Effect of catheter-directed arterial embolization and laparoscopic endovascular stapling on stapled vessel integrity in a porcine model

Arterial embolization is a frequently performed adjunctive maneuver prior to laparoscopic splenectomy or nephrectomy to facilitate laparoscopic dissection and reduce intraoperative bleeding. However, little is known regarding the effect of laparoscopic stapling across thrombosed vessels with imbedded embolic materials. This study analyzed the stapled line integrity by comparing visceral arteries treated with either platinum coils or polyvinyl alcohol (PVA) particles. Using a porcine model, 30 visceral vessels including splenic and renal arteries were treated with either coil or PVA embolization, which was followed by laparoscopic stapling. Vessel integrity and bursting pressure analysis was performed using an in vitro flow circuitry. The mean bursting pressure of the coil and the PVA group was 158 +/- 56 and 350 +/- 34 mm Hg, respectively (p < .001). The lowest bursting pressure in the coil and the PVA group was 70 and 280 mm Hg, respectively. The highest bursting pressure in the coil and the PVA group was 225 and 420 mm Hg, respectively. The bursting pressure in the splenic artery between the PVA and the coil group was 345 +/- 29 and 150 +/- 54 mm Hg, respectively (p < .001). Significant difference in the bursting pressure in the renal artery was noted in the PVA and the coil group, which was 350 +/- 40 and 160 +/- 40 mm Hg, respectively (p < .001). Our findings showed that preoperative coil embolization followed by laparoscopic vessel stapling sustained a poor busting pressure. Such a practice appears to be unsafe based on our findings and should be performed with caution in a clinical setting.     

Evaluation of hydrogel tissue sealant in porcine laparoscopic partial-nephrectomy model

BACKGROUND AND PURPOSE: Laparoscopic partial nephrectomy (LPN) is technically challenging with a steep learning curve, primarily because techniques used to control bleeding on the cut surface of the kidney can be ineffective, inconsistent, or challenging. Hemostatic techniques can include intracorporeal suturing, vascular coagulation (argon-beam coagulator, bipolar cautery, laser), and application of various tissue sealants. There is no uniformity of opinion regarding which hemostatic technique is optimal for this application. CoSeal, a hydrogel (Baxter Healthcare Corp, Deerfield, IL), has been effective following vascular surgery but has not been applied to a partial-nephrectomy model. We evaluated the effectiveness of this hydrogel in controlling bleeding and sealing the collecting system by comparing it with intracorporeal suturing and fibrin sealant (Tisseel; Baxter) in a porcine laparoscopic partial-nephrectomy model. MATERIALS AND METHODS: Bilateral synchronous upper-pole partial nephrectomies were performed in two groups of 18 farm pigs, and the three hemostatic techniques (suturing, Tisseel, CoSeal) were applied. In the first group, partial nephrectomies were performed and the pigs sacrificed 3 days postoperatively (acute group). In the second group, the pigs were euthanized 6 weeks postoperatively (chronic group). In both groups, weight, blood pressure, estimated blood loss, weight of the partial and completion nephrectomy specimen, presence/ absence of urinary leak on retrograde study, histopathologic findings, and complications were recorded. RESULTS: The mean weight, blood pressure, estimated blood loss, histopathology findings, and weight of the partial and completion nephrectomy specimens were similar in the three groups. CoSeal did not adhere well to the renal parenchyma compared with Tisseel. All three animals in the acute CoSeal group and three of the six pigs in the sutured group had small urinary leaks during retrograde ureteral study, whereas none of the pigs in the fibrin-glue cohort had urinary leaks. There was one complication (urinary leak) in the CoSeal group, necessitating sacrifice of the animal on postoperative day 8 because of sepsis. CONCLUSIONS: CoSeal is not as effective as fibrin glue in adhering to the cut renal surface and sealing the collecting system during laparoscopic partial nephrectomy.     

