Joel E. Abbott

Predictors of radiation exposure to providers during percutaneous nephrolithotomy

Background: Limited studies have reported on radiation risks of increased ionizing radiation exposure to medical personnel in the urologic community. Fluoroscopy is readily used in many urologic surgical procedures. The aim of this study was to determine radiation exposure to all operating room personnel during percutaneous nephrolithotomy (PNL), commonly performed for large renal or complex stones. Materials and Methods: We prospectively collected personnel exposure data for all PNL cases at two academic institutions. This was collected using the Instadose™ dosimeter and reported both continuously and categorically as high and low dose using a 10 mrem dose threshold, the approximate amount of radiation received from one single chest X-ray. Predictors of increased radiation exposure were determined using multivariate analysis. Results: A total of 91 PNL cases in 66 patients were reviewed. Median surgery duration and fluoroscopy time were 142 (38–368) min and 263 (19–1809) sec, respectively. Median attending urologist, urology resident, anesthesia, and nurse radiation exposure per case was 4 (0–111), 4 (0–21), 0 (0–5), and 0 (0–5) mrem, respectively. On univariate analysis, stone area, partial or staghorn calculi, surgery duration, and fluoroscopy time were associated with high attending urologist and resident radiation exposure. Preexisting access that was utilized was negatively associated with resident radiation exposure. However, on multivariate analysis, only fluoroscopy duration remained significant for attending urologist radiation exposure. Conclusion: Increased stone burden, partial or staghorn calculi, surgery and fluoroscopy duration, and absence of preexisting access were associated with high provider radiation exposure. Radiation safety awareness is essential to minimize exposure and to protect the patient and all providers from potential radiation injury.

In vitro head-to-head comparison of the durability, versatility and efficacy of the NGage and novel Dakota stone retrieval baskets

Background To compare head to head two end-engaging nitinol stone retrieval devices available to urologists, in terms of durability, versatility and efficacy. Methods For durability testing, 30 NGage and Dakota baskets were cycled 20 times between grasping and releasing synthetic stone models and evaluated for damage or device failure. For versatility and efficacy testing, baskets were assessed in their ability to capture and release stone models from 1 to 11 mm. Each stone was raised above the capture site and the basket was opened to passively release the stone. If the stone did not release, the basket handle was shaken and the OpenSure feature employed if needed. Manual release was used as a last resort. Results Durability—the Cook NGage demonstrated a statistically significant increased rate of visible device breakdown (P=0.0046) in 8 of 30 (26.7%) devices vs. 0 of 30 Dakota devices, with mean damage at 13.5 cycles. Versatility and efficacy—both 8 mm baskets successfully captured stones from 1–8 mm. The Dakota more effectively released 7–8 mm stones (P<0.0001). NGage required manual release of 8 mm stones in 13 cases compared to none with Dakota. For 11 mm baskets, the Dakota released all stones up to 10 mm with simple opening, while the NGage released 10 of 15 (67%) of 9 mm stones and 1 of 15 (7%) of 10 mm stones by simple opening. For 11 mm stones, the Dakota captured 100% whereas NGage could not capture any. Conclusions Both baskets showed similar durability characteristics. The Dakota basket more effectively captured and released stones over 7 mm, as compared to the NGage basket. The OpenSure aspect conferred an advantage in handling and release of larger stones. These in vitro results demonstrate potential versatility, durability and efficacy of the Dakota basket.

PD35-03 A RANDOMIZED CONTROL TRIAL OF PREOPERATIVE PROPHYLACTIC ANTIBIOTICS PRIOR TO PERCUTANEOUS NEPHROLITHOTOMY IN THE LOW RISK POPULATION: A REPORT FROM THE EDGE CONSORTIUM

INTRODUCTION AND OBJECTIVES: Single institution studies have suggested possible benefit of a week of preoperative antibiotics prior to percutaneous nephrolithotomy (PNL). Yet prior studies are limited by lower methodology (Level IIa)1, including heterogeneous populations2, or utilizing quasi-sepsis definitions2. Other than the recommended peri-operative dose of IV antibiotics <24 hours per AUA Best Practice Statement, the duration/benefit of preoperative antibiotics remains unclear. We sought to perform a rigorous (adhering to CONSORT guidelines) multi-institutional trial assessing utility of preoperative PNL antibiotics for patients at low risk of infectious complications. METHODS: We performed a randomized controlled trial (RCT) coordinated across 7 academic stone centers for low risk PNL patients. Low risk patients were defined as those with negative urine cultures and under no antibiotic treatment course within 14 days of procedure, and without any urinary drains (catheters, stents, nephrostomy tubes). Patients randomized to the intervention arm received nitrofurantoin 100 mg twice daily for 7 days preceding surgery. All enrolled patients received standard preoperative dose of ampicillin (vancomycin if allergic) and gentamicin (ceftriaxone if eGFR<60 or allergic). PNL was performed per the usual practice of each treating surgeon. Baseline patient and stone characteristics were recorded. Perioperative infection related adverse events within the first 30 days were compared in both groups. RESULTS: Thirty-four patients were randomized to each arm. Adverse events occurring within the first 30 days of procedure are reported in Table 1. The infection rate after PNL in the intervention arm was 17.6% (6/34) versus 11.8% (4/34), p1⁄40.49. Two of the patients in the intervention arm with infectious complications needed readmission and two others required admission to the intensive care unit. Total length of hospital stay demonstrated no difference between the two groups (1.09 versus 1.47, p1⁄40.2). There was no mortality reported during this study period. CONCLUSIONS: There appears to be no advantage to providing one week of preoperative oral antibiotics in patients at low risk for infectious complications. Less than 24 hours peri-operative antibiotics as per AUA Best Practice Statement appears sufficient. We continue to analyze this low risk group with a more robust data set, as well as analyze preoperative antibiotic benefit in other stratified risk groups. 1. Mariappan et al. BJU Int 2006 2. Kumar et al. Urol Res 2012

