Stone Parameters Research Articles

PD47-11 PREDICTORS OF EMERGENCY DEPARTMENT REVISITS FOR URETERAL STONES

You have accessJournal of UrologyStone Disease: Epidemiology & Evaluation II1 Apr 2016PD47-11 PREDICTORS OF EMERGENCY DEPARTMENT REVISITS FOR URETERAL STONES Vishnu Ganesan, Christopher Loftus, Bryan Hinck, Daniel Greene, Yaw Nyame, Sri Sivalingam, and Manoj Monga Vishnu GanesanVishnu Ganesan More articles by this author , Christopher LoftusChristopher Loftus More articles by this author , Bryan HinckBryan Hinck More articles by this author , Daniel GreeneDaniel Greene More articles by this author , Yaw NyameYaw Nyame More articles by this author , Sri SivalingamSri Sivalingam More articles by this author , and Manoj MongaManoj Monga More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2016.02.2699AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Patients with ureteral stones frequently present to the emergency department (ED) when they first become symptomatic. A proportion of these patients end up returning to the ED. Our objective was to identify predictors among patient characteristics, stone parameters, and management approaches associated with an increased risk of ED revisits. METHODS We analyzed all emergency department visits in the Cleveland Clinic health care network with an ICD-9 diagnosis of nephrolithiasis and a computed tomography (CT) scan between 2010 and 2013. CT scans were independently reviewed to confirm stone size and location and degree of hydronephrosis. The primary outcome was the occurrence of a second ED visit within 30 days of the initial visit for reasons related to the stone. Patient presenting characteristics and stone parameters were recorded. Comparisons among the various factors were computed using a T-test test for numerical data and Fisher exact test for categorical data. A multivariable analysis using logistic regression was used to identify predictive factors for revisit. RESULTS We reviewed the records of 1414 patient > 18 years of age who presented to the ED with a diagnosis of ureteral stones confirmed by CT. Of these, 161 (11%) patients had a revisit to the ED within 30 days. There were no differences in gender, stone size, degree of hydronephrosis, use of alpha blockers, or serum WBC and creatinine between the patients who returned to the ED and those who did not (Table 1). Patients who returned to the ED were more likely to have proximal stones, be < 30 years old, have higher VAS pain score on presentation, and been treated with IV narcotics in their initial visit. On multivariable analysis, presence of a proximal ureteral stone and age < 30 remained independent predictors for a revisit to the ED (Table 2). CONCLUSIONS Patients who present with proximal ureter stones or age less than 30 were strongly associated with return visits to the ED within 30 days. Consideration may be given for early follow-up or intervention. © 2016FiguresReferencesRelatedDetails Volume 195Issue 4SApril 2016Page: e1174 Advertisement Copyright & Permissions© 2016MetricsAuthor Information Vishnu Ganesan More articles by this author Christopher Loftus More articles by this author Bryan Hinck More articles by this author Daniel Greene More articles by this author Yaw Nyame More articles by this author Sri Sivalingam More articles by this author Manoj Monga More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Impact of hours worked by a urologist prior to performing ureteroscopy on its safety and efficacy

Objective: The aim of this study was to evaluate the impact of hours worked by a urologist before performing ureteroscopy on its safety and efficacy. Materials and methods: Patients treated at a single institution from January 2010 to December 2013 were analyzed. The study assessed patient, stone and surgical parameters, stone-free rates and intraoperative complications performed in three work duration categories: less than 6 h, 6–12 h and more than 12 h of urologist’s work. Statistical analyses included the chi-squared test, Kruskal–Wallis test, and univariate and multivariate logistic regression analyses. Results: In total, 469 ureteroscopies were analyzed. Intraoperative complications differed non-significantly in the corresponding time categories: ureteral perforations (< 6 h 4.4%, 6–12 h 3.2%, > 12 h 7%, p = 0.46) and avulsions (all 0%). Rates for complete stone removal were 82% within the first 12 h vs 70.2% after 12 h (p = 0.03). Corresponding partial stone-free rates were 4.1% vs 3.5% (p = 0.83) and rates of unsuccessful ureteroscopy were 13.8% vs 26.3% (p = 0.01). In multivariate regression analysis, patients treated after 12 h of urologist’s work had a 2.4 times higher risk of an unsuccessful ureteroscopy [odds ratio (OR) = 2.4, 95% confidence interval (CI) 1.2–4.7, p = 0.001] and lower chances of complete stone removal (OR = 0.46, 95% CI 0.24–0.89, p = 0.02). The odds of ureteral perforations were similar (p = 0.28). Conclusion: Work duration before ureteroscopy did not affect its safety. Stone-free rates decreased with increasing working time. Working time exceeding 12 h was identified as an independent risk factor for impaired stone-free rates.

