Cheryl Napper

Transvaginal laparoscopic nephrectomy: Development and feasibility in the porcine model

OBJECTIVES To assess feasibility of laparoscopic nephrectomy completed entirely by way of the vagina in the porcine model. METHODS Six transvaginal laparoscopic nephrectomies were performed in female farm pigs. Two acute and two 1-week survival animals were used for the study. Before killing the survival animals, a second transvaginal laparoscopic nephrectomy was performed on the remaining renal unit. For one renal unit, the laparoscopic nephrectomy was completed entirely by way of the vagina. In five renal units, a single, 5-mm transabdominal trocar for the laparoscope was required to facilitate visualization. RESULTS The operative time for the procedure completed entirely by way of the vagina was 360 minutes, and the mean operative time for the procedures requiring placement of a single 5-mm transabdominal trocar was 210 minutes. In 5 cases, dissection, control of the renal pedicle, and extraction of the kidney were successfully completed using a transvaginal approach. In 1 acute case, an uncontrollable vascular injury occurred during placement of the Endo-GIA stapler, resulting in exsanguination. In all other cases, the mean blood loss was less than 30 mL, and no significant perioperative complications were noted. Both survival pigs had normal bowel and bladder function before being killed. CONCLUSIONS Complete transvaginal laparoscopic dissection and nephrectomy is feasible in the porcine model using a single, 5-mm abdominal trocar for visualization. A completely transvaginal laparoscopic nephrectomy was performed once, but limitations imposed by the porcine anatomy and by the currently available instrumentation made the procedure very cumbersome. Additional development of this technique in animal models and improved instrumentation is needed before clinical assessment is warranted.

THE IMPACT OF INTENSE LAPAROSCOPIC SKILLS TRAINING ON THE OPERATIVE PERFORMANCE OF UROLOGY RESIDENTS

PURPOSE As laparoscopy has become more commonplace in urology, increased emphasis has been placed on laparoscopic education. We assessed the impact of laparoscopic skills training on the operative performance of urological surgeons inexperienced with laparoscopy. MATERIALS AND METHODS Urology residents were prospectively randomized to undergo laparoscopic skills training (6) or no training (6). Baseline assessment of operative performance (scale 0 to 35) during porcine laparoscopic nephrectomy was completed by all subjects. Cumulative time to complete laparoscopic tasks using an inanimate trainer was also recorded. The skills training group then practiced inanimate trainer tasks for 30 minutes daily for 10 days. The 2 groups then repeated the timed inanimate trainer tasks and underwent repeat assessment of the ability to perform porcine laparoscopic nephrectomy. RESULTS At baseline no statistical difference was noted in laparoscopic experience, inanimate trainer time or overall operative assessment in the 2 groups. In the skills training group mean cumulative time to complete inanimate trainer tasks decreased from 341 to 176 seconds (p = 0.003), while in the control group it decreased from 365 to 301 (p = 0.15). Operative assessment improved from initial to repeat porcine laparoscopic nephrectomy regardless of the trained versus control randomization grouping (22.0 to 27.8, p = 0.0008 and 20.8 to 26.5, p = 0.00007, respectively). CONCLUSIONS In vivo experience enables urological surgeons inexperienced with laparoscopy to improve significantly in all aspects of complex laparoscopic procedures. In this pilot study the magnitude of improvement was independent of additional training in laparoscopic skills. Educational curriculum should include in vivo practice in addition to skills training.

Sutureless laparoscopic heminephrectomy using laser tissue soldering.

