General Anaesthetic for Caesarian Section

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

Provision of general anaesthesia for a caesarian section.

Considerations

In addition to general considerations, particular considerations for caesarian under general anaesthesia are:

  • A
    • Aspiration prophylaxis
    • Airway plan
  • D
    • High risk of anaesthetic awareness
      • Reluctance to use opioid for foetal effects
      • Desire to preserve haemodynamic stability
      • Most occur at, or shortly after, induction
        Multifactorial:
        • Rapid offset of IV agents and slower uptake of volatile in this population
          Remember to mind the gap!
        • Common avoidance of opioid
        • Maximal surgical stimulus occurring immediately post-induction
    • Foetal effects
      Foetus will be affected by agents.
      • Volatile agents will diffuse across placenta
        Aim is to minimise induction-to-delivery time to reduce the magnitude of this effect.
      • Opioids ↑ foetal respiratory depression
        Consider using smaller doses of shorter acting agents.
  • O
    • Tocolytic effects of volatile agents
      ↑ risk of bleeding related adverse events without ↑ transfusion requirement.

Preparation

  • Surgeons scrubbed
  • Abdomen prepped and draped

Induction

  • Preoxygenate well
  • Perform RSI
    Ensure adequate doses induction agent and relaxant.
    • Thiopentone 5mg/kg
    • Propofol 3-4mg/kg
      High sympathetic drive - heavier doses tolerated well.
      • May be associated with poorer neonatal status, but is commonly used
    • Relaxant
      • Suxamethonium 1-2mg/kg
        Additional relaxation should not be required
      • Rocuronium 1.2-2mg/kg Remember that magnesium will prolong duration of action of non-depolarising agents.
    • Opioid
      Not necessarily required, but tell the paediatrician that it has been given if used.
      • Alfentanil
        Reasonable in patients with severe cardiac disease or hypertensive disorders of pregnancy.
      • Remifentanil
        1μg/kg bolus with intubation, minimal foetal effects.
      • Fentanyl
        Intubating doses will cause significant foetal effects.
  • Intubate
    A slightly smaller tube may make intubation easier and will be adequate to ventilate with.
  • Commence ventilation
    • 30% O2/70% N2O
      MAC, thereby reducing tocolytic effects of volatile agent.
      • Make sure to avoid maternal hypoxia, and decrease the FiN2O if needed
    • Sevoflurane ~1.5%
      Use high flows (10L/min) to reach target quickly.
      • Consider overpressuring the volatile, but remember to turn it down again
        Can be easy to forget in this chaotic situation.

Maintenance

  • Consider changing to TIVA
  • Aim low-normal CO2
  • Following delivery
    • Give oxytocin
    • Give analgesia
      • Paracetamol
      • NSAID
      • Opioid
        20-30mg IV morphine. Opioid, paracetamol, NSAID.
  • Consider regional analgesia
    • TAP block
    • Rectus sheath catheters.
  • Extubate awake

Postoperative

  • Regular PO analgesia
  • PCA
  • Follow-up about experience
    • Often a confusing, stressful time
    • Risk of awareness

Complications of GA in Caesarian Section

  • Awareness
    High risk in obstetric population, and especially CS:
    • Occurs in ~1/670
      In NAP 5.
    • Multifactorial:
      • High CO
        • ↑ onset/offset of IV agents
        • ↓ onset/offset of volatile agents
      • No premedication
      • Rapid onset of surgical stimulation following induction
      • ↑ VD
      • Airway difficulty
        ↓ time to delivery of volatile.
      • Often junior staff, after hours
    • 20% risk of new psychological morbidity following an awareness event
  • Failed intubation
    Higher risk in obstetric population.
    • Occurs in ~1/300
    • Major cause of death in obstetric population
    • Anatomical changes
      • Laryngeal oedema
      • ↑ breast size
      • ↓ safe apnoea time
        • ↑ VO2
        • ↓ FRC
  • Aspiration
    ↑ risk in obstetric population.
    • Major cause of death in obstetric population
    • Occurs in 0.15% of obstetric GAs with unsecured airways
    • 25mls of gastric contents may cause pulmonary complications
    • Multifactorial:
      • Lower gastric pH
      • ↑ gastric volume

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.
  6. Chaggar, Rs, and Jp Campbell. ‘The Future of General Anaesthesia in Obstetrics’. BJA Education 17, no. 3 (March 2017): 79–83. https://doi.org/10.1093/bjaed/mkw046.