Magnetic properties of 2D nickel nanostrips: structure dependent magnetism and Stoner criterion

We have investigated different geometries of two-dimensional (2D) infinite length Ni nanowires of increasing width using spin density functional theory calculations. Our simulations demonstrate that the parallelogram motif is the most stable and structures that incorporate the parallelogram motif are more stable as compared to rectangular structures. The wires are conducting and the conductance channels increase with increasing width. The wires have a non-linear behavior in the ballistic anisotropic magnetoresistance ratios (BAMR) with respect to the magnetization directions. All 2D nanowires as well as Ni (1 1 1) and Ni (1 0 0) monolayer investigated are ferromagnetic under the Stoner criterion and exhibit enhanced magnetic moments as compared to bulk Ni and the respective Ni monolayers. The easy axis for all nickel nanowires under investigation is observed to be along the wire axis. The double rectangular nanowire exhibits a magnetic anomaly with a smaller magnetic moment when compared to Ni (1 0 0) monolayer and is the only structure with an easy axis perpendicular to the wire axis. The Stoner parameter which has been known to be structure independent in bulk and surfaces is found to vary with the structure and the width of the nanowires. The less stable rectangular and rhombus shaped nanowires have a higher ferromagnetic strength than parallelogram shaped nanowires.

First-principles theory of electron-spin fluctuation coupling and superconducting instabilities in iron selenide

We present first-principles calculations of the coupling of quasiparticles to spin fluctuations in iron selenide and discuss which types of superconducting instabilities this coupling gives rise to. We find that strong antiferromagnetic stripe-phase spin fluctuations lead to large coupling constants for superconducting gaps with $s_\pm$-symmetry, but these coupling constants are significantly reduced by other spin fluctuations with small wave vectors. An accurate description of this competition and an inclusion of band structure and Stoner parameter renormalization effects lead to a value of the coupling constant for an $s_\pm$-symmetric gap which can produce a superconducting transition temperature consistent with experimental measurements.

Torque-Controlled Adaptive Speed Control on a CNC Marble Saw Machine

Although CNC marble saw machines can automatically cut marble slabs to desired dimensions, saw speed and feed rate are selected by operator according to stone parameters, features of the saw, and its immersion depth. If the feed rate is selected lower than the optimal value, there will be time-loss and capacity deficiencies or if it is selected faster, cutting quality will decrease, spindle motor will draw more current, and saw blade will corrode faster. While cutting especially thick materials, saw may be stacked in the stone, cutting quality may be impaired, saw blade may be abraded earlier, precision quality may go down because of increase in measurement errors, and machine may be damaged with the increase in vibrations when improper feed rates are selected. Because of nonhomogeneity of the slabs and deterioration of the saw blade, operator cannot determine a persistent feed rate. This study is targeted to find saw speeds according to saw diameter and optimum feed rate by means of limiting vibrations and current drawn from saw motor and torque accordingly in order to increase working performance of CNC marble saw machines. Thanks to adaptive adjustment of feed rate, one can save on material as well as time, labour, and cost by making use of optimum energy.

Multidrug resistant bacteriuria before percutaneous nephrolithotomy predicts for postoperative infectious complications.

