Introduction: Miniaturized percutaneous nephrolithotomy (mini-PCNL) requires saline irrigation at high-pressures to maintain visual clarity. However, this may raise the intrarenal pelvic pressures (IRPs) beyond a safe range and may result in a higher complication rate. The aim of this study was to make and validate an automated pressure saline irrigation system to regulate IRPs during mini-PCNL. Materials and Methods: A ureteric catheter was connected to an urodynamic machine and the minimum, maximum, and average IRPs reached during a standard 15 Fr mini-PCNL were measured in ten cases. Next, an intrarenal pressure regulation system (IPRS) was conceptualized, designed, patented, and constructed. IPRS was then tested on a mannequin model using the routine instruments. Lastly, the IPRS was evaluated on – five cases of 15 Fr mini-PCNL. The mean maximum IRP as recorded in the baseline data was set as the maximum permissible pressure on IPRS. The efficacy of IPRS was assessed by measuring the IRP, recorded in parallel, on both the IPRS and the urodynamic machine at various stages of the procedure. Results: The mean maximum IRP reached during baseline evaluation was 25 cm of water which was set as the maximum permissible limit of the IPRS. Evaluation of the IRPS on mannequin models and validation clinical cases showed that IPRS measured the IRP accurately and prevented the pressure surge above the set limits Overall, higher IRPs were recorded during stone pulverization as compared to the other surgical steps. Conclusions: The current IPRS is the first of its kind open platform, portable, automated pressure saline irrigation system. It precisely monitors and controls the IRP and has the potential to reduce the irrigation pressure-related complications.

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INTRODUCTION AND OBJECTIVES:The objective of this study is to compare the efficiency of stone fragmentation and removal of the LithAssist (Cook Medical, Bloomington, IN, USA), a disposable combination holmium laser and suction handheld device, to an ultrasonic lithotripter in patients undergoing percutaneous nephrolithotomy (PNL) for renal stones.METHODS: With IRB approval, we performed a randomized controlled multicenter clinical trial to compare the LithAssist to an ultrasonic lithotripter. Patients undergoing a PNL with non-staghorn renal stones were eligible for the study. The primary outcomes were the time to stone clearance and stone clearance rate. In addition, stone burden, S.T.O.N.E nephrolithometry score, postoperative complications, stone-free rates, need for additional modalities, device malfunction, and surgeon comfort with the device were measured.RESULTS: A total of 27 PNLs were performed with 14 patients randomized to the LithAssist device (9 female: 5 male, age 60.5AE15.1) and 13 patients randomized to an ultrasonic lithotripter (8 female: 5 male, age 59.5AE9.7). There was no significant difference between the two devices for stone size (LithAssist 830.8 mm 2 vs Ultrasonic 1209.6 mm 2 ), S.T.O.N.E nephrolithometry score (LithAssist 8.5 vs Ultrasonic 9.2), time to stone clearance (LithAssist 57.6 min vs Ultrasonic 43.9 min) or overall operative time (LithAssist 164.6 min vs Ultrasonic 147.5 min). There was a trend for higher stone clearance rate with the ultrasonic lithotripter compared to the LithAssist device, 107.1 mm 2 /min vs 27.9 mm 2 / min respectively, p¼0.1. Post-operative complications, stone-free rates, need for additional modalities, and device malfunction were similar in both treatment groups. There were two cases that required switching from the LithAssist to the ultrasonic lithotripter. Surgeon comfort with the device was higher for the ultrasonic lithotripter (p<0.001).CONCLUSIONS: Preliminary results suggest no significant difference between the LithAssist and ultrasonic lithotripter, however there was a trend for higher stone clearance rate with the ultrasonic lithotripter. Specifically the LithAssist device had poor suctioning secondary to the small caliber of the probe and required more retrieval of stone fragments. Surgeon comfort was significantly higher with the ultrasonic lithotripter.

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