High-Performance Liquid-Chromatographic Analysis of Plasma Iohexol Concentrations.

In this study, a high-performance liquid-chromatographic (HPLC) method using photodiode array detection and isocratic conditions was developed for the analysis of plasma iohexol concentrations. Plasma proteins were precipitated with 1:1 volume of plasma and acetonitrile-ethanol-water (60:38.4:1.6, v/v/v). Iohexol concentrations in the supernatant phase were analyzed on a Waters Symmetry C-18 reversed-phase column under isocratic conditions at 245 nm. The extraction recoveries of iohexol from plasma were >95% and the plasma iohexol calibration curves were linear (R(2) ≥ 0.9998) from 10 to 1500 µg/mL. The within-day coefficients of variation (CVs) at plasma iohexol concentrations of 100, 375, 750 and 1500 µg/mL were 5.1, 3.5, 1.3 and 2.5%, respectively; the between-day CVs at 100, 375, 750 and 1500 µg/mL were 8.6, 4.2, 4.0 and 3.7%, respectively. The day-to-day accuracies of the method at plasma iohexol concentrations of 50, 100, 375, 750 and 1500 µg/mL were 89.0, 99.4, 108.4, 103.6 and 101.2%, respectively (n = 5). The lower limit of plasma iohexol quantitation was 10 µg/mL and no interferences >9 µg/mL were found in over 75 pre-dose porcine plasma samples. The applicability of the method was demonstrated by determining the glomerular filtration rates of iohexol in the porcine (Sus scrofa) model.

Fluoroscopy time during uncomplicated unilateral ureteroscopy for urolithiasis decreases with urology resident experience.

PURPOSE: To determine predictors of fluoroscopy time during uncomplicated, unilateral ureteroscopy for urolithiasis performed by urology residents during the first 2 years of residency. METHODS: The patient charts and computed tomography scans of consecutive, unilateral, uncomplicated ureteroscopy cases for urolithiasis were retrospectively reviewed. The cases were performed by beginning urology residents over the course of their first 2 years of urology residency training. RESULTS: A total of 200 ureteroscopy cases were reviewed. The mean stone diameter was 7.1 (±3.2) mm. Forty-three percent of cases were performed for renal stones and 58 % for ureteral stones. The mean operative time was 80.2 (±36.9) min. The mean fluoroscopy time was 69.1 (±38.2) s. No significant differences existed between cases performed by each of the two residents, and no statistical differences in case difficulty were observed throughout the study period. Linear regression analysis revealed the strongest association with lower fluoroscopy time to be increasing resident experience (p < 0.001). By the end of the 2-year review, fluoroscopy time decreased by 79 % from 135 to 29 s per case. Other significant factors associated with increasing fluoroscopy time were placement of a postoperative stent under fluoroscopic guidance (p < 0.001), utilization of a flexible ureteroscope as opposed to a semirigid ureteroscope (p < 0.001), and balloon dilation of the ureteral orifice (p < 0.001). CONCLUSIONS: Fluoroscopy time during uncomplicated, unilateral ureteroscopy for urolithiasis decreases with increasing urology resident operative experience. Other technical options during ureteroscopy were also found to influence fluoroscopy time.

Safety, minimization, and awareness radiation training reduces fluoroscopy time during unilateral ureteroscopy.

OBJECTIVE: To determine the impact of Safety, Minimization and Awareness Radiation Training (SMART) on fluoroscopy time during unilateral uncomplicated ureteroscopy for urolithiasis performed by urology residents. MATERIALS AND METHODS: All consecutive ureteroscopy cases for urolithiasis meeting inclusion criteria and performed by first-year urology residents over a 2-year period were reviewed. Fluoroscopy times during SMART and without SMART were compared. RESULTS: A total of 202 ureteroscopy cases were reviewed. The mean patient age was 48.7 years. The mean stone diameter was 7.6 ± 3.3 mm. The mean operating time was 79.8 ± 34.3 minutes. The mean cumulative fluoroscopy time was 85.6 ± 36.9 seconds per case. A Spearman rank correlation identified 8 variables significantly correlated with fluoroscopy time, with the most significant correlation between shorter fluoroscopy time and SMART exposure (rho = 0.532; P <.001). Multivariate regression analysis (r = 0.701) revealed that fluoroscopy time was significantly shorter with SMART (P <.001). Post hoc comparisons revealed the fluoroscopy time of the cases performed during SMART (mean, 45 seconds) to be significantly shorter than the fluoroscopy time of cases performed by the same residents before SMART (mean, 102 seconds; P = .005), and the fluoroscopy time of cases performed by residents the previous year with similar ureteroscopic experience but without SMART (mean, 78 seconds; P <.001). CONCLUSION: SMART reduces fluoroscopy time during unilateral uncomplicated ureteroscopy for urolithiasis performed by urology residents by 56%.

