Regional Anaesthesia for Caesarian Section

General principles of caesarian section and general anaesthesia for caesiarian are covered separately.

Provision of regional anaesthesia for a caesarian section:

Considerations

  • E
    • BMI
      Affects technical difficulty.
    • Previous back surgery
      May make procedure harder or inadvisable.

Preparation

Adequate patient preparation and expectation management is key:

  • Discuss with patient that:
    • Spinal does not remove all sensation
    • It will be uncomfortable at certain points, and this is normal
      • Pull prior to uterine incision
      • Upper abdominal pressure to deliver baby
    • Pain should not occur
  • Sitting position preferred if patient will tolerate this
  • Premedication is acceptable for anxiolysis
    • Midazolam 0.02mg/kg

Induction and Maintenance

“It is easier to manage a high block than an inadequate one”

Covers:

Single-shot Spinal

Detailed approach to performance of spinal anesthesia is covered here.

  • Perform spinal
    Many different options for dosing. A reliable recipe (with a total volume of 3ml) is:
    • 2.2ml of 0.5% heavy bupivacaine
    • 15μg of fentanyl
    • 100μg intrathecal morphine
  • Lie supine with pillow
    • Trendelenburg can be used to ↑ the cranial spread
    • Reverse Trendelenburg will reduce cranial spread
      ↑ the degree of tilt if block is rising/rises too cranially.
  • Place wedge
  • Commence phenylephrine infusion
    30ml/hr of 100μg/ml solution.
  • Test the block
    • No block
      • Consider repeat spinal
        May cause exaggerated haemodynamic response.
      • Consider GA
    • Inadequate block
      Consider epidural and slow titration of LA.

Principles of Spinal Dosing

In general:

  • Much research has been done
  • Little of it demonstrates significant superiority for one technique over another
  • Local anaesthetics:
    • Bupivacaine 8-12mg
      Block will recede after 1.5 hours, though some block will remain after 2.5 hours.
      • Hyperbaric bupivacaine has a more rapid onset and the level can be adjusted by moving the table
    • Lignocaine generally avoided because of transient neurological symptoms
    • Ropivacaine has a much shorter intrathecal duration of action
  • Opioids
    May be added to improve analgesia intra- and post-operatively.
    • Fentanyl 10-25μg
    • Morphine 50-150μg
      Provides longer lasting analgesia in exchange for risks of PONV, pruritis (can be severe), and late respiratory depression.

Epidural Top-Up

  • Examine the back and make sure the catheter has not moved
  • Test the current block
  • Incrementally top up epidural
    • 2% lignocaine with 1:200,000 of adrenaline
      10-12ml initial bolus, with further 5ml Q2-3 min, up to 7mg/kg.
    • Additional opioid
      e.g. 100μg fentanyl.
  • Test the block
    • No block
      Catheter may be inadequately positioned. Consider:
      • Resiting epidural
      • Performing spinal
    • Inadequate block
      Epidural may be resited or withdrawn.
      • Consider
        • Further top-up
          Ensure that further top-ups will not prohibit performing a spinal if required.
        • Spinal
      • If LA dose limit has been reached:
        • Consider abandoning
          For elective procedures.
        • Convert to GA
          For emergency procedures.
  • Post-operative analgesia
    • Consider 1.5mg epidural morphine during skin closure for post-operative analgesia
      Avoid if any suspicion of intrathecal catheter.

Combined Spinal-Epidural

  • Sit patient up
  • Perform CSE
    Can be performed as:
    • Needle-through-needle technique
    • Two-needle technique
  • Dosing
    • Most cases given a full-dose spinal with subsequent epidural top-up if required In addition to top up with LA, 10mls 0.9% NaCl can be given through the epidural to compress the dural sac and encourage cranial spread of intrathecal LA.
    • Can alternatively give a half-dose spinal, followed by intentional titration
      More haemodynamically stable, and confirms adequate positioning of epidural.
  • Test the block
    As per epidural top-up.

Complications of Regional Techniques in Caesarian Section

Bradycardia:

  • May be due to vena cava compression or blockade of cardioaccelerator fibres
  • Should be treated if <50 and associated with hypotension
  • 200-400ug glycopyrrolate is the preferred agent
    Does not cross placenta.

Nausea and vomiting: * Predominantly due to hypotension * May be due to visceral manipulation or rapid administration of oxytocic
Amenable to vasopressors.

Hypotension:

  • First line treatment should be pressor agents
    Adjust phenylephrine infusions, covered here.

Inadequate blockade/Pain:

  • Generally due to no block of high thoracic dermatomes
  • Alternate technique required in up to 10%
  • Additional analgesia required in up to 15%
    Options include:
    • Conversion to GA
      • Offer early and often
      • Usually required if pain prior to delivery
      • Generally comply with this if the patient requests it and risk is not extreme
      • Often required if pain occurs before foetal delivery
      • Occurs in 2%
    • Supplemental analgesia
      • Epidural top-up (if available)
      • Nitrous oxide
      • IV opioid
        Alert paediatrics if this is given prior to delivery. Short acting agents preferred:
        • Alfentanil
        • Fentanyl
      • Sedation
        Midazolam 1-2mg IV.
      • Ketamine
        10-30mg IV. Pretreat with midazolam.
      • Additional local anaesthetic by obstetric team
        Can be delivered locally to site of wound, especially if pain occurs during closure.

High block:

  • Common
  • Reassurance adequate in the majority
  • Occasionally requires supplemental oxygen
  • Upper limb motor block usually indicates requirement for ETT

References

  1. Maronge, L., & Bogod, D. (2018). Complications in obstetric anaesthesia. Anaesthesia.
  2. Aberdeen Maternity Hospital Anaesthetic Guidelines. Management of Blood Pressure during Caesarean Sections under Spinal Anaesthesia. 2009.
  3. Nixon H, Leffert L. Anesthesia for cesarian delivery. Post TW, ed. UpToDate. Waltham, MA: UpToDate Inc. http://www.uptodate.com
  4. Rollins M, Lucero J. Overview of anesthetic considerations for Cesarean delivery. Br Med Bull. 2012;101:105-25. doi: 10.1093/bmb/ldr050. Epub 2012 Jan 4.
  5. McGlennan A, Mustafa A. General anaesthesia for Caesarean section. Continuing Education in Anaesthesia Critical Care & Pain, Volume 9, Issue 5, 1 October 2009, Pages 148–151.