Intrarenal temperature measurement associated with holmium laser intracorporeal lithotripsy in an ex vivo model.

INTRODUCTION: The aim of this article was to quantify the effect of the use of holmium laser during intracorporeal lithotripsy in an ex vivo model. MATERIAL AND METHODS: A simulated model for laser nephro-lithotripsy was designed. Two ex vivo porcine kidneys were used. Electronic thermometer electrodes were inserted on the upper calyx. Intracorporeal lithotripsy was simulated with a holmium laser. Intrarenal temperature was recorded both at the beginning and after one minute of laser use with delta temperature (DT) defined as the difference between them. Measurements were made at different irrigation heights (30, 40, and 50 cm H2O), frequency (Hz), and laser energy (J) in addition to the presence or absence of the access sheath. Analysis of factors associated with temperature change was performed. RESULTS: Thirty-eight observations were recorded. The measurement without the use of access sheath showed an average DT of 4.9, 5.1, and 6.5°C for 5, 10, and 15 Hz, respectively; however, with a sheath, DTs were 0.2, 0.5, and 1.5°C. In terms of energy, mean DTs of 4.3, 6.1, 5.2, and 13.9°C for 0.5, 0.8, 1.0, and 1.5 J were recorded; in contrast, with a sheath, averages of 0.4, 0.5, 0.5, and 3.8°C, respectively were noted. In the adjusted model, energy, frequency, and use of sheath and water height were significant. CONCLUSIONS: The configuration of the laser significantly modifies the intrarenal temperature and height of the bladder irrigation. The use of an access sheath provides lower intrarenal temperatures regardless of laser configuration and water height.

Early ureteroscopic treatment in patients with urosepsis associated with ureteral calculi is a safe approach. A pilot study.

INTRODUCTION: Emergency drainage of the urinary tract is the first necessary approach in patients with urosepsis secondary to obstructive ureteral calculi. The appropriate waiting time before definitive treatment has not been determined. We hypothesized that early ureteroscopic treatment after the patient has been stabilized is as safe as deferred treatment. MATERIAL AND METHODS: A pilot study was developed between November 2013 and September 2017. Patients with urosepsis associated with ureteral calculi were included. All the patients were initially decompressed with a ureteral stent. Patients were randomized to early ureteroscopic treatment (EUT), who received definitive treatment during the initial hospitalization, or deferred ureteroscopic treatment (DUT), that received definitive treatment in a second hospitalization. The stone location and size, sex distribution, age, APACHE II score, length of hospital stay, days with ureteral catheter and complications were registered. Statistical analysis was performed using Stata 12.0. RESULTS: A total of 13 patients were included in the EUT group and 13 in the DUT group. No differences in sex distribution, stone location, APACHE II score, age, stone size and time between admission and urinary drainage were found. Total length of hospital stay and complications were also similar between both groups. A statistically significant difference was found in terms of duration of antibiotic treatment (p = 0.04) and total days with double J catheter (p = 0.0009). CONCLUSIONS: EUT for ureteral stone is as safe as DUT in patients admitted with urosepsis secondary to ureterolithiasis. EUT is associated with a shorter period of ureteral stent and it is not associated with an increase in complications.

Treatment Response in Patients with Stones, and Low Urinary pH and Hypocitraturia Stratified by Body Mass Index.

PURPOSE: Obesity has been shown to be a risk factor for kidney stone formation. Obesity leads to insulin resistance which subsequently leads to low urinary pH. Low urinary pH is typically treated with potassium citrate. We determined if the response to potassium citrate for the treatment of low urinary pH and hypocitraturia varied when patients were stratified by body mass index. MATERIALS AND METHODS: We retrospectively reviewed the records of patients with urolithiasis and concomitant hypocitraturia and low urinary pH as unique abnormalities upon metabolic evaluation treated exclusively with potassium citrate. Based on body mass index the cohort was divided into the 4 groups of normal weight, overweight, obese and morbidly obese. Metabolic data were compared among the 4 groups at baseline and subsequent followup visits up to 2 years. We compared urinary pH and citrate in absolute values and the relative changes in these parameters from baseline. Similarly, we compared the rates of potassium citrate treatment failure. RESULTS: A total of 125 patients with hypocitraturia and low urinary pH were included in this study. Median patient age was 61 years, 80 patients were male and median body mass index was 30.4 kg/m(2). Patients with a higher body mass index tended to be younger (p=0.010), and had a lower urinary citrate but higher sodium, oxalate and uric acid levels. Urinary pH was similar across body mass index groups. pH values and their absolute changes from baseline were lower as body mass index increased (p ≤0.001). Similarly, we noted an association between increasing body mass index category and lower urinary citrate levels accompanied by a statistically significant trend indicating lower absolute changes in citrate with increasing body mass index (p ≤0.001). Potassium citrate dose was increased more frequently among the higher body mass index groups. CONCLUSIONS: Patients with a higher body mass index presented with a lower increase in citrate excretion and urinary pH levels after they were started on potassium citrate, and they needed more frequent adjustments to their therapy.

