Does stone entrapment with ″Uro-Net″ improve Ho:YAG laser lithotripsy efficiency in percutaneous nephrolithotomy and cystolithopaxy?: an in vitro study.
OBJECTIVE
to test the effect of stone entrapment on laser lithotripsy efficiency.


METHODS
Spherical stone phantoms were created using the BegoStone® plaster. Lithotripsy of one stone (1.0 g) per test jar was performed with Ho:YAG laser (365 µm fiber; 1 minute/trial). Four laser settings were tested: I-0.8 J,8 Hz; II-0.2J,50 Hz; III-0.5 J,50 Hz; IV-1.5 J,40 Hz. Uro-Net (US Endoscopy) deployment was used in 3/9 trials. Post-treatment, stone fragments were strained though a 1mm sieve; after a 7-day drying period fragments and unfragmented stone were weighed. Uro-Net nylon mesh and wire frame resistance were tested (laser fired for 30s). All nets used were evaluated for functionality and strength (compared to 10 new nets). Student's T test was used to compare the studied parameters; significance was set at p < 0.05.


RESULTS
Laser settings I and II caused less damage to the net overall; the mesh and wire frame had worst injuries with setting IV; setting III had an intermediate outcome; 42% of nets were rendered unusable and excluded from strength analysis. There was no difference in mean strength between used functional nets and non-used devices (8.05 vs. 7.45 lbs, respectively; p = 0.14). Setting IV was the most efficient for lithotripsy (1.9 ± 0.6 mg/s; p < 0.001) with or without net stabilization; setting III was superior to I and II only if a net was not used.


CONCLUSIONS
Laser lithotripsy is not optimized by stone entrapment with a net retrieval device which may be damaged by high energy laser settings.
Glickman Urological and Kidney Institute, Cleveland Clinic Foundation, Cleveland, OH, USA.
Giovanni Scala
GS
Marchini
Aayushi
A
Rai
Shubha
S
De
Carl
C
Sarkissian
Manoj
M
Monga
D004867:Equipment Design; D053844:Lasers, Solid-State / Q000627:therapeutic use*; D017602:Lithotripsy, Laser / Q000295:instrumentation* / Q000379:methods*; D008422:Materials Testing; D008488:Medical Illustration; D009403:Nephrostomy, Percutaneous / Q000379:methods*; D015203:Reproducibility of Results; D013997:Time Factors; D014545:Urinary Calculi / Q000628:therapy*