Chandru P. Sundaram

Evaluation of a Vessel Sealing System, Bipolar Electrosurgery, Harmonic Scalpel, Titanium Clips, Endoscopic Gastrointestinal Anastomosis Vascular Staples and Sutures for Arterial and Venous Ligation in a Porcine Model

PURPOSE We assessed the usefulness of the LigaSure (Valleylab, Boulder, Colorado) vessel sealing system for vascular control during laparoscopic surgery and compared it with other available hemostatic modalities. MATERIALS AND METHODS A total of 31 domestic pigs were divided into 5 groups. In groups 1 and 2 the vessel sealing system was compared with titanium clips and Endo-GIA (United States Surgical, Stamford, Connecticut) staples. In group 3 the vessel sealing system was compared with standard Klepinger (Karl Storz, Culver City, California) bipolar forceps. In group 4 the harmonic scalpel and Trimax (United States Surgical) bipolar forceps were compared. In group 5 in vivo laparoscopic application of the vessel sealing system was evaluated. RESULTS The 5 mm. laparoscopic vessel sealing system sealed arteries up to 6 mm. and veins up to 12 mm. in diameter at supraphysiological bursting pressure. We evaluated 13 arteries with a diameter of 6 mm. or less at a mean bursting pressure of 662 mm. Hg (range 363 to 1,985) and 11 veins with a diameter of 12 mm. or less with a mean bursting pressure of 233 mm. Hg (range 63 to 440). Collateral tissue damage extended 1 to 3 mm. from the application site. Standard bipolar energy with Klepinger and Trimax forceps was less reliable and in some cases vessel sealing could not be accurately assessed before vessel division. Collateral tissue injury was 1 to 6 mm. The harmonic scalpel did not reliably seal vessels larger than 3 mm. but resulted in the least acute collateral tissue injury of 0 to 1 mm. CONCLUSIONS In the porcine model the LigaSure system is a viable option for laparoscopic management of arteries up to 6 mm. and veins up to 12 mm. in diameter.

Renal hypothermia achieved by retrograde endoscopic cold saline perfusion: technique and initial clinical application

We describe the technique and initial clinical results with application of a novel method to achieve renal parenchymal hypothermia using retrograde ureteral access. A 38-year-old man was scheduled to undergo an open right partial nephrectomy for renal cell carcinoma. Before the open procedure, a ureteral access sheath was advanced to the ureteropelvic junction under fluoroscopic guidance; through the access sheath, a 7.1F pigtail catheter was also advanced. After clamping the renal artery and vein, ice-cold saline (-1.7 degrees C) was circulated through the access sheath and drained via the 7.1F pigtail catheter; renal cortical and medullary parenchymal temperatures were measured using thermocouples. This technique of intrarenal cooling achieved a renal cortical temperature of 24 degrees C and a medullary temperature of 21 degrees C. The endoscopic procedure required an additional 35 minutes of operation time to complete. Histopathologic investigation of the specimen revealed no associated damage to the ureteral urothelium from access sheath placement or to the collecting system urothelium from exposure to ice-cold saline irrigation. Retrograde endoscopic renal hypothermia is feasible and effective. The technique requires no novel equipment or special surgical skills. This method can be applied to patients undergoing open or laparoscopic complex renal ablative and reconstructive procedures that require renal hypothermia.

