David Lee

Retroperitoneal laparoscopic cryoablation of small renal tumors: intermediate results

OBJECTIVESnTo present our experience with laparoscopic renal cryoablation with up to 3 years of follow-up. Laparoscopic renal cryoablation remains a viable option for the treatment of small peripheral renal masses in patients with significant comorbidities. Although partial nephrectomy has been shown to be a safe and reliable method of renal parenchymal preservation, laparoscopic cryoablation still requires longer term data to prove its efficacy.nnnMETHODSnTwenty patients with small renal masses (1.4 to 4.5 cm) underwent laparoscopic renal cryosurgery at our institution. A retroperitoneal laparoscopic approach was used to expose the kidney. Intraoperative ultrasound guidance was used to localize the lesions and monitor iceball formation. A double-freeze technique was used. Needle biopsies of solid masses were performed intraoperatively.nnnRESULTSnRenal biopsies revealed renal cell carcinoma in 11 of the 20 patients. Of these 11 patients, none had evidence of recurrent disease at last follow-up, and follow-up scans showed no enhancement of any lesions. Of the 8 patients with follow-up of 2 years or greater, 4 had complete resolution of the renal lesions. The remainder had lesions that were reduced and stable in size. Complications included surgical re-exploration to evaluate pancreatic injury in 1 patient and failure to ablate a lesion in another.nnnCONCLUSIONSnLaparoscopic renal cryoablation appears to be an effective tool for ablation of small renal lesions. A moderate length of follow-up continues to demonstrate efficacy because no patients had growth of treated pathologic lesions or developed metastasis to date. Continued maturation of data is necessary to determine the long-term efficacy.

Characterization of intrapelvic pressure during ureteropyeloscopy with ureteral access sheaths.

OBJECTIVESnTo evaluate the impact of the ureteral access sheath on intrarenal pressures during flexible ureteroscopy in light of the recent resurgence in their use. As such, using human cadaveric kidneys, we studied changes in intrarenal pressure in response to continuous irrigation at different pressures with and without access sheaths of various sizes and lengths.nnnMETHODSnThis study was performed using seven cadaveric kidneys. In three kidneys the study was done in situ with a 7.5F flexible ureteroscope (URS) passed by itself and then passed through a 10/12F sheath (35 and 55 cm in length), whereas, in four kidneys, due to narrowing of the intramural ureter, the study was done ex vivo using the unsheathed URS and then passing the 7.5F flexible URS via the 10/12F, 12/14F, and 14/16F sheaths (all 35 cm in length). A 10F Cope loop pyelostomy was placed to measure intrapelvic renal pressure. Three sets of 3-minute readings (ie, flow and intrarenal pressure) were taken with the tip of the URS at the distal ureter, middle ureter, and renal pelvis (just above the ureteropelvic junction); the entire process was done at three different irrigant pressure settings: 50, 100, and 200 cm H(2)O. Irrigant flow and intrarenal pressures were measured at all three settings using the URS passed without a sheath and then with the URS passed through the various sheaths positioned at the distal ureter, middle ureter, and renal pelvis.nnnRESULTSnWith all of the sheaths, intrapelvic pressure remained low (less than 30 cm H(2)O), and there was a 35% to 80% increase in irrigant flow versus the control unsheathed URS. With the sheath in place, the majority of the irrigant drained alongside the URS and out the sheath. Flow and pressure with the 12/14F sheath were equivalent to the 14/16F sheath.nnnCONCLUSIONSnThe 12/14F access sheath provides for maximum flow of irrigant while maintaining a low intrarenal pelvic pressure. Even with an irrigation pressure of 200 cm H(2)O, renal pelvic pressure remained below 20 cm H(2)O.