Efficacy of ultrasonic tissue dissector and tissue glue for laparoscopic partial nephrectomy in a porcine model

The purpose of this study was to evaluate the efficacy and long-term tissue effects of ultrasonic dissector and cyanoacrylate glue during laparoscopic partial nephrectomy in a porcine model. Nine domestic pigs underwent laparoscopic left lower pole partial nephrectomy without vascular control. An ultrasonic tissue dissector was used to assist in the parenchymal incision, and the raw surfaces of the kidneys, including the exposed urinary system, were sealed with cyanoacrylate glue. No internal stents or additional sutures were placed. Intraoperative hemorrhages and urinary extravasation were recorded. The animals were humanely killed 28 days after undergoing the operations. The long-term effects of ultrasonic dissector and cyanoacrylate glue on the healing process of urothelium and renal parenchyma were determined histologically. All pigs survived the laparoscopic partial nephrectomy, and the blood loss ranged from 0 to 120 ml (mean, 60 ml). The average operative time was 89 +/- 10 min. The severity of the bleeding was minimal in six animals and moderate in three animals. No urinary extravasation was found using intravenous urography at the 28th postoperative day. No urinary fistula or renal abscess formation was found histologically. Cyanoacrylate glue infiltrated into the tissue defects and did not dissolve. The glue was encased by fibrotic tissue with minimal foreign body inflammatory reaction. Ultrasonic dissector was effective in achieving hemostasis during laparoscopic partial nephrectomy without the need of vascular control in pigs. Cyanoacrylate glue achieved good long-term adhesive power. The sealing effects provided by cyanoacrylate glue were adequate to prevent urinary extravasation from urothelial defects at least for 1 month.     

经阴道NOTES辅助腹腔镜肾切除术猪动物模型的构建

目的:介绍构建经阴道NOTES辅助腹腔镜肾切除术猪动物模型的经验和体会,并评价其应用价值。方法:本组选择6头健康雌性小型猪,中位重量46(42～48)kg。全麻,取70°侧卧位,双后肢外展。于脐两侧缘分别置入一5mm和10mm trocar。自阴道后穹窿置入一5mm trocar。自阴道trocar置入腹腔镜,脐缘两tro-car置入操作器械。用电凝钩和吸引器锐性和钝性相结合游离肾脏,逐步显露肾蒂,用Hem-o-lock和钛夹阻断肾动静脉及输尿管,完整切除肾脏,装入自制标本袋,扩大阴道后穹窿切口取出。结果:6例经阴道NOTES辅助腹腔镜猪肾切除术均成功完成,未中转标准腹腔镜或开放手术,亦未另增操作通道。其中左侧3例,右侧3例。中位手术时间100(70～150)min。其中建立通道中位时间10(9～22)min,肾脏切除中位时间15(7～30)min,标本取出中位时间65(40～80)min;术中中位失血量30(20～40)ml。术中无大血管及腹腔脏器损伤等严重并发症发生。结论:建立经阴道NOTES辅助腹腔镜肾切除术的动物模型可行。该模型较真实地模仿人体NOTES的操作过程,是现阶段进行学员培训和特殊器械研发较适宜的方式。     

经阴道内镜胆囊切除术的实验研究

目的:探讨在动物模型上完成经阴道联合经脐入路内镜胆囊切除术的安全性及可行性。方法:用6只3~5个月、体重28~30kg的三元杂交雌猪行经阴道内镜胆囊切除术。实验猪取仰卧位,经脐部切口穿刺两个自制直径5mm Trocar,插入腹腔镜探查腹腔,并在腔镜直视下从阴道后穹窿穿刺自制5mm Trocar及操作器械。在腔镜下解剖胆囊三角,电刀游离胆囊,分离出胆囊管,用可吸收线圈套器圈扎胆囊管后用超声刀离断胆囊管,切除胆囊标本后由阴道取出。阴道切口不予缝合。实验动物术后24h开始进食,饲养1周后处死解剖。结果:6例手术均成功完成,手术时间24~42m in,平均(31.7±10.6)m in。术中无明显出血及周围脏器损伤。术后饲养1周,均生长良好,未见明显并发症。尸检见手术创面及阴道切口愈合良好,腹壁未见疤痕。结论:经阴道联合经脐胆囊切除术安全可行,此手术径路具有手术效率高、美容效果好等优点。     

