Evaluation of surgical models for renal collecting system closure during laparoscopic partial nephrectomy

Renal cryoablation - does deep endophytic ablation affect the renal collecting system?

Objective: To investigate to what extent the urothelium of the renal collecting system is affected when performing deep endophytic cryoablation.Methods: The study was conducted as an in vivo animal model with a total of 15 female pigs. Each animal was subjected to bilateral endophytioc renal cryoablation and randomized to a postoperative follow-up period of either one, two or four weeks. At the end of follow-up all animals had a magnetic resonance imaging (MRI) examination and bilateral nephrectomy was performed. On MRI-imaging the extent of the cryolesions, as well as signs of urinomas or fistulas, were examined. Histopathologic examinations were performed to investigate the effect on the urothelium.Results: All animals tolerated the procedure well without any postoperative complications. MRI examinations found the renal collecting system to be involved in the cryolesions at all three stages of follow-up and revealed no signs of hematomas, urinomas or fistula formations. Epithelial edema was found at all three stages of follow-up while significant parenchymal fibrosis adjacent to the urothelium was most pronounced in the four weeks of follow-up group. The urothelium was significantly affected with luminal hemorrhage as well as hemorrhage in and underneath the urothelium and urothelial dissociation from the underlying renal parenchyma. Despite these impacts on the urothelium, this was found to be intact and vital at all three stages of follow-up, in sharp contrast to the renal parenchyma that underwent fibrotic changes.Conclusions: In this, in vivo non-tumor pig model CA effectively destroyed the renal parenchyma while the impacted renal urothelium remained intact and did not undergo fibrotic changes, nor was urinomas or fistulas observed.

Histomorphometric comparison of the human, swine, and ovine collecting systems

The ovine kidney has been recently determined to be a better model than the swine kidney for the study of collecting system healing after partial nephrectomy. However, there is no histological study comparing the collecting systems of these species. To compare human, swine, and ovine collecting systems using histomorphometry. The collecting systems of 10 kidneys from each species (human, swine, and ovine) were processed for histomorphometry. The thickness of the three layers (mucosal connective tissue, submucosal muscular, and adventitial connective tissue) were measured. The densities of smooth muscle fibers, elastic system fibers, and cells were also measured. Additionally, blood vessel density in the adventitial connective tissue was measured. Analysis of the collecting systems from the three species presented several differences. The adventitial connective tissue from the swine samples was thicker, with more blood vessels and smooth muscle fibers, compared with that from the human and ovine samples. Swine also had higher density of elastic fibers on the submucosal muscular layer. Ovine and human collecting systems shared several similar features, such as blood vessel and elastic fiber density in all layers and the density of cellular and muscular fibers in the submucosal muscular and adventitial connective tissue layers. The collecting system of the ovine kidney is more similar to that of the human kidney compared with that of the swine kidney. This may explain the differences between the healing mechanisms in swine and those in humans and sheep after partial nephrectomy. Anat Rec, 299:967-972, 2016. © 2016 Wiley Periodicals, Inc.

Chicken and porcine models for training in laparoscopy and robotics

PURPOSE OF REVIEW

To review the most recent literature and contemporary role of the use of porcine and chicken models in laparoscopic and robotic simulation exercises, for training and skill assessment.

RECENT FINDINGS

There are multiple types of the simulators which include mechanical, virtual reality, hybrid simulators and animal models. The recent literature has seen insurgence of several of such simulators, specifically the animate ones comprising porcine and chicken models. The different training models reported have evolved from generalized and simpler, to a more task dedicated and complex versions. Unlike in the past, the recent publications include analysis of these models incorporating different measures of validity assessment.

SUMMARY

On account of the natural tissue properties inherent to these porcine and chicken models, they are proving to be instrumental in acquisition of higher surgical skills such as dissection, suturing and use of energy sources, all of which are required in real-time clinical scenarios be it laparoscopy or robotic-assisted procedures. In-vivo training in the animal model continues to be, perhaps, the most sophisticated training method before resorting to real-time surgery.