Does the nephrostomy tract length impact the outcomes of percutaneous nephrolithotomy (PNL)?

PURPOSE: Different factors can determine the outcomes of percutaneous nephrolithotomy (PNL). We analyzed the effect of tract length (TL) on outcomes after PNL. METHODS: We performed a retrospective review of patients undergoing PNL between 2006 and 2011. Patients with preoperative computed tomography (CT), one percutaneous access tract and follow-up imaging within 3 months were included. TL was defined as distance between the skin to the calyx of puncture as measured on preoperative CT. Measurements were independently performed by two urologists and the average was used for analysis. Stone-free rate (SFR) was defined as zero fragments on follow-up imaging. Factors independently associated with the likelihood of being stone-free after PNL were determined using multivariable analysis adjusted for TL, location of access, the presence of incomplete or complete staghorn calculi and type of follow-up imaging. Complications (Clavien score) were independently assessed. RESULTS: A total of 222 patients were included. Median stone burden and body mass index (BMI) was 239.4 mm(2) and 30.5 [interquartile range (IQR): 25.7-36.2]. The median TL was 85.0 mm (IQR: 70.3-100.0) and highly correlated with BMI (ρ = 0.66, p < 0.001). A total of 101 patients (45.5 %) were stone-free. TL was not associated with SFR (p = 0.53). Clavien 1 and 2 complications occurred in 38 (17 %) while Clavien 3 and 4 complications occurred in 17 (8 %) patients. Multivariable analysis revealed no association between complications and TL even when adjusted for gender. CONCLUSIONS: Percutaneous TL is not associated with outcomes of PNL. PNL is a safe and effective treatment for stones in patients with differing body habitus.

Does body mass index impact the outcomes of tubeless percutaneous nephrolithotomy?

OBJECTIVE: To evaluate whether body mass index (BMI) has an impact on the outcomes of tubeless percutaneous nephrolithotomy (PCNL). PATIENTS AND METHODS: We retrospectively reviewed patients who underwent tubeless PCNL at our institution from 2006 to 2011. Specifically, stone-free rates, complications, and hospital length of stay (LOS) were assessed. Patients were divided into four groups based on BMI: <25, 25-29.9, 30-34.9 and ≥35 kg/m(2) . Baseline characteristics and outcomes were compared between BMI groups. Multivariable logistic regressions were used to evaluate the independent contribution of BMI as a predictor of outcomes. RESULTS: We identified 268 patients who fulfilled study requirements. The overall stone-free and complication rates were 52.5% and 19.0%, respectively. Minor and severe complication comprised 10.4% and 8.6%, respectively. Univariate and multivariable analyses showed no association between BMI and stone-free or complication rates. However, patients with a normal BMI had significantly higher transfusion rates (P = 0.005), and were significantly more likely to have a prolonged LOS (≥2 days), when compared with an overweight BMI (P = 0.032) CONCLUSIONS: BMI did not impact the stone-free, or complication rates of tubeless PCNL. Normal BMI was found to be a risk factor for prolonged LOS, which may be due to an increase in clinically significant bleeding in this patient population. Tubeless PCNL appears to be a safe and effective procedure for the treatment of complex renal calculi, independent of BMI.

Digital tomosynthesis: a new technique for imaging nephrolithiasis. Specific organ doses and effective doses compared with renal stone protocol noncontrast computed tomography.