BACKGROUND AND PURPOSE Widespread application of laparoscopic partial nephrectomy has been limited by the lack of a reliable means of attaining hemostasis. We describe laser tissue welding using human albumin as a solder to control bleeding and seal the collecting system during laparoscopic heminephrectomy in a porcine model. MATERIALS AND METHODS Laparoscopic left lower-pole heminephrectomy was performed in five female domestic pigs after occluding the hilar vessels. Using an 810-nm pulsed diode laser (20 W), a 50% liquid albumin-indocyanine green solder was welded to the cut edge of the renal parenchyma to seal the collecting system and achieve hemostasis. Two weeks later, an identical procedure was performed on the right kidney, after which, the animals were sacrificed and both kidneys were harvested for ex vivo retrograde pyelograms and histopathologic analysis. RESULTS All 10 heminephrectomies were performed without complication. The mean operative time was 82 minutes, with an average blood loss of 43.5 mL per procedure. The mean warm ischemia time was 11.7 minutes. For each heminephrectomy, a mean of 4.2 mL of solder was welded to the cut parenchymal surface. In three of the five acute kidneys and all five 2-week kidneys, ex vivo retrograde pyelograms demonstrated no extravasation. In addition, no animal had clinical evidence of urinoma or delayed hemorrhage. Histopathologic analysis showed preservation of the renal parenchyma immediately beneath the solder. DISCUSSION Laser tissue welding provided reliable hemostasis and closure of the collecting system while protecting the underlying parenchyma from the deleterious effect of the laser during porcine laparoscopic heminephrectomy.

Ureteral replacement using porcine small intestine submucosa in a porcine model

OBJECTIVES To investigate an alternative technique using an onlay patch of porcine small intestine submucosa (SIS) allograft to bridge a ureteral defect. For ureteral strictures that fail endourologic management, few options are available for minimally invasive repair or reconstruction. Although laparoscopic interposition of a tubularized allograft of porcine SIS has great promise, animal studies have yielded mixed results. METHODS In 9 anesthetized female pigs, cystoscopy and retrograde pyelography were performed, and a ureteral stent was placed. Transperitoneal laparoscopic access was obtained, and a segment of ureter 2 cm long and encompassing one half the ureteral circumference was excised. An oval-shaped patch of SIS was sutured to the native ureter to cover the defect. In one control survival animal, the ureter was excised and a stent placed, but no SIS onlay was performed. Two pigs were killed immediately. In the survival group (6 pigs), the stents were removed at 1 week (n = 2), 2 weeks (n = 2), or 4 weeks (n = 2) and the corresponding animals were killed at 3 weeks (n = 2), 6 weeks (n = 2), and 9 weeks (n = 2). Intravenous urography was performed to evaluate renal function, and retrograde pyelography was performed after harvest to identify ureteral stricture or obstruction. The ureteral grafts were measured and examined histologically. RESULTS All 6 kidneys from the survival group were grossly normal, appeared promptly on intravenous urography, and were patent on retrograde pyelography. The control animal demonstrated complete ureteral obstruction. By 9 weeks, the SIS graft was replaced with ureteral tissue, including the muscle layers. The epithelium was primarily transitional epithelium, with focal intestinal metaplasia. The submucosa and ureteral musculature appeared histologically normal. CONCLUSIONS In the porcine model, a patch graft technique using SIS appears to induce ureteral regrowth. Renal function remained intact, and no evidence of stricture was demonstrated on radiographic imaging. Before clinical application of this technique, evaluation in a stricture model is required.

Laparoscopic partial nephrectomy with a diode laser: porcine results.

PURPOSE To develop a safe and effective technique for laparoscopic partial nephrectomy without need for hilar occlusion. MATERIALS AND METHODS Laparoscopic transperitoneal lower-pole partial nephrectomy was performed in five 45- to 50-kg female farm pigs using a 980-nm diode laser. Standard transperitoneal access was obtained, and a four-port approach was used to perform a laparoscopic right partial nephrectomy using a diode laser (23 W) without hilar occlusion. The pigs were allowed to recover and 2 weeks later underwent a left laparoscopic partial nephrectomy. Postoperatively, renal function was monitored by serial serum creatinine measurements. Both kidneys and ureters were removed for ex-vivo retrograde pyelograms and histologic analysis. RESULTS The 980-nm diode laser resulted in successful lower-pole partial nephrectomy without hilar occlusion in all 10 of the kidneys. In three cases, laser hemostasis was insufficient, and adjunctive hemostatic clips were necessary to stop bleeding. The mean operative time was 126 minutes, and the mean laser time was 84 minutes. An average of 23% (range 13%-33%) of the kidney parenchyma was resected. The mean blood loss was 150 mL (range 50-300 mL). There was no evidence of urinary extravasation on ex-vivo retrograde pyelograms at 2 weeks in any of the kidneys. CONCLUSION Laparoscopic partial nephrectomy without hilar occlusion using the 980-nm diode laser is feasible in the porcine model. Because adjunctive hemostatic measures may be necessary in some cases, clinical trials in humans should be limited to small exophytic tumors.