Multidrug resistant (MDR) uropathogens are increasing in prevalence and may contribute to significant morbidity after percutaneous nephrolithotomy (PCNL). We investigate the presence of MDR bacteriuria and occurrence of postoperative infectious complications in patients who underwent PCNL at our institution. Retrospective review was performed of 81 patients undergoing PCNL by a single surgeon (RLS) between 2009 and 2013. Patient demographics, comorbidities, stone parameters on imaging, and microbial data were compiled. MDR organisms were defined as resistant to three or more of the American Urological Association Best Practice Statement antimicrobial classes for PCNL. Postoperative complications were graded by Clavien score and European Association of Urology infection grade. Univariate comparisons were analyzed between patients with and without a postoperative infectious complication. Multivariate logistic regression was performed to determine significant predictor variables for postoperative infectious complications. Of the 81 patients undergoing PCNL, 41/81 (51%) had positive preoperative urine culture, 24/81 (30%) had positive MDR urine culture, and 16/81 (19%) had a postoperative infectious complication. Multivariate analysis revealed a positive preoperative MDR urine culture significantly increased the risk of postoperative infectious complication (odds ratio [OR]=4.89, 95% confidence interval [CI] 1.134-17.8, P=0.016). The presence of more than one access tract during PCNL also predicted for infectious complications (OR=7.5, 95% CI 2.13-26.4, P=0.003) Of the 16 patients with a postoperative infection 3 (18%) had postoperative urine cultures discordant with the preoperative urine cultures. Our institution demonstrated a relatively high prevalence of MDR bacteriuria in patients undergoing PCNL and that MDR is a significant risk factor for postoperative infectious complications despite appropriate preoperative antibiotics. Further investigations regarding prophylaxis modalities and infection prevention strategies are needed.

Noncontrast computed tomography can predict the outcome of shockwave lithotripsy via accurate stone measurement and abdominal fat distribution determination

Urolithiasis is a common disease of the urinary system. Extracorporeal shockwave lithotripsy (SWL) has become one of the standard treatments for renal and ureteral stones; however, the success rates range widely and failure of stone disintegration may cause additional outlay, alternative procedures, and even complications. We used the data available from noncontrast abdominal computed tomography (NCCT) to evaluate the impact of stone parameters and abdominal fat distribution on calculus-free rates following SWL. We retrospectively reviewed 328 patients who had urinary stones and had undergone SWL from August 2012 to August 2013. All of them received pre-SWL NCCT; 1 month after SWL, radiography was arranged to evaluate the condition of the fragments. These patients were classified into stone-free group and residual stone group. Unenhanced computed tomography variables, including stone attenuation, abdominal fat area, and skin-to-stone distance (SSD) were analyzed. In all, 197 (60%) were classified as stone-free and 132 (40%) as having residual stone. The mean ages were 49.35 ± 13.22 years and 55.32 ± 13.52 years, respectively. On univariate analysis, age, stone size, stone surface area, stone attenuation, SSD, total fat area (TFA), abdominal circumference, serum creatinine, and the severity of hydronephrosis revealed statistical significance between these two groups. From multivariate logistic regression analysis, the independent parameters impacting SWL outcomes were stone size, stone attenuation, TFA, and serum creatinine. [Adjusted odds ratios and (95% confidence intervals): 9.49 (3.72–24.20), 2.25 (1.22–4.14), 2.20 (1.10–4.40), and 2.89 (1.35–6.21) respectively, all p < 0.05]. In the present study, stone size, stone attenuation, TFA and serum creatinine were four independent predictors for stone-free rates after SWL. These findings suggest that pretreatment NCCT may predict the outcomes after SWL. Consequently, we can use these predictors for selecting the optimal treatment for patients with urinary stones.

Factors affecting outcomes of percutaneous nephrolithotomy in horseshoe kidneys.