OBJECTIVE: To determine organ-specific doses (ODs) and effective dose (ED) for digital tomosynthesis (DT) and compare it with our institutional renal stone protocol noncontrast computed tomography (NCCT). METHODS: A validated anthropomorphic male phantom was placed supine on a digital GE Definium 8000 radiological scanner. Thermoluminescent dosimeters were placed in 256 locations and used to measure OD. A routine DT study was performed consisting of 2 scout images and 1 tomographic sweep in a 14.2-degree arc over the phantom. Software is used to recreate a series of coronal images from the sweep. ODs were determined as the sum of the doses for the study. Equivalent doses were calculated by multiplying OD with the appropriate tissue weighting factor. ED is the summation of the equivalent doses. OD and ED were determined in a similar fashion (using dosimeters) for a renal stone protocol NCCT and doses were compared. RESULTS: ODs for DT are significantly lower compared with NCCT. The ED for NCCT is 3.04 ± 0.34 mSv. The calculated ED for DT is 0.87 ± 0.15 mSv (2 scouts at 0.17 mSv and 0.14 mSv and 1 sweep at 0.56 mSv), P <.0001. CONCLUSION: DT exposes patients to substantially less radiation than NCCT. This is particularly true for radiation-sensitive organs. Further studies are needed to compare the sensitivity and specificity of DT as compared with NCCT. However, its low overall radiation dose makes it an ideal study for the follow-up of recurrent stone formers in the office setting.

Radiation exposure in urology: a genitourinary catalogue for diagnostic imaging.

PURPOSE: Computerized tomography use increased exponentially in the last 3 decades, and it is commonly used to evaluate many urological conditions. Ionizing radiation exposure from medical imaging is linked to the risk of malignancy. We measured the organ and calculated effective doses of different studies to determine whether the dose-length product method is an accurate estimation of radiation exposure. MATERIALS AND METHODS: An anthropomorphic male phantom validated for human organ dosimetry measurements was used to determine radiation doses. High sensitivity metal oxide semiconductor field effect transistor dosimeters were placed at 20 organ locations to measure specific organ doses. For each study the phantom was scanned 3 times using our institutional protocols. Organ doses were measured and effective doses were calculated on dosimetry. Effective doses measured by a metal oxide semiconductor field effect transistor dosimeter were compared to calculated effective doses derived from the dose-length product. RESULTS: The mean±SD effective dose on dosimetry for stone protocol, chest and abdominopelvic computerized tomography, computerized tomography urogram and renal cell carcinoma protocol computerized tomography was 3.04±0.34, 4.34±0.27, 5.19±0.64, 9.73±0.71 and 11.42±0.24 mSv, respectively. The calculated effective dose for these studies Was 3.33, 2.92, 5.84, 9.64 and 10.06 mSv, respectively (p=0.8478). CONCLUSIONS: The effective dose varies considerable for different urological computerized tomography studies. Renal stone protocol computerized tomography shows the lowest dose, and computerized tomography urogram and the renal cell carcinoma protocol accumulate the highest effective doses. The calculated effective dose derived from the dose-length product is a reasonable estimate of patient radiation exposure.

Radiation exposure in the follow-up of patients with urolithiasis comparing digital tomosynthesis, non-contrast CT, standard KUB, and IVU.

OBJECTIVE: To compare the effective doses (EDs) associated with imaging modalities for follow-up of patients with urolithiasis, including stone protocol non-contrast computed tomography (NCCT), kidney, ureter, and bladder radiograph (KUB), intravenous urogram (IVU), and digital tomosynthesis (DT). METHODS: A validated Monte-Carlo simulation-based software PCXMC 2.0 (STUK) designed for estimation of patient dose from medical X-ray exposures was used to determine the ED for KUB, IVU (KUB scout plus three tomographic images), and DT (two scouts and one tomographic sweep). Simulations were performed using a two-dimensional stationary field onto the corresponding body area of the built-in digital phantom, with actual kVp, mAs, and geometrical parameters of the protocols. The ED for NCCT was determined using an anthropomorphic male phantom that was placed prone on a 64-slice GE Healthcare volume computed tomography (VCT) scanner. High-sensitivity metal oxide semiconductor field effect transistors dosimeters were placed at 20 organ locations and used to measure organ radiation doses. RESULTS: The ED for a stone protocol NCCT was 3.04±0.34 mSv. The ED for a KUB was 0.63 and 1.1 mSv for the additional tomographic film. The total ED for IVU was 3.93 mSv. The ED for DT performed with two scouts and one sweep (14.2°) was 0.83 mSv. CONCLUSIONS: Among the different imaging modalities for follow-up of patients with urolithiasis, DT was associated with the least radiation exposure (0.83 mSv). This ED corresponds to a fifth of NCCT or IVU studies. Further studies are needed to demonstrate the sensitivity and specificity of DT for the follow-up of nephrolithiasis patients.

