Biomedical subjects

Fernando C Delvecchio

Publications and source records attributed to Fernando C Delvecchio.

17 recordsLinked to original sources

PubMed2006

Forced versus minimal intravenous hydration in the management of acute renal colic: a randomized trial.

BACKGROUND AND PURPOSE: The management of acute renal colic is a problem commonly encountered by both urologists and emergency medicine physicians. The classic approach to managing uncomplicated acute renal colic involves hydration, along with imaging and pain control. Previous studies have suggested that hydration has a significant impact on patient comfort, as well as spontaneous stone passage. This study evaluated the effects of maintenance v forced hydration and its effect on the pain experienced from renal colic. PATIENTS AND METHODS: Forty male and 18 female patients with a mean age of 41 years suspected to have acute renal colic were identified in the emergency department. After screening and informed consent, the patients were enrolled in the study, and 43 patients were eventually available for analysis. Patients received intravenous (IV) analgesia, imaging with a noncontrast CT scan of abdomen and pelvis, and assignment to either forced IV hydration with 2 L of normal saline over 2 hours (N = 20) or minimal IV hydration at 20 mL of normal saline per hour (N = 23). A visual analog pain scale was completed hourly for a total of 4 hours. Demographic information, laboratory and imaging results, narcotic use in morphine equivalents (ME), and pain scores were recorded and compared. Spontaneous stone passage rates were also calculated by careful patient follow-up. Results were considered statistically significant at p < 0.05. RESULTS: Stone size was equivalent in the two treatment groups (p > 0.05). There was no difference in the narcotic requirement in ME (p = 0.644) between the two groups. Similarly, there was no difference in hourly pain score or stone-passage rates between the groups (p > 0.05). CONCLUSIONS: Treatment of uncomplicated renal colic has traditionally included vigorous intravenous hydration, as well as medications for the control of pain and nausea. Our data suggest that maintenance intravenous fluids are as efficacious as forced hydration with regard to patient pain perception and narcotic use. Moreover, it appears the state of hydration has little impact on stone passage.

Adult↗

PubMed2005

Citrate and vitamin E blunt the shock wave-induced free radical surge in an in vitro cell culture model.

Free radical formation plays a major role in shock wave lithotripsy induced renal damage. Moreover, previous studies suggest that free radicals may also promote de novo calcium oxalate crystallization of previously damaged urothelium. Citrate is a known inhibitor of renal stone formation and has also been used as a free radical scavenger. Using an in vitro model with Madin-Darby canine kidney (MDCK) cells, we investigated the influence of two free radical scavengers, citrate and vitamin E, on the prevention of the shock wave-induced free radical surge. Suspensions of MDCK cells were placed in containers for shock wave exposure. Six groups of six containers each were examined: (a) no scavengers 0 shocks, (b) no scavengers 100 shocks, (c) citrate 0 shocks, (d) citrate 100 shocks, (e) vitamin E 0 shocks, (f) vitamin E 100 shocks. An unmodified HM3 was used to deliver 100 shocks at 24 kV. The cell groups that were not shocked acted as the control group and were handled identically, except for the lack of shock wave exposure. After shock wave administration, the containers were emptied and cell suspensions were immediately centrifuged. The supernatant was examined for lactate dehydrogenase (LDH) and 8-isoprostane (8-IP), markers of cellular injury and free radical formation, respectively. Intracellular LDH uniformly increased in all groups exposed to shock wave energy. Similarly, 8-IP increased in all shocked groups. However, the 8-IP increase was significantly reduced when the free radical scavengers were employed. As citrate is a well-known inhibitor of calcium nephrolithiasis, its mechanism of action may be further enhanced, based on its ability to reduce free radical formation, by a protective effect on the urothelium. These data further support the use of citrate based medications during the peri-operative period of shock wave lithotripsy, not only to inhibit stone formation and facilitate fragment passage, but also to reduce the incidence of shock wave induced renal damage. Further studies are warranted to clinically test this hypothesis.

Animals↗

PubMed2005

Anastomotic contracture and incontinence after radical prostatectomy: a graded approach to management.