To analyze the patient- and procedure-related factors affecting the outcomes of percutaneous nephrolithotomy (PNL) in horseshoe kidneys (HSKs). A retrospective analysis was done of patients with stones in HSKs treated with PNL in 3 referral centers between 1998 and 2013. Demographics, along with perioperative characteristics, were evaluated in detail as to whether or not they had an effect on the success and complication rates. A total of 54 HSKs with calculi in 53 patients were treated with PNL. Mean stone size was 28.4 ± 19.6 mm (range, 10-120 mm). Fifty-three patients were treated through a single tract, and 1 patient required additional access. Access was directed to the upper calyx (n = 27), middle calyx (n = 17), and lower calyx (n = 10) through the intercostal (n = 23) and subcostal (n = 31) areas. Flexible nephroscopy was used in 18.5% of the procedures. Postoperative complications were observed in 9 (16.7%) of the procedures. Success rate was 66.7% after a single session of PNL and increased to 90.7% with additional treatments. Although patient demographics, preoperative imaging, and other operative measures did not have significant effect on the complication rate, stone complexity and multiplicity, in combination with flexible nephroscopy, were found to significantly affect the success rate (P = .026, P = .043, and P = .021, respectively). However, in multivariate analysis stone multiplicity was the only factor that affected success rate (P = .004). Stone parameters play an important role in achieving stone-free status in HSKs. Use of flexible nephroscopy positively affects the success rate by allowing reaching the peripherally located calices.

Which is the preferred modality of renal access for a trainee urologist: ultrasonography or fluoroscopy? Results of a prospective randomized trial.

In percutaneous nephrolithotomy (PCNL), placement of the access tract into the kidney is an important aspect of the procedure and is responsible for the steep learning curve associated with the operation. The aim of the current prospective randomized trial was to assess the duration of radiation exposure along with the safety and efficacy of PCNL done by a trainee, utilizing either ultrasonography (US) or fluoroscopic guidance to obtain access. Sixty-four patients with ≤3 cm renal calculi undergoing single-tract PCNL by trainee urologists (experience of <25 PCNL's) were randomized into US- and fluoroscopic-guided access groups (32 in each). In Group 1 (US guided), puncture was done using a 3.5/5 MHz US probe with a puncture attachment, whereas the triangulation technique with biplanar C-arm fluoroscopy was utilized in group 2 (fluoroscopic guided). Patient demographics, stone parameters, intraoperative characteristics, fluoroscopy durations, and postoperative outcomes were analyzed. Both groups were comparable as far as patient and stone characteristics were concerned. The fluoroscopy exposure during the puncture phase (T2) and overall (T) was significantly lower in the US group at 9.0±20.8 vs 43.8±34.8, (p<0.0001) and 204.3±84 vs 239.9±77.5, (p=0.04). Six patients in group1 required fluoroscopic adjustment (p=0.03). All other intra- and postoperative parameters were similar in both the groups. Both ultrasound and fluoroscopic guidance for renal access are equally safe and feasible in the hands of a trainee urologist. Total fluoroscopy duration and exposure time during puncture were both significantly less in the ultrasound group. Expertise in fluoroscopic-guided access is essential for a novice to effectively achieve access in all possible situations.

Increased frequency of gallbladder stone and related parameters in hemodialysis patients.

The prevalence of gallbladder stone (GBS) is shown to be increased in some studies in patients with chronic kidney disease (CKD). Nevertheless, some other studies did not confirm these findings. The controversial results about the prevalence of GBS in hemodialysis (HD) patients demand new studies to search GBS prevalence and associating risk factors in HD patients. In the present study, we aimed to investigate GBS prevalence and risk factors in our HD patients. A total of 104 HD and 149 control patients were involved. Complete physical examinations, including measurements of dry body weight and height, were done. Abdominal ultrasonography was conducted by the same experienced radiologist. Blood samples were drawn via venipuncture from the study participants after they had fasted overnight just before a midweek hemodialysis session for laboratory examinations. The prevalence of GBS in HD patients was 34.6 % (36/104), and that was significantly higher than that of control group 12.9% (17/149; p=0.0001). In all study participants (HD patients and control group), patients with GBS were older than patients with no GBS (63.2±14.2 vs 53.7±16.7; p=0.0001). However, in HD patients, mean age was similar in patients with GBS and no GBS (64.3±13.8 vs 60.1±16.6; p>0.05). Patients with GBS had a higher prevalence of units of blood transfusions than patients with no GBS in hemodialysis patients (2.0±2.9 vs 0.9±1.3; p=0.047) CONCLUSION: The present study showed an increased prevalence of GBS in HD patients compared to healthy controls. The number of blood transfusions and autonomic neuropathy may be responsible for the increased prevalence of GBS in HD patients.

