Ryan F. Paterson

Randall’s plaque of patients with nephrolithiasis begins in basement membranes of thin loops of Henle

Our purpose here is to test the hypothesis that Randalls plaques, calcium phosphate deposits in kidneys of patients with calcium renal stones, arise in unique anatomical regions of the kidney, their formation conditioned by specific stone-forming pathophysiologies. To test this hypothesis, we performed intraoperative biopsies of plaques in kidneys of idiopathic-calcium-stone formers and patients with stones due to obesity-related bypass procedures and obtained papillary specimens from non-stone formers after nephrectomy. Plaque originates in the basement membranes of the thin loops of Henle and spreads from there through the interstitium to beneath the urothelium. Patients who have undergone bypass surgery do not produce such plaque but instead form intratubular hydroxyapatite crystals in collecting ducts. Non-stone formers also do not form plaque. Plaque is specific to certain kinds of stone-forming patients and is initiated specifically in thin-limb basement membranes by mechanisms that remain to be elucidated.

Variability of renal stone fragility in shock wave lithotripsy.

OBJECTIVES To measure, in an in vitro study, the number of shock waves to complete comminution for 195 human stones, representing six major stone types. Not all renal calculi are easily broken with shock wave lithotripsy. Different types of stones are thought to have characteristic fragilities, and suggestions have been made in published reports of variation in the fragility within some types of stones, but few quantitative data are available. METHODS Kidney stones classified by their dominant mineral content were broken in an unmodified Dornier HM3 lithotripter or in a research lithotripter modeled after the HM3, and the number of shock waves was counted for each stone until all fragments passed through a sieve (3-mm-round or 2-mm-square holes). RESULTS The mean +/- SD number of shock waves to complete comminution was 400 +/- 333 per gram (n = 39) for uric acid; 965 +/- 900 per gram (n = 75) for calcium oxalate monohydrate; 1134 +/- 770 per gram (n = 21) for hydroxyapatite; 1138 +/- 746 per gram (n = 13) for struvite; 1681 +/- 1363 per gram (n = 23) for brushite; and 5937 +/- 6190 per gram (n = 24) for cystine. The variation for these natural stones (83% +/- 15% coefficient of variation) was greater than that for artificial (eg, gypsum-based) stones (17% +/- 8%). CONCLUSIONS The variability in stone fragility to shock waves is large, even within groups defined by mineral composition. Thus, knowing the major composition of a stone may not allow adequate prediction of its fragility in lithotripsy treatment. The variation in stone structure could underlie the variation in stone fragility within type, but testing of this hypothesis remains to be done.

Major Complications in 213 Laparoscopic Nephrectomy Cases: The Indianapolis Experience

PURPOSE We assessed the incidence of and analyzed factors that may help prevent major complications and open conversion during laparoscopic nephrectomy at our institutions. MATERIALS AND METHODS We retrospectively analyzed all laparoscopic nephrectomies performed between August 1, 1999 and July 31, 2001. Data were stratified for nephrectomy type, intraoperative and postoperative complications. Conversion to open surgery was stratified for emergency versus elective procedures. RESULTS Of the 292 laparoscopic procedures performed at our institutions in 2 years 213 (73%) involved laparoscopic nephrectomy, including 84 live donor nephrectomies, 61 radical nephrectomies, 55 simple nephrectomies and 13 nephroureterectomies. A total of 16 major complications (7.5%) occurred, including access related, intraoperative and postoperative complications in 3, 9 and 4 cases, respectively. The conversion rate was 6.1% (13 patients), the transfusion rate was 1.9% and the mortality rate was 0.5% (1 death). Only 1 complication was related to simple laparoscopic nephrectomy, although this group showed the highest rate of elective conversion (7 of 8 elective conversions). Laparoscopic live donor nephrectomy showed the highest rate for emergency conversion (3 of 5 emergency conversions). CONCLUSIONS Our results reinforce the importance of thorough preoperative imaging, careful patient selection, surgeon experience and skill maintenance in laparoscopy as well as a low threshold for conversion to open surgery. This series provides additional evidence to support the evolution of laparoscopic nephrectomy into a standard of care.

Stone Fragmentation During Shock Wave Lithotripsy is Improved by Slowing the Shock Wave Rate: Studies With a New Animal Model