Determination of renal hypothermic temperature adequacy for renoprotection during ischemia using renal interstitial glycerol concentrations in a porcine model.

OBJECTIVES: To determine the effect of renal cooling on interstitial glycerol concentration during renal ischemia. The rate of cellular release of glycerol into the interstitial fluid at various hypothermic temperatures during ischemia was used to assess adequacy for renoprotection at those temperatures. METHODS: Twenty-four renal units in 12 pigs underwent ischemia during measurement of renal interstitial fluid glycerol concentration. Kidneys were categorized into a body temperature control group or various hypothermic temperature groups (n = 4): 5°, 10°, 15°, 20°, and 25°. RESULTS: The glycerol concentration of all kidneys increased directly with ischemic time. The rate of increase in glycerol concentrations over ischemic time decreased sequentially as renal temperature decreased. The glycerol concentration of the kidneys cooled to 25°C during ischemia was significantly less (P = .03) relative to the glycerol levels obtained from the kidneys subjected to warm ischemia at 120 minutes. CONCLUSIONS: Renal hypothermia decreases the rate of cellular release of glycerol into the interstitial fluid. Hypothermia at 25°C doubles the time required for renal interstitial glycerol to accumulate to levels associated with irreparable renal function damage. Therefore, relatively warmer hypothermic temperatures may be sufficient to extend a significant renoprotective effect during ischemia.

Effects of ischemia on human renal interstitial fluid metabolites.

PURPOSE: Microdialysis is a technique for monitoring the concentration of molecules in the interstitial fluid of living tissue. We report the effects of ischemia on human renal interstitial fluid molecules. MATERIALS AND METHODS: Ten patients with a renal mass or upper tract transitional cell carcinoma who elected laparoscopic nephrectomy or nephroureterectomy were studied with in situ renal microdialysis. Microdialysate was continuously collected into separate vials every 10 minutes before and after the renal artery was stapled. Samples were analyzed for the glucose, pyruvate, lactate and glycerol concentration. RESULTS: The concentration of all 4 molecules was stable throughout the pre-ischemia baseline period. Glucose and pyruvate concentrations decreased to almost zero during the first 60 minutes of ischemia. Lactate increased during the initial 60 minutes of ischemia and then plateaued with continued ischemia. The glycerol concentration increased directly throughout the ischemia time. CONCLUSIONS: The trends of human interstitial metabolite concentrations during ischemia are similar to trends found in the porcine model. The human renal interstitial glycerol concentration increases directly throughout the duration of ischemia and serves as a marker of nephron damage. Microdialysis is a tool that provides real-time, renal unit specific, minimally invasive data on the metabolic status of the human kidney during ischemia. It may be helpful for avoiding permanent renal ischemic injury.

Predicting irreparable renal ischemic injury using a real-time marker in the porcine model.

