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PurposeTo evaluate the thermal effect of high-power holmium:yttrium–aluminum–garnet (Ho:YAG) laser lithotripsy in flexible/semirigid ureteroscopy (fURS/sURS) and percutaneous nephrolithotomy (PNL) in a standardized ex vivo porcine kidney model with real-time temperature assessment.MethodsThe experimental setup consisted of three models designed to evaluate the thermal effects of Ho:YAG laser lithotripsy in fURS, sURS and PNL, respectively. In all setups, a postmortem porcine kidney was placed in a 37 °C water bath. Three thermocouples were inserted into the renal parenchyma while a flexible thermocouple was placed 3–4 mm proximal to the laser fiber to measure temperature variations in the collecting system. The thermal impact was evaluated in relation to laser power between 5 and 100 W and various irrigation rates (37 °C, 0–100 ml/min).ResultsIn all three experimental setups, sufficient irrigation was required to prevent potentially damaging temperatures into the renal pelvis and parenchyma. Even 5 W in fURS can lead to a potentially harming temperature rise if insufficient irrigation is applied. Particularly, high-power settings ≥ 30 W carry an elevated risk for critical temperature rises. The results allow the definition of a specific irrigation threshold for any power setting to prevent critical temperatures in the present study design.ConclusionsHo:YAG laser lithotripsy bears the risk of thermal damages to the urinary tract even at low-power settings if inadequate irrigation is applied. Sufficient irrigation is mandatory to perform safe Ho:YAG laser lithotripsy. Based on the results, we developed a formula calculating the approximate ΔT for irrigation rates ≥ 30 ml/min: ΔT = 15 K × (power [W]/irrigation [ml/min]).

Transurethral resection of the prostate (TURP) is a minimally invasive endoscopic procedure that requires experience and skill of the surgeon. To permit surgical training under realistic conditions we report a novel phantom of the human prostate that can be resected with TURP. The phantom mirrors the anatomy and haptic properties of the gland and permits quantitative evaluation of important surgical performance indicators. Mixtures of soft materials are engineered to mimic the physical properties of the human tissue, including the mechanical strength, the electrical and thermal conductivity, and the appearance under an endoscope. Electrocautery resection of the phantom closely resembles the procedure on human tissue. Ultrasound contrast agent was applied to the central zone, which was not detectable by the surgeon during the surgery but showed high contrast when imaged after the surgery, to serve as a label for the quantitative evaluation of the surgery. Quantitative criteria for performance assessment are established and evaluated by automated image analysis. We present the workflow of a surgical simulation on a prostate phantom followed by quantitative evaluation of the surgical performance. Surgery on the phantom is useful for medical training, and enables the development and testing of endoscopic and minimally invasive surgical instruments.

Within the BUSTER trial, we analyzed the surgeon’s amount of experience and other parameters associated with URS procedures regarding the stone-free rate, complication rate, and operative time. Patient characteristics and surgical details on 307 URS procedures were prospectively documented according to a standardized study protocol at 14 German centers 01–04/2015. Surgeon’s experience was correlated to clinical characteristics, and its impact on the stone-free rate, complication rate, and operative time subjected to multivariate analysis. 76 (25%), 66 (21%) and 165 (54%) of 307 URS procedures were carried out by residents, young specialists, and experienced specialists (> 5 years after board certification), respectively. Median stone size was 6 mm, median operative time 35 min. A ureteral stent was placed at the end of 82% of procedures. Stone-free rate and stone-free rate including minimal residual stone fragments (adequate for spontaneous clearance) following URS were 69 and 91%, respectively. No complications were documented during the hospital stays of 89% of patients (Clavien–Dindo grade 0). According to multivariate analysis, experienced specialists achieved a 2.2-fold higher stone-free rate compared to residents (p = 0.038), but used post-URS stenting 2.6-fold more frequently (p = 0.023). Surgeon’s experience had no significant impact on the complication rate. We observed no differences in this study’s main endpoints, namely the stone-free and complication rates, between residents and young specialists, but experienced specialists’ stone-free rate was significantly higher. During this cross-sectional study, 75% of URS procedures were performed by specialists. The experienced specialists’ more than two-fold higher stone-free rate compared to residents’ justifies ongoing efforts to establish structured URS training programs.