PD28-01 DOES PRE-OPERATIVE MULTI-DRUG RESISTANT URINE CULTURE PREDICT INFECTIOUS COMPLICATIONS AFTER PERCUTANEOUS NEPHROLITHOTOMY?

You have accessJournal of UrologyStone Disease: Evaluation I1 Apr 2014PD28-01 DOES PRE-OPERATIVE MULTI-DRUG RESISTANT URINE CULTURE PREDICT INFECTIOUS COMPLICATIONS AFTER PERCUTANEOUS NEPHROLITHOTOMY? Nishant Patel, MD Omer Raheem, MD Michael Liss, MD David Wenzler, MD William Shi, Craig Schallhorn, BS Charles Lakin, MD Michelle Ritter, andMD Roger L. SurMD Nishant PatelNishant Patel More articles by this author , Omer RaheemOmer Raheem More articles by this author , Michael LissMichael Liss More articles by this author , David WenzlerDavid Wenzler More articles by this author , William ShiWilliam Shi More articles by this author , Craig SchallhornCraig Schallhorn More articles by this author , Charles LakinCharles Lakin More articles by this author , Michelle RitterMichelle Ritter More articles by this author , and Roger L. SurRoger L. Sur More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.2112AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES American Urological Association (AUA) Best Practice guidelines are in place to minimize infectious complications from percutaneous nephrolithotomy (PCNL). Multidrug resistant (MDR) uropathogens are increasing in prevalence and may contribute to significant morbidity following PCNL. We sought to document the prevalence of MDR baceteruria in patients whom underwent PCNL at our institution and evaluate whether presence of MDR bacteruria predicts for post-operative infectious complications. METHODS A retrospective review was performed of 83 patients undergoing PNCL by a single surgeon (RLS) between 2009-2013. Patient demographics, comorbidities, stone parameters on imaging, and microbial data was compiled. MDR organisms were defined as resistance to three or more of the AUA Best Practice Statement antimicrobial classes for PCNL (cephalosporin, aminoglycoside, fluoroquinolone, penicillin, clindamycin). Complications, Clavien score, and presence of post-operative infectious complications (EUA infection grade) were recorded. Univariate comparisons were analyzed between patients with and without a post-operative infectious complication. Multivariate logistic regression was performed to determine predicting variables for post-operative infectious complications. RESULTS Of the 83 patients undergoing PCNL, 49% had positive preoperative urine culture and 29% had positive MDR urine culture. Patients who had a post-operative infectious complication compared to those that did not, had an increased prevalence of staghorn calculus (50% vs. 18.6%, p=0.006) and an increased prevalence of pre-operative MDR urine culture (50% vs 20.3%, p=0.015). Controlling for age, stone size, and presence of renal structure abnormalities, multivariate analysis revealed presence of staghorn calculus increased the risk of a post-operative infectious complications by 4.15 times (95% CI 1.39-12.44, p=0.011). A positive pre-operative MDR urine culture increased the risk of post-operative infectious complication by 3.65 times (95% CI 1.23-10.87, p=0.02) despite appropriate culture-specific antibiotics. CONCLUSIONS Our institution demonstrated a relatively high prevalence of multi-drug resistant bacteruria in patients undergoing PCNL. The presence of a staghorn calculus and positive MDR urine culture predicted for a post-operative infectious complication. The higher risk of complications should be provided to patients undergoing PCNL and warrant extra attention to post-operative care by urologists. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e769 Advertisement Copyright & Permissions© 2014MetricsAuthor Information Nishant Patel More articles by this author Omer Raheem More articles by this author Michael Liss More articles by this author David Wenzler More articles by this author William Shi More articles by this author Craig Schallhorn More articles by this author Charles Lakin More articles by this author Michelle Ritter More articles by this author Roger L. Sur More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Characterization of iron ferromagnetism by the local atomic volume: from three-dimensional structures to isolated atoms

