Anesthetic Considerations for Cesarean Section

1. Overview and Anesthetic Choice

• Urgency (elective vs. emergency)
• Maternal comorbidities and contraindications
• Presence of a pre-existing epidural catheter
• Fetal condition
• Maternal and obstetrician preferences
• Anesthetist skills

• Morgan and Mikhail's Clinical Anesthesiology, 7e - "Spinal or epidural anesthesia is preferred to general anesthesia for cesarean section because regional anesthesia is associated with less hemodynamic fluctuation, more gradual resolution of analgesia during anesthetic recovery, and lower maternal mortality."

2. Physiological Changes Relevant to Anesthesia

• Aortocaval compression: the gravid uterus compresses the inferior vena cava and aorta in the supine position, reducing venous return and cardiac output. Prevented by 15-20° left lateral tilt (wedge under right hip).
• Reduced FRC and increased O₂ consumption: leads to rapid desaturation during apnea - prolonged preoxygenation (3-5 min of 100% O₂) is mandatory before general anesthesia.
• Airway edema and engorgement: increases difficulty of intubation; failed intubation rate in obstetric patients is at least 8x higher than non-pregnant females.
• Decreased lower esophageal sphincter tone: with delayed gastric emptying, increases aspiration risk.
• Aspiration prophylaxis is required: nonparticulate antacid (sodium citrate) within 30 min of surgery; H₂-receptor antagonists and/or metoclopramide as per ASA guidelines.

3. Regional Anesthesia

Required Dermatomal Level

A. Spinal Anesthesia

• Hyperbaric bupivacaine 10-15 mg intrathecally (preferred if surgery > 45 min)
• Hyperbaric lidocaine 50-60 mg (shorter procedures)
• Adjuvants: Fentanyl 10-25 mcg or sufentanil 5-10 mcg intrathecally - enhances block intensity and duration without neonatal harm
• Preservative-free morphine 0.1-0.3 mg intrathecally - prolongs postoperative analgesia up to 24 h (monitor for delayed respiratory depression)

B. Epidural Anesthesia

• An epidural catheter is already in situ from labor analgesia
• Continuous titration is needed (high-risk patients, prolonged surgery)
• Better hemodynamic control is desired

C. Combined Spinal-Epidural (CSE)

• Patients with severe pain early in labor receiving immediate pre-delivery analgesia/anesthesia
• When both rapid onset AND ability to extend the block are desired

4. Hypotension - Prevention and Management

• Left uterine displacement (wedge under right hip)
• IV fluid administration (crystalloid or colloid co-loading)
• Colloids are more effective than crystalloids (Cochrane review: RR 0.69 for hypotension with colloids), though synthetic colloid safety concerns exist

• Phenylephrine (40-120 mcg IV boluses or infusion) is the vasopressor of choice - less fetal transfer, less neonatal acidosis compared to ephedrine
• Norepinephrine is an emerging alternative with similar efficacy and hemodynamic profile
• Ephedrine 5-10 mg IV may be added if hypotension occurs with bradycardia (since phenylephrine can reduce HR)
• Supplemental oxygen (40-50%)
• Slight Trendelenburg positioning helps achieve T4 level and reduces hypotension (extreme Trendelenburg impairs pulmonary gas exchange)
• BP measured every 1-2 min until stabilized after spinal injection

5. General Anesthesia

• Contraindications to regional (coagulopathy, patient refusal, infection at site)
• Emergent situations: fetal bradycardia, maternal hemorrhage with hemodynamic instability, uterine rupture, cord prolapse, maternal trauma
• Failed or inadequate regional block

Rapid Sequence Induction (RSI) Technique

1. Supine with wedge under right hip for left uterine displacement
2. Preoxygenation - 100% O₂ for 3-5 min (or 4 vital capacity breaths if time critical)
3. Prepare and drape; surgeons ready at the table
4. Cricoid pressure (Sellick's maneuver) applied
5. Induction agents:
   • Propofol 2 mg/kg (preferred for hemodynamically stable patients)
   • Ketamine 1-2 mg/kg (preferred if hypovolemic/hemorrhaging)
   • Etomidate and methohexital offer little benefit in obstetrics
6. Neuromuscular blocking agent:
   • Succinylcholine 1.5 mg/kg (classic choice - rapid onset, ultra-short duration)
   • Rocuronium 1.0-1.2 mg/kg (acceptable alternative; if failed intubation occurs, can be reversed with sugammadex 16 mg/kg)
7. Confirm ETT placement; avoid excessive hyperventilation (PaCO₂ <25 mmHg reduces uterine blood flow and causes fetal acidosis)