PURPOSE: We present a heterogeneous group of men presenting with varying degrees of anastomotic contracture (AC) and associated stress urinary incontinence (SUI) following radical prostatectomy. It is particularly important that AC should be resolved before artificial urinary sphincter (AUS) implantation, because instrumentation through the AUS can risk erosion. MATERIALS AND METHODS: The records of 54 consecutive men who were referred for the management of AC and associated SUI were reviewed. Patient treatment and outcomes were stratified according to their unique characteristics. RESULTS: A total of 54 patients underwent radical prostatectomy alone (48), or in combination with radiation therapy (7) or cryotherapy (1). In group 1, 35 patients had previously undiscovered AC, or 1 or more prior contracture incisions (CIs) with SUI. CI and AUS were performed simultaneously in 33 patients and sequentially in 2. In group 2, 7 patients with intractable AC following multiple CIs/dilations and self-calibration, or an indwelling urethral or suprapubic catheter underwent simultaneous (3) or sequential (2) CI/AUS or CI only (2). Five patients required temporary self-calibration. In group 3, in 12 patients with total outlet obliteration recanalization was accomplished with combined antegrade/retrograde endoscopy and CI. Ten patients had re-obliteration, of whom 1 underwent suprapubic diversion and 9 underwent repeat recanalization with placement of a UroLume stent (American Medical Systems, Minnetonka, Minnesota) across the anastomosis. Eight patients underwent artificial urinary sphincter (AUS) placement 4 to 6 weeks later and 1 awaits an AUS. Of those implanted with an AUS 2 required repeat endoscopic procedures because of recurrent but manageable stent ingrowth. CONCLUSIONS: Most ACs are treated successfully with simultaneous, aggressive CI/AUS. A history of many CIs or long, dense contractures suggest the need for staged management. In those with obliterated outlets we prefer to reestablish patency and if rapid recurrence develops, we place a UroLume stent. Regardless of a history of radiation therapy, continence is restored with an AUS.

Anastomosis, Surgical↗

PubMed2004

Management of nephropleural fistula after supracostal percutaneous nephrolithotomy.

OBJECTIVES: Access to complex urinary tract pathology may require supracostal access placing patients at risk for intrathoracic complications. Our objective was to retrospectively review our experience with percutaneous renal surgery with a particular emphasis on identifying the incidence of nephropleural fistula and management of this unusual complication. METHODS: The records of 375 consecutive patients who underwent percutaneous renal surgery between 1993 and 2001 were reviewed. Supracostal access was placed to address the intrarenal pathologic findings most directly in 120 (26.0%) of the 462 tracts, with 87 (18.8%) above the 12th rib, 32 (6.9%) above the 11th rib, and 1 (0.2%) above the 10th rib. RESULTS: Of 375 patients, 4 (1%) developed a nephropleural fistula. Of the 87 with supracostal-12th rib access, 2 (2.3%) developed a nephropleural fistula, and 2 (6.3%) of the 32 with supracostal-11th rib access developed the same complication. The overall incidence of nephropleural fistulas in our patient population per access tract placed was 0.87% (4 of 462 percutaneous tracts), which increased to 3.3% (4 of 120) when considering only supracostal access. All patients were treated conservatively, although 1 patient required thoracoscopy with decortication for persistent pleural effusion. No further sequelae developed in any of the other 3 patients, and all fistulas had resolved at 3 months of follow-up. CONCLUSIONS: As aggressive percutaneous renal surgery with supracostal access to the collecting system becomes more common, the incidence of intrathoracic complications, including nephropleural fistula, may increase. Early recognition and management of a pleural injury is critical to avoid life-threatening situations. Low-morbidity measures are typically successful; however, more aggressive treatment may be required on occasion.

Adult↗

PubMed2004

Bilateral renal calculi: assessment of staged v synchronous percutaneous nephrolithotomy.