PURPOSE: We determined the maximal renal tolerance of warm ischemia using renal cortical interstitial metabolic changes to identify a potential real-time marker of irreparable renal function. MATERIALS AND METHODS: Using a single kidney model 3 groups of 5 pigs each underwent 120, 150 and 180 minutes of warm ischemia, respectively. Microdialysis samples were collected before, during and after ischemia. Renal function assessments consisting of serum creatinine and GFR measurements were performed before ischemia and on post-ischemia days 1, 5, 9, 14 and 28. Kidneys exposed and not exposed to ischemia were collected for histological study. RESULTS: Interstitial glucose and pyruvate concentrations decreased, while lactate concentrations increased to stable levels during ischemia. Glutamate spiked at 30 minutes of ischemia and subsequently tapered, while glycerol increased throughout warm ischemia time. At post-ischemia day 28 renal function returned to pre-ischemia baseline levels in the group with 120 minutes of ischemia but did not recover to baseline in the 150 and 180-minute ischemic groups. Functional data correlated with histological findings. The 120-minute maximal renal tolerance of warm ischemia correlated with a mean +/- SD glycerol concentration of 167 +/- 24 micromol/l. CONCLUSIONS: Interstitial glycerol is a real-time, renal unit specific, minimally invasive marker of renal function deterioration. Exposure of porcine kidneys to ischemic insults resulting in renal cortical interstitial glycerol concentrations higher than 167 micromol/l is associated with irreparable functional damage in this model.

Longterm changes in creatinine clearance after laparoscopic renal surgery.

BACKGROUND: Controversy exists about the impact of ischemia on renal function. We evaluated the creatinine clearance of patients having undergone laparoscopic renal extirpative and ablative surgery. STUDY DESIGN: The records of patients undergoing laparoscopic procedures for renal masses from February 2000 to March 2004 were examined. Creatinine clearance (CrCl) for each patient was determined using the Cockcroft-Gault equation and ideal body weight. We compared CrCl changes of patients undergoing laparoscopic partial nephrectomy (without renal ischemia [LPN-none], with warm ischemia [LPN-warm], and with cold ischemia [LPN-cold]) with patients undergoing laparoscopic radical nephrectomy (LRN) and laparoscopic cryoablation. Patients predisposed to medical renal disease were substratified and evaluated. RESULTS: All patients who underwent LRN or LPN-warm sustained a significant drop in CrCl on the first postoperative day, compared with patients who had LPN without ischemia or cryoablation (p < 0.01). The CrCl decrease correlated directly with warm ischemia time. Six months postoperatively, CrCl changes were no longer significant. Patients with medical renal disease risk factors were more likely to sustain longterm (1 year postoperatively) renal damage if they had renal ischemia, trending toward statistical significance. CONCLUSIONS: Ischemia causes acute renal damage, which is apparently reversible in patients without evidence of medical renal disease. Patients with known medical renal disease have substantial longterm changes in renal function associated with unilateral renal ischemia. Considering the insensitivity of creatinine-based renal function metrics, only eliminating ischemic time will realize the goal of maximal nephron preservation, particularly in patients with preexisting medical renal disease.

Real-time analysis of renal interstitial metabolites during induced renal ischemia*.

PURPOSE: Microdialysis is an innovative technique used to monitor the chemistry of the interstitial fluid in living tissue. We documented changes in concentration of interstitial fluid metabolites before, during, and after induced renal ischemia. MATERIALS AND METHODS: Under general anesthesia, a microdialysis probe was laparoscopically positioned into the renal cortex of six pigs. Isotonic sterile perfusion fluid was pumped through the probe at 2 microL/min. After collecting a baseline sample, the renal artery was occluded with a Satinsky clamp for 90 (n = 3) or 120 (n = 3) minutes. A dialysate sample was collected every 30 minutes during the ischemic and 3-hour postischemic period. The samples were analyzed for glucose, lactate, pyruvate, glutamate, urea, and glycerol concentrations with the CMA/600 Microdialysis Analyzer. Serum metabolic panels from peripheral venous samples drawn before ischemia, after ischemia, and 3 hours after ischemia were analyzed. RESULTS: Glucose and pyruvate concentrations significantly declined (P = 0.01, P = 0.05, respectively) while lactate and glycerol concentrations significantly increased during ischemia (P = <0.01, P < 0.01, respectively). Glutamate increased to 2.5 times the baseline concentration (P < 0.01) at 1 hour of ischemia and subsequently declined during ischemia. The lactate/pyruvate ratio increased sharply during ischemia and returned to baseline within 1 hour postischemia. There were no changes noted in serum creatinine levels before and after ischemia. CONCLUSIONS: Microdialysis can accurately measure minute real-time changes in the renal interstitial environment caused by ischemia not detected with serum studies. These local changes may be correlated with ischemic times to predict tissue preservation in future studies.

