A fundamental study on expansive splitter lithotripsy

: The application of expansive splitter for industrial use to lithotripsy was studied. A natural rubber latex catheter 350 mm in length, 3.5 mm in diameter and 0.1 mm in thickness was newly developed for prevention from alkalization by expansive splitter. Expansive pressure generated by expansive splitter was measured to calculate the fragmentation time of urinary stones. Urinary stones 20, 30 or 40 mm in diameter were expected to be fragmented in 7.5, 9 and 11 minutes. Human bladder stone 55 x 54 x 33 mm in size was divided into two parts in 24 minutes using expansive splitter. The fragmentation test of model calculi was performed to decide the boring length necessary for the fragmentation of urinary stones. The necessary boring length was a half of the stone diameter in stones smaller than 20 mm in diameter and was 3/4 of it in stones larger than 30 mm in diameter. A tolerance test of the catheter was performed. When the used catheters for splitting were immersed in water, no change was observed in pH, in spite of the elevation of pH from 6.6 to 12.3 when the splitter itself was immersed in water. No leakage of water from the catheter was observed in this tolerance test. Histological change on the epithelium of the bladder and the renal pelvis by expansive splitter was examined. The mucosa of the dog; bladder and the pig renal pelvis, to which expansive splitter was made contact, showed no histological change after 30, 45 or 60 minutes after the contact. In conclusion, expansive splitter enclosed in the natural rubber latex catheter can be employed for clinical use to fragment urinary calculi in endourological procedures.