What is the recommended anaesthetic management for a patient with MELAS (Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like episodes) syndrome undergoing emergency laparoscopic appendectomy?

Anaesthetic Management for Emergency Laparoscopic Appendectomy in MELAS Syndrome

For patients with MELAS syndrome undergoing emergency laparoscopic appendectomy, regional anesthesia (spinal or epidural) should be the first choice when neurological abnormalities of the spinal cord or peripheral nerves have been ruled out, as it avoids potential complications associated with general anesthesia in these patients. 1

Preoperative Assessment and Preparation

Key Considerations in MELAS

• Assess for multi-system involvement:
  • Neurological: Encephalopathy, stroke-like episodes, seizures
  • Cardiac: Conduction abnormalities, cardiomyopathy
  • Metabolic: Baseline lactic acidosis, electrolyte abnormalities
  • Respiratory: Muscle weakness, risk of aspiration
  • Renal: Dysfunction or impairment

Laboratory Investigations

• Complete blood count
• Electrolytes (particularly sodium and potassium)
• Renal and liver function tests
• Arterial blood gas analysis (assess baseline lactate levels)
• Blood glucose levels
• Coagulation profile

Preoperative Optimization

• Correct electrolyte abnormalities (particularly hyponatremia and hyperkalemia) 2
• Optimize hydration status
• Continue mitochondrial cocktail medications if patient is on them
• Ensure normoglycemia (maintain glucose between 140-180 mg/dL) 3
• Administer appropriate antibiotic prophylaxis 30-60 minutes before surgery 4

Anesthetic Management Algorithm

Option 1: Regional Anesthesia (Preferred)

• Consider spinal anesthesia if no contraindications exist and neurological abnormalities of spinal cord/peripheral nerves are ruled out 1
• Benefits:
  • Avoids potential complications of general anesthesia
  • Reduces risk of malignant hyperthermia-like reactions
  • Minimizes exposure to agents that may worsen mitochondrial function
  • Allows early detection of neurological deterioration

Option 2: General Anesthesia (If regional is contraindicated)

Induction

• Rapid sequence induction recommended due to emergency nature and risk of aspiration 4
• Preferred agents:
  • Propofol (short-acting) with careful titration 5
  • Short-acting opioid (fentanyl, alfentanil, or remifentanil infusion) 4
  • Rocuronium for muscle relaxation (with neuromuscular monitoring) 4

Maintenance

• Total intravenous anesthesia (TIVA) with propofol and remifentanil is preferable for shorter procedures 5
• For longer procedures (>2 hours), consider low-dose volatile anesthetics (sevoflurane or desflurane) to minimize propofol exposure and risk of lactic acidosis 6
• Use depth of anesthesia monitoring (BIS) to titrate anesthetic agents precisely 4
• Maintain normothermia (avoid hypothermia which can worsen mitochondrial function)
• Ensure adequate oxygenation (maintain SpO₂ >95%)

Ventilation Strategy

• Protective lung ventilation with appropriate PEEP
• Avoid hyperventilation which may worsen acidosis
• Consider pressure-controlled ventilation for laparoscopy 4

Intraoperative Monitoring

• Standard ASA monitors (ECG, NIBP, SpO₂, EtCO₂)
• Temperature monitoring
• Neuromuscular monitoring
• Consider arterial line for frequent blood gas sampling and continuous BP monitoring
• Monitor blood glucose levels
• Consider BIS monitoring, especially in elderly patients 4

Fluid Management

• Avoid lactated Ringer's solution due to risk of worsening lactic acidosis
• Prefer balanced crystalloid solutions without lactate
• Target-directed fluid therapy using clinical parameters
• Maintain normovolemia and avoid fluid overload
• Consider use of vasopressors rather than excessive fluid administration to maintain blood pressure 4

Postoperative Care

• Close monitoring for metabolic decompensation
• Regular assessment of electrolytes, especially sodium and potassium 2
• Multimodal analgesia to minimize opioid requirements:
  • Regular acetaminophen (paracetamol) if no liver dysfunction 4
  • NSAIDs if no contraindications and renal function is normal 4
  • Consider TAP blocks for additional analgesia
• Early mobilization and resumption of oral intake
• Prophylaxis for PONV using a multimodal approach 4
• Consider ICU/HDU admission for close monitoring, especially if the procedure was prolonged or complicated

Special Considerations and Pitfalls

Potential Complications

• Metabolic acidosis: Monitor closely and correct promptly
• Electrolyte disturbances: Particularly hyponatremia and hyperkalemia 2
• Hypothermia: Maintain normothermia throughout
• Prolonged neuromuscular blockade: Use neuromuscular monitoring
• Malignant hyperthermia-like reactions: Be prepared with dantrolene
• Cardiac arrhythmias: Monitor ECG continuously

Key Pitfalls to Avoid

• Prolonged propofol infusion: May exacerbate lactic acidosis in MELAS patients 6
• Use of lactated solutions: May worsen lactic acidosis
• Inadequate depth of anesthesia monitoring: May lead to awareness or excessive anesthetic depth
• Overlooking electrolyte disturbances: MELAS patients are prone to significant electrolyte abnormalities 2
• Inadequate temperature management: Both hyperthermia and hypothermia can worsen mitochondrial function

By following this structured approach to anesthetic management, the risks associated with emergency laparoscopic appendectomy in patients with MELAS syndrome can be minimized, leading to improved outcomes and reduced perioperative morbidity.