Lapra-Ty holding strength and slippage with various suture types and sizes.

OBJECTIVES: To investigate the holding strength and slippage of Lapra-Ty clips on various suture types and sizes. METHODS: Using an automated materials testing system with the Lapra-Ty in a fixed position, Lapra-Ty holding strength and displacement were determined with 0, 2-0, 3-0, and 4-0 Vicryl, Monocryl, and polydioxanone suture (PDS). To simulate clinical application, Lapra-Tys were also tested by applying a load to these sutures after being passed through a full-thickness layer of tautly suspended fresh porcine bladder tissue. Three trials were performed with each suture type and size. RESULTS: The Lapra-Ty holding strength with Vicryl suture was significantly higher than with Monocryl or PDS of the same suture size in bladder tissue trials. Monocryl suture had a significantly higher displacement than Vicryl or PDS of the same suture size in bladder tissue trials (except for 4-0 Monocryl and PDS having insignificantly different displacements). Lapra-Tys slipped off Vicryl, Monocryl, and PDS in 25%, 67%, and 67% of their respective trials. Lapra-Tys did not slip during any of the trials with 2-0 suture of any type or 3-0 Vicryl. Lapra-Tys with holding strengths on suture less than approximately 8 Newtons (N) slipped and greater than 8 N pulled through the bladder tissue without slipping. CONCLUSIONS: The optimal suture type and size to maximize Lapra-Ty holding strength and minimize slippage was determined to be 2-0 and 3-0 Vicryl, 2-0 Monocryl, and 2-0 PDS. Monocryl suture stretches more than Vicryl and PDS at higher loads.

The effects of ureteral mobilization and transection on ureteral oxygenation.

OBJECTIVES: To determine the impact of ureteral transection with and without prior ureteral mobilization on ureteral oxygen partial pressure (p(u)O(2)). METHODS: Sixteen pigs underwent general anesthesia with laparoscopic transperitoneal access to the right ureter. With no dissection and minimal manipulation, a tissue oxygen probe (Licox, Kiel, Germany) was introduced via a trocar and inserted into the ureter. The probes were placed at the ureteropelvic junction (UPJ, n = 8) and ureterovesical junction (UVJ, n = 8). Baseline p(u)O(2) was measured. Subsequently, half of the animals at each level (n = 4) underwent complete ureteral transection proximal to UPJ probes and distal to UVJ probes with or without prior mobilization. p(u)O(2) levels were measured after ureteral mobilization and transection. RESULTS: Of the ureters transected at the UPJ without mobilization, the mean p(u)O(2) level declined by 13 mm Hg relative to baseline (P = 0.07). The baseline UPJ p(u)O(2) level declined by 5 mm Hg after ureteral mobilization alone and subsequently by 31 mm Hg after transection (P <0.01). Of the ureters transected at the UVJ without mobilization, the p(u)O(2) level decreased by 4 mm Hg relative to baseline (P = 0.08). The baseline UVJ p(u)O(2) level decreased by 15 mm Hg after ureteral mobilization alone and subsequently by 39 mm Hg after transection (P <0.01). At both the UPJ and UVJ, the transected-only p(u)O(2) level was statistically higher than the mobilized and transected level (P = 0.03, respectively). CONCLUSIONS: During ureteral surgery, mobilization alone exposes the distal ureter to more ischemia than the proximal ureter, and efforts to minimize ureteral mobilization when transection is necessary are crucial in maintaining tissue oxygenation.

Shock wave lithotripsy success for renal stones based on patient and stone computed tomography characteristics.