PURPOSE The current trend toward ungated shock wave lithotripsy means that more patients are being treated with shock waves delivered at a rapid rate (120 shock waves per minute or greater). However, no benefit of an increased shock wave rate has been shown and in vitro studies indicate that slowing the shock wave rate actually improves stone fragmentation. We tested the effect of the shock wave rate on stone comminution in a new animal model. MATERIALS AND METHODS Gypsum model stones were inserted via upper pole percutaneous access into the lower pole calix of the kidneys of female pigs weighing approximately 100 pounds. Shock wave lithotripsy was performed (400 shock waves uninterrupted at 20 kV. and 30 or 120 shock waves per minute) 2 hours later using an unmodified HM3 lithotriptor (Dornier Medical Systems, Marietta, Georgia). After en bloc excision of the urinary tract stone fragments were collected and sieved through 2 mm. mesh. The particles were weighed and surface area was determined. RESULTS Stones treated at 30 shock waves per minute broke more completely than stones treated at 120 shock waves per minute. The percent of fragments greater than 2 mm. was significantly higher for stones treated at the fast rate of 120 versus the slow rate of 30 shock waves per minute (mean +/- SEM 81% +/- 14% versus 45% +/- 12%, p <0.005). When stone fragmentation was expressed as the percent increase in fragment surface area, significantly greater fragmentation occurred at the slower than at the more rapid rate (327% +/- 63% versus 135% +/- 136%, p <0.02). CONCLUSIONS Slowing the rate of shock wave administration during shock wave lithotripsy significantly improves the efficiency of stone fragmentation in vivo.

Bacterial sepsis after prostate biopsy--a new perspective.

OBJECTIVES To determine the incidence of sepsis following transrectal ultrasound (TRUS)-guided prostate biopsy at our center. METHODS We retrospectively reviewed a group of 24 men who presented with urosepsis after undergoing TRUS biopsy at our center. RESULTS Of the 24 men, 22 were given prophylactic ciprofloxacin. The median time to presentation of sepsis was 1 day after biopsy. The median length of hospitalization was 4 days. Escherichia coli was the most frequent cause of urosepsis (67%). Variable resistance patterns were observed. Enterobacter cloacae and Streptococcus viridans were isolated in 2 cases. No bacteria were isolated in 6 cases. Two patients who received extensive antibiotic prophylaxis still developed urosepsis. Treatment of patients infected with multiresistant anaerobic strains using metronidazole among others, proved successful. High sensitivities toward cefazolin, gentamicin, and tobramycin were observed. The number of cases reported was likely an underestimation, because some patients may have reported to other hospitals and were not captured by this study. In addition, some patients may not have developed infection and urosepsis despite harboring ciprofloxacin-resistant bacteria. CONCLUSIONS Prophylactic ciprofloxacin is still a useful option for the prevention of urosepsis after TRUS biopsy, as the incidence is relatively low. For the patient who develops urosepsis after TRUS biopsy, ciprofloxacin resistance needs to be suspected and the treatment regime should be tailored to the resistance profiles of the local region, the patients medical history, and the culture and sensitivity reports.

Holmium Laser Enucleation of the Prostate (HoLEP): A Technical Update

IntroductionHolmium laser enucleation of the prostate (HoLEP) combined with mechanical morcellation represents the latest refinement of holmium:YAG surgical treatment for benign prostatic hyperplasia (BPH). Utilizing this technique, even the largest of glands can be effectively treated with minimal morbidity. The learning curve remains an obstacle, preventing more widespread adoption of this procedure. This paper provides an outline of the HoLEP technique as is currently used at two centers in hopes of easing the initial learning curve.Technical considerationsDetailed descriptions of the major steps of the HoLEP procedure are provided with attention to critical steps such as identification of the surgical capsule, median and lateral lobe enucleation, and morcellation of enucleated tissue.ConclusionsHoLEP is a promising alternative for the surgical treatment of BPH which allows complete removal of intact lobes of the prostate. Obstruction is relieved immediately with superior hemostasis, no risk of TUR syndrome, and a minimal hospital stay.

Laparoscopic treatment for ureteropelvic junction obstruction

OBJECTIVES To assess retrospectively the subjective and objective outcomes achieved after laparoscopic treatment for ureteropelvic junction obstruction at our institutions. METHODS Between August 1999 and July 2001, 19 patients (11 women and 8 men), with a mean age of 31.2 years (range 17 to 67), underwent laparoscopic treatment for ureteropelvic junction obstruction. Of these, 17 patients were eligible for postoperative analysis. Nine of these patients had a history of prior surgical intervention on the affected side. The patients were subjectively assessed by an analog pain scale performed before and at least 6 months after surgery. Preoperatively, patients had a diuretic renal scan to confirm the presence of obstruction. Helical computed tomography was also performed preoperatively to assess for the presence of crossing vessels. The renal scan was repeated at least 12 weeks after surgery to document the relief of obstruction objectively. RESULTS Helical computed tomography correctly predicted the presence of crossing vessels in 12 patients (63%). The Anderson-Hynes and Fenger pyeloplasty techniques were performed in 16 and 2 patients, respectively. In 1 patient, a small crossing vein over the ureteropelvic junction was identified and divided without complications. The average operative time was 240 minutes (range 128 to 470). The blood loss was minimal, and no open conversions were required. The mean hospital stay was 2.9 days (range 2 to 7). Two postoperative complications occurred (11.7%). The average subjective follow-up was 14.4 months (range 6 to 27), and the average objective follow-up was 7.8 months (range 3 to 12). Of 17 assessable patients, 16 (94%) had subjective and objective success (postoperative improvement in analog pain score and half-life of radiotracer washout). The average split renal function improved from 34.1% to 38.5% (P <0.01). CONCLUSIONS On the basis of our data, laparoscopic pyeloplasty has a similar success rate compared with the traditional open approach and better results than other minimally invasive techniques. Longer follow-up and further experience are needed to validate these data.