Assessment of basic human performance resources predicts operative performance of laparoscopic surgery

BACKGROUND Interest in laparoscopic surgery has prompted development of educational programs designed to teach and assess laparoscopic skills. Although these programs are beneficial, because of the inherent demands imposed by laparoscopy some aspects of operative performance might not improve with practice. This suggests that innate ability could predict level of operative skill. Assessment of operative and technical potential to date has relied largely on subjective rather than objective criteria. In this study, the relationships between objective measures of human basic performance resources (BPRs) and laparoscopic performance were evaluated using Nonlinear Causal Resource Analysis (NCRA), a novel predictive and explanatory modeling approach based on General Systems Performance Theory. STUDY DESIGN Twenty urology residents were voluntary enrolled. Thirteen validated BPRs were measured and analyzed relative to operative laparoscopic performance (assessed by two experts) of two porcine laparoscopic nephrectomies (LN). The laparoscopic procedure, representing a High Level Task (HLT), was evaluated using a modified Global Rating of Operative Performance Scale. NCRA models were devised to predict performance of the HLT laparoscopic nephrectomies based on BPRs and to determine the limiting performance resource. RESULTS NCRA models predicted excellent agreement with actual operative performance, suggesting that measures of innate ability (or BPRs) predicted performance of laparoscopic nephrectomy. In 65%, the prediction by NCRA was near identical to the expert rating on the HLT. In 25% of cases, NCRA overpredicted performance; in 10%, NCRA underpredicted performance of the HLT compared to the subjective ratings. Neuromotor channel capacity was the most common performance-limiting resource. CONCLUSIONS Preliminary findings suggest objective prediction of laparoscopic performance with limiting resource diagnostics for an individual surgeon is possible and practical using appropriate new measurement and modeling methods. Selection of surgical candidates, training, and educational curriculum could be positively affected.

Laparoscopic radical nephrectomy: prospective assessment of impact of intact versus fragmented specimen removal on postoperative quality of life.

PURPOSE We prospectively compared postoperative recovery and quality of life for groups of patients undergoing laparoscopic radical nephrectomy with intact or fragmented specimen removal. PATIENTS AND METHODS A prospective evaluation of 12 patients having a transperitoneal laparoscopic nephrectomy was completed. In each case, a radical dissection was performed regardless of the surgical indication. Fragmented specimens (N = 7) were extracted at the umbilical port, and intact specimens (N = 5) were extracted through an infraumbilical incision. Demographic and perioperative data including specimen removal incision, narcotic requirements, and recovery interval were recorded. Subjective pain and activity assessments were administered prospectively on postoperative days 1, 2, 7, and 14. RESULTS The mean incision length for intact specimen removal was 7.6 cm and that for fragmented removal was 1.2 cm (P < 0.05). Pain and activity self-assessments improved over time in each group. No significant differences in pain or activity scores were noted between treatment groups at any queried interval. Time to return of normal activity was not significantly different in the two groups. CONCLUSIONS In this pilot study, no subjective or objective advantage was demonstrated for kidney fragmentation during laparoscopic radical nephrectomy. A larger randomized study is required to better assess any clinical advantage to specimen morcellation.

Radiofrequency Coagulation of Renal Parenchyma: Comparison of Effects of Energy Generators on Treatment Efficacy

PURPOSE We compared experimental renal lesions created with temperature-based or impedance-based radiofrequency (RF) generators using normal renal parenchyma in an animal model with protocols recommended by the manufacturer. MATERIALS AND METHODS Bilateral renal mobilization was completed in seven farm pigs in preparation for RF ablation, and the tines of each RF probe were expanded to a 2-cm diameter. Pigs were sacrificed immediately (N = 3) or at 24 hours (N = 4) after treatment. Lesions were examined grossly and microscopically after hematoxylin and eosin (H&E) and nicotinamide adenine dinucleotide (NADH) staining. RESULTS Gross lesions were firm and white with a hemorrhagic border, regardless of RF generator. Staining with H&E revealed preservation of renal architecture but loss of distinct cytoplasmic features with both RF systems. Staining for NADH showed no viable cells within the lesions produced by either RF system. Immediately and after a 24-hour survival, the mean sizes of the treatment lesions were 1.6 x 1.8 x 1.3 cm and 2.0 x 1.6 x 1.9 cm, respectively, for the temperature-based RF generator and 2.7 x 2.4 x 2.5 cm and 2.2 x 2.1 x 1.8 cm, respectively, for the impedance-based RF generator. CONCLUSION Use of a specific RF energy generator with recommended treatment protocols does not appear to affect coagulation of normal renal parenchyma in the porcine model.