BACKGROUND AND PURPOSE: Percutaneous stone removal has replaced open renal surgery and has become the treatment of choice for large or complex renal calculi. However, patients with large bilateral stone burdens still present a challenge. Simultaneous bilateral percutaneous nephrolithotomy (PCNL) has been demonstrated to be a well-tolerated, safe, cost-effective, and expeditious treatment. We present what is, to our knowledge, the first large retrospective series comparing synchronous and asynchronous bilateral PCNL. PATIENTS AND METHODS: A chart review was performed on 26 patients undergoing 57 PCNLs for bilateral renal calculi over a 7-year period. Seven patients received synchronous PCNL (same anesthesia; Group 1), and 19 patients underwent asynchronous PNL (procedures separated by 1-3 months; Group 2). Complete surgical and hospital records were available on all patients. The average stone burden for Group 1 was 8.03 cm(2) on the left and 9.18 cm(2) on the right v 10.1 cm(2) on the left and 14.23 cm(2) on the right for Group 2 (P> 0.05). Variables of interest included anesthesia time, operative time, blood loss, transfusion rates, length of hospital stay, and complication rates. Each variable was evaluated per operation and per renal unit. Follow-up imaging with stone assessment was available on 20 patients. RESULTS: Group 1 required 1.14 access tracts per renal unit to attempt complete clearance of the targeted stones v 1.88 tracts per renal unit in Group 2 (P> 0.05). The average operative time per renal unit was significantly less in Group 1 (83 minutes) than in Group 2 (168.5 minutes) (P< 0.0001), as was blood loss (178.5 mL v 307.4 mL, respectively; P= 0.02). However, blood loss per operation was similar at 357 mL in Group 1 and 282 mL in Group 2. Comparable transfusion rates of 28.6% and 36.8%, respectively, were noted. Forty percent of the patients in Group 1 were completely stone free compared with 36% of the patients in Group 2; however, an additional 50% and 57%, respectively, had residual stone burden <4 mm (P> 0.05). Complications occurred in 2 of 7 operations (28%) in Group 1 and 8 of 42 operations (19%) in Group 2. The total length of hospital stay was nearly doubled for patients undergoing staged PCNL (P= 0.0005). CONCLUSIONS: These results demonstrate similar stone-free rates, blood loss per operation, and transfusion rates for simultaneous and staged bilateral PCNL. The reduced total operative time, hospital stay, and total blood loss, along with the requirement for only one anesthesia, makes synchronous bilateral PCNL an attractive option for select individuals. However, in patients with larger, less easily accessible stones, excessive bleeding may be encountered more frequently on the first side, thereby delaying management of the second side to a later date. Synchronous bilateral PCNL should be considered in patients in whom the first stage of stone removal is accomplished quickly and safely.

Adolescent↗

PubMed2003

Durability of the medical management of cystinuria.

PURPOSE: Cystinuria is an autosomal recessive disorder of dibasic amino acid transport in the kidney that leads to an abundance of cystine in the urine. This molecule is poorly soluble in urine and it is prone to crystallization and stone formation at concentrations above 300 mg./l. Medical treatment in these patients has incorporated increasing urine volumes, alkalinization and thiol medications that decrease the availability of free cystine in urine. Despite a reasonable prognosis for reduced stone formation we and others have noted difficulties in patients complying with medical management recommendations. Therefore, we evaluated the durability of treatment success in our patients with cystinuria. MATERIALS AND METHODS: A retrospective chart review was performed in all patients with cystinuria referred to the comprehensive kidney stone center at our institution for an 8-year period. Medical therapy, stone recurrence rates, compliance with medications and scheduled followup, and the results of metabolic evaluations via 24-hour urine collections were reviewed. The average concentrations of urinary cystine in initial and followup 24-hour samples were compared in patients compliant and noncompliant with medical treatment. In addition, each patient was mailed a 1-page questionnaire to assess the self-perception of medical compliance. RESULTS: We identified 26 patients with a mean age of 32 years at referral (range 13 to 67) who were followed an average of 38.2 months (range 6 to 83). Females represented 58% of those with cystinuria. Overall compliance with medical recommendations was poor with a short duration of success. Of the 26 patients followed at our stone center only 4 (15%) achieved and maintained therapeutic success, as defined by urine cystine less than 300 mg./l. An additional 11 patients (42%) achieved therapeutic success but subsequently had failure at an average of 16 months (range 6 to 27). Of these patients 7 (64%) regained therapeutic success at an average of 9.4 months (range 4 to 20). Five patients (19%) never achieved therapeutic success, while an additional 6 (23%) failed to present to followup appointments or provide subsequent 24-hour urine studies despite referral to a tertiary care center. Patient self-assessment of medical compliance was uniformly high regardless of physician perceptions or treatment results. CONCLUSIONS The durability of medically treating patients with cystinuria is limited with only a small percent able to achieve and maintain the goal of decreasing cystine below the saturation concentration. Greater physician vigilance in these complicated stone formers is required to achieve successful prophylactic management. Furthermore, these patients require better insight into the own disease to improve compliance.