Assessment of a modified acoustic lens for electromagnetic shock wave lithotripters in a swine model.

PURPOSE: The acoustic lens of the Modularis electromagnetic shock wave lithotripter (Siemens, Malvern, Pennsylvania) was modified to produce a pressure waveform and focal zone more closely resembling that of the original HM3 device (Dornier Medtech, Wessling, Germany). We assessed the newly designed acoustic lens in vivo in an animal model. MATERIALS AND METHODS: Stone fragmentation and tissue injury produced by the original and modified lenses of the Modularis lithotripter were evaluated in a swine model under equivalent acoustic pulse energy (about 45 mJ) at 1 Hz pulse repetition frequency. Stone fragmentation was determined by the weight percent of stone fragments less than 2 mm. To assess tissue injury, shock wave treated kidneys were perfused, dehydrated, cast in paraffin wax and sectioned. Digital images were captured every 120 µm and processed to determine functional renal volume damage. RESULTS: After 500 shocks, the mean ± SD stone fragmentation efficiency produced by the original and modified lenses was 48% ± 12% and 52% ± 17%, respectively (p = 0.60). However, after 2,000 shocks, the modified lens showed significantly improved stone fragmentation compared to the original lens (mean 86% ± 10% vs 72% ± 12%, p = 0.02). Tissue injury caused by the original and modified lenses was minimal at a mean of 0.57% ± 0.44% and 0.25% ± 0.25%, respectively (p = 0.27). CONCLUSIONS: With lens modification the Modularis lithotripter demonstrates significantly improved stone fragmentation with minimal tissue injury at a clinically relevant acoustic pulse energy. This new lens design could potentially be retrofitted to existing lithotripters, improving the effectiveness of electromagnetic lithotripters.

Increasing dwell time of mitomycin C in the upper tract with a reverse thermosensitive polymer.

UNLABELLED: Abstract Background and Purpose: Topical chemotherapy for urothelial cancer is dependent on adequate contact time of the chemotherapeutic agent with the urothelium. To date, there has not been a reliable method of maintaining this contact for renal or ureteral urothelial carcinoma. We evaluated the safety and feasibility of using a reverse thermosensitive polymer to improve dwell times of mitomycin C (MMC) in the upper tract. MATERIALS AND METHODS: Using a porcine model, four animals were treated ureteroscopically with both upper urinary tracts receiving MMC mixed with iodinated contrast. One additional animal received MMC percutaneously. The treatment side had ureteral outflow blocked with a reverse thermosensitive polymer plug. MMC dwell time was monitored fluoroscopically and intrarenal pressures measured. Two animals were euthanized immediately, and three animals were euthanized 5 days afterward. RESULTS: In control kidneys, drainage occurred at a mean of 5.3±0.58 minutes. Intrarenal pressures stayed fairly stable: 9.7±14.0 cm H20. In treatment kidneys, dwell time was extended to 60 minutes, when the polymer was washed out. Intrarenal pressures in the treatment kidneys peaked at 75.0±14.7 cm H20 and reached steady state at 60 cm H20. Pressures normalized after washout of the polymer with cool saline. Average washout time was 11.8±9.6 minutes. No histopathologic differences were seen between the control and treatment kidneys, or with immediate compared with delayed euthanasia. CONCLUSIONS: A reverse thermosensitive polymer can retain MMC in the upper urinary tract and appears to be safe from our examination of intrarenal pressures and histopathology. This technique may improve the efficacy of topical chemotherapy in the management of upper tract urothelial carcinoma.

Obesity triples the radiation dose of stone protocol computerized tomography.

PURPOSE: Patients with recurrent nephrolithiasis are often evaluated and followed with computerized tomography. Obesity is a risk factor for nephrolithiasis. We evaluated the radiation dose of computerized tomography in obese and nonobese adults. MATERIALS AND METHODS: We scanned a validated, anthropomorphic male phantom according to our institutional renal stone evaluation protocol. The obese model consisted of the phantom wrapped in 2 Custom Fat Layers (CIRS, Norfolk, Virginia), which have been verified to have the same radiographic tissue density as fat. High sensitivity metal oxide semiconductor field effect transistor dosimeters were placed at 20 organ locations in the phantoms to measure organ specific radiation doses. The nonobese and obese models have an approximate body mass index of 24 and 30 kg/m(2), respectively. Three runs of renal stone protocol computerized tomography were performed on each phantom under automatic tube current modulation. Organ specific absorbed doses were measured and effective doses were calculated. RESULTS: The bone marrow of each model received the highest dose and the skin received the second highest dose. The mean ± SD effective dose for the nonobese and obese models was 3.04 ± 0.34 and 10.22 ± 0.50 mSv, respectively (p <0.0001). CONCLUSIONS: The effective dose of stone protocol computerized tomography in obese patients is more than threefold higher than the dose in nonobese patients using automatic tube current modulation. The implication of this finding extends beyond the urological stone population and adds to our understanding of radiation exposure from medical imaging.