Needle-based ablation of renal parenchyma using microwave, cryoablation, impedance- and temperature-based monopolar and bipolar radiofrequency, and liquid and gel chemoablation: Laboratory studies and review of the literature

BACKGROUND AND PURPOSEnSmall renal tumors are often serendipitously detected during the screening of patients for renal or other disease entities. Rather than perform a radical or partial nephrectomy for these diminutive lesions, several centers have begun to explore a variety of ablative energy sources that could be applied directly via a percutaneously placed needle-like probe. To evaluate the utility of such treatment for small renal tumors/masses, we compared the feasibility, regularity (consistency in size and shape), and reproducibility of necrosis produced in normal porcine kidneys by different modes of tissue ablation: microwaves, cold impedance-based and temperature-based radiofrequency (RF) energy (monopolar and bipolar), and chemical. Chemoablation was accomplished using ethanol gel, hypertonic saline gel, and acetic acid gel either alone or with simultaneous application of monopolar or bipolar RF energy.nnnMATERIALS AND METHODSnA total of 107 renal lesions were created laparoscopically in 33 domestic pigs. Microwave thermoablation (N=12) was done using a Targis T3 (Urologix) 10F antenna. Cryoablation (N=16) was done using a single 1.5-mm probe or three 17F microprobes (17F SeedNet system; Galil Medical) (N=10 single probe and N=6 three probes); a double freeze cycle with a passive thaw was employed under ultrasound guidance. Dry RF lesions were created using custom-made 18-gauge single-needle monopolar probe with two or three exposed metal tips (GelTx) (N=12) or a single-needle bipolar probe (N=6) at 50 W of 510 kHz RF energy for 5 minutes. In addition, a multitine RF probe (RITA Medical Systems) was used in one set of studies (N=6). Both impedance- and temperature-based RF were evaluated. Chemoablation was performed with 95% ethanol (4 mL), 24% hypertonic saline (4 mL), and 50% acetic acid (4 mL) as single injections. In addition, chemoablation was tested with monopolar and bipolar RF (wet RF). Tissues were harvested 1 week after ablation for light microscopy.nnnRESULTSnIn 11 of the 15 ablation techniques, there was complete necrosis in all lesions; however, three ethanol gel lesions had skip areas, three hypertonic saline gel lesions showed no necrosis or injury, and one monopolar RF and one bipolar RF lesion showed skip areas. In contrast to impedance-based RF, heat-based RF (RITA) caused complete necrosis without skip areas. All cryolesions resulted in complete tissue necrosis, and cryotherapy was the only modality for which lesion size could be effectively monitored using ultrasound imaging.nnnCONCLUSIONSnCryoablation and thermotherapy produce well-delineated, completely necrotic renal lesions. The single-probe monopolar and bipolar RF produce limited areas of tissue necrosis; however, both are enhanced by using hypertonic saline, acetic acid, or ethanol gel. Hypertonic saline gel with RF consistently provided the largest lesions. Ethanol and hypertonic saline gels tested alone failed to produce consistent cellular necrosis at 1 week. In contrast, RITA using the Starburst XL probe produced consistent necrosis, while impedance-based RF left skip areas of viable tissue. Renal cryotherapy under ultrasound surveillance produced hypoechoic lesions, which could be reasonably monitored, while all other modalities yielded hyperechoic lesions the margins of which could not be properly monitored with ultrasound imaging.

Evaluation of overall costs of currently available small flexible ureteroscopes

OBJECTIVESnTo perform a meta-analysis of the currently available data regarding the durability of flexible ureteroscopes to establish cost estimates for the purchase and use of five currently available, smaller than 9F, ureteroscopes. Healthcare costs have become increasingly germane to the determination of disease management strategies. Improved ureteroscope technology has expanded the role of these instruments. However, the initial purchase costs and high maintenance costs have become problematic with these fragile instruments.nnnMETHODSnUreteroscope durability data on the Storz 11274AA, Olympus URF-P3, Wolf 7325.172, ACMI AUR-7, and ACMI DUR-8 were collected from three prior studies. Combining the durability data and cost data regarding the initial purchase price and maintenance costs of these instruments, we calculated the overall costs associated with the use of each of the ureteroscopes for 25, 50, 75, and 100 cases during the first year (warranties included) and with subsequent use.nnnRESULTSnThe variability in the costs associated with the use of the currently available smaller than 9F ureteroscopes was significant. The initial instrument purchase price, durability, repair costs, and associated warranties all contributed to large discrepancies in the cost of performing ureteroscopy. In this model, during the first year of ownership, the projected cost of performing 100 ureteroscopic cases varied by a difference of 95% depending on the ureteroscope used.nnnCONCLUSIONSnPhysicians and institutions that perform ureteroscopy should strongly consider the purchase price, durability, repair cost, and associated warranties before the purchase of small flexible ureteroscopes.