Adolescent↗

PubMed2003

Assessment of stricture formation with the ureteral access sheath.

OBJECTIVES: To analyze the long-term incidence of ureteral stricture formation in a series of patients in whom a new-generation ureteral access sheath was used. A new generation of ureteral access sheaths has been developed to facilitate ureteroscopic procedures. However, some have questioned their safety and whether the device might cause significant ureteral trauma. METHODS: Between September 1999 and July 2001, 150 consecutive ureteroscopic procedures with adjunctive use of an access sheath were performed. A retrospective chart review to April 2002 was done. Of the 150 patients, 130 underwent ureteroscopy for ureteral stones. Patients who underwent endoureterotomy or treatment of transitional cell carcinoma were excluded from this analysis. Sixty-two patients had follow-up greater than 3 months and were included in the analysis. Overall, 71 ureteroscopic procedures were performed, with 9 patients undergoing multiple procedures. Ninety-two percent of the patients had pathologic findings above the iliac vessels. The average patient age was 45.3 years (range 17 to 76), and 70% and 30% of the patients were male and female, respectively. The mean clinical follow-up was 332 days (range 95 to 821), and follow-up imaging was performed within 3 months after ureteroscopy in all patients. RESULTS: The 10/12F access sheath was used in 8 ureteroscopic procedures (11.2%), the 12/14F access sheath in 56 (78.9%), and the 14/16F access sheath in 7 (9.8%). One stricture was identified on follow-up imaging of 71 procedures performed, for an incidence of 1.4%. The patient developed the stricture at the ureteropelvic junction after multiple ureteroscopic procedures to manage recurrent struvite calculi. The access sheath did not appear to be a contributing factor. CONCLUSIONS: The results of our series indicate that the ureteral access sheath is safe and beneficial for routine use to facilitate flexible ureteroscopy. However, awareness of the potential ischemic effects with the use of unnecessarily large sheaths for long periods in patients at risk of ischemic injury should be considered. We advocate the routine use of the device for most flexible ureteroscopic procedures proximal to the iliac vessels.

Adolescent↗

PubMed2003

In vitro analysis of stone fragmentation ability of the FREDDY laser.

BACKGROUND AND PURPOSE: The Frequency-Doubled Double-Pulse Nd:Yag) (FREDDY) laser (World of Medicine, Berlin Germany) is a short-pulsed, double-frequency solid-state laser with wavelengths of 532 and 1064 nm. This low-power, low-cost laser was developed for intracorporeal lithotripsy. We designed an experimental set-up to test its fragmentation efficiency at different energy and frequency settings. MATERIALS AND METHODS: Forty previously weighed plaster-of-Paris stone phantoms were divided into four groups in order to test fragmentation at 5 and 10 Hz for 2 and 4 minutes. A hands-off underwater laboratory set-up including a holder to keep the stone phantom in contact with the quartz laser fiber was utilized. The 280-microm laser fiber was cleaved and stripped between runs to ensure optimal energy delivery. After fragmentation was completed, all of the stone fragments remaining within the holder were allowed to desiccate for 48 hours and reweighed. Fragmentation was measured as the percentage weight loss. RESULTS: Stone phantoms fragmented at 5 Hz for 2 minutes sustained a mean 24% loss of weight, whereas the 4-minute treatment at 5 Hz reduced stone weight by 54%. Treatment at 10 Hz for 2 minutes demonstrated results similar to those of stones treated for 4 minutes at 5 Hz, reducing stone weight by 51%. Fragmentation at 10 Hz for 4 minutes revealed a 64% loss of mass, less than expected for these power settings. Fiber deterioration observed at the higher energy settings may be the cause of the reduced stone-fragmentation efficiency. CONCLUSIONS: Fragmentation with the FREDDY laser in the 5 Hz, 4 minutes and 10 Hz, 2 minutes protocols is comparable, suggesting that stone fragmentation correlates well with the total energy delivered to the stone. The slight drop in fragmentation efficiency at 10 Hz, 4 minutes is most likely explained by fiber damage occurring consistently at these higher energy settings. The safety profile and low investment and running costs of this laser are advantages that suggest the laser warrants further clinical trials.

In Vitro Techniques↗

PubMed2003

Medical management of stone disease.

