Pneumatic lithotripsy (lithoclast)
Use of ballistic forces to transfer kinetic energy from handheld probe to stone surface – usually using compressed gas (from OT gas supply) to deliver pneumatic blast which drives a projectile forcefully against probe tip.
Compliant surfaces like soft tissue absorb the energy, while poorly compliant hard surfaces fracture.
Pros:
- Least amount of inadvertent tissue damage – safe
- Good for hard stones – effective
- Reusable and therefore cost efficient
- Do not cut through wire
- No thermal component
Cons:
- High rates of retropulsion
- Cannot be used in flexible ureteroscopes or in the kidney
Ultrasonic lithotripsy
Application of electrical energy to excite a piezoceramic plate in the ultrasound transducer, creating ultrasonic waves at 23 000 – 25 000 Hz.
Ultrasonic energy transformed into vibrations of the hollow steel probe, transmitting energy to stone. The vibrations are well absorbed by tissue.
Some heat develops at probe tip, but relatively cooled by irrigation.
Connected to suction which effectively removes stone debris and irrigation fluid whilst treating stone.
Pros:
- Simultaneous fragmentation and suction removal
- Relatively low risk of tissue damage
- Very efficient in PCNL as high volume irrigation possible
Cons:
- Fairly rigid and requires irrigations for cooling – limited use in ureter / best for PCNL
- More expensive cf. lithoclast
Ultrasonic and pneumatic lithotripsy can be combined
Electrohydraulic lithotripsy (EHL)
2 electrodes at the tip of the probe with a spark created, which creates a rapidly expanding plasma shockwave. Collapse of shockwave creates cavitation bubble and microjets from waves from negative shockwave.
Risk of significant tissue damage and perforation.