OBJECTIVES: To determine the patient and noncontrast computed tomography (NCCT) stone characteristics that predict either of 2 extracorporeal shock wave lithotripsy (ESWL) outcomes: stone-free (SF) status or ESWL success. METHODS: The records of 200 consecutive patients with nephrolithiasis treated with ESWL were reviewed. Patient age, sex, stone laterality, body surface area, body mass index, maximal stone dimension, mean stone Hounsfield units (HU), stone Hounsfield density, skin-to-stone distance (SSD), and intrarenal stone location were studied as potential predictors. Patients with no calcifications on postoperative kidneys, ureters, and bladder (KUB) at 6 weeks were defined as SF. ESWL success was defined as SF or remaining stone fragments less than 4 mm. RESULTS: Intrarenal stone location was found to be the only predictor of SF status. Renal pelvic/ureteropelvic junction (UPJ) stones cleared better than calyceal stones, and upper/middle calyceal stones cleared better than lower calyceal stones. Stone size, mean HU, and location predicted ESWL fragmentation success. Smaller stones and stones with lower mean HU levels were more successfully fragmented. Higher SF and ESWL success rates were found with a shorter SSD among calyceal stones when renal pelvic/UPJ stones were excluded from analysis. CONCLUSIONS: Stone location is the most important factor in achieving SF status after ESWL. NCCT stone characteristics such as stone size, mean HU, and intrarenal location are important predictors of ESWL success.

Comparison of novel tissue apposing device and standard anastomotic technique for vesicourethral anastomoses.

OBJECTIVES: To evaluate a novel sutureless tissue apposing vesicourethral anastomosis (VUA) device in a porcine model and compare it with standard laparoscopically sutured VUA. METHODS: Thirty domestic pigs were divided into six groups. In groups 1, 2, and 3, a standard laparoscopic sutured running VUA was performed. In groups 4, 5, and 6, a novel device VUA was performed. In all cases, cystography was completed immediately after completion of the anastomosis and when each pig was killed. At necropsy, the gross findings of the VUA were documented, and each anastomosis was excised en bloc for histopathologic evaluation of healing parameters. RESULTS: In the 30 pigs, 29 (97%) device or sutured VUAs were successfully performed laparoscopically without conversion to an open approach. The mean operative time for the standard and device groups was 87 and 68 minutes, respectively (P = 0.04). The anastomotic time for the standard and device groups was 41 and 12 minutes, respectively (P <0.01). Histopathologic evaluation of the groups at 1 week of follow-up revealed significantly lower fibrosis scores for the novel anastomosis device VUA compared with the standard sutured VUA (median score 1 and 3, respectively; P = 0.04). The evaluation of groups 2 and 5 (3-week survival) and groups 3 and 6 (7-week survival) revealed no significant differences in any of the histopathologic parameters evaluated. CONCLUSIONS: The novel device requires little technical skill to deploy and is expeditious, requiring less time than a standard sutured anastomosis. At the 1 week follow-up point, histopathologic examination revealed that the novel device was superior regarding fibrotic reactions.

Analysis of surgical smoke produced by various energy-based instruments and effect on laparoscopic visibility.

PURPOSE: We analyzed the smoke plume produced by various energy-based laparoscopic instruments and determined its effect on laparoscopic visibility. MATERIALS AND METHODS: The Bipolar Macroforceps, Harmonic Scalpel, Floating Ball, and Monopolar Shears were applied in vitro to porcine psoas muscle. An Aerodynamic Particle Sizer and Electrostatic Classifier provided a size distribution of the plume for particles >500 nm and <500 nm, and a geometric mean particle size was calculated. A Condensation Particle Counter provided the total particle-number concentration. Electron microscopy was used to characterize particle size and shape further. Visibility was calculated using the measured-size distribution data and the Rayleigh and Mie light-scattering theories. RESULTS: The real-time instruments were successful in measuring aerosolized particle size distributions in two size ranges. Electron microscopy revealed smaller, homogeneous, spherical particles and larger, irregular particles consistent with cellular components. The aerosol produced by the Bipolar Macroforceps obscured visibility the least (relative visibility 0.887) among the instruments tested. Particles from the Harmonic Scalpel resulted in a relative visibility of 0.801. Monopolar-based instruments produced plumes responsible for the poorest relative visibility (Floating Ball 0.252; Monopolar Shears 0.026). CONCLUSIONS: Surgical smoke is composed of two distinct particle populations caused by the nucleation of vapors as they cool (the small particles) and the entrainment of tissue secondary to mechanical aspects (the large particles). High concentrations of small particles are most responsible for the deterioration in laparoscopic vision. Bipolar and ultrasonic instruments generate a surgical plume that causes the least deterioration of visibility among the instruments tested.