High resolution detection of internal structure of renal calculi by helical computerized tomography.

PURPOSE There is considerable interest in using radiological imaging to predict kidney stone fragility before patient treatment. Case series of shock wave lithotripsy show that shock wave lithotripsy is repeated and/or ancillary procedures are done to remove shock wave resistant stones in a significant number of cases. If the fragility of stones were predicted at diagnosis, unnecessary shock wave treatment would be avoided. However, plain radiography allows little discrimination of stone type and simple numerical analysis of computerized tomography (CT) images by measuring Hounsfield units has been shown to be limited in its ability to predict stone fragility. MATERIALS AND METHODS Urinary stones of known composition were imaged by helical CT in vitro at various slice widths and the images were assessed using a range of window settings. RESULTS Visualization of stone structure was greatly enhanced using bone windows and a narrow slice width. Surface structure, such as crystalline leaves of calcium oxalate dihydrate, and internal structure showing the heterogeneity of composition or cracks were detected. Stones of similar mineral composition differed dramatically in terms of CT visible structure. CONCLUSIONS Using a narrow slice width and bone windows greatly improves the visualization of kidney stone structure on helical CT. These results open up new possibilities for determining the relationship of stone structure and fragility for shock wave lithotripsy.

Laparoscopic Partial Kidney Ablation With High Intensity Focused Ultrasound

PURPOSE High intensity focused ultrasound has been performed for transrectal and extracorporeal thermal ablation of tissues. We developed and tested a laparoscopic probe that allows real-time ultrasound imaging during partial renal ablation using high intensity focused ultrasound. METHODS A Sonablate 200 (Focus Surgery, Indianapolis, Indiana) high intensity focused ultrasound system with a modified 18 mm. laparoscopic probe was used in all experiments. In 13 Yucatan mini-pigs a 5Fr ureteral catheter was inserted into the renal pelvis and 10 cc air were instilled into the collecting system. The kidney was laparoscopically dissected, the high intensity focused ultrasound probe was inserted through a 33 mm. laparoscopic port and the targeted renal pole was treated. RESULTS Renal lesions were created in 12 of 13 treated kidneys under real-time ultrasound visualization. Median operative time was 180 minutes, average high intensity focused ultrasound activation time was 18.3 minutes and lesion size was 23 x 17 x 11 mm. At 4 and 14 days 4 (acute group) and 6 (subacute group) animals were available for renal functional and anatomical evaluation, respectively. No difference in renal function was seen in treated and untreated kidneys. Pathological examination at 14 days revealed homogenous and complete tissue necrosis throughout the whole volume of the lesion with sharp demarcation from adjacent normal tissue. CONCLUSIONS We were able to refine a probe for laparoscopic high intensity focused ultrasound delivery capable of simultaneous ultrasound imaging. Partial renal ablation using this probe is feasible and safe, and resulted in homogenous, complete and reproducible lesions.

Holmium laser enucleation of the prostate: morbidity in a series of 206 patients

OBJECTIVES To review the complications associated with 206 holmium laser enucleation of the prostate (HoLEP) procedures. HoLEP is a minimally invasive surgical treatment for benign prostatic hyperplasia. METHODS A retrospective review was conducted of HoLEPs performed from April 1, 1999 to October 1, 2001. Patients with previous diagnoses of prostate carcinoma or who had undergone HoLEP after admission for unrelated problems were excluded. Demographic, intraoperative, and immediate postoperative data were recorded to determine the incidence of complications. Patients were also contacted by telephone or mailed surveys for documentation of longer term complications. RESULTS The mean age and procedure time was 70.5 years (range 45 to 91) and 133.6 minutes (range 25 to 473), respectively. The mean specimen weight was 68.2 g (range 3 to 376), with 20 (9.7%) of 206 patients diagnosed with adenocarcinoma. The mean hospital stay was 1.1 days, with 86.9% of patients discharged after an overnight stay without a catheter. Two patients required postoperative transfusions (1.0%). No deaths, major complications (myocardial infarction or pulmonary embolism), or transurethral resection syndrome episodes occurred. Intraoperative complications consisted of three capsular perforations (1.5%), one bladder neck false passage (0.5%), four incomplete morcellations (1.9%), and four minor bladder mucosal morcellation injuries (1.9%). Of 206 patients, 173 (84.0%) provided follow-up data (mean 19.0 +/- 8.4 months), allowing documentation of longer term complications, including five clot retention episodes (2.4%), five urethral strictures (2.4%), eight bladder neck contractures (3.9%), and 16 patients requiring re-catheterization (7.8%). CONCLUSIONS HoLEP can be performed with minimal complication risks and blood loss. Patients can expect an overnight hospital stay and discharge without an indwelling catheter.