PURPOSE OF REVIEW: Dietary manipulation still remains one of the most important strategies for therapy. A growing body of evidence, however, suggests that severe calcium restriction is inappropriate in patients with recurrent nephrolithiasis. Dietary recommendations based on recent evidence and the role of bacteria in the pathogenesis of calcium nephrolithiasis are discussed. RECENT FINDINGS: New evidence strongly supports the role of oxalate, salt and animal protein dietary restrictions in the prevention of calcium stone recurrence. Moderate calcium restriction is only effective in absorptive hypercalciuria. Calcium restriction is not effective in other etiologies of calcium stones and its implementation can lead to bone demineralization. New evidence has implicated the lack of intestinal bacteria to be responsible for the degradation of dietary oxalate, with its higher absorption resulting in an increased risk of calcium oxalate stone formation. The role of Oxalobacter formigenes is herein discussed. SUMMARY: Metabolic abnormalities responsible for stone recurrence are currently identified in 97% of evaluated patients and remission rates of medical prophylaxis in calcium stone formers are approaching 80%. Urinary calcium excretion in most renal stone formers is more dependent on the dietary acid load than on the dietary calcium intake itself. Reducing the acid-ash content of the diet has an impact on decreasing stone recurrence, while preventing bone loss. New evidence associates the decolonization of oxalate degrading intestinal flora with a higher risk of calcium oxalate stone formation, possibly opening the door for biological manipulation as a novel approach for the prevention of urinary stone formation.

Calcium Oxalate↗

PubMed2003

Ureteral access sheath facilitates inspection of incision of ureteropelvic junction.

PURPOSE: The Acucise (Applied Medical, Rancho Santa Margarita, California) electrocautery balloon is a highly successful device used in managing congenital and secondary ureteropelvic junction obstruction. Correct orientation of the cutting wire is essential during insertion of the Acucise catheter to avoid injury to crossing vessels. Moreover, confirmation of the lateral ureteropelvic junction incision is typically verified by fluoroscopic identification of extravasated contrast material. We describe a technique of facilitated passage of the Acucise balloon through a ureteral access sheath followed by ureteroscopic visualization of the incision, affording the opportunity to improve the incision with the holmium laser if necessary. MATERIALS AND METHODS: After retrograde pyelography and guidewire placement, a 12/14Fr, 35 cm. ureteral access sheath is fluoroscopically introduced to the proximal ureter. The Acucise balloon is advanced across the ureteropelvic junction and the balloon is partially inflated to confirm proper placement. Following lateral Acucise incision, flexible ureteroscopy allows direct visualization of the ureteropelvic junction, confirming a through-and-through incision. Completion of a partial incision can be performed if needed with a 200 micro holmium laser fiber followed by routine stent placement. RESULTS: During the last 8 months we have used the Acucise device through a ureteral access sheath to treat congenital or secondary ureteropelvic junction obstruction in 8 patients. All incisions demonstrated extravasation of contrast material on retrograde pyelography, and 6 incisions (75%) were noted to be transmural by flexible ureteroscopic inspection. Two patients (25%) with only a partial incision despite contrast extravasation underwent extended incision using the holmium laser. Short-term followup demonstrated patency of the ureteropelvic junction in 7 of the 8 patients (87.5%) with 1 eventually requiring a secondary open pyeloplasty. CONCLUSIONS: The ureteral access sheath greatly facilitates placement of the Acucise device and allows rapid ureteroscopic confirmation of the incision. Insertion and removal of the ureteral access sheath and flexible ureteroscope do not compromise or significantly increase the duration of the procedure. Moreover, flexible ureteroscopic visualization allows confirmation of a complete transmural incision and potentially increases success rates of this minimally invasive approach to ureteropelvic junction obstruction. Continued followup is necessary to confirm the long-term benefits of this procedure.

Catheterization↗

PubMed2003

Perineal repair of pelvic fracture urethral distraction defects: experience in 120 patients during the last 10 years.