Laparoscopic cryoablation for small renal masses: three-year follow-up.

OBJECTIVES: To report our experience with laparoscopic renal cryoablation for patients who have completed a minimum of 3 years of follow-up. METHODS: From July 2000 to March 2005, 81 patients underwent laparoscopic renal cryoablation for renal masses. Of these 81 patients, 31 (38%) underwent laparoscopic renal cryoablation for 36 tumors and have completed a minimal follow-up of 3 years (mean 45.7 months). The postoperative follow-up protocol consisted of serial contrast-enhanced computed tomography or magnetic resonance imaging at 1 day, 1, 3, 6, and 12 months, and yearly thereafter. RESULTS: Twenty-seven tumors were partially exophytic, five were totally endophytic, and four were hilar tumors. The mean operative time was 2.9 hours, with a mean estimated blood loss of 97 mL. The mean renal tumor size was 2.1 cm. In early follow-up, the ablation zone was larger than the tumor but subsequently diminished to the original tumor size 6 months postoperatively. Thereafter, the ablation zone size decreased. The biopsy results revealed that 22 tumors (61%) were malignant and 14 (39%) were benign. The renal tumor 3-year cancer-specific survival rate was 100%, and no patient developed metastatic disease. One patient demonstrated return of abnormal enhancement within the cryolesion during follow-up, suggesting tumor recurrence. One patient had a hemorrhage and urinary leak after cryoablation of an endophytic tumor and was treated conservatively. CONCLUSIONS: Renal cryoablation is safe and offers a minimally invasive nephron-sparing alternative. The oncologic adequacy of renal cryoablation requires long-term follow-up data, but the intermediate-term data seem equivalent to that achieved with extirpative therapy.

Feasibility of laparoscopic renal cooling with near-freezing saline irrigation delivered with a standard irrigator aspirator.

OBJECTIVES: To determine the feasibility of laparoscopic renal cooling with near-freezing saline irrigation in the porcine model delivered using readily available operating room equipment. METHODS: Five pigs underwent laparoscopic renal surgery with temperature sensors placed in the medulla and upper, middle, and lower pole renal cortex. After complete occlusion of the renal artery and vein, near-freezing saline was delivered with a standard irrigator/aspirator onto the renal surface. The run-off was simultaneously suctioned as it pooled in the hilum with a second aspirator. The kidney and body temperatures were monitored throughout the 1-hour ischemic period and for 10 minutes after unclamping the hilum. RESULTS: Continuous irrigation of the kidney with near-freezing saline in the first pig resulted in hypothermic renal (13.8 degrees C) and core body (33.1 degrees C) temperatures. For the subsequent four pigs, irrigation was limited to the first 5 minutes of ischemia to achieve renal cortical and medullary temperatures of less than 20.0 degrees C within 6 and 8 minutes of ischemia, respectively. Subsequently, the kidney was irrigated for 1 minute every 12 to 14 minutes to maintain renal temperatures of less than 20.0 degrees C. The core body temperatures decreased from a mean baseline of 37.0 degrees to 35.4 degrees C using the intermittent irrigation technique. Our early clinical experience with near-freezing saline intermittent irrigation during laparoscopic partial nephrectomy with 10 patients showed stable core body temperature and serum creatinine with a mean ischemic time of 48 minutes. CONCLUSIONS: Using standard, readily available laparoscopic irrigator/aspirators, renal cooling during laparoscopic partial nephrectomy with near-freezing saline creates acceptable renal tissue temperatures for preservation of renal function.

Pharmacologic manipulation of the porcine ureter: Acute impact of topical drugs on ureteral diameter and peristaltic activity.