Combined Percutaneous And Retrograde Approach To Staghorn Calculi With Application Of The Ureteral Access Sheath To Facilitate Percutaneous Nephrolithotomy

PURPOSEnWe describe our technique and clinical experience with application of the ureteral access sheath for single access ablation of staghorn and partial staghorn calculi.nnnMATERIALS AND METHODSnWe retrospectively reviewed our experience with 9 patients who underwent percutaneous nephrolithotomy for staghorn (6) or partial staghorn (3) renal calculi using a combined antegrade and retrograde approach. Patient data, operative parameters, efficacy of stone ablation and convalescence parameters were reviewed.nnnRESULTSnMean operative time for the primary procedure was 3.1 hours with a mean estimated blood loss of 290 ml. Postoperatively, the mean analgesic requirement was 33.2 mg. MSO(4) equivalents. Hospital stay was 3.2 days. There were no major and 4 minor (44%) complications. No patient required transfusion. Complete stone clearance was achieved in 7 of the 9 cases (78%) using a single percutaneous nephrostomy tract.nnnCONCLUSIONSnOur preliminary clinical experience using the ureteral access sheath during percutaneous nephrolithotomy for simultaneous antegrade and retrograde stone treatment has been favorable. A large renal stone burden can be successfully managed with a single percutaneous access and limited blood loss.

Determination of burn depth with noncontact ultrasonography.

Early excision and grafting is the current treatment of choice for deep dermal and full-thickness burn wounds that will not heal spontaneously within 3 weeks. The time needed for the burn wound to heal is estimated with clinical assessment of the burn depth; this is often an inaccurate method. Therefore we have developed a new and unique noncontact ultrasonographic method to estimate burn depth. This study was designed to determine the practical utility and accuracy of noncontact ultrasonography for the assessment of burn depth. Seventy-eight burn sites and 42 normal skin sites (control sites) of 15 patients (age, 18-63 years) with burns of 2% to 35% total body surface area were evaluated. The burn sites were scanned with a prototype noncontact ultrasonographic system 1 and 3 days after the burn injuries. The probe was held 1 inch from the skin, and the time spent on each site was approximately 5 minutes. The ultrasonographic results were interpreted by an investigator who was blinded to the clinical findings. Clinical assessment of the burn wounds was made on the same days by 2 experienced physicians who were blinded to the results of the ultrasonography. The investigators were asked to categorize the burn wounds into those that would heal within 3 weeks and those that would not. With this method, we were able to visualize the epidermis, dermis, and dermal-fat interface in normal skin. The destruction of the dermal-fat interface was interpreted as a deep burn, which would not heal within 3 weeks. The overall accuracy of the noncontact ultrasonography in the prediction of which burn wounds would heal within 3 weeks was 96%. The results of this study show that noncontact ultrasonography will allow for the rapid evaluation of burn depth with high accuracy, without contacting the patient, and without causing pain or discomfort.

Comparison of intrarenal pressure and irrigant flow during percutaneous nephroscopy with an indwelling ureteral catheter, ureteral occlusion balloon, and ureteral access sheath.

OBJECTIVESnTo determine the differential effects on renal pressures and irrigation flow associated with the application of different ureteral catheters during percutaneous nephrolithotomy.nnnMETHODSnUsing ex vivo fresh cadaveric tissue, we established a percutaneous nephrolithotomy model. After obtaining lower pole percutaneous access, we recorded the pressure and irrigant flow measurements. Measurements were made with an empty ureter, 6F ureteral catheter, occlusion balloon catheter, and ureteral access sheaths (10/12F and 12/14F). Three 1-minute trials for each condition were recorded in each of four kidneys.nnnRESULTSnUreteral catheterization with both the 10/12F and the 12/14F ureteral access sheaths resulted in significantly decreased intrarenal pressures in the pressure range tested compared with an empty ureter, a ureteral catheter, or an occlusion balloon application. Total irrigant flow for the 12/14F ureteral access sheath was significantly higher than for the empty ureter, ureteral catheter, or occlusion balloon in the entire pressure range evaluated.nnnCONCLUSIONSnIn this in vitro cadaveric model, application of the ureteral access sheath during percutaneous nephrolithotomy resulted in decreased intrarenal pressures and increased irrigant flow.