PURPOSE: We report the long-term success of a 1-stage perineal anastomotic repair in patients with pelvic fracture urethral distraction defects. MATERIALS AND METHODS: A retrospective analysis of 120 patients undergoing perineal bulboprostatic anastomotic repair of pelvic fracture urethral distraction defect in a single stage using our progressive approach between May 1991 and May 2001 was performed. Patients with posterior urethral stricture due to other etiologies, or those who underwent substitution urethroplasty or abdominoperineal repair were excluded from this review. Preoperative evaluation of the urethral defect included simultaneous retrograde urethrogram and voiding cystourethrogram. Postoperative retrograde urethrogram was performed at 3 weeks, 3 months, 12 to 18 months and as indicated thereafter. RESULTS: Mean patient age was 32 (range 6 to 82) years. The estimated preoperative radiographic length of the distraction defect was 3.1 cm (range 0.5 to 10). Mean followup was 64 (range 9 to 128) months, mean hospital stay was 1.8 days and duration of urethral stenting was 3.4 weeks. Perineal anastomotic repair was successful in 103 of 109 (95%) adults, in 8 of 11 (73%) prepubescent boys and in 25 of 29 (86%) undergoing secondary repairs. All treatment failures were at the anastomosis and occurred within the first postoperative year. Successful management of failed repairs was accomplished endoscopically in 3 of 7 and by repeat perineal anastomotic repair in 2 of 2, resulting in a final success rate of 97% in adults, 91% in prepubescent boys and 97% in secondary repairs. CONCLUSIONS: The overall success of our progressive 1-stage perineal anastomotic repair of pelvic fracture urethral distraction defect continues to be excellent with the majority of failures occurring in prepubescent boys and secondary repairs.

Adolescent↗

PubMed2003

Determining the incidence of horseshoe kidney from radiographic data at a single institution.

PURPOSE: An estimated 150,000 children are born with birth defects each year. One of the most frequent genitourinary abnormalities is horseshoe kidney (HSK). The incidence of HSK in the population is estimated to be 1/400 to 1,600 births based on autopsy data from the 1940s and 1950s. We prospectively evaluated the incidence of HSK based on radiographic studies to determine the contemporary incidence of HSK. MATERIALS AND METHODS: In a 6-month period patients undergoing abdominal computerized tomography, renal ultrasonography and excretory urography were screened for HSK. After identification medical charts were reviewed for demographics, history, study indication and findings. A literature review of 12 studies of 825 patients with HSK was compared with the current series with regard to common associated findings. RESULTS: From 15,320 radiographs 23 patients were identified with HSK for an overall incidence of 1/666. Computerized tomography, excretory urography and ultrasound identified 16, 5 and 2 patients, respectively, while 16 were male, 7 were female, 20 were adults and 3 were children. The most common concomitant urological disorder was nephrolithiasis in 9 patients (39%), prompting operative intervention in 4. The radiographic incidence of HSK closely matched data from autopsy series and yet it differed from that in current radiographic series using ultrasound in the perinatal period. CONCLUSIONS: Our radiographic evaluation of the HSK incidence closely matches past autopsy series. This finding suggests that the incidence of HSK remains stable despite an increasing number of birth defects. Moreover, it appears that radiographic studies can accurately estimate the incidence of congenital anatomical disorders. Our data suggest that HSK is a relatively benign condition with a low requirement for operative intervention in these incidentally identified patients.

Adolescent↗

PubMed2002

Hypertonic saline-augmented radiofrequency ablation of the VX-2 tumor implanted in the rabbit kidney: a short-term survival pilot study.

OBJECTIVES: The increased incidental detection of small (less than 4 cm) renal tumors has stimulated investigations of minimally invasive therapies. Radiofrequency energy is a relatively new and evolving technology that has been used for a variety of experimental and clinical applications. We evaluate the efficacy of hypertonic interstitial saline-augmented radiofrequency therapy to ablate a malignant VX-2 tumor implanted in a rabbit kidney, as measured by the completeness of tumor destruction and progression to metastasis. METHODS: The VX-2 tumor was surgically implanted into the left lower pole parenchyma of 18 New Zealand white rabbit kidneys. Ten days after implantation, hypertonic interstitial saline-augmented radiofrequency ablation was performed (n = 12) using a radiofrequency therapy system (RFT, United States Surgical Corp.). A sham operation was performed on a control group (n = 6). Animals were humanely killed at 5, 10, and 15-day intervals, and the clinical response and effect of radiofrequency energy on the malignant renal tissue was assessed. RESULTS: No postoperative complications were encountered. The mean size of the implanted VX-2 tumor was 1.87 cm2. Kidneys in the treated group exhibited marked destruction of tumor tissue. Histologic analysis revealed coagulative necrosis of both malignant and normal renal tissue in the treated group. Three rabbits (1 control, 2 treated) died of metastatic disease. CONCLUSIONS: Coagulative necrosis of renal parenchyma and tumor tissue was clearly demonstrated after radiofrequency ablation using the RFT system. The aggressive growth pattern of the VX-2 tumor often resulted in progression to metastatic disease while precluding complete tumor ablation. Hypertonic saline-augmented radiofrequency ablation is a promising new technology for the management of small, locally confined, renal tumors and has the potential for use with a minimally invasive approach.