MP50-14 PERCUTANEOUS NEPHROLITHOTOMY IN A FREE-STANDING AMBULATORY SURGERY CENTER: FIRST 100 CASES REPORTED

INTRODUCTION AND OBJECTIVES: Percutaneous nephrolithotomy (PCNL) is the treatment of choice for patients with staghorn calculi. Opinions tend to vary whether an upper pole (UP) versus lower pole (LP) approach offers the best access. The literature suggests an UP approach is more favorable due to higher stone-free rates (SFR), however this access carries a higher risk of bleeding and pleural injury. We developed a modified LP (more medial and inferior puncture angle) to allow single tract staghorn removal with better stone free rates while minimizing thoracic complications and compared this technique to primary UP access PCNL outcomes for staghorn stones. METHODS: In this IRB approved retrospective analysis, 79 out of 473 patients had PCNL for staghorn calculi. 58/79 underwent our modified LP access technique and 21 patients had primary UP (17) or interopolar (4) access. Outcomes assessed included stone free rate (SFR), and number of punctures, EBL, OR time, and intraand post-op complications. RESULTS: A total of 58/79 (73%) patients received initial LP access using our modified technique. Of these 58 patients, 45 (78%) needed only a single tract, while 13 needed multiple accesses. In patients having primary UP access, 13/17 (76%) required only a single tract (no statistical difference). SFR’s are in Table 1. Complication rates were 6.7% for primary single site LP access (3.5% for all LP initial punctures) vs. 23.1% for primary single site UP access (29.4 for all UP initial punctures) (p < .05). There was no statistical difference in EBL, fluoro time, LOS, stone volume, or stone density among the groups. OR time was less in the single tract LP group (113 min vs. 148 min, p1⁄40.006). There were 2 pulmonary complications in the UP group, with none in LP group; Table 1. CONCLUSIONS: Our modified LP access technique was feasible in 73% (58/79) of staghorn patients without increasing the need for multiple tracts compared to primary UP access. Complication rates were lower and SFR rates higher for our modified technique, which will be described in detail.

Optimization of urinary dipstick pH: Are multiple dipstick pH readings reliably comparable to commercial 24-hour urinary pH?

Purpose Accurate measurement of pH is necessary to guide medical management of nephrolithiasis. Urinary dipsticks offer a convenient method to measure pH, but prior studies have only assessed the accuracy of a single, spot dipstick. Given the known diurnal variation in pH, a single dipstick pH is unlikely to reflect the average daily urinary pH. Our goal was to determine whether multiple dipstick pH readings would be reliably comparable to pH from a 24-hour urine analysis. Materials and Methods Kidney stone patients undergoing a 24-hour urine collection were enrolled and took images of dipsticks from their first 3 voids concurrently with the 24-hour collection. Images were sent to and read by a study investigator. The individual and mean pH from the dipsticks were compared to the 24-hour urine pH and considered to be accurate if the dipstick readings were within 0.5 of the 24-hour urine pH. The Bland-Altman test of agreement was used to further compare dipstick pH relative to 24-hour urine pH. Results Fifty-nine percent of patients had mean urinary pH values within 0.5 pH units of their 24-hour urine pH. Bland-Altman analysis showed a mean difference between dipstick pH and 24-hour urine pH of -0.22, with an upper limit of agreement of 1.02 (95% confidence interval [CI], 0.45–1.59) and a lower limit of agreement of -1.47 (95% CI, -2.04 to -0.90). Conclusions We concluded that urinary dipstick based pH measurement lacks the precision required to guide medical management of nephrolithiasis and physicians should use 24-hour urine analysis to base their metabolic therapy.

When is a Urology Drug Safe Enough for Pregnancy

IN a retrospective study in this issue of The Journal subjects is likely invalid. The report also reveals Bailey et al (page 99) have published the first report to date to my knowledge on tamsulosin medical expulsion therapy given during pregnancy. Their report is timely since medical expulsion therapy, although considered an off label Food and Drug Administration indication, has clearly become widespread in use as supported by numerous studies that demonstrate its validity. Yet, ironically, a recent large sample size, level 1b evidence article challenges all prior studies and has stimulated conversations regarding the efficacy of tamsulosin medical expulsion therapy. In this context understanding the efficacy, and more importantly, the safety of a drug during pregnancy becomes paramount. The results of the report by Bailey et al suggest that tamsulosin is efficacious and likely safe during pregnancy. But as a reviewer I apply the brakes on full endorsement of their results. An evidence-based approach merits 3 questions, in the particular order of 1) Are the results valid? 2) What are the results? and 3) How can I apply the evidence to my patient population?

Hemostatic Plug: Novel Technique for Closure of Percutaneous Nephrostomy Tract

Percutaneous nephrolithotomy (PCNL) is a standard treatment for patients with large or complex kidney stones. The procedure has traditionally included postoperative placement of a nephrostomy tube to allow for drainage and possible reentry. This practice was first implemented after complications incurred after tubeless PCNL in a small patient population. Recently, tubeless PCNL has reemerged as a viable option for selected patients, resulting in decreased pain and analgesic use, shorter hospitalization, quicker return to normal activity, and decreased urine extravasation. Gelatin matrix sealants are occasionally used in nephrostomy tract closure. Techniques for delivery of these agents have been ill described, and placement may be performed with varying results. We present a literature review comparing tubeless PCNL to its traditional variant with indications for use of each, as well as a comparison of agents used in closure. Finally, we outline a novel, reproducible technique for closure of the dilated percutaneous renal access tract.