Effect of prosthetic material on adhesion formation after laparoscopic ventral hernia repair in a porcine model

Intraperitoneal placement of prosthetic mesh causes adhesion formation after laparoscopic incisional hernia repair. A prosthesis that prevents or reduces adhesion formation is desirable. In this study, 21 pigs were randomized to receive laparoscopic placement of plain polypropylene mesh (PPM), expanded polytetrafluoroethylene (ePTFE), or polypropylene coated on one side with a bioresorbable adhesion barrier (PPM/HA/CMC). The animals were sacrificed after 28 days and evaluated for adhesion formation. Mean area of adhesion formation was 14% (SD±15) in the PPM/HA/CMC group, 40% (SD±17) in the PPM group, and 41% (SD±39) in the ePTFE group. The difference between PPM/HA/CMC and PPM was significant (P=0.013). A new visceral layer of mesothelium was present in seven out of seven PPM/HA/CMC cases, six out of seven PPM cases, and two out of seven ePTFE cases. Thus, laparoscopic placement of PPM/HA/CMC reduces adhesion formation compared to other mesh types used for laparoscopic ventral hernia repairs.This work was presented as an oral presentation at the American Hernia Society Meeting, Tucson, Ariz. USA in May, 2002.This study was funded by a grant from Genzyme, Corp., Cambridge, Mass. USA     

A porcine model for laparoscopic adrenalectomy

Laparoscopic adrenalectomy has been successfully performed and described in humans. Though it is presently not widely employed it offers tremendous potential for adrenal surgery. It remains, however, an advanced technique requiring demonstration and practice. The aim of this study is to develop a porcine model of adrenalectomy for teaching and advancing the technique applicable to human surgery.Five female pigs weighing 10–20 kg underwent bilateral adrenalectomy by the lateral approach using endotracheal intubation. The left adrenal was resected with the pig in the right decubitus position. The animal was repositioned to left decubitus and the right adrenal was resected. In each case four 10-mm trochars were placed over the respective flanks. There was no need to mobilize the colon or liver (in the pig model). The peritoneum over each gland was incised and the gland dissected in a cephalocaudal manner. The vessels were ligated and divided particularly those from the vena cava.Upon completion blood loss (<100 cc) and operating times (mean 60 min for the left and 90 min for the right) were assessed and the animal was sacrificed. The glands were weighed (mean 1.23 g R and 1.15 g L) and measured.Using this model, experience is gained in positioning the subject as well as trocars, in fine dissection in a lateral orientation, and in techniques of hemostasis. Although porcine and human adrenal anatomy differ in some details the pig constitutes an excellent model for the development of the technical experience required to perform adrenalectomy in humans.     

腹腔镜下输尿管膀胱再植术动物模型的建立方法

目的 建立训练腹腔镜下输尿管膀胱再植术的动物模型. 方法 10只体质量30kg左右小型雌性猪作为实验动物,氯氨酮(10 mg/kg)诱导麻醉,3.5%戊巴比妥钠(0.25 g/kg)术中维持.取仰卧位经脐点穿刺导人CO2制备气腹,放置3个工作套管.游离子宫角以替代扩张的输尿管.按膀胱外黏膜下隧道法(Lich-Gregoir)标准步骤进行手术.4名具有腹腔镜体外模拟训练经验的学员参加培训,根据手术时间评估学员的学习曲线. 结果 能够在该动物模型上成功完成腹腔镜下输尿管膀胱再植术的各项操作技术,每侧可进行2次手术.学员接受10次输尿管再植术训练后,平均手术时间从最初的(170±10)min降至(90±4)min(P<0.01),学员均能熟练完成腹腔镜下输尿管膀胱再植术. 结论 该模型利用子宫角替代扩张输尿管提供多次训练机会,能使学员掌握膀胱外黏膜下输尿管膀胱再植术的腔内操作技巧和手术方法.     