Animals↗

PubMed2002

Techniques to maximize flexible ureteroscope longevity.

OBJECTIVES: To assess methods to improve the longevity and durability of flexible ureteroscopes by using the ureteral access sheath, 200-microm holmium laser fiber, and nitinol baskets or graspers during routine ureteroscopic procedures. Despite adequate advances in fiberoptics and endoscope design, the decreased size of currently available flexible ureteroscopes makes damage inevitable after repeated use. However, new auxiliary tools may be able to enhance ureteroscope durability. METHODS: The indications for performing flexible ureteroscopy were proximal ureteral stones (n = 32), renal calculi (n = 59), treatment of upper tract transitional cell carcinoma (n = 3), evaluation of hematuria or filling defect (n = 7), and treatment of ureteral strictures or ureteropelvic junction obstruction (n = 8). Using four new 7.5F flexible ureteroscopes, we prospectively evaluated the number of passes of each ureteroscope until more than 20 optical fibers were broken, more than a 25 degrees loss of deflection in either direction had occurred, or the instrument sustained injury requiring repair by the manufacturer. RESULTS: One hundred nine flexible ureteroscopic procedures (average 27.5 procedures per instrument; range 19 to 34) were performed with the four new flexible ureteroscopes before being sent for repair. Adjuncts to reduce scope damage during these procedures were the use of the ureteral access sheath (n = 109), nitinol devices allowing lower pole stone retrieval (n = 27), and the 200-microm holmium laser fiber for stone fragmentation, tumor ablation, and incision of ureteropelvic junction/ureteral stenoses (n = 91). The average number of passes until more than 20 optical fibers were broken was 15.3 (range 12 to 20), until more than a 25 degrees loss of deflection occurred was 50.3 (range 42 to 66), or until the scope required repair was 66.7 (range 46 to 82). CONCLUSIONS: Flexible ureteroscopy will be used increasingly to manage upper urinary tract pathologic findings. Historically, the number of procedures performed before a flexible ureteroscope requires repair averaged 6 to 15. By incorporating the new ureteroscopic accessories, such as nitinol devices, a ureteral access sheath, and the 200-microm holmium laser fiber into common practice, one can reduce the strain on these fragile 7.5F endoscopes, thereby maximizing their longevity.

Equipment Failure↗

PubMed2002

Computed tomography urography, three-dimensional computed tomography and virtual endoscopy.

Spiral computed tomography technology allows an entire body region to be imaged as a continuous volume of computed tomography data. The acquisition of genitourinary images can be performed at different intervals after intravenous contrast injection in order to characterize the renal vasculature, the renal parenchyma or the collecting system. Computed tomography scanning as contrast is excreted into the collecting system is termed a 'computed tomography urogram'. Volumetric data from spiral computed tomography can be rendered into conventional two-dimensional images or even reformatted into three-dimensional views of organ systems or hollow structures, as in 'fly-through' virtual endoscopy. Although virtual endoscopy of the urinary tract remains in its infancy, three-dimensional imaging is currently a useful adjunct in the evaluation of renal transplant and donor patients and partial nephrectomy candidates. The role of computed tomography urography compared with intravenous urography in the evaluation of hematuria is discussed.

Humans↗

PubMed2002

In vivo assessment of free radical activity during shock wave lithotripsy using a microdialysis system: the renoprotective action of allopurinol.