The sheep as a model for healing studies after partial nephrectomy

BACKGROUND

The pig has been considered the best model for renal surgery. However, recent research has demonstrated that the kidney of pigs heals differently from that of humans. The objective of this study was to evaluate sheep as an alternative animal model for studying collecting system healing after laparoscopic partial nephrectomy.

MATERIALS AND METHODS

The caudal pole of the left kidney was removed from eight female adult domestic sheep using laparoscopic partial nephrectomy. Monopolar energy was used for hemostasis only in the parenchyma, avoiding coagulation near the collecting system, which was left opened. After 14 d, all animals were euthanized, and their left kidney was removed. Serum levels of urea and creatinine were assessed preoperatively and postoperatively (on days 2, 6, 10, and 14), and peritoneal fluid samples were collected during necropsy for urea and creatinine evaluation. An ex vivo retrograde pyelogram was performed, and a retrograde injection of methylene blue ink was administered to evaluate urinary leakage. Samples from the operated pole were analyzed using histologic methods.

RESULTS

During necropsy, an urinoma surrounding the operated kidney was observed in one animal. Peritoneal fluid levels of urea and creatinine were elevated. Retrograde pyelograms exhibited contrast-medium extravasation through the operated pole in all kidneys. The opened collecting system was also confirmed by methylene blue ink injection. The operated pole was covered by collagenous tissue and adhered to adjacent organs.

CONCLUSIONS

Sheep should be considered as an adequate experimental model for research on collecting system healing after partial nephrectomy.

Nonischemic laparoscopic partial nephrectomy using a novel wet monopolar device in a porcine model

BACKGROUND AND PURPOSE

Laparoscopic partial nephrectomy (LPN) is the minimally invasive standard of care for the management of a cT(1a) renal mass. We evaluated a novel saline enhanced electrosurgical resection (SEER) device for performance of a nonischemic LPN.

MATERIALS AND METHODS

Six pigs were used in a nonsurvival pilot study. Energy penetration was characterized by applying the SEER to the lower pole of each kidney for 30 seconds, 1 minute, and 3 minutes using pure cutting energy at 100W and a drip rate of 1 drip per second. Energy testing was performed with the hilum clamped in six kidneys and without clamping in six kidneys. Subsequently, a nonischemic upper pole LPN was performed with the SEER device, and the kidneys were harvested. The areas of necrosis were sectioned and stained with hematoxylin and eosin. Depth of necrosis was visualized grossly and microscopically for each time point. We also recorded time to perform LPN, estimated blood loss (EBL), and subjective severity of bleeding.

RESULTS

The average operative time was 15.4 minutes. The mean EBL was 44.2 mL with nine (75%) cases classified as minimal, 2 (17%) moderate, and 1 (8%) severe bleeding. The mean depth of necrosis on the kidney remnants was 2.97 mm. The mean depth of necrosis for unclamped kidneys at 30 seconds, 1 minute, and 3 minutes was 0.38 mm, 0.88 mm, and 1.27 mm, respectively. The mean depths for the clamped kidneys were 2.73 mm, 3.23 mm, and 8.68 mm respectively. Depth of necrosis was significantly higher in the clamped kidneys at 3 minutes (P=0.0035).

CONCLUSIONS

In the porcine model, the SEER transected parenchyma and collecting system with low resection times and minimal blood loss. Use of coagulation during resection is the main advantage of a monopolar resection compared with cold scissors. Testing performed for 3 minutes during hilar clamping demonstrated a significantly deeper level of necrosis.

Sutureless Laparoscopic Heminephrectomy: Safety and Efficacy in Physiologic and Chronically Obstructed Porcine Kidney