SummaryBackgroundDespite the high utilisation of ureterorenoscopy (URS) in interventional stone treatment, there is little evidence of any link between annual hospital volume and outcome.MethodsFrom January to April 2015, data from 307 URS patients were prospectively recorded in the multicentre observational BUSTER-Trial (Benchmarks of ureterorenoscopic stone treatment-results in terms of complications, quality of life, and stone-free rates). The best threshold value for annual hospital volume with an independent effect on the outcome (measured on stone-free and complication rates) of our study group was established with logistic regression.ResultsIn 38.4% of cases of renal and 61.6% of ureteral stones, median stone size was 6 mm with an interquartile range (IQR) of 4–8 mm. The annual URS rate in the 14 participating hospitals ranged from 77 to 333 (median 144; IQR 109–208). The binary endpoint as a combination of completely stone-free or residual fragments small enough to pass spontaneously and a maximum complication severity of Clavien–Dindo grade 1 was attained in 234/252 (92.9%) cases with a hospital volume of ≥ 99 URS compared with 43/55 (78.2%) in < 99 URS (p = 0.002). Adjusted for patient-, stone- and physician-related factors, an annual hospital URS volume of ≥ 99 increases the chance of an optimum outcome (OR = 3.92; 95% CI 1.46–10.51; p = 0.007).ConclusionsAn independent effect of URS hospital volume on outcome quality in the 14 participating hospitals was demonstrated. Threshold values for annual case numbers should be scientifically established irrespective of the considered procedure.

HintergrundDie „Post-Ureteroscopic Lesion Scale“ (PULS) wurde als eine Klassifikation zur Standardisierung der iatrogenen Harnleiterläsionen während der Ureterorenoskopie (URS) vorgestellt. Mit der vorliegenden Studie sollen die praktische Anwendung und der mögliche klinische Nutzen des PULS-Scores an einem repräsentativen Patientenkollektiv überprüft werden.Material und MethodeIm Rahmen der prospektiven BUSTER-Studie (Bewertung der ureterorenoskopischen Steintherapie – Ergebnisse hinsichtlich Komplikationen, Lebensqualität und Steinfreiheitsrate) konnten Daten von 307 Patienten aus 14 deutschen Kliniken aufgezeichnet werden. Für die hier vorgestellte Arbeit wurden drei Studienhypothesen (H) überprüft: Es besteht eine hohe Übereinstimmung der unabhängig zu einander erfolgten PULS-Graduierungen von Operateur und Pflegeassistenzpersonal (H1), es gibt eine positive Korrelation der PULS-Grade mit der postoperativen Komplikationsdichte während des stationären Aufenthalts (H2), es liegt eine signifikante Übereinstimmung des postinterventionellen Harnleiterstentings mit den verursachten PULS-Graden vor (H3).ErgebnisseDas mediane Alter der Studienpatienten lag bei 54,4 („interquartile range“ [IQR] 44,4–65,84) Jahren; 65,5 % der Patienten waren männlichen Geschlechts. Die mediane Steingröße des Indexkonkrements betrug 6 (IQR, 4–8) mm, wobei 117 (38,4 %) und 188 (61,6 %) der Indexkonkremente in der Niere bzw. im Harnleiter lagen. 70 und 82,4 % erhielten ein präoperatives bzw. postoperatives Harnleiterstenting. 68,7 % der Studienpatienten waren nach einer URS komplett steinfrei, die Komplikationsrate betrug 10,8 % (dominant Grad 1 oder 2 nach Clavien-Dindo). Die PULS-Grade 0, 1, 2 und 3 nach Einschätzung des Operateurs lagen bei 40 %, 52,1 %, 6,9 % bzw. 1 %. Es bestand eine hohe Interobserver-Übereinstimmung der erfolgten Pulsgraduierungen zwischen Operateur und Pflegeassistenzpersonal (κ = 0,883, p < 0,001; H1+). Eine signifikante Korrelation zwischen dem PULS-Grad und den aufgezeichneten Komplikationen konnte nicht gefunden werden (ρ = 0,09, p = 0,881; H2−). Es bestand hingegen eine signifikante positive Korrelation zwischen dem PULS-Grad und der postoperativen Einlage eines Harnleiterstents (ρ = 0,287, p < 0,001; H3+), wobei hier beispielsweise ein PULS-Grad 1 (im Vergleich zu PULS-Grad 0) die Wahrscheinlichkeit um den Faktor 3,24 erhöhte (95 %-Konfidenzintervall 1,43–7,34, p = 0,005).SchlussfolgerungDie URS ist in der täglichen Routine ein sicheres und effektives Verfahren zur Behandlung von Konkrementen des oberen Harntrakts. Die vorliegenden „Real-world-Daten“ bestätigen die hohe Interrater-Reliabilität des PULS-Scores und dessen potentiellen Anwendernutzen hinsichtlich der Indikationsstellung zur postoperativen Harnleiterschienung. Auf der Basis des PULS-Scores sollte jetzt eine prospektiv-randomisierte Studie prüfen, inwieweit die Standardisierung einer postoperativen Harnleiterstenteinlage erfolgen kann.