In vitro comparisons of retropulsion and fragmentation efficacy of 2 cordless, handheld pneumatic and electromechanical lithotripsy devices.
OBJECTIVE
To compare, in vitro, probe velocity/displacement, retropulsion, and fragmentation capacity of the cordless electromechanical (LithoBreaker) (hard vs soft probe guide) and pneumatic (StoneBreaker).


METHODS
Probe velocities/displacements were measured using high-speed resolution camera (100.000 frames/s). The lithotripsy probes were projected through a 7.5F ureteroscope against a nonfrangible led ball placed in a 15F horizontally mounted silicone tube immersed in water bath as an in vitro ureter model. Retropulsion is considered as displacement distance of led ball. Fragmentation efficiency was quantified as number of shots required to break Bego-stone phantoms (hard [15:3] and soft [15:6], average size 7.5 × 5.5 mm) placed on metal mesh into <3-mm fragments. Mean and standard deviation of repetitive measurements were statistically analyzed.


RESULTS
StoneBreaker yielded higher probe velocity (22 ± 1.9 m/s) compared with LithoBreaker with hard (14.2 ± 0.5 m/s) and soft (11.5 ± 0.5 m/s) probe. Maximum probe displacement for StoneBreaker was 1.04 mm vs 0.9 mm and 1.1 mm (hard vs soft LithoBreaker-probe, respectively). Retropulsion using 1-mm probes showed no statistical differences. Using harder 2-mm probe decreased Lithobreaker retropulsion significantly compared with Stonebreaker. The amount of shots (1-mm probe) to fragment soft Bego stones was significantly higher for LithoBreaker with soft (mean 31.5 ± 11.31) and hard (mean 21.5 ± 5.29) probe guide vs StoneBreaker (mean 11.2 ± 2.65). Fragmentation efficiency for hard Bego stones showed similar statistically significant outcome. Comparison of the 2 probe guides showed higher velocity linked to harder-probe that improved LithoBreaker fragmentation performance and reduce propulsion.


CONCLUSIONS
Both examined lithotripters are effective in cracking stone phantoms with relatively low pulse number. They produce comparable retropulsions. Fragmentation improved substantially using LithoBreaker with hard probe guide. More tests are required to assess differences in stone clearance time.
Department of Urology, University Hospital Munich-Grosshadern, Ludwig-Maximilians-University-Munich, Munich, Germany; Laser Research Laboratories, Campus Großhadern, Ludwig-Maximilians-University-Munich, Munich, Germany. Electronic address: wael.khoder@med.uni-muenchen.de.
Wael Y
WY
Khoder
Department of Urology, University Hospital Munich-Grosshadern, Ludwig-Maximilians-University-Munich, Munich, Germany; Laser Research Laboratories, Campus Großhadern, Ludwig-Maximilians-University-Munich, Munich, Germany.
Markus J
MJ
Bader
Department of Urology, University Hospital Munich-Grosshadern, Ludwig-Maximilians-University-Munich, Munich, Germany.
Nikolas
N
Haseke
Department of Urology, University Hospital Munich-Grosshadern, Ludwig-Maximilians-University-Munich, Munich, Germany.
Christian G
CG
Stief
Laser Research Laboratories, Campus Großhadern, Ludwig-Maximilians-University-Munich, Munich, Germany.
Michael
M
Baumgartl
Laser Research Laboratories, Campus Großhadern, Ludwig-Maximilians-University-Munich, Munich, Germany.
Thomas
T
Pongratz
Laser Research Laboratories, Campus Großhadern, Ludwig-Maximilians-University-Munich, Munich, Germany.
Ronald
R
Sroka
D004867:Equipment Design; D006244:Hardness; D006801:Humans; D007669:Kidney Calculi / Q000628:therapy*; D008096:Lithotripsy / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D012828:Silicones / Q000737:chemistry; D013314:Stress, Mechanical; D014513:Ureter / Q000473:pathology; D014514:Ureteral Calculi / Q000628:therapy*; D020709:Ureteroscopes; D018666:Ureteroscopy / Q000379:methods; D014741:Video Recording
D012828:Silicones