We present a comprehensive study of the relationship between the ferromagnetism and the structural properties of Fe systems from three-dimensional ones to isolated atoms based on the spin-density functional theory. We have found a relation between the magnetic moment and the volume of the Voronoi polyhedron, determining, in most cases, the value of the total magnetic moment as a function of this volume with an average accuracy of ±0.28 μB and of the 3d magnetic moment with an average accuracy of ±0.07 μB when the atomic volume is larger than 22 Å3. It is demonstrated that this approach is applicable for many three-dimensional systems, including high-symmetry structures of perfect body-centered cubic (bcc), face-centered cubic (fcc), hexagonal close-packed (hcp), double hexagonal close-packed (dhcp), and simple cubic (sc) crystals, as well as for lower-symmetry ones, for example atoms near a grain boundary (GB) or a surface, around a vacancy or in a linear chain (for low-dimensional cases, we provide a generalized definition of the Voronoi polyhedron). Also, we extend the validity of the Stoner model to low-dimensional structures, such as atomic chains, free-standing monolayers and surfaces, determining the Stoner parameter for these systems. The ratio of the 3d-exchange splitting to the magnetic moment, corresponding to the Stoner parameter, is found to be I3d = (0.998 ± 0.006) eV /μB for magnetic moments up to 3.0 μB. Further, the 3d exchange splitting changes nearly linearly in the region of higher magnetic moments (3.0–4.0 μB) and the corresponding Stoner exchange parameter equals . The existence of these two regions reflects the fact that, with increasing Voronoi volume, the 3d bands separate first and, consequently, the 3d magnetic moment increases. When the Voronoi volume is sufficiently large (≥22 Å3), the separation of the 3d bands is complete and the magnetic moment reaches a value of 3.0 μB. Then, when the volume further increases, the 4s bands start to separate, increasing thus the 4s magnetic moment. Surprisingly, in the region of higher magnetic moments (≥3.0 μB), there is also a linear relationship between the 4s exchange splitting and the total magnetic moment with a slope of eV /μB, which is nearly identical to I3d for magnetic moments up to 3.0 μB. These linear relations can be considered as an extension of the Stoner model for low-dimensional systems.

Structural, electronic and magnetic properties of Fe, Co, Ni monatomic nanochains encapsulated in BeO nanotubes bundle

First-principles calculations have been performed to determine the structural, electronic and magnetic properties of transition metal TM (TM = Fe, Co and Ni) monatomic nanochain encapsulated inside and between (9, 0) beryllium oxide nanotube (BeONT) bundle. The generalized gradient approximation (GGA) was employed to describe the exchange-correlation potential. Our results show that the geometrical structure of the BeONT bundle is significantly changed after encapsulating TM nanochains. All configurations of TM chains @ (9, 0) BeONTs bundle systems have negative formation energy so they are stable and exothermic. Total density of states and partial densities of states analyses show that the spin polarization and the magnetic moment of TM chains @ BeONT systems come mostly from the TM atoms chain. The values of total and partial magnetic moment, spin polarization and Stoner parameter are calculated for all configurations of TM chains @ (9, 0) BeONTs bundle systems.

Does Simultaneous Inversion During Extracorporeal Shock Wave Lithotripsy Improve Stone Clearance: A Long-term, Prospective, Single-blind, Randomized Controlled Study

To determine the efficacy of a combination of simultaneous shock wave lithotripsy (SWL), hydration with controlled inversion therapy compared with SWL with hydration alone in patients with lower pole calyx stones. Patients with lower pole stones (4-20mm) were randomized to SWL or SWL with simultaneous inversion therapy (30° head down Trendelenburg position). Standardized shock waves were given to all patients stratified according to stone size. Subsequent standardized shock waves were given to patients with stone fragments determined by plain abdominal radiography and ultrasound by 2 radiologists blinded to treatment at day 1, weeks 2, 4, 12, 24, and at 1 year. The primary endpoint is stone-free rate (SFR) at week12. A total of 140 patients were recruited into the study. Patients were comparable with respect to age, sex, race, and stone parameters at baseline. The overall SFR at week 12 was 72% (n= 49 of 68) in patients with SWL and 76% (n= 54 of 71) in SWL with simultaneous inversion at the end of study (P= .591). There was a trend for SFR to improve over time with >80% of patients being stone-free after 1 year in both groups. No significant adverse effects were noted in both groups of patients. Although not statistically significant, SWL with simultaneous inversion is a valuable adjunct in assisting the passage of lower pole renal stones with a SFR of 76%. In clinical practice, this also translates to a 1.28 times improvement in SFR with no or minimal additional costs.

