Lithotripsy

Introduction

• Lithotripsy involves various methods to break down kidney stones into smaller pieces that can pass through the urinary tract. The three main types are: ESWL, EHL, and ultrasonic lithotripsy.^1-4
• Lithotripsy method selection primarily depends on factors including the stone’s location, size, and composition, as well as patient-specific considerations such as anatomy and comorbidities.^1-4

ESWL

• This is a noninvasive technique that uses externally generated shock waves and high-frequency sound waves delivered through a probe to break stones with minimal injury to surrounding tissue.^1-4
• Most effective for renal and proximal ureteral stones that are 2 cm or smaller in patients with favorable anatomy and no contraindications such as pregnancy or bleeding disorders.^1-4
• Less effective for lower-pole stones with unfavorable angles, dense stones (more than1000 HU), and stones larger than 2 cm.^1-4

EHL

• This is an intracorporeal method that uses electrical shock waves to treat ureteral and renal stones, including larger or lower-pole stones.^1-4
• Useful after unsuccessful ESWL and particularly effective for hard or dense stones and complex anatomy, but has high fragmentation rates.^1-4

Ultrasonic Lithotripsy

• This is an intracorporeal technique performed during ureteroscopy that uses high-frequency sound waves delivered through a probe.^1-4
• Ideal for middle and lower ureteral stones as well as for stones that have failed ESWL.^1-4
• Provides high stone-free rates for lower ureteral stones with low complication rates but is less effective for upper tract stones.^1-4

Indications for Anesthesia in Lithotripsy

General Indications

• The intensity of the shock waves largely determines the level of anesthesia needed. High-energy systems often require general or regional anesthesia, whereas lower-energy units may be performed with monitored anesthesia care.^5-7
• Maintaining patient immobility is essential for keeping the stone in the focal zone; even subtle movement from discomfort or anxiety can reduce fragmentation success.^5-7
• Deep anesthesia is appropriate for children, anxious patients, or those unable to cooperate. Procedures longer than 30 minutes, or those involving ureteroscopy or percutaneous access, typically require general anesthesia for airway control and procedural stability.^5-7
• Respiratory motion impacts stone alignment, especially with older lithotripters that require accurate positioning within a narrow focal zone; in these cases, controlled ventilation under general anesthesia may help minimize diaphragmatic movement.^5-7
• Newer lithotripters with wider focal zones or advanced targeting systems can often be used with spontaneous ventilation, provided the patient maintains a stable, predictable breathing pattern.^5-7

Lithotripsy-Specific Indications

ESWL

• Many ESWL procedures can be performed with minimal anesthesia, including topical anesthetics, local infiltration anesthesia, or intravenous sedation.^5-7
• General or regional anesthesia may be needed for pediatric patients, highly anxious adults, and situations that require complete stillness or breath-holding for optimal shock-wave targeting.^5-7
• Device type affects anesthetic needs. Electromagnetic units typically deliver lower-intensity shocks and permit lighter sedation, whereas older water-bath or electrohydraulic units may require deeper anesthesia.^5-7
• Routine neuromuscular blockade is not commonly used during ESWL because many lithotripters depend on the patient’s natural breathing for targeting and gating, which can be affected by paralysis.^5-7

Ultrasonic and EHL

• General anesthesia is typically preferred to maintain immobility, protect the airway, and provide stable conditions for precise endoscopic manipulation.^5-7
• EHL may be associated with higher complication rates and mucosal injury. Proper anesthesia and close monitoring are essential.^5-7
• Neuromuscular blockade may be selectively used to reduce movement, improve endoscopic control, and reduce the risk of ureteral or mucosal injury.^5-7
• Some avoid muscle relaxation when spontaneous respiratory motion aids shock-wave timing or assists with lithotripter tracking.^5-7

Contraindications and Special Considerations for Lithotripsy

Contraindications to Lithotripsy

• Pregnancy: absolute contraindication for ESWL. It should be avoided during pregnancy because shock waves may pose a risk to the fetus. Ultrasonic or EHL can be performed during pregnancy with obstetric consultation.^1,6-7
• Bleeding disorders: Coagulopathy should be corrected before treatment because shock-wave therapy may increase the risk of bleeding; coagulation testing is performed when clinically indicated.^6-8

Special Considerations

• Cardiac implantable devices: Pacemakers and defibrillators can be safely managed as long as they are placed outside the shock-wave path and temporarily set to a non-demand mode with continuous monitoring during the procedure.^6,9
• Orthopedic implants: Hip prostheses or spinal hardware generally do not interfere with treatment unless located directly within the trajectory of the shock waves.⁶