What are the recommended anesthesia techniques for patients with monoclonal gammopathy of renal significance (MGRS) undergoing surgery to minimize renal complications?

Anesthesia Management for Patients with Monoclonal Gammopathy of Renal Significance (MGRS)

For patients with monoclonal gammopathy of renal significance (MGRS), the safest anesthesia approach is to use agents with minimal renal metabolism and toxicity, such as lidocaine, mepivacaine, desflurane, sevoflurane, propofol, and remifentanil, while maintaining adequate renal perfusion pressure throughout the perioperative period. 1

Preoperative Assessment

• Evaluate current renal function:

  • eGFR and creatinine levels
  • Assess for proteinuria and hematuria
  • Review recent kidney biopsy results if available 2

• Screen for comorbidities common in MGRS:

  • Hypertension
  • Cardiovascular disease
  • Electrolyte imbalances (particularly potassium)

• Review medications and potential drug interactions:

  • Identify and hold nephrotoxic medications
  • Check for hyperviscosity syndrome in patients with high monoclonal protein levels 2

Anesthetic Agent Selection

Local/Regional Anesthesia

• Preferred agents: Lidocaine and mepivacaine (no dose adjustment needed) 1
• Acceptable agent: Articaine (maximum dose not exceeding 7 mg/kg) 1
• Caution: Reduce epinephrine doses when using local anesthesia due to risk of increasing blood pressure (hypertension is common in MGRS patients) 1

General Anesthesia

• Inhalational agents: Desflurane and sevoflurane are safest for patients with impaired renal function 1
• Intravenous agents:
  • Propofol and remifentanil are excellent choices for total intravenous anesthesia 1
  • Benzodiazepines (diazepam, midazolam) can be safely used for sedation 1

Analgesics

• Preferred opioids: Fentanyl (minimal renal metabolism) 1
• Alternative opioids: Buprenorphine (primarily hepatic metabolism) 1
• Use with caution: Methadone (requires careful titration due to long half-life) 1
• Avoid: Morphine and diamorphine (accumulation of potentially toxic metabolites) 1

Intraoperative Management

Hemodynamic Management

• Maintain adequate renal perfusion pressure:
  • Avoid hypotension (can worsen renal function)
  • Target MAP within 20% of baseline 1
  • Consider invasive arterial monitoring for longer cases

Fluid Management

• Careful fluid management is essential:
  • Avoid both hypovolemia and fluid overload
  • Consider using balanced crystalloid solutions
  • Monitor urine output closely 1

Medication Considerations

• Lengthen interval between doses according to degree of elimination impairment 1
• Completely avoid nephrotoxic drugs 1
• For patients with significant renal impairment, consider consulting nephrology for medication guidance

Special Considerations for MGRS

• MGRS represents a spectrum of renal disorders caused by monoclonal immunoglobulins that can affect any part of the nephron 2, 3
• These patients are at increased risk of progression to end-stage renal disease 4
• Patients may have received chemotherapy or stem cell transplantation to target the underlying clone 4
• Post-transplant recurrence is possible in MGRS patients 5

Postoperative Care

• Continue monitoring renal function with regular laboratory tests
• Maintain adequate hydration and blood pressure
• Resume clone-directed therapy as soon as appropriate 2
• Avoid NSAIDs and other nephrotoxic medications
• Consider early nephrology consultation for any signs of acute kidney injury

Potential Complications

• Acute kidney injury due to hypoperfusion
• Electrolyte disturbances (particularly hyperkalemia)
• Fluid overload in patients with pre-existing renal dysfunction
• Drug accumulation due to impaired renal clearance

By following these guidelines and maintaining vigilance throughout the perioperative period, anesthesia can be safely administered to patients with MGRS while minimizing the risk of further renal complications.