Calculating the Number of Shock Waves, Expulsion Time, and Optimum Stone Parameters Based on Noncontrast Computerized Tomography Characteristics

To define the parameters that accompanied a successful extracorporeal shock wave lithotripsy (ESWL), namely the number of shock waves (SWs), expulsion time (ET), mean stone density (MSD), and the skin-to-stone distance (SSD). A total of 368 patients diagnosed with renal calculi using noncontrast computerized tomography had their MSD, diameter, and SSD recorded. All patients were treated using a Siemens lithotripter. ESWL success meant a stone-free status or presence of residual fragments <3 mm, ET was the time in days for the successful clearance of stone fragments. Correlation was performed between the stone characteristics, number of SWs, and ET. Two multiple regression analysis models defined the number of SWs and ET. Two receiver operating characteristic curves plotted the best MSD cutoff value and optimum SSD for a successful ESWL. Three hundred one patients were ESWL successes. A significant positive correlation was elicited between number of SWs and stone diameter, density and SSD; between ET and stone diameter and density. Multiple regressions concluded 2 equations: Number of SWs = 265.108 + 5.103 x1 + 22.39 x2 + 10.931 x3 ET (days) = -10.85 + 0.031 x1 + 2.11 x2 x1 = stone density (Hounsfield unit [HUs]), x2 = stone diameter (mm), and x3 = SSD (mm). Receiver operating characteristic curves demonstrated a cutoff value of ≤ 934 HUs with 94.4% sensitivity and 66.7% specificity and P = .0211. The SSD curve showed that a distance ≤ 99 mm was 85.7% sensitive, 87.5% specific, P <.0001. Stone disintegration is not recommended if MSD is >934 HUs and SSD >99 mm. The required number of SWs and the expected ET can be anticipated.

A Randomized, Double-Blinded, Placebo-Controlled Trial of Intercostal Nerve Block After Percutaneous Nephrolithotomy

The optimal method of pain control after percutaneous nephrolithotomy (PCNL) remains controversial. We sought to determine whether intercostal nerve block with bupivicaine provided superior pain control, when compared with placebo, with a lower need for narcotics and improved health-related quality of life (HRQL) in the immediate postoperative period. Sixty-three patients were randomized to receive intercostal blockade with either 20 mL of 0.5% bupivacaine with epinephrine or 20 mL physiologic saline. All patients received intravenous narcotic patient-controlled analgesia (PCA) postoperatively. Data were collected on stone parameters, demographics, analgesic usage, length of stay, and HRQL as assessed by the Postoperative Recovery Scale. The mean age was 47.7±1.2 years; mean body mass index was 28.0±5.0 kg/m(2); mean stone diameter was 29.2±15.8 mm. Within the first 3 to 6 hours after surgery, there was a significant reduction in narcotic use for the group receiving intercostal nerve blockade with bupivacaine compared with placebo. At 3 hours, narcotic use was 2.4±3.1 mg vs 4.3±3.8 mg morphine equivalents (P=0.034), and within 6 hours of surgery, narcotic use was 5.9±6.1 mg vs 8.8±7.4 mg (P=0.096). Durable improvement in HRQL was also observed in patients receiving intercostal nerve blockade with bupivacaine compared with placebo (P=0.034). No complications were attributable to the intercostal nerve blocks in either group. Intercostal blockade with bupivacaine significantly improves both pain control and HRQL in the early postoperative period. The effectiveness of bupivacaine disappears within 6 hours of surgery, after which narcotic use becomes indistinguishable. Intercostal nerve blockade is an easy, safe, and inexpensive method that can be used to optimize pain control after PCNL.

