and neonatal drug concentrations safe.
Regimen
0.0625% - 0.08% bupivacaine with
2-3 mcg /ml fentanyl, with or without
epinephrine, infusing at 10-12
ml/hour

39. Patient Controlled Epidural Analgesia (PCEA)
Advantages:
 Flexibility and benefit of self
administration
 Ability to minimize drug dosage
 Reduced demand on professional time
Disadvantages:
 May provide uneven block
Addition of a basal infusion provides:
 More even block producing greater
patient satisfaction

40. Continuous Spinal Analgesia
• Use of spinal microcatheters restricted by FDA in
1992 due to reports of Cauda Equina Syndrome
• 28 or 32-G catheters for 22 or 26-G spinal needles
• Ongoing multi-institutional study with FDA
approval for evaluating the safety and efficacy of
delivering sufentanil and/or bupivacaine via 28-G
catheters

41. Continuous Spinal Analgesia
• Results still preliminary but it
appears safe for labor analgesia
and may offer some advantages
• Some routinely use spinal macro
catheters through standard
epidural needles for obese
parturient or parturient with
kyphoscoliosis

42. Neuraxial Labor Techniques

43. Cesarean section
With all cesarean sections, it is vital that the
obstetrician clearly communicates the degree of
urgency to all staff. A recommended classification is:
Emergency: there is immediate threat to the life of
mother or fetus.
Urgent: maternal or fetal compromise that is not
immediately life threatening.
Scheduled: no maternal or fetal compromise, but
needs early delivery.
Elective: delivery timed to suit mother and staff.
NICE GUIDELINES/ CG132

44. Cesarean section
• For all emergency cesarean
sections, the patient must be
transferred to theatre as rapidly as
possible.
• In most centres, general
anaesthesia is used when an
immediate cesarean section is
required.
• Urgent cesarean sections are
usually performed under regional
anaesthesia.
• There is an expectation that the
decision to delivery time should be
less than 30min when the indication
for cesarean section is fetal
distress.
oxford handbook of Anaesthesia

45. SPINAL
59%
EPIDURAL
23%
G.A
11%
CSE
07%
UK CESAREAN SECTION, 2011

46. ANAESTHETIC TECHNIQUES FOR
CESAREAN SECTION
 Spinal anaesthesia
 Epidural anaesthesia
 Combined spinal epidural (CSE)
 General anaesthesia
OXFORD HANDBOOK OF OBGYN

47. Spinal anaesthesia
 This technique accounts for the majority of CS
performed in the UK.
 Fasting and antacid precautions are ideal, as GA
may be required if the block is unsatisfactory.
 Good intravenous access is essential to provide
fluids rapidly to counteract hypotension that may
occur. Vasopressor drugs, such as phenylephrine or
ephedrine, should also be available.
 Hyperbaric bupivacaine 0.5% in a dose of 12.5-
15mg is usually used, together with an opiate such
as fentanyl(20mcg) or diamorphine (around
250mcg).
OXFORD HANDBOOK OF ANAESTHESIA

48. Spinal anaesthesia
o Advantages:
• Technically relatively easier than
epidurals to perform.
• Enable mother to bond immediately
with baby.
• The most reliable option for
establishing a dense, bilateral block.
o Disadvantages:
• May cause severe hypotension.
• My wear off if surgery is unexpectedly
prolonged.
OXFORD HANDBOOK OF OBGYN.

49. Epidural anaesthesia
o Advantages:
• Can be topped up to prolong the
anaesthesia, should the surgery be
extended.
• Can be used for good postoperative
analgesia.
o Disadvantages:
• Patchy or unilateral blockade.
• Takes longer to establish an adequate
block.
• Can be technically difficult to perform
with > incidence of headache in the
event of inadvertent dural puncture.
• Fatal complications in case of
misplacement.
• Larger doses of anesthesia is required.
OXFORD HANDBOOK OF OBGYN

50. Combined spinal epidural anaesthesia
o Advantages:
• Can be topped-up.
• Smaller volume of local anaesthesia is
required.
• Give postoperative analgesia.
o Disadvantages:
• Higher risk of failure.
• Higher risk of meningitis.
• Epidural component is untested and
any local anaesthetic agent must be
given in small boluses.
OXFORD HANDBOOK OF OBGYN

51. General anaesthesia
Indications for GA includes:
• Maternal request.
• Urgent surgery.
• Regional anaesthesia contraindicated (
coagulopathy, maternal hypovolaemia).
• Failed regional anaesthesia.
• Additional surgery planned at the same
time as cesarean section.
Problems with GA:
• Potential airway difficulties.
• Pulmonary aspiration of gastric
contents.
• Awareness.
OXFORD HANDBOOK OF OBGYN