BACKGROUND AND PURPOSE: Intraluminal application of pharmacologic agents for acute ureteral dilation may facilitate difficult ureteroscopy. We characterized the in-vivo effects of intraluminal application of verapamil and theophylline on ureteral peristalsis and diameter in a porcine model. MATERIALS AND METHODS: Twenty-four female domestic pigs (35-40 kg) were incorporated into the study. We deployed a giant magneto resistive (GMR) sensor and electromagnetic (EMG) electrodes laparoscopically onto the ureteral surface for simultaneous measurement of the mechanical and electrical signals of ureteral peristalsis, respectively. The ureteral-luminal diameter was measured at three levels by digital retrograde pyelography and standardized to a 10-mm laparoscope. The results were calculated as change in peristalsis and ureteral diameter from baseline during the first hour after drug injection. We tested two smooth-muscle relaxants, verapamil (2 mg/kg) and theophylline (70 mg/kg), with saline and dimethylsulfoxide (DMSO; solvent) as controls. Six pigs were studied for each of the four groups. Hydration, anesthesia, and intra-abdominal pressure were standardized. The serum concentrations of the drugs were measured to determine systemic absorption. RESULTS: During the first 10 minutes after intraluminal drug injection, theophylline caused a significant decrease in ureteral peristalsis (6.75 waves/10 minutes) compared with the control group (1.00/10 minutes; P = 0.02). This trend persisted for the next hour. However, there were no changes from baseline in ureteral width. Ureteral peristalsis and dilation remained similar after the saline and DMSO injections. Verapamil increased the diameter of the proximal ureter compared with the controls throughout the hour after drug injection. Fifteen minutes after the drug injection, the change in the ureteral diameter with verapamil was 1.38 mm (4.14F), while the control group showed a change of 0.27 mm (P = 0.03). At 1 hour, the width of the proximal ureter in the verapamil group had increased by 1.72 mm (5.16F), while the control group had changed by 0.55 mm (P = 0.03). There were no statistically significant changes in the widths of the mid or distal ureter. No ureteral dilation was observed in the other groups. CONCLUSIONS: In the porcine model, intraluminal application of pharmacologic agents produced independent effects on ureteral dilation and peristalsis. Theophylline inhibited ureteral peristalsis, and verapamil produced acute proximal-ureteral dilation. The ability to alter ureteral diameter or peristaltic activity acutely may facilitate ureteroscopy.

Precise characterization of renal parenchymal response to single and multiple cryoablation probes.

PURPOSE: We characterized the size and shape of the ablated area, and the surrounding indeterminate zone associated with renal cryolesions produced by single and multiple cryoablation probe configurations in a porcine model. MATERIALS AND METHODS: Laparoscopic cryoablation, consisting of 2, 10-minute double freeze cycles followed by a 3-minute active thaw, was performed in 18 pigs. Three groups of 6 pigs each were studied, including a single IceRod, 3 rods arranged in a triangular configuration 2 cm apart from each other and 4 rods arranged in a quadratic configuration 2 cm from each other. Cryoablated kidneys were harvested after 14 days for histopathological evaluation. RESULTS: The mean diameter of the area of complete ablation produced by a 1, 3 and 4 rod configuration 1 cm from the tip of the rod was 2.0, 4.4 and 4.9 cm, respectively. Cryolesions were elliptical with 1 cryoablation probe and in the 3 and 4 rod configurations they conformed to triangular and quadratic cross-sectional shapes, respectively. In the zone, ablation a single small focus of peri-arteriolar renal cell viability was noted less than 1 mm from the edge of the cryolesion in 1 of the 18 cryolesions. Otherwise no viable renal cells were detected. CONCLUSIONS: Multirod configurations can be used with templates to space cryoablation probes 2 cm apart from each other with reliable and complete ablation overlap between the rods. However, around larger blood vessels the ice ball must be extended to a larger margin to ensure complete tissue ablation.

Evaluation of a novel knotless self-anchoring suture material for urinary tract reconstruction.

