Development of an innovative intrarenal pressure regulation system for mini-PCNL: A preliminary study.

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.

Impact of case volume on outcomes of ureteroscopy for ureteral stones: the clinical research office of the endourological society ureteroscopy global study.

BACKGROUND: The Clinical Research Office of the Endourological Society (CROES) undertook the Ureteroscopy Global Study to establish a prospective global database to examine the worldwide use of ureteroscopy (URS) and to determine factors affecting outcome. OBJECTIVE: To investigate the influence of case volume on the outcomes of URS for ureteral stones. DESIGN, SETTING, AND PARTICIPANTS: The URS Global Study collected prospective data on consecutive patients with urinary stones treated with URS at 114 centres worldwide for 1 yr. Centres were identified as low or high volume based on the median overall annual case volume. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Pre- and intraoperative characteristics, and postoperative outcomes in patients at low- and high-volume centres were compared. The relationships between case volume and stone-free rate (SFR), stone burden, complications, and hospital stay were explored using multivariate regression analysis. RESULTS AND LIMITATIONS: Across all centres, the median case volume was 67; 58 and 56 centres were designated as low volume and high volume, respectively. URS procedures at high-volume centres took significantly less time to conduct. Mean SFR was 91.9% and 86.3% at high- and low-volume centres, respectively (p<0.001); the adjusted probability of a stone-free outcome increased with increasing case volume (p<0.001). Patients treated at a high-volume centre were less likely to need retreatment, had shorter postoperative hospital stay, were less likely to be readmitted within 3 mo, and had fewer and less severe complications. At case volumes approximately >200, the probability of complications decreased with increasing case volume (p=0.02). The study is limited by the heterogeneity of participating centres and surgeons and the inclusion of patients treated by more than one approach. CONCLUSIONS: In the treatment of ureteral stones with URS, high-volume centres achieve better outcomes than low-volume centres. Several outcome measures for URS improve with an increase in case volume. PATIENT SUMMARY: Outcomes following treatment of ureteral stones by ureteroscopy (URS) were studied in a large group of patients at centres worldwide. The proportion of successful procedures (ie, those in which patients became stone free) increased as the annual volume of URS at a hospital increased. Hospital stays were shorter and postoperative complications were less likely at high-volume hospitals. We conclude that for URS, the best outcomes are seen in patients treated at high-volume hospitals.

A novel paraboloid intracorporeal lithotripter: computer aided design analysis and in vitro comparison with holmium laser for large renal calculi.

PURPOSE: An intracorporeal lithotripsy probe tip was designed with a paraboloid shaped tip and compared with holmium laser for stone pulverization. MATERIALS AND METHODS: The paraboloid tip concept was developed and designed using computer aided design (CAD), fabricated, and patented. CAD analysis and in vitro comparison (with laser) of pulverization and propulsion dynamics were performed in an underwater hands-free bench arrangement using phantom stones. SPSS analysis for different energy cohorts was performed. RESULTS: CAD analysis: At "point contact" with the tip, the paraboloid lithotripter generated 3590 bars at generator settings of 4 bars. During "follow-up impacts," the tip pressure exponentially decreased (graduated tip pressure) and the lateral/centrifugal forces increased, converting the probe into a side-firing energy source. Bench analysis: At point contact, the paraboloid lithotripter at 2, 3, and 4 bars was comparable to that of a 6, 10, and 15 W laser, respectively (P<0.005). The paraboloid lithotripter showed a statistically significant advantage in breaking the phantoms, as against a laser that always bored through the phantom. Stone propulsion was comparable within all energy cohorts (P>0.05). CONCLUSION: The paraboloid lithotripter generates highly focused impact force with low propulsion, at point contact. As stone pulverization progresses, the tip forces exponentially decrease and the probe converts into a lateral firing energy source resulting in pulverization into larger fragments. Thus, the paraboloid lithotripter has all the advantages of laser at point contact and advantages of pneumatic lithotripter at follow-up hits, akin to being a bimodal energy source.

In vitro assessment of a novel spearheaded pneumatic intracorporeal lithotriptor.

BACKGROUND AND PURPOSE: Intracorporeal lithotripsy is an important modality used for stone pulverization. To improve the pulverization properties of intracorporeal lithotriptors, a novel intracorporeal "spearheaded lithotriptor" was designed by our institute. It was compared in vitro with the conventional lithotriptor. MATERIALS AND METHODS: The pulverization and propulsion dynamics were evaluated at various pressure settings on an in vitro bench arrangement with phantom stones. Lateral displacement during pulverization was also compared. RESULTS: The spearheaded lithotriptor had a better first hit (P<0.001) and follow-up hit dynamics (P<0.01). Stone propulsion and lateral displacement were low for the spearheaded lithotriptor at all pressure settings (P<0.05). CONCLUSION: The spearheaded lithotriptor improved stone pulverization without increasing the risk of stone migration. Further clinical evaluation of this novel probe is necessary.