Postoperative adhesion formation after laparoscopic uterine horn resection in a porcine model: comparison of five instruments

PURPOSE: To evaluate the postoperative adhesion formation caused by instruments used in gynecologic laparoscopic surgery and to determine the optimal instruments to use to reduce adhesions. MATERIALS AND METHODS: Seventeen juvenile pigs underwent laparoscopic bilateral resection of the uterine horns under general anesthesia and pneumoperitoneum. The laparoscopic procedures were carried out using monopolar electrocautery (ME) (n = 8), an electrothermal bipolar vessel sealer (EBVS) (n = 6), an ultrasonically activated scalpel (UAS) (n = 6), a loop-type ligature (LTL) with a steel scalpel for severing the tissues (n = 6), and an automatic stapling device (ASD) (n = 8). Second- look laparotomy was performed 14 days postoperatively, and the degree of postoperative adhesions was scored from 0 to 6. RESULTS: The mean and range of adhesion scores were 0.00 with EBVS, 0.13 (range, 0-1) with ASD, 0.33 (range, 0-2) with LTL, 1.17 (range, 0-3) with UAS, and 3.13 (range, 2-6) with ME. We found a statistically significant difference in the extent of postoperative adhesion formation associated with these 5 instruments (P < 0.001, Kruskal-Wallis test). CONCLUSION: Adhesion formation increased in the order EBVS < ASD < LTL < UAS < ME. Our study strongly suggests that surgical instruments can be selected to reduce postoperative adhesion formation, a particular concern in women of reproductive age.     

Hand-assisted laparoscopic aorto-aortic bypass: initial experience in a porcine model

Videoscopic surgical techniques have been developed to reduce morbidity of open aortic reconstructions. The advantage of hand-assisted laparoscopic surgery (HALS) technique is the introduction of the surgeon's hand into the peritoneal cavity. The aims of this study were to assess the feasibility and to examine the learning curve, limitations, and pitfalls of the HALS technique to perform aortic reconstruction in a porcine model for training purposes. HALS aorto-aortic 8 mm polytetrafluoroethylene (PTFE) interposition grafts were placed in 12 pigs. Proficiency was judged by measuring operative time points, satisfactory completion of the operation, and the need to convert to open procedure. The strength of the relationship between order number in which a procedure was performed and the various surgical time point measures was described with the Spearman rank correlation. HALS aortic grafting was successful in the last 8 pigs. The first 2 pigs required conversion to open repair, and the graft of the third and fourth animals occluded early. Median operative time was 115 minutes (range: 75 to 205), median intestinal retraction time was 28 minutes (range: 10 to 40), median aortoiliac dissection time was 30 minutes (range: 20 to 60), and median aortic cross-clamp time was 48 minutes (range: 35 to 82). The Spearman rank correlations and p values between the order of the procedure and the intestinal retraction time, aortoiliac dissection time, clamping time, and total operative time were -0.62 (0.06), -0.47 (0.17), -0.69 (0.03), and -0.83 (0.03), respectively. HALS facilitates intestinal retraction and completion of laparoscopic aortoiliac dissection. It offers adequate exposure in pigs for aortic grafting and allows open sutured aortic anastomosis. The learning curve for HALS aortic surgery in a porcine model is short and within reach of surgeons with standard laparoscopic surgery skills, since no laparoscopic suturing is required. Training on this porcine model may be an efficient and safe way to introduce surgeons to HALS for aortoiliac reconstruction.     