FLEXIBLE URETEROSCOPES: A SINGLE CENTER EVALUATION OF THE DURABILITY AND FUNCTION OF THE NEW ENDOSCOPES SMALLER THAN 9Fr

PURPOSE Flexible ureteroscopes smaller than 9Fr are widely used in endourology. We systematically evaluated the functional durability of these instruments in the clinical setting. MATERIALS AND METHODS We performed ureteronephroscopy 92 consecutive times in 84 patients at our hospital using a flexible Storz model 11274AA,double dagger Circon-ACMI model AUR-7, section sign Wolf model 7325.172 parallel and Olympus model URF/P3 ureteroscope paragraph sign. Preoperatively and postoperatively we evaluated all flexible ureteroscopes for luminosity, irrigant flow at 100 mm. Hg, number of broken image fibers and active deflection range. During the procedure a record was kept of the duration that the endoscope remained in the urinary tract, average irrigation pressure, method of insertion, various devices used within the working channel, need for lower pole access, and surgeon overall impression of visibility and maneuverability. RESULTS The luminosity and irrigant flow of all endoscopes remained relatively unchanged during consecutive applications, while active deflection deteriorated 2% to 28%. Endoscopes were used for an average of 3 to 13 hours before they needed repair. The most fragile part of these instruments was the deflection unit. CONCLUSIONS Small diameter flexible ureteroscopes are effective for diagnosing and treating upper urinary tract pathology but improved durability is required. Currently they represent a highly effective but high maintenance means of achieving retrograde access to the ureter and kidney with a need for repair after only 6 to 15 uses.

Current Management of Urolithiasis: Progress or Regress?

PURPOSE To assess the impact of the development of less powerful second- and third-generation shockwave lithotripters on surgical stone therapy in light of recent advances in ureteroscopy and laser lithotripsy. As such, we sought to identify current trends in the treatment of stone disease, both at our university medical center and nationally, and to contrast them with the corresponding data from 1990. PATIENTS AND METHODS All urolithiasis procedures (ureteroscopy, SWL, open surgery, and percutaneous stone removal) performed in 1998 were compared with all urolithiasis procedures performed 8 years earlier (1990) at a single institution (Washington University, St. Louis). In addition, Medicare data for each year from 1988 through 2000 were collected from the Health Care Financing Administration to assess the national trends for open stone surgery, ureteroscopic stone removal, SWL, and percutaneous nephrolithotomy. RESULTS At Washington University, the number of percutaneous stone removals remained stable; however, the overall number of ureteroscopies increased by 53%, while the number of SWLs, decreased by 15%. The Medicare data likewise reflect a marked decrease in open stone surgery and a marked increase in ureteroscopic stone surgery with a slight increase in SWL. Utilization of percutaneous nephrolithotomy remained unchanged. CONCLUSIONS We believe this trend toward ureteroscopy is attributable to several factors: improved, smaller rigid and flexible ureteroscopes; the availability of more effective intracorporeal lithotripters (e.g., pneumatic and holmium laser), and the lack of development of lower cost, more effective SWL. This is an unfortunate trend, as we are moving away from the noninvasive treatment that was the hallmark of urolithiasis therapy at the beginning of the last decade toward more invasive endoscopic therapy. Increased research efforts in SWL technology are sorely needed.

Does Training on a Virtual Reality Robotic Simulator Improve Performance on the da Vinci® Surgical System?

PURPOSE The primary objective of this study is to determine if training on the Mimic dV-Trainer (MdVT) simulator results in improved ability on the da Vinci surgical system (dVSS) using exercises with inanimate objects. MATERIALS AND METHODS Twelve trainees (MdVT group) and 10 residents and one fellow (dVSS group) were recruited for the study. Each participant in the MdVT group completed one session of five exercises on the dVSS that were scored for timing and accuracy, followed by four training sessions on the MdVT, and concluded with a final session on the dVSS in which the initial exercises were repeated. Improvement on the dVSS exercises was compared with dVSS group who completed four to six training sessions using the same exercises on the dVSS without any simulator training. RESULTS Both groups had similar significant improvements in the Letter Board and String Running exercises for both timing and accuracy. The MdVT group demonstrated significant improvement in the Pattern Cutting and Peg Board times. Only the dVSS group significantly improved in the Knot Tying time and the Peg Board accuracy. CONCLUSION Training with the MdVT provided similar improvement on five exercises performed on the dVSS when compared with training on the dVSS alone. The use of this simulator in resident and student training may help bridge the gap between the safe acquisition of surgical skills and effective performance during live robot-assisted surgery.

Characterization of intrapelvic pressure during ureteropyeloscopy with ureteral access sheaths.

OBJECTIVES To 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. METHODS This 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. RESULTS With 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. CONCLUSIONS The 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.

