What are the anesthetic considerations for Extracorporeal Shock Wave Lithotripsy (ESWL) procedures?

Anesthetic Considerations for Extracorporeal Shock Wave Lithotripsy (ESWL)

For ESWL procedures, adequate pain management with minimal sedation is the optimal anesthetic approach, as it provides effective analgesia while maintaining patient cooperation and minimizing complications.

Patient Assessment and Preparation

• Obtain urine culture prior to procedure to rule out urinary tract infection (UTI) 1
• Assess for contraindications to ESWL:
  • Pregnancy
  • Bleeding disorders or ongoing anticoagulation therapy
  • Uncontrolled UTI
  • Severe obesity
  • Skeletal malformations
  • Arterial aneurysm near the stone
  • Anatomic obstructions distal to the stone 1

Anesthetic Options

1. Monitored Anesthesia Care (MAC) with Sedation

• First-line approach for most patients
• Options include:
  • Patient-Controlled Sedation and Analgesia (PCSA) with propofol and fentanyl
    • Provides higher patient and surgeon satisfaction
    • Allows for quicker recovery compared to anesthesiologist-administered sedation 2
  • Anesthesiologist-administered propofol/fentanyl
    • Typically requires higher doses than patient-controlled methods 2

2. Regional Anesthesia Techniques

• Ultrasound-guided Quadratus Lumborum Block (QLB)
  • Significantly reduces pain scores and opioid consumption
  • Improves stone fragmentation success rates (95% vs 70%)
  • Increases patient satisfaction 3
  • Consider for patients with anticipated moderate-to-severe pain

3. Local Anesthesia Options

• Topical anesthetics (EMLA cream, xylocaine gel)
  • May reduce procedural duration and need for supplemental analgesia
  • More effective in male patients than female patients
  • May not significantly reduce opioid requirements during procedure 4, 5

Procedural Considerations

• Positioning: Proper positioning is crucial for effective acoustic coupling between treatment head and skin
• Monitoring: Standard ASA monitoring (ECG, BP, SpO2)
• Cardiac Considerations:
  • For patients with pacemakers or defibrillators, ESWL is feasible with technical precautions
  • Newer lithotripters may eliminate need for reprogramming defibrillators 1
• Shockwave Parameters:
  • Decreasing frequency (60-90/min instead of 120/min) improves stone-free rates and reduces tissue damage
  • Stepwise energy ramping minimizes renal injury 1

Post-Procedure Management

• Monitor for complications:
  • Macroscopic hematuria (occurs in ~17.2% of patients)
  • Pain (12.1%)
  • Steinstrasse (stone street formation) (4%)
  • Symptomatic hematoma (0.21%)
  • Asymptomatic hematoma (1.2%)
  • Sepsis (0.15%) 1, 6
• Provide adequate hydration to promote urine flow and prevent clot formation
• Recommend rest and activity limitation for 24-48 hours
• Consider medical expulsive therapy (MET) with α-blockers to facilitate passage of stone fragments 6

Special Considerations

• Cardiovascular: Dysrhythmias may occur in 1-11% of patients 1
• Bleeding Risk: ESWL is classified as a procedure with high risk of bleeding; patients on antithrombotic therapy should be referred to an internist for appropriate management 1
• Antibiotic Prophylaxis: Single-dose prophylactic antibiotic is recommended for all patients undergoing ESWL to prevent infectious complications 1

Pitfalls to Avoid

1. Inadequate pain control leading to patient movement and compromised stone targeting
2. Excessive sedation causing respiratory depression or inability to cooperate
3. Failure to recognize contraindications (especially undiagnosed UTI or bleeding disorders)
4. Insufficient acoustic coupling between treatment head and skin, reducing effectiveness
5. Performing ESWL too soon after a previous session (allow 2-4 weeks between sessions) 6

By following these considerations, anesthesia providers can optimize patient comfort and procedural success while minimizing complications during ESWL procedures.