Francisco Pedro Juan Daels

A nephrolithometric nomogram to predict treatment success of percutaneous nephrolithotomy.

PURPOSE Imaging is routinely done preoperatively and postoperatively to assess patients treated with percutaneous nephrolithotomy. We developed a nomogram for percutaneous nephrolithotomy success. MATERIALS AND METHODS From November 2007 to December 2009 the CROES (Clinical Research Office of the Endourological Society) collected data on consecutive patients at 96 centers globally. Patients were evaluated for stone-free status using plain x-ray of the kidneys, ureters and bladder. Treatment success was defined as no visible stones or residual fragments less than 4 mm. Multivariate regression was used to model the relationship between preoperative descriptors and the stone-free rate. Variables included case load, prior treatment, body mass index, staghorn stones, renal anomalies, and stone burden, location and count. Bootstrapping techniques were used to validate the model. Adjusted chi-square statistic values were used to rank the prognostic value of variables. A nomogram was developed using significant predictors from the model. We assessed the predictive accuracy of the nomogram using the ROC curve AUC. The nomogram was calibrated. RESULTS Stone burden was the best predictor of the stone-free rate (chi-square = 30.27, p <0.001). Other factors associated with the stone-free rate were case volume (chi-square = 35.75, p <0.001), prior stone treatment (chi-square = 14.55, p <0.012), staghorn stone (adjusted chi-square = 4.73, p <0.029), stone location (chi-square = 14.74, p <0.001) and stone count (chi-square = 4.78, p <0.004). A nephrolithometric nomogram was developed with predictive accuracy (AUC 0.76). CONCLUSIONS The percutaneous nephrolithotomy stone-free rate can be predicted using preclinical data and radiological information. We present a nephrolithometric nomogram for percutaneous nephrolithotomy.

Does imaging modality used for percutaneous renal access make a difference? A matched case analysis.

OBJECTIVE To assess perioperative outcomes of percutaneous nephrolithotomy (PCNL) using ultrasound or fluoroscopic guidance for percutaneous access. METHODS A prospectively collected international Clinical Research Office of the Endourological Society (CROES) database containing 5806 patients treated with PCNL was used for the study. Patients were divided into two groups based on the methods of percutaneous access: ultrasound versus fluoroscopy. Patient characteristics, operative data, and postoperative outcomes were compared. RESULTS Percutaneous access was obtained using ultrasound guidance only in 453 patients (13.7%) and fluoroscopic guidance only in 2853 patients (86.3%). Comparisons were performed on a matched sample with 453 patients in each group. Frequency and pattern of Clavien complications did not differ between groups (p=0.333). However, postoperative hemorrhage and transfusions were significantly higher in the fluoroscopy group: 6.0 v 13.1% (p=0.001) and 3.8 v 11.1% (p=0.001), respectively. The mean access sheath size was significantly greater in the fluoroscopy group (22.6 v 29.5F; p<0.001). Multivariate analysis showed that when compared with an access sheath ≤ 18F, larger access sheaths of 24-26F were associated with 3.04 times increased odds of bleeding and access sheaths of 27-30F were associated with 4.91 times increased odds of bleeding (p<0.05). Multiple renal punctures were associated with a 2.6 odds of bleeding. There were no significant differences in stone-free rates classified by the imaging method used to check treatment success. However, mean hospitalization was significantly longer in the ultrasound group (5.3 v 3.5 days; p<0.001). CONCLUSIONS On univariate analysis, fluoroscopic-guided percutaneous access was found to be associated with a higher incidence of hemorrhage. However, on multivariate analysis, this was found to be related to a greater access sheath size (≥ 27F) and multiple punctures. Prospective randomized trials are needed to clarify this issue.

Percutaneous lithotripsy in Valdivia-Galdakao decubitus position: our experience.

Percutaneous nephrolithotripsy (PNL) is actually the first therapeutic option to resolve complex renal stones. Our department initiated its experience in 1985 and treated the first 585 patients in ventral decubitus, as the original technique was described. Then, in 1998, the dorsal decubitus was adopted (Valdivia Uria), in which 695 patients were treated. Since 2006 the Valdivia Galdakao variant has been used. The Valdivia Galdakao position is an intermediate dorsal decubitus with extension of its homolateral lower limb and flexion of the contralateral. It is a practical way to place the patient for percutaneous renal surgery, avoiding hyperextensions and hyperflexions that can result in articular damage. It preserves cardiovascular and ventilatory dynamics and allows a better access to the respiratory tract. In this position, the bowel slips away from the puncture area lowering the risk of its damage. A single lumbar and genital sterile surgical field is created allowing antegrade and retrograde simultaneous endoscopic and even laparoscopic access, increasing efficiency and safety of the minimal invasive procedures. Between April 2006 and March 2008, 175 PNLs were performed in our department with the patient in Valdivia Galdakao position. The aim of this article is to describe our experience in this decubitus confirming that the Valdivia Galdakao is a safe, practical and versatile position that should be considered as first choice when a percutaneous renal surgery is indicated.