Ureteroscopes: flexible, rigid, and semirigid

Since its introduction, the ureteroscope has undergone significant improvements. Using the currently available rigid, semirigid, and flexible ureteroscopes and working instruments, urologists can diagnose and treat lesions throughout the upper urinary tract. Over the past 25 years, the ureteroscope in combination with shock wave lithotripsy has transformed the diagnosis and treatment of more than 90% of upper urinary tract pathology from an open to an endourologic procedure. With endoscope manufacturers continually incorporating new technology into their ureteroscopes, future models will undoubtedly provide better optics, increased durability, and improved capabilities, resulting in greater success when urologists perform endoscopic forays into the upper urinary tract.

Robotic revelation ☆: laparoscopic radical prostatectomy by a nonlaparoscopic surgeon

In most areas of surgery, minimally invasive procedures have made significant inroads because of major advances in the realm of laparoscopy. But laparoscopic surgery is an entirely new skill to be learned by the well-trained open surgeon. For the classically trained open surgeon, the drawbacks to laparoscopy are many: twodimensional view, disjunction between the actual surgical field and the view of the surgeon (ie, the television screen is not aligned with the actual surgical field), poor haptic feedback, inability of the surgeon to physically control the view of the surgical field, and the need for continual counterintuitive movement of instruments in order to access the surgical site. Given these substantial hurdles, many urologic surgeons have elected to shun laparoscopic surgery, awaiting further proof of benefit or a less rigorous alternative. Recently, two three-armed robotic systems have become available that provide the surgeon with both control of the camera and the two working ports. One of these, the da Vinci system (Intuitive Surgical Inc) has end effectors that provide six degrees of freedom similar to the human wrist. The instrumentation provides a three-dimensional view of the surgical field at 10 to 12 magnification and intuitive movement of the instruments. In addition, the controls have 1:5 motion scaling and insensitivity to intention tremor. The ergonomic robotic console is separate from the table, allowing the surgeon to sit comfortably while viewing the surgical field. The surgeon neither scrubs nor gowns, but a tableside surgical assistant is required to aid in tissue retraction, suction, instrument exchanges, and the introduction and removal of suture material. The presumption has been that in order to perform robotic laparoscopic surgery, intense training and mastery of basic and advanced laparoscopic skills are necessary. But the current model of the da Vinci robot truly mimics the movements made during standard open surgery, raising the question: Using the da Vinci robot as an interface, does an accomplished open surgeon still require intense training in laparoscopy in order to perform a complex laparoscopic procedure? Herein we report the successful completion of a robotic laparoscopic prostatectomy by an experienced open surgeon with no formal basic or standard laparoscopic training.

Bare Naked Baskets: Ureteroscope Deflection and Flow Characteristics With Intact and Disassembled Ureteroscopic Nitinol Stone Baskets

PURPOSEnLower pole renal access during flexible ureterorenoscopy is often limited by the active deflection capabilities of the ureteroscope. Deterioration in the deflection and flow capabilities of ureteroscopes occurs with the passage of instrumentation through the working channel. We performed in vitro evaluation of a novel technique using unsheathed nitinol baskets to minimize the deterioration in deflection and maximize the irrigant flow associated with instrument passage through the working channel during flexible ureterorenoscopy.nnnMATERIALS AND METHODSnAlterations in the irrigant flow and active deflection of 4 ureteroscopes from different manufacturers were evaluated. Each ureteroscope was evaluated with an empty working channel, and then with sheathed and unsheathed 2.2, 3 and 3.2Fr (Cook Urological, Inc., Indianapolis, Indiana), 2.4 and 3Fr (Microvasive Urology, Natick, Massachusetts) nitinol baskets in the working channel.nnnRESULTSnWith all baskets tested and in all ureteroscopes the deterioration in active deflection and irrigant flow was improved with the unsheathed baskets. The disassembled basket within the working channel allowed an additional 15 to 20 degrees of active deflection. In addition, the disassembled basket allowed for a 2 to 30-fold increase in irrigant flow compared with an intact basket.nnnCONCLUSIONSnThe combination of improved deflection and irrigant flow with this technique may improve ureteroscopic access to lower pole renal calculi.