PURPOSE: Shock wave lithotripsy is believed to cause renal damage directly through cellular injury from high energy shock waves and indirectly through vascular injury and resultant ischemia, which gives rise to oxygen free radical compounds. The transient and volatile nature of free radicals and derived products makes their detection difficult. Moreover, certain medications may provide a protective effect against shock wave lithotripsy induced renal parenchymal injury. We introduced an innovative microdialysis system for in vivo sampling of interstitial fluids that can be analyzed for free radical mediated lipid peroxidation products after shock wave lithotripsy treatment in the swine model. In addition, this system was used to test the antioxidant or renoprotective action of allopurinol. MATERIALS AND METHODS: Ten juvenile swine were assigned to a nonmedicated control group that underwent shock wave lithotripsy or to a group that was premedicated with allopurinol before shock wave lithotripsy. Each group of animals underwent shock wave lithotripsy to the lower pole of the right kidney and received a total of 10,000 shock waves. Dialysate fluid was collected at 1,000-shock wave increments via probes surgically implanted into the lower pole of the right and left kidneys before lithotripsy. Samples were immediately preserved in liquid nitrogen and subsequently analyzed for the presence and concentration of conjugated diene levels, a measure of lipid peroxidation. Five additional juvenile swine were assigned to a sham treated group that did not undergo shock wave lithotripsy. Dialysate fluid was collected from the lower pole of the right and left kidneys to establish baseline or pre-lithotripsy levels of conjugated dienes. RESULTS: After shock wave lithotripsy conjugated diene levels increased almost 100-fold over that in the right kidneys of the nonmedicated control group. The difference was statistically significant compared to levels in the contralateral untreated kidneys (p <0.01). Right kidneys in the group premedicated with allopurinol did not demonstrate an increase in conjugated diene levels during shock wave lithotripsy. CONCLUSIONS: The results of this study confirm shock wave lithotripsy induced free radical activity as well the antioxidant and protective nature of allopurinol. The newly described microdialysis system enables real-time sampling of interstitial fluids during shock wave lithotripsy. It represents a unique method for assessing free radical formation and evaluating the protective effects of additional antioxidant medications.

Allopurinol↗

PubMed2002

Routine postoperative imaging is important after ureteroscopic stone manipulation.

PURPOSE: Improved fiber optics and advanced intracorporeal lithotripsy devices have significantly decreased the incidence of complications during ureteroscopic procedures. Despite recent reports suggesting that radiographic imaging may not be necessary in all individuals after routine ureteroscopy silent obstruction may develop in some, ultimately resulting in renal damage. We determined the incidence of postoperative silent obstruction at our institution and assessed the need for routine functional radiographic studies after ureteroscopy. MATERIALS AND METHODS: We retrospectively reviewed the charts of 320 patients who underwent a total of 459 ureteroscopic procedures for renal or ureteral calculi in a 3-year period. Complete followup with imaging was available for 241 patients (75%). Average patient age was 47.2 years. The variables of interest reviewed included preoperative pain, preoperative obstruction, targeted calculous site, stone-free rate, postoperative pain and postoperative obstruction. Mean followup was 5.4 months (range 2 to 43). RESULTS: A total of 241 patients with complete followup were identified in this analysis. Preoperative pain was present in 202 patients (84%) and 168 (70%) had preoperative obstruction. Overall targeted calculous clearance was successful in 73% of the patients and an additional 15.8% had residual fragments less than 4 mm. The renal, proximal or mid and distal ureteral stone-free rate was 32.1%, 81.9% and 90.5%, while in an additional 46.4%, 6.3% and 6.7% of cases, respectively, residual fragments were less than 4 mm. Of the 241 patients 30 (12.3%) had obstruction postoperatively due to residual stone in 25 (83.3%), stricture in 3 (10%), edema of the ureteral orifice in 1 (3.3%) and a retained encrusted stent in 1 (3.3%). Postoperatively obstruction correlated with postoperative pain in 23 of the 30 patients (76.7%). Pain was present postoperatively in 30 of the 211 patients (14%) without evidence of ureteral obstruction postoperatively. However, silent obstruction developed in 7 patients (23.3%) or 2.9% of the total cohort. All 7 patients underwent secondary ureteroscopy to alleviate obstruction. A single patient ultimately received chronic hemodialysis for renal failure, 1 was lost to followup and in 5 there was documented successful resolution of the cause of obstruction. CONCLUSIONS: Our analysis suggests that silent obstruction remains a potentially significant complication after stone management. Relying on postoperative pain to determine the necessity of postoperative imaging places patients at risk for progressive renal failure due to unrecognized obstruction. Therefore, we recommend that imaging of the collecting system should be performed by excretory urography, spiral computerized tomography or ultrasound within 3 months after routine ureteroscopic stone treatment to avoid the potential complications of unrecognized ureteral obstruction.

Adult↗