Tomografía computada como predictor de composición y fragilidad de la litiasis urinaria al tratamiento con litotricia extracorporea por ondas de choque in vitro

OBJECTIVES To evaluate the ability of non contrast computed tomography (NCCT) to predict stone composition and fragility for treatment with extracorporeal shock wave lithotripsy (ESWL). METHODS 27 stones of about 10 mm from patients who had undergone different endourological procedures were collected. All patients had been evaluated with NCCT. To perform in vitro ESWL an experimental device was designed. Three thousand pulses were applied with 17.2 Kv intensity using an electromagnetic generator (Lithostar) to all stones. Composition of each fragment was studied with crystallographic study. Results were statistically analyzed with Student Test, Chi2 Test and multivariate study. RESULTS In vitro ESWL had a success rate of 59.26%. Average stone HU, grouped by composition: cistine 1015 HU, Calcium monohydrate oxalate 1193 HU, uric acid 419 HU, dihydrate calcium oxalate 2122 HU, struvite 1543 HU and basic phosphate magnesium 1517 HU. A statistically significant relationship was found between values which were lower than 500 HU and uric acid composition (p=0.0006), as well as values higher than 2000 HU and composition of dihydrated calcium acid (p=0.0244). In the group of stones with less than 1000 HU (n=11) efficacy was 81.1%, whereas it was 43.75% in the others (p=0.0479). We found a statistically significant relationship between uric acid and effectiveness (p=0.021). There was not statistically significant relationship between size and treatment effectiveness. CONCLUSIONS The use of NCCT will allow predicting stone composition and fragility.

Percutaneous nephrolithotomy: technique.

Percutaneous nephrolithotomy (PCNL) is considered to be the first line of treatment for large renal stones. Though PCNL comes with higher morbidity, its efficacy is unbeaten by other minimally invasive modalities. However, potential complications, such as bleeding, occur. Improved skills and modifications of the procedure may reduce the probability of adverse outcomes. This article discusses the current trends and standards in PCNL technique with special focus on all important steps as positioning, access, instruments, dilation, disintegration, and exit, including outcomes, complication management, and training modalities.

Intraoperative Complications: How to Avoid Them?

At present, PNL is the minimally invasive technique of choice to treat complex renal stones. Despite being a safe surgical intervention, PNL is not exempt from potential complications, which can arise at any stage of the procedure: patient positioning, renal puncture, tract dilation, intraoperative manipulation, stone fragmentation and postoperative management. Besides being the majority of them minor, they can be kept to a minimum in experienced hands with the development of new techniques and improved technologies. However, patient positioning-related complications are not considered in any classification, as well as those related to anaesthesiological problems, which are the ones minimised adopting ECIRS in the Galdakao-modified supine Valdivia position. In particular, with regard to the potential complications due to decubitus, haemodynamic conditions, management of the respiratory tract and the relative location of the colon with respect to the puncture site, PNL performed in supine decubitus or in any of its variations proves to be safer than in prone decubitus.

ECIRS: Patient Positioning and Organization of the Operating Room

A standardized patient positioning and operating room organization are fundamental in order to perform a successful ECIRS. In particular, reference lines for the renal puncture and correct patient positioning in order to prevent pressure damages are described, as well as sterile draping and preparation of the surgical field. The operating room (OR) is very crowded and therefore it is relevant to define the right place for any operator and device. This aspect may appear time-consuming but is essential in order to optimize the cooperation of all the working team and to avoid both intraoperative problems and postoperative complications.

Percutaneous Nephrolithotomy (PCNL): The Supine Approach – Overcoming the Difficulties

Percutaneous nephrolithotomy (PCNL) is today accepted as the first-choice technique when managing complex renal stones. When taking into consideration the retroperitoneal position of the kidney, its relationship with other organs, and its own particular vascular distribution, the safest access to the urinary tract appears to be through a posterior calyx papilla, and the approach will always be through the lumbar area of the patient. Therefore, traditionally, the patient has been placed in the prone position. Nevertheless, other decubitus positions have been used for patients (supine, Valdivia-Galdakao, and intermediate supine).