The clinical application of suctioning flexible ureteroscopy with automatically controlling renal pelvic pressure

Objective To evaluate the safety and efficacy of suctioning flexible ureteroscopy with automatic control of renal pelvic pressure. Methods A total of consecutive 87 patients, including 54 male cases and 33 female cases, with upper urinary tract calculi were enrolled in this study from November 2014 to August 2015. The average size of stone was (15.9±4.2)mm. The average age was (48.2±13.1 )years old. All patients were performed suctioning flexible ureteroscopic lithotripsy under general anesthesia in low lithotomy position. They were treated by suctioning flexible ureteroscopy with automatic control of renal pelvic pressure (RPP) by a patented intelligent system including an irrigation and suctioning platform and a ureteral access sheath (F12/14) with a pressure-sensitive tip. There are two connecting channels on the back end of the UAS, which are connected to the vacuum device with suctioning effect and pressure monitoring feedback device, respectively. On the platform, control value was set at -15--5 mmHg(1 mmHg=0.133 kPa), RPP warning value was set at 20 mmHg, and RPP limit value was set at 30 mmHg. Infusion flow rate was set at 50-150 ml/min .Intraoperatively, Holmium laser was used to powderize the stone at 0.6-0.8J/pulse with a frequency of 20-30 Hz (fiber diameter 200μm). Statistical analysis was performed regarding RPP, operative time, stone-free rates, and complications. Results 76 of 87 patients only accepted one surgery to remove the stone. There were 7 cases who failed the first surgery due to difficulty in placing the ureteral access sheath but flexible ureteroscopy were successfully performed in these patients after indwelling a D-J stent for 2 weeks. Four cases were converted to percutaneous nephrolithotomy due to significant ureteral stenosis. For the 83 patients who underwent successful flexible ureterosocopy the actual RPP was controlled under 20 mmHg with clear operative visualization. The average operative time was (24.8±14.7) min. The stone-free rates at day 1 and day 30 were 86.7%(72/83) and 95.2%(79/83), respectively. Complication occurred in 16 cases. The ClavienⅠcomplications were noted in 14 cases, including pain in 6 cases , fever in 5 cases, nausea/vomiting in 2 cases and tachycardia 1 case. While ClavienⅡhypertension complications were noted in 2 cases. Conclusions Suctioning flexible ureteroscopy with automatically controlling RPP is technically feasible, safe, and efficacious for treating upper urinary tract calculi with the advantages of breaking stones at high efficacy and low complication rates. Key words: Upper urinary tract calculi; Renal pelvic pressure; Pressure feedback; Equipment