Validation of a Novel Virtual Reality Robotic Simulator

PURPOSE We evaluated the face, content, and construct validity of what is, to our knowledge, the only available virtual reality simulator based on a complete kinematic representation of the da Vinci surgical system. MATERIALS AND METHODS A total of 5 experts (EPs) and 15 novices (NVs) completed exercises on the Mimic dV-Trainer (MdVT). All participants completed three repetitions of the following tasks: (1) Ring and Cone, (2) String Walk, and (3) Letterboard. Participants rated parameters of face and content validity on a five-point Likert-scale questionnaire. Workload imposed by the simulator was assessed using a NASA Task Load Index questionnaire (TLX). RESULTS Face validity of the MdVT was established as all 20 participants rated the simulator between average to easy-to-use and above-average to high in all parameters of realism. Participants in both EP and NV groups rated the MdVTs overall relevance to robotic surgery as very high. All five EPs assessed the simulator to be a very good practice format and very useful for training residents, thereby affirming content validity. A preliminary assessment of construct validity suggested that the MdVT could differentiate EPs from NVs. The overall TLX workload scores were lower in the EP group for all parameters except for temporal demand. CONCLUSIONS The MdVT demonstrated excellent face and content validity as well as reasonable workload parameters. The use of this simulator in resident training may help bridge the gap between the safe acquisition of surgical skills and effective performance during live robot-assisted surgery.

Best Practices for Robotic Surgery Training and Credentialing

PURPOSE With the rapid and widespread adoption of robotics in surgery, the minimally invasive surgical landscape has changed markedly within the last half decade. This change has had a significant impact on patients, surgeons and surgical trainees. This is no more apparent than in the field of urology. As with the advent of any new surgical technology, it is imperative that we develop comprehensive and responsible training and credentialing initiatives to ensure surgical outcomes and patient safety are not compromised during the learning process. MATERIALS AND METHODS A literature search was conducted on surgical training curricula as well as robotic surgery training and credentialing to provide best practice recommendations for the development of a robotic surgery training curriculum and credentialing process. RESULTS For trainees to attain the requisite knowledge and skills to provide safe and effective patient care, surgical training in robotics should involve a structured, competency based curriculum that allows the trainee to progress in a graduated fashion. This structured curriculum should involve preclinical and clinical components to facilitate the proper adoption and application of this new technology. Robotic surgery credentialing should involve an expert determined, standardized educational process, including a minimum criterion of proficiency. CONCLUSIONS Rather than being based on a set number of completed cases, robotic surgery credentialing should involve the demonstration of proficiency and safety in executing basic robotic skills and procedural tasks. In addition, the accreditation process should be iterative to ensure accountability to the patient.

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 PURPOSE Small 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. MATERIALS AND METHODS A 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. RESULTS In 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. CONCLUSIONS Cryoablation 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.

Second Prize: Renal Hypothermia Achieved by Retrograde Intracavitary Saline Perfusion

BACKGROUND AND PURPOSE Hypothermia during vascular clamping protects the kidney from ischemia-induced nephron loss. Traditionally, cooling is achieved by packing the kidney in ice, which lowers the temperature of the rest of the surgical field as well, and the method cannot be used during laparoscopy. We evaluated the utility of a newly developed ureteral access system for circulating ice-cold saline. MATERIALS AND METHODS Domestic pigs underwent retrograde endoscopic cooling through an access sheath without (N = 2) or with (N = 3) renal artery occlusion, traditional ice-slush cooling with renal artery occlusion (N = 3), or occlusion without hypothermia (N = 3). Five days later, the pigs were sacrificed and the kidneys and ureters examined histologically. RESULTS Endoscopic cooling with renal artery occlusion and ice-slush cooling both produced renal hypothermia. The former produced medullary and cortical temperatures of 21.3 degrees C and 27.3 degrees C, respectively, and the latter medullary and cortical temperatures of 28.8 degrees C and 23.7 degrees C, respectively. Histologically, there were minimal changes in the first three groups, whereas venous congestion, multifocal chronic inflammation, and periarteriolar hemorrhage were seen after renal artery occlusion without hypothermia. CONCLUSION Retrograde endoscopic renal hypothermia is effective and requires no novel equipment or special surgical skills. Clinical application has not yet been attempted.