Proceedings Article | 8 February 2008
KEYWORDS: Ultrasonics, Ultrasonography, Bladder, Renal calculi, Surgery, Particles, Statistical analysis, Safety, In vitro testing, Diagnostics
The Lithoclast Ultra(R) is a combined ultrasonic and pneumatic lithotrite shown to speed the fragmentation and clearance
of renal calculi. We constructed an ex vivo cystolitholapaxy model to investigate the optimal pneumatic frequency for
the Lithoclast Ultra(R). Bego and U-30 test stones were used. Ten trials of each stone type were performed at each
setting. Each trial consisted of ultrasonic lithotripsy alone, and then in combination with pneumatic lithotripsy at
frequencies of 2Hz, 4Hz, 8Hz, and 12 Hz. Ultrasonic lithotripsy alone was the control group. The ultrasound settings
remained constant at 100% power and 90% duty. Time to 5mm fragments and time to stone clearance were recorded.
Mean time to 5mm fragments for Bego stones using ultrasound alone, and with the pneumatic lithotrite at 2Hz, 4Hz,
8Hz, and 12Hz was 21min, 14min, 10min, 13min, and 14min respectively. Mean time to stone clearance for Bego
stones was 29min, 25min, 23min, 22min, and 22min respectively. Mean time to 5mm fragments for U-30 stones was
101s, 89s, 68s, 64s, and 66s respectively. Mean time to stone clearance for U-30 stones was 162s, 148s, 133s, 137s, and
127s respectively. The combination of pneumatic and ultrasonic lithotrites decreases the time to stone fragmentation and
clearance compared to ultrasound alone. The optimal pneumatic frequency appears to reach a plateau at 4Hz.