We sought to develop and examine the feasibility and efficacy of a streamlined sutureless system of repairing parenchymal and collecting system defects using BioGlue (bovine albumin-glutaraldehyde adhesive) and ProPatch (bovine pericardial patch) in swine under physiological conditions and mechanical stress imposed by chronic ureteral obstruction caused by complete ureteral transaction. Five pigs (10 kidneys) underwent left-side transperitoneal laparoscopic heminephrectomy, followed 2 weeks later by right-sided heminephrectomy with complete ureteral transaction (between clips) to provide a mechanical stressor on the repair, followed 2 weeks later by euthanasia. In each case, after hilar clamping, the lower pole was removed with a bipolar dissector. Hemostasis was obtained with argon beam coagulator and FloSeal (thrombin-gelatin matrix), followed by sutureless repair (ProPatch-BioGlue “sandwich”). At euthanasia, harvested kidneys underwent ex vivo retrograde-pyelography and pathological examination to rule out urinoma/perinephric fluid collection and determine collecting system/parenchymal healing. Mean operative time was 77.8 minutes. Mean warm ischemia time was 12.3 ± 5.6 minutes. Estimated blood loss was 49.5 ± 39.0 mL. All animals demonstrated immediate hemostasis on hilar clamp release. Pyelography failed to demonstrate any collecting system leakage, and closure and healing was confirmed in all. Four of 5 pigs had intact renal function at euthanasia. Two pigs were euthanized for causes unrelated to procedures 4 days prior to study end. This study provides proof of principle that sutureless laparoscopic heminephrectomy is effective in physiological and chronic obstruction conditions in the porcine model. The procedure is reproducible, and resection/renorrhaphy was completed on average with approximately 12 minutes warm ischemia time.

[Experimental laparoscopic renal autograft as learning laparoscopic model]

INTRODUCTION

Laparoscopic surgery requires a long training period of time in which the complexity of the training is increased.

GOALS

The technique presented in this paper has been developed in order to find an experimental model that allows us to improve the learning of the vascular suture. Our main goal was to evaluate this technique as an experimental model for the vacular anastomosis, not to obtain a functional autotransplant. In this regard, here we summarize our experience during the first two cases performed.

MATERIAL AND METHODS

Laparoscopic renal autotransplant was perfomed in female lab pigs weighing 15-20 kg. International Experimental Animal Care rules were accomplished.

RESULTS

After sacrifizing the animals, only one case of vascular thrombosis was observed. The other cases showed normal arterial and venous flow.

CONCLUSIONS

Experimental Renal Laparoscopic autotransplant constitutes a good surgical model. We are trying to implement the technique in the clinics in the next future.

Use of concentrated human albumin with argon-beam coagulation in laparoscopic partial nephrectomy

PURPOSE

Laparoscopic partial nephrectomy (LPN) remains a technically challenging procedure mainly because of the lack of reliable methods of hemostasis. We evaluated the feasibility of using concentrated human albumin with argon-beam coagulation to control hemorrhaging and urinary leakage during LPN.

MATERIALS AND METHODS

Six domestic swine underwent heparinization, then lower-pole LPN after renal-hilar vascular control had been obtained. The animals received argon-beam coagulation either alone (control) or with 38% albumin. Three days later, an identical procedure was performed on the contralateral kidney. Retrograde pyelography was employed to assess for urine leakage. The animals were then euthanized, and both kidneys were harvested for histologic examination.

RESULTS

The mean operative and warm-ischemia times were similar in the two groups and were 27 and 15 minutes, respectively, using albumin with argon-beam coagulation and 25 and 16 minutes with argon coagulation alone. The albumin group required shorter coagulation times (187 v 312 seconds; P = 0.04), which resulted in less thermal injury. By retrograde pyelography, two kidneys (33%) in the albumin group and all six in the control group had urine leakage.

CONCLUSIONS

Adding concentrated albumin to argon-beam coagulation substantially increases the reliability and durability of parenchymal repair after LPN. The time needed to achieve stable hemostasis and closure of the collecting system was reduced compared with standard argon-beam coagulation.

Methods for laparoscopic training using animal models

To reduce the learning curves in humans, several training models have been developed for teaching laparoscopic surgery. The aim of various in vitro or in vivo training models is to help surgeons acquire basic laparoscopic skills such as hand-eye coordination, depth perception, and knot-tying, which should always be acquired prior to organ- or procedure-specific skills. Inexpensive video box trainers are best suited for this purpose. However, advanced laparoscopic skills, such as dissection, cutting, coagulation, and stitching, require more sophisticated animal or human cadaver models. The perfect training model should teach the skills required and should be inexpensive, universally available, and anatomically and physiologically identical to an anesthetized patient. In this paper, we review the different animal models for acquiring advanced laparoscopic skills and try to define their advantages and disadvantages.