In-vitro assessment of a new portable ballistic lithotripter with percutaneous and ureteroscopic models.

BACKGROUND AND PURPOSE: The EMS Swiss LithoBreaker is a new, portable, electrokinetic lithotripter. We compared its tip velocity and displacement characteristics with a handheld, pneumatic lithotripter LMA StoneBreaker.™ We also evaluated fragmentation efficiency using in vitro models of percutaneous and ureteroscopic stone fragmentation. MATERIALS AND METHODS: Displacement and velocity profiles were measured for 1-mm and 2-mm probes using a laser beam aimed at a photo detector. For the percutaneous model, 2-mm probes fragmented 10-mm spherical BegoStone phantoms until the fragments passed through a 4-mm mesh sieve. The ureteroscopic model used 1-mm probes and compared the pneumatic and electrokinetic devices to a 200-µm holmium laser fiber. Cylindrical (4-mm diameter, 4-mm length) BegoStone phantoms were placed into silicone tubing to simulate the ureter; fragmented stones passed through a narrowing in the tubing. RESULTS: For both 1-mm and 2-mm probes, the electrokinetic device had significantly higher tip displacement and slower tip velocity, P<0.01. In the percutaneous model, the electrokinetic device needed an average of 484 impulses over 430 seconds to fragment one BegoStone, while the pneumatic device needed 29 impulses over 122 seconds to fragment one stone. Both clearance times and number of impulses needed for percutaneous stone clearance were significantly different at P<0.01. Ureteroscopically, the mean clearance time was 97 seconds for the electrokinetic lithotripter, 145 seconds for the pneumatic lithotripter, and 304 seconds for the laser. Comparing the pneumatic device with the electrokinetic device ureteroscopically, there was no significant difference in clearance time, P=0.55. Both the pneumatic and electrokinetic lithotripters, however, demonstrated decreased clearance times compared with the laser, P=0.027. CONCLUSIONS: The portable electrokinetic lithotripter may be better suited for ureteroscopy instead of percutaneous nephrolithotomy. It appears to be comparable to the portable pneumatic device in the ureter. Further clinical studies are needed to confirm these findings in vivo.

Optical performance comparison of deflectable laparoscopes for laparoendoscopic single-site surgery.

BACKGROUND AND PURPOSE: Flexible working angles and fine optical visualization are major requisite factors in performing laparoendoscopic single-site (LESS) urologic procedures. Multiple mechanical design approaches have been used to develop deflectable laparoscopes for LESS procedures. We compared the optical characteristics of three such devices using a bench top approach to simulate LESS in straight and deflected positions. MATERIALS AND METHODS: A 10-mm fixed-rod rotating lens device (Storz EndoCameleon) and two 5-mm articulating devices (Olympus EndoEye and Stryker IdealEye) were compared using standard industry testing protocols for image resolution (United States Air Force-1951 test target), distortion (multifrequency grid distortion target), and color reproducibility (Gretag Macbeth color checker). RESULTS: The 10-mm fixed-rod rotating lens system demonstrated the highest image resolution (5.04 line pairs/mm), but also the highest distortion (22.8%). Among the 5-mm flexible articulating laparoscopes, resolution was superior with the Olympus EndoEye (4.00 line pairs/mm) compared with the Stryker IdealEye (3.17 line pairs/mm). Distortion (7.0%) and color reproduction (1.18) were superior with the IdealEye vs the EndoEye (18.8 %, 1.27). Laparoscope deflection resulted in attenuation of resolution by 11% with both articulating models, but not with the fixed rod system. CONCLUSIONS: Definition of these optical characteristics may inform further development and selection of laparoscopic systems optimized for LESS surgery. A narrow but flexible camera can be crucial in the limited working space available during these procedures. Further investigation is warranted to determine if these objective findings translate into improved surgeon performance.