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BackgroundAs laparoscopic partial nephrectomy increases in prominence, more needs to be understood about the combined effect of the pneumoperitoneum and renal ischemia during tumor resection. The purpose of this study is to investigate the effect of combined renal hilar clamping (arterial only versus arteriovenous) and retrograde intrarenal cooling on renal temperature and oxygenation in a porcine laparoscopic partial nephrectomy model.Materials and MethodsUnder general anesthesia, laparoscopic access with intra-abdominal pressure of 15mmHg to the left renal hilum was obtained. Licox®tissue oxygenation and temperature probes were placed into the kidney transcutaneously; measurements were taken every 30 seconds. After establishing baseline readings, either the artery alone (n 18) or the artery and vein (n 18) were clamped for 30, 60 or 90 minutes (n 12 each). During vascular clamping, retrograde, intrarenal cooling was performed with ice cold saline infused via a percutaneously placed ureteric catheter in 18 pigs. Changes in renal pO2and temperature were analyzed with repeated measures ANCOVA in SPSS 16.ResultsRetrograde cooling decreased renal parenchyma to 75.8 of baseline temperature (27.9°C) within 15 minutes. There were no differences in cooling whether arterial or arteriovenous clamping was used (p 0.79). In uncooled animals, there was no significant difference in the decrease in renal pO2during the clamp phase (p 0.18) or during the recovery phase (p 0.52). During the recovery phase, renal pO2in uncooled animals was significantly higher than in those who received cooling (p 0.01). Animals who underwent hilar clamping for extended periods (60 and 90min) had a slower recovery of renal pO2to baseline than those with hilar clamping for 30 minutes (p 0.04)ConclusionRetrograde intrarenal cooling can reliably cool the porcine kidney to 28°C, regardless of whether arterial or arteriovenous clamping is used. Renal pO2is not significantly different between animals that undergo artery only versus en bloc hilar clamping. Pigs that were provided with retrograde cooling had a slower return of pO2to baseline following release of hilar clamps, possibly due to hypothermic vasospasm. Clamp durations greater than 60 minutes were also associated with slower return of renal oxygenation to baseline. [ABSTRACT FROM AUTHOR]

Background and Purpose The use of stone baskets for repositioning of stones or removal of fragment in conjunction with ureterorenoscopy has become widespread. We tested the performance of the ACMI Sur-Catch NT, Bard Dimension, Boston Scientific Zero-tip, and Cook N-Circle in a pig kidney model of flexible ureterorenoscopy.Materials and Methods Opening characteristics of the basket were measured with mechanical calipers at 1-mm increments and compared with published reports to ensure the tested baskets were representative. Pig kidneys were placed in a basin and the ureters secured with a suture to a weight for stability. Flexible renoscopy was performed using a 16F flexible cystonephroscope. An 8-mm calculus was placed in the lower pole. Using each of four designs, the time necessary to grasp the stone, time to release the stone, and total time to move a stone from the lower-pole calix to the upper-pole were recorded. Total time experiments were repeated six times with each basket by three surgeons for a total of 18 attempts, and catch-and-release experiments were repeated six times by four surgeons for a total of 24 attempts per basket.Results The Sur-Catch was significantly slower for catch and release (P< 0.001) and total time; P< 0.05) compared with all other baskets. There were no differences between the other baskets in either catch, release, or total times. There was no difference between surgeons (P< 0.0634) or between attempts one through six (P 0.538).Conclusions Baskets with added complexity of the wire configurations (Sur-Catch) or a deflectable-wire mechanism (Dimension) offer no advantages and may slow capture and release of stones. [ABSTRACT FROM AUTHOR]

PURPOSE:: The rate of shock wave administration is a factor in the per shock efficiency of shock wave lithotripsy (SWL). Experimental evidence suggests that decreasing shock wave frequency from 120 shocks per minute results in improved stone fragmentation. To our knowledge this study is the first to examine the effect of decreased shock wave frequency in patients with renal stones.MATERIALS AND METHODS:: Patients with previously untreated radiopaque stones in the renal collecting system were randomized to SWL at 60 or 120 shocks per minute. They were followed at 2 weeks and 3 months. The primary outcome was the success rate, defined as stone-free status or asymptomatic fragments less than 5 mm 3 months after treatment.RESULTS:: A total of 220 patients were randomized, including 111 to 60 shocks per minute and 109 to 120 shocks per minute. The 2 groups were comparable in regard to age, sex, body mass index, stent status and initial stone area. The success rate was higher for 60 shocks per minute (75% vs 61%, p = 0.027). Patients with larger stones (stone area 100 mm or greater) experienced a greater benefit with treatment at 60 shocks per minute. The success rate was 71% for 60 shocks per minute vs 32% (p = 0.002) and the stone-free rate was 60% vs 28% (p = 0.015). Repeat SWL was required in 32% of patients treated with 120 shocks per minute vs 18% (p = 0.018). Fewer shocks were required with 60 shocks per minute (2,423 vs 2,906, p <0.001) but treatment time was longer (40.6 vs 24.2 minutes, p <0.001). There was a trend toward fewer complications with 60 shocks per minute (p = 0.079).CONCLUSIONS:: SWL treatment at 60 shocks per minute yields better outcomes than at 120 shocks per minute, particularly for stones 100 mm or greater, without any increase in morbidity and with an acceptable increase in treatment time. [ABSTRACT FROM AUTHOR]

BackgroundShock wave lithotripsy (SWL), ureteroscopy, and percutaneous nephrolithotomy are established treatments for renal stones. Historically, SWL has been a predominant and commonly used procedure for treating upper tract renal stones smaller than 20 mm in diameter due to its noninvasive nature. However, the reported failure rate of SWL after one treatment session ranges from 30% to 89%. The failure rate can be reduced by identifying candidates likely to benefit from SWL and manage patients who are likely to fail SWL with other treatment modalities. This would enhance and optimize treatment results for SWL candidates. ObjectiveWe proposed to develop a machine learning model that can predict SWL outcomes to assist practitioners in the decision-making process when considering patients for stone treatment. MethodsA data set including 58,349 SWL procedures performed during 31,569 patient visits for SWL to a single hospital between 1990 and 2016 was used to construct and validate the predictive model. The AdaBoost algorithm was applied to a data set with 17 predictive attributes related to patient demographics and stone characteristics, with success or failure as an outcome. The AdaBoost algorithm was also applied to a training data set. The generated model’s performance was compared to that of 5 other machine learning algorithms, namely C4.5 decision tree, naïve Bayes, Bayesian network, K-nearest neighbors, and multilayer perceptron. ResultsThe developed model was validated with a testing data set and performed significantly better than the models generated by the other 5 predictive algorithms. The sensitivity and specificity of the model were 0.875 and 0.653, respectively, while its positive predictive value was 0.7159 and negative predictive value was 0.839. The C-statistics of the receiver operating characteristic (ROC) analysis was 0.843, which reflects an excellent test. Conclusions We have developed a rigorous machine learning model to assist physicians and decision-makers to choose patients with renal stones who are most likely to have successful SWL treatment based on their demographics and stone characteristics. The proposed machine learning model can assist physicians and decision-makers in planning for SWL treatment and allow for more effective use of limited health care resources and improve patient prognoses.