Feasibility of Laparoscopic Partial Nephrectomy Using Pledgeted Compression Sutures for Hemostasis

PURPOSE To develop a technique for laparoscopic partial nephrectomy (LPN) without the use of hilar occlusion that allows large renal resection and excellent hemostasis. MATERIALS AND METHODS Five female domestic pigs underwent right laparoscopic transperitoneal lower-pole partial nephrectomy after placement of pledgeted parenchymal compression sutures tied intracorporeally to induce regional renal hypoperfusion. Postoperatively, serial serum creatinine measurements were obtained to monitor renal function. The pigs were allowed to recover and 2 weeks later underwent an identical procedure on the left side. The animals were sacrificed after the second procedure, and both renal units were removed for ex vivo retrograde urograms and histologic analysis. RESULTS The median operative time was 154.5 minutes (range 110-305 minutes), and the median blood loss was 137.5 mL (range 100-300 mL). On average, 35% (range 31%-36.8%) of the kidney was resected. All cases required use of adjunctive hemostatic clips to control bleeding from central vessels. All animals survived 2 weeks and had no evidence of urinary extravasation clinically or on ex vivo retrograde urograms. CONCLUSIONS In the porcine model, LPN with placement of pledgeted sutures allows resection of large renal segments, although technical refinements are required to improve hemostasis. Currently, the need for adjunctive hemostatic measures limits the initial clinical application of this technique to small, exophytic tumors.

Laparoscopic Interstitial Laser Coagulation of Renal Tissue with and without Hilar Occlusion in the Porcine Model

PURPOSE To evaluate the safety and efficacy of interstitial laser coagulation (ILC), applied via a laparoscopic approach, with and without hilar occlusion in the porcine model. MATERIALS AND METHODS In nine female farm pigs, bilateral renal mobilization was performed via a transperitoneal laparoscopic approach. Using a 600- micro m bare-tip silicon diode laser fiber inserted 0.5 cm into the lower pole of each kidney, diode laser energy (wavelength 805 nm) was applied for 15 minutes at 6 W. In each pig, the left renal hilum was clamped during ILC. Animals were sacrificed immediately (N = 3) or at 2 weeks (N = 3) or 4 weeks (N = 3). The kidneys were inspected grossly, and the lesions were evaluated microscopically. Nicotinamide adenine dinucleotide (NADH) histochemical staining was performed to assess viability. RESULTS Grossly, parenchymal lesions appeared firm and white with a central zone of carbonization, cavitation, or both. Histopathology examination revealed cellular inflammation in acute lesions; chronic lesions demonstrated coagulative necrosis with progressive fibrosis. The NADH staining showed residual viable cells within the treatment zone of survival animals but not in acute animals. The mean size of the treatment zone in kidneys with unoccluded blood flow was 2.4 x 2.1 x 2.0 cm, 4.0 x 3.3 x 2.8 cm, and 3.3 x 3.5 x 2.0 cm in the acute, 2-week, and 4-week group, respectively. Hilar occlusion resulted in a slightly, but statistically insignificantly, larger lesion. In the 2-week survival group, one animal had a left subcapsular hematoma on the hilar-occluded side. In another 2-week animal, extension of the ILC zone was noted beyond the kidney into the psoas muscle. In the 4-week survival group, two animals developed gross hematuria; one had a left perinephric urinoma and urine leak noted at necropsy. CONCLUSIONS Renal ILC may represent an alternative minimally invasive technique for ablation of renal tumors. However, histologic evidence of viable cells within the treatment zone mandates refinement of the technique in the animal model before further application in humans. Hilar occlusion does not appear to enhance tissue ablation.