OBJECTIVES: To evaluate a novel prototype self-anchoring suture (SAS) material that incorporates unidirectional "barbs" designed to grip and approximate tissue without the need for suture ligation for urinary tract reconstructive procedures. METHODS: The in vitro failure strength of various porcine tissue approximations with SAS was compared with the strength of similar approximations with standard ligated suture. For in vivo analysis, 3 pigs underwent laparoscopic pyeloplasty with SAS on one side and 2-0 Vicryl suture on the contralateral side. Nine pigs underwent bladder neck anastomoses (BNA) performed with SAS (n = 3) and standard ligated interrupted suturing (n = 3) or standard ligated running suturing (n = 3). The operative times were compared. One week after surgery, the integrity of each anastomosis was evaluated radiographically and histopathologically. RESULTS: The in vitro analysis revealed no statistically different (P = 0.22) failure forces between the approximations performed with SAS (13.2 +/- 2.6 N) and standard suture (14.1 +/- 3.1 N). The in vitro analysis revealed no difference in operative times for the pyeloplasties (P = 0.72) or BNA (P = 0.31). None of the 1-week postoperative radiographic studies revealed extravasation. The histopathologic analysis revealed more fibrotic reaction associated with the SAS BNA procedures (P <0.01). CONCLUSIONS: Self-anchoring suture secures tissue approximations at loads equivalent to tissue approximations with standard tied suture. Self-anchoring suture obviates the need for knot tying and provides a watertight anastomosis. With laparoscopic knot tying experience, anastomotic time with SAS and standard suture do not differ. Self-anchoring suture might induce more fibrosis. Long-term follow-up evaluation will be required before clinical application.

Comparison of mechanical and in vivo performance of new and reprocessed harmonic scalpels.

OBJECTIVES: To compare the mechanical and clinical performance of new and reprocessed harmonic scalpels (HS). METHODS: A total of 89 reprocessed and 90 new HS (laparoscopic coagulating shears with a curved blade and 5-mm-diameter shaft) were subjected to visual inspection, destructive testing, and nondestructive mechanical testing. Subsequently, new HS, randomly selected reprocessed HS, and selected reprocessed HS with known abnormalities were graded on clinical performance by 14 surgeons in a porcine model. RESULTS: Visual inspection of the HS discriminated between the new and reprocessed instruments in 11 of the 12 visual criteria (P < or = 0.02). In vitro mechanical testing revealed greater clamp arm dislodge forces for the new HS (P < 0.01) and greater midshaft temperatures for reprocessed HS (P < 0.01). Overall, 65 (73%) of 89 reprocessed and 7 (7.8%) of 90 new HS had gross abnormalities noted on inspection and mechanical evaluation (P < 0.01). The surgeons' evaluation of the instruments during in vivo testing demonstrated that the new instruments manifested significantly greater hemostatic control compared with randomly selected reprocessed HS (P = 0.01) and were significantly better for tissue sticking (P = 0.01), tissue transection (P = 0.02), tissue dissection (P < 0.01), grasping (P < 0.01), and hemostatic control (P = 0.04) compared with reprocessed HS with obvious defects. CONCLUSIONS: In vitro and in vivo data demonstrated significantly greater performance for new HS compared with reprocessed HS. Mechanical testing of reprocessed HS could not adequately distinguish which HS would result in decreased performance. These findings raise important issues of clinical safety in the contemporary quest for cost-effectiveness.

Evolution of surgical technique and patient outcomes for laparoscopic partial nephrectomy.

OBJECTIVES: To review the operative technique, complication rates, and short-term oncologic efficacy of the first 60 laparoscopic partial nephrectomies performed by a single surgeon and to report changes in our technique and the associated outcomes. METHODS: Between January 2002 and December 2004, data regarding patient characteristics, intraoperative technique, and outcome of 60 consecutive patients undergoing laparoscopic partial nephrectomy were prospectively collected. RESULTS: All 60 procedures were successfully completed laparoscopically without conversion to an open or hand-assisted approach. Histopathologic examination revealed renal cell carcinoma in 60% of patients with no positive margins or recurrences at a mean follow-up of 25.3 months. The overall complication rate was 30.0%, with 8 urologic (13.3%) and 10 nonurologic (16.7%) complications. CONCLUSIONS: With experience, laparoscopic partial nephrectomy is a viable alternative to open partial nephrectomy for small renal masses. At present, energy technologies and surgical pharmaceuticals are helpful adjuncts, but are not reliable for primary hemostasis and collecting system closure. Adaptation of traditional open techniques, including vascular control, excision of the tumor with cold scissors, and suture reconstruction of the collecting system and parenchyma, remain necessary to consistently perform laparoscopic partial nephrectomy successfully.