The Impact of Body Mass Index on the Outcomes of Retrograde Intrarenal Stone Surgery

To compare the outcomes of using retrograde intrarenal surgery (RIRS) for treating renal stones among normal weight, overweight, and obese patients. From December 2008 to March 2012, 207 patients who underwent RIRS were included in the study. Patients were categorized into 3 groups according to their body mass index (BMI): normal weight<25 kg/m(2) (group 1), overweight 25-29.9 kg/m(2) (group 2), and obese≥30 kg/m(2) (group 3). We compared the 3 groups with regard to preoperative characteristics, operative parameters, and postoperative outcomes. There were no significant differences in age, gender, or renal stone parameters (size, localization, laterality, multiplicity) among the 3 groups. The mean stone sizes were 18.6 ± 7.1mm in group 1, 16.9 ± 7.0mm in group 2, and 18.5 ± 8.4mm in group 3 (P= .365). The stone-free rates (SFRs) of a single procedure for the groups were 79.0%, 77.9%, and 75.5% for groups 1, 2, and 3, respectively (P= .897). After additional treatments, the final SFR for the groups increased to 85.2%, 84.4%, and 81.6% for groups 1, 2, and 3, respectively (P= .861). We did not find any significant differences among the groups with regard to the operation times, complication rates, and hospital length of stay (LOS). Major complications were not observed either during or after the operations. Our study demonstrates that the outcomes of RIRS for treating renal stones are similar in overweight and obese patients when compared with patients who are of normal weight. Therefore, these patients can be treated safely and successfully with RIRS.

Evaluación de la influencia de la rugosidad superficial sobre la colonización epilítica de calizas mediante técnicas sin contacto

The importance of stone colonisation by microorganisms has led to an extensive literature on mechanisms and rates of physicochemical degradation of stone surface, both in laboratory and field contexts. Biological colonisation of a stone surface depends on intrinsic stone parameters like mineral composition, texture, porosity, and permeability, as well as on environmental parameters. In the present study, quantification of stone surface roughness and its relationship to epilithic colonisation was demonstrated for three types of limestones throughout non-destructive techniques, namely optical surface roughness instrument and digital image analysis. According to the roughness average (R a ) and mean roughness depth (R z ) determined for Anca limestone, Lioz limestone and Lecce stone, it can be concluded that great surface roughness stones render them prone to microbial colonisation.

The Most Reliable Preoperative Assessment of Renal Stone Burden as a Predictor of Stone-free Status After Flexible Ureteroscopy With Holmium Laser Lithotripsy: A Single-center Experience

To examine which parameters should be measured to preoperatively determine the stone burden as predictors of stone-free (SF) status after a single flexible ureteroscopy (URS). Although several stone parameters reportedly influence the outcome of treatment for urinary stones, the most reliable indicators of stone burden remain unclear. Patients with renal stones treated by flexible URS with holmium laser lithotripsy between October 2009 and December 2011 at a single institute were retrospectively evaluated. The SF status was determined by kidney-ureter-bladder (KUB) films at postoperative day 1. Correlations of possible predictors with the SF status were analyzed using a logistic regression model. According to the univariate analysis, the following variables were significantly associated with failed treatment: number of stones (P = .001), cumulative stone diameter (CSD) (P < .001), stone surface area (SA) (P < .001), stone volume (P < .001), and presence of lower pole calculi (P = .008). According to the multivariate analysis, the stone volume (P < .001) and the CSD (P = .015) were found to be independent predictors of SF status. The SA (P = .598) had no significant independent influence on the SF status. Among the several parameters regarding the renal stone burden, the stone volume determined by noncontrast computed tomography and the CSD of the KUB were significantly and independently inversely related to the success rate of URS. Among the 3 parameters of stone burden, the SA was found to have a lower clinical utility and priority as a predictor of a SF status after URS.

Defect induced local moment in ZnO as a consequence of Stoner mechanism

We have examined the formation of a local moment by considering various defects in ZnO. The localization of the defect induced state is found to determine the presence/absence of a local moment. A lot of attention on the probable origin of magnetism in wide band gap oxides has focused on cation vacancies. Here we show that oxygen interstitial atoms give rise to a large magnetic moment which results in a spin polarization of both the conduction and valence bands, in addition to spin polarized gap states. A Stoner mechanism is invoked and the relevant Stoner parameters are determined to be 0.7 eV for an oxygen atom in the presence of an oxygen interstitial but reduced to 0.2 eV on oxygen in the presence of a Zn vacancy.