Use of hydro-jet cutting for laparoscopic partial nephrectomy in a porcine model

Objectives. To evaluate whether a laparoscopic hydro-jet device can provide a safe and effective partial nephrectomy. Partial nephrectomy is still one of the most challenging operations in urologic laparoscopy. The control of hemorrhage is very difficult to achieve with laparoscopic techniques. In open surgery, hydro-jet resection is used to cut the renal parenchyma selectively, avoiding damage to the vascular structures or collecting system.Methods. Laparoscopic wedge, as well as pole, resections of the kidney were performed in 5 pigs under general anesthesia. After exposure of the kidney, the renal capsule was incised using electrocautery. The hydro-jet was then used to dissect the renal parenchyma. In pole resections, the collecting system and central vessels were divided using an Endo-GIA. Hemostasis was achieved by electrocoagulation or clips. The dissection time and intraoperative complications were evaluated.Results. The operations were performed successfully in all animals without temporary ischemia. The hydro-jet generator allowed precise and effective tissue dissection without significant hemorrhage. The parenchymal vessels were selectively coagulated. The collecting system and central vessels remained intact and could be divided after application of the Endo-GIA. The mean dissection time was 42 ± 6 minutes for the wedge resections and 54 ± 8 minutes for the pole resections.Conclusions. These experimental results demonstrate the suitability of hydro-jet dissection for safe laparoscopic partial nephrectomy without temporary ischemia and with reduction of the operative trauma to the kidney. On the basis of our own experiences with other techniques, including electrocautery and laser technology for partial nephrectomy, we conclude that laparoscopic hydro-jet resection represents an interesting alternative to other techniques.     

Less smoke and minimal tissue carbonization using a thulium laser for laparoscopic partial nephrectomy without hilar clamping in a porcine model

PURPOSE: We evaluated the utility of a thulium laser and a novel implementation of its use for laparoscopic partial nephrectomy to achieve precise, smokeless, and hemostatic dissection without hilar clamping and with minimal charring in a porcine model. MATERIALS AND METHODS: Laparoscopic transperitoneal lower-pole partial nephrectomy was performed in five Yorkshire farm pigs without clamping of the renal hilum. All animals were kept alive for 1 week. Using a 365-mum laser fiber, a 30 W thulium laser was used to produce full-thickness cortical excisions of the lower-pole renal cortex. The laser fiber was delivered through the working channel of a 16F flexible cystoscope inserted through a 10-mm laparoscopic port. The laser incision was directed by manual deflection of the cystoscope along with low-pressure saline irrigation through the cystoscope. RESULTS: Laparoscopic partial nephrectomy was completed in all cases without perioperative complications and with an estimated blood loss of <50 mL. The thulium laser was able to cut tissue and simultaneously to coagulate vessels as large as 1.6 mm. The flexible cystoscope with concurrent saline irrigation permitted precise laser control for dissection with minimal tissue charring and no smoke to obscure visibility. At 1 week, the cut edge of the tissue showed minimal necrosis with preservation of histologic architecture. CONCLUSIONS: Laparoscopic partial nephrectomy with the thulium laser provides precise dissection and hemostasis without hilar clamping. Minimal tissue charring and no smoke generation improve visibility.     

A novel spleen-preserving laparoscopic technique using radiofrequency ablation in a porcine model

Background Partial splenectomy is considered to be the optimal management for a variety of diseases. At the same time, laparoscopic procedures are increasingly used because they present certain advantages against their open counterparts. In this study, the safety and efficacy of radiofrequency ablation (RFA) were evaluated in laparoscopic partial splenectomy performed in a pig model. Methods Eight domestic pigs were used. Four abdominal trocars were inserted under general anesthesia and the spleen was stabilized with laparoscopic clamps. A RFA needle electrode was inserted transcutaneously, and coagulative necrosis of a zone of the splenic parenchyma between the body and the lower pole was performed. Bloodless sharp division and removal of the lower pole followed. After 0, 7, 30, or 120 days, the animals were killed and examined. Results Blood loss and operation time were minimal. Mortality and morbidity were zero. No abnormal findings were encountered during the postmortem abdominal exploration. Conclusion This study demonstrates the feasibility, safety, and efficacy of laparoscopic RFA-assisted partial splenectomy. The RFA-assisted laparoscopic partial splenectomy adds a novel technique to the surgeon’s armamentarium for the preservation of a part of the spleen.     