Maintenance of Anesthesia (pre-delivery)

• 50% air in O₂ with up to 1 MAC volatile agent until delivery of infant
• Avoid N₂O pre-delivery (fetal exposure concerns)
• Post-delivery: N₂O up to 70% can be added; reduce volatile agent to 0.75 MAC (minimizes uterine relaxation, ensures amnesia)

Post-delivery: Oxytocin Management

• Slow IV bolus of 0.3-1 IU over 1 min, then 5-10 IU/h infusion for 4 h (low risk of PPH)
• If uterus does not contract: discontinue volatile agent, give methylergonovine 0.2 mg in 100 mL NS over 10 min, or 15-methyl PGF₂α 0.25 mg IM

Emergence

• Aspirate gastric contents via orogastric tube before extubation
• Fully reverse neuromuscular blockade
• Extubate awake (with intact airway reflexes) to minimize aspiration risk

6. Difficult and Failed Airway Management

• Multiple laryngoscope blades + short handle
• Extra stilette ETT (6 mm)
• LMA and intubating LMA (Fastrach)
• Video laryngoscope (GlideScope, Stortz CMAC) - strongly recommended as first-line or backup device
• Fiberoptic bronchoscope
• Transtracheal jet ventilation capability
• Esophageal-tracheal Combitube

7. Emergency Cesarean Section

• If an epidural catheter is already in place, rapidly top-up with 15-20 mL of 2% lidocaine ± bicarbonate ± opioid to achieve surgical level quickly
• If no regional is in place and situation allows, spinal anesthesia can still be used if time permits
• General anesthesia is used for true crash CS when immediate delivery is required (active hemorrhage, sudden fetal bradycardia with no time for regional)

8. Special Situations

9. Postoperative Analgesia

• Intrathecal morphine 0.1-0.3 mg
• Scheduled NSAIDs and paracetamol
• Transversus abdominis plane (TAP) blocks if intrathecal morphine not given
• Minimize opioids (affects breastfeeding and neonatal sedation)

Priority Order in Emergency OT

🥇 1st — Fetal Distress (Emergency Cesarean)

• Fetal distress (Category I/crash CS) means acute fetal hypoxia — the fetus can suffer irreversible brain damage or death within minutes.
• You are managing two patients simultaneously — mother and fetus.
• The "decision-to-delivery interval" standard is ≤30 minutes (ideally ≤15 min for Category I).
• Every minute of delay increases perinatal morbidity and mortality.
• The fetal heart rate pattern (late decelerations, prolonged bradycardia, sinusoidal pattern) dictates extreme urgency.

🥈 2nd — Emergency Laparotomy

• Emergency laparotomy is indicated for conditions like bowel perforation, peritonitis, mesenteric ischemia, internal bleeding, or hollow viscus injury — all of which carry risk of septic shock, hemorrhagic shock, or multi-organ failure within hours if untreated.
• One life at risk, but the threat is imminent and rapidly progressive.
• Delay worsens sepsis, ongoing hemorrhage, and mortality significantly.

🥉 3rd — Compartment Syndrome

• Compartment syndrome causes irreversible muscle and nerve damage if fasciotomy is delayed beyond 6 hours from symptom onset (the classic teaching threshold).
• However, it is a limb threat, not a direct life threat (unless rhabdomyolysis with renal failure has already set in, which is a later complication).
• The window for saving the limb is measured in hours, not minutes.
• This gives sufficient time to complete the first two cases and then proceed.

Summary Table

Important Caveats

1. This order is NOT absolute - if the laparotomy is for a ruptured aortic aneurysm or exsanguinating hemorrhage, it may leapfrog even the CS. Always reassess the actual clinical status of each patient.
2. Concurrent management: While you are managing case 1, another team or anesthetist should be pre-assessing and consenting the laparotomy patient simultaneously.
3. Compartment syndrome timing: Confirm the onset time. If it has been >5 hours already, urgency escalates and you may need to overlap preparation.
4. Communication is key: Inform all surgical teams of the decision and estimated start times immediately. The orthopedic/general surgery teams should be actively preparing their patients in parallel.
5. The rule of thumb:
   • Immediate life threat > Immediate dual-life threat > Organ/limb threat
   • But two lives always outrank one when both are at equal immediacy — hence CS first.