52. TECHNIQUE OF GENERAL ANAESTHESIA
• History and examination.
• Antacid prophylaxis
• Appropriate monitoring.
• Position supine with left lateral tilt or wedge.
• Preoxygenate for 3-5mins.
• Intubation for adequate ventilation.
• Propofol has also been used for cesarean section without any
major reported complications, although at present thiopental
probably is still the most commonly used agent in the UK.
• Ventilate with 50% oxygen in nitrous oxide.
• At the end of procedure give an NSAID e.g. 100mg diclofenac PR.
• Extubate awake in the head-down left lateral position.
• Give additional IV analgesia as required.
OXFORD HANDBOOK OF ANAESTHESIA

53. Effect of general anaesthesia on the
fetus
• Most anaesthetic agents, except muscle relaxants, rapidly
cross the placenta.
• Thiopental can be detected in the fetus within 30sec of
administration.
• Umbilical artery to umbilical vein concentration approach
unity at 8mins.
• Opioids administered before delivery may cause fetal
depression.
• If there is specific indication for opioid before delivery, they
should be given and the paediatrician informed.
• Hypotension, hypoxia, hypocapnia and excessive maternal
catecholamine secretion may all be harmful to the fetus.
OXFORD HANDBOOK OF ANAESTHESIA

54. Local
anesthetics

55. Bupivacaine
• Standard local anaesthetic in
obstetrics
• Highly protein bound to α1-
glycoprotein and has a long duration
of action, both of which minimize
the fetal dose.
• The maximum safe dose of
bupivacaine is 3 mg/kg.

56. Levobupivacaine
• Binds to cardiac sodium channels
less intensely than
dextrobupivacaine,
• Less cardiotoxicity than bupivacaine.

57. Lidocaine
May not provide
analgesia comparable to
bupivacaine, umbilical
vein/ maternal vein ratio:
twice than bupivacaine

58. Neuraxial Opioids
• The following opioids have been used:
• Morphine, fentanyl, sufentanil, meperidine,
diamorphine.

59. Complications of Regional
Anesthesia

60. Complications of regional
anesthesia
Post Dural Puncture Headache (PDPH)
 severe, disabling fronto-occipital headache with
radiation to the neck and shoulders.
 present 12 hours or more after the dural puncture
 worsens on sitting and standing
 relieved by lying down and abdominal
compression.

61. Complications of regional
anesthesia
PDPH syndrome
1. Photophobia
2. Nausea
3. Vomiting
4. Neck stiffness
5. Tinnitus
6. Diplopia
7. Dizziness

62. Complications of regional
anesthesia
Differential diagnosis of post-dural puncture
headache in the obstetric patient:
1. Non-specific headache
2. Caffeine-withdrawal headache
3. Migraine
4. Meningitis
5. Sinus headache
6. Pre-eclampsia
7. Drugs (amphetamine, cocaine)
8. Pneumocephalus-related headache
9. Intracranial pathology (hemorrhage, venous
thrombosis)

63. Complications of regional
anesthesia
Management of PDPH
Conservative:
 Bed rest
 Encourage oral fluids and/or intravenous hydration
 Caffeine - either i.v. (e.g. 500mg caffeine in 1litre
of saline) or orally
 Regular Analgesia
 Reassurance

64. Complications of regional
anesthesia
Management of PDPH
Others
1. Theophylline
3. Sumatriptan
4. Epidural saline
5. Epidural dextran
6. Subarachnoid catheter
7. Epidural blood patch

65. Effect of epidural analgesia on
the progress and outcome of
labour
 The recently published guidelines on intrapartum
care by the UK national institute of health and
clinical excellence indicate that epidural analgesia
is:
 Not associated with a longer first stage of labour
or an increased chance of a caesarean birth
 Associated with a longer second stage of labour
and an increased chance of an instrumental birth.

66. Complications of regional
anesthesia
Neurological complications
 Needle damage to spinal cord, cauda equina or
nerve roots.
 Spinal haematoma
 Spinal abscess
 Meningitis and Arachnoiditis
 Neurotoxicity

67. Complications of regional
anesthesia
Miscellaneous
 Venous puncture e.g. of dural veins
 Catheter breakage
 Extensive block (including unplanned blocks)
 Shivering
 Backache - Long-term backache is not a
complication of neuraxial techniques.

68. Complications of regional
anesthesia
Drug side effects
 Nausea and vomiting (opiates)
 Respiratory depression (opiates)
 Anaphylaxis
 Toxicity (including intravascular injection of local
anaesthetics)

69. Conclusion
“The delivery of the infant into the arms of a
conscious and pain-free mother is one of the most
exciting and rewarding moments in medicine.”
Moir DD. Extradural analgesia for caesarean section.
Br J Anaesth 1979; 51: 1093.

70. Thank you