Hydro-jet assisted laparoscopic partial nephrectomy: initial experience in a porcine model

PURPOSE: Hemostasis represents a challenge when performing laparoscopic partial nephrectomy. Hydro-Jet cutting is an advanced technology that has been used to create an ultra-coherent water force that functions like a sharp knife. In the surgical field, it has mainly been used for liver surgery and initial clinical experience with laparoscopic cholecystectomies has been favorable. This technique allowed selective parenchymal cutting with preservation of vessels and bile ducts. We describe a novel Hydro-Jet assisted dissection technique for laparoscopic partial nephrectomy in a porcine model. MATERIALS AND METHODS: Ten partial nephrectomies were performed in 5 pigs using a Muritz 1000 (Euromed Medizintechnik, A. Pein, Schwerin, Germany) Hydro-Jet generator. A thin stream of ultra coherent fluid is forced at a high velocity through a small nozzle. A modified probe allows both blunt dissection concomitantly with high-pressure water application. Coagulation can be applied via a bipolar thermoapplicator as needed. RESULTS: Laparoscopic partial nephrectomy was successful in all animals. Water-jet cutting through the parenchyma was virtually bloodless and preserved the vasculature and the collecting system. The vessels were then ligated or coagulated under direct vision. The continuous water flow established a bloodless operating field and a clear view for the surgeon. The mean dissection time and warm ischemia time were 45+/-9 and 17+/-3 minutes, respectively. CONCLUSIONS: This preliminary study supports the suitability of this technique for laparoscopic partial nephrectomy to improve hemostasis. The improved anatomical dissection and hemostasis may further decrease morbidity and operative time. Further studies are underway to compare this technique with laser coagulation for laparoscopic partial nephrectomy.     

Effectiveness of a hands-on training course for laparoscopic spine surgery in a porcine model

Background: Although it is widely proposed that surgeons, before introducing a novel laparoscopic technique in man, should practice in an appropriate animal model for acquisition of the necessary technical skills, the effectiveness of those hands-on training courses are rarely documented. Methods: In 1995 we have organized eight hands-on training courses for laparoscopic anterior interbody spine fusion in an in vivo porcine model. A total of 72 colleagues from 50 different centers of 12 countries participated, including orthopedic, trauma, visceral, neuro-, and vascular surgeons. Quality and effectiveness of the course were evaluated by a questionnaire after a 1.5- to 2.5-year period. Results: During this time, 42.2% of the participating centers had applied the new technique successfully in man. Centers which participated in the course with a team that included a skilled laparoscopic surgeon and an orthopedic or trauma surgeon introduced the technique more frequently to clinical practice (57.9%) than those represented by only one participant (30.8%). Moreover, there was a tendency toward a more frequent introduction of the technique to clinical practice in centers associated with university hospitals (57.1% vs. 29.2%), indicating the requirement of a particular infrastructure for this complex interdisciplinary procedure. Almost all participants (98.3%) agreed that for novel surgical techniques requiring advanced technical skills, there should first be training in a large animal model before the technique is applied in man. Conclusions: Complex laparoscopic procedures (i.e., laparoscopic spine surgery) can be successfully learned by in vivo hands-on training courses. We propose that for refinements and modifications of the technique (e.g., the lumboscopic approach), there should also first be training in a large animal model before these are applied in man. Received: 30 July 1997/Accepted: 26 March 1998