Standardized technique of laparoscopic surgery in the rat

Efficacy of Engraftment and Safety of Human Umbilical Di-Chimeric Cell (HUDC) Therapy after Systemic Intraosseous Administration in an Experimental Model

Cell-based therapies hold promise for novel therapeutic strategies in regenerative medicine. We previously characterized in vitro human umbilical di-chimeric cells (HUDCs) created via the ex vivo fusion of human umbilical cord blood (UCB) cells derived from two unrelated donors. In this in vivo study, we assessed HUDC safety and biodistribution in the NOD SCID mouse model at 90 days following the systemic intraosseous administration of HUDCs. Twelve NOD SCID mice (n = 6/group) received intraosseous injection of donor UCB cells (3.0 × 106) in Group 1, or HUDCs (3.0 × 106) in Group 2, without immunosuppression. Flow cytometry assessed hematopoietic cell surface markers in peripheral blood and the presence of HLA-ABC class I antigens in lymphoid and non-lymphoid organs. HUDC safety was assessed by weekly evaluations, magnetic resonance imaging (MRI), and at autopsy for tumorigenicity. At 90 days after intraosseous cell administration, the comparable expression of HLA-ABC class I antigens in selected organs was found in UCB control and HUDC therapy groups. MRI and autopsy confirmed safety by no signs of tumor growth. This study confirmed HUDC biodistribution to selected lymphoid organs following intraosseous administration, without immunosuppression. These data introduce HUDCs as a novel promising approach for immunomodulation in transplantation.

Laparoscopic left hepatectomy in a goat as a training model for laparoscopic anatomic liver resection: results of training courses with a total of 70 goats

BACKGROUND

To create a suitable animal model for the training of laparoscopic anatomic liver resection, we performed left hepatectomy using a goat and found its suitability. We have since started using goats for wet-lab training and have gradually standardized the relevant procedures. Herein, we report our standardized training procedures using a goat and discuss its feasibility as a novel training model.

METHODS

The standardized wet-lab training courses of laparoscopic liver resection conducted on 62 tables with a total of 70 goats were reviewed. The training course began by encircling the hepatoduodenal ligament for the Pringle maneuver, which was repeated during the parenchymal dissection. Following partial liver resection of the left lateral section, left hepatectomy was performed by a standardized procedure for humans in which the liver was split, exposing the entire length of the middle hepatic vein trunk from the dorsal side after extrahepatic transection of the left Glissonean pedicle. If a goat deceased before initiating left hepatectomy, the training was restarted with a new goat. The surgical procedures were performed by surgeons of varying skill levels.

RESULTS

A total of 184 surgeons including 10 surgical residents participated in the training. Partial liver resection was initiated in 62 tables, with 8 (13%) dying during or after the procedure of partial liver resection. Subsequently, left hepatectomy was initiated in 61 and completed in 59 tables (98%), regardless of whether the goat survived or deceased, and was not completed in 2 tables (3%) due to time limitation. In 14 tables (23%), the goats deceased during the procedure, however, the procedure was completed. The causes of death were multifactorial, including massive bleeding, reperfusion injury after the Pringle maneuver, and carbon dioxide gas embolism.

CONCLUSIONS

Left hepatectomy in a goat is useful as a training model for laparoscopic anatomic liver resection.

Standardization of operative technique in minimally invasive right hepatectomy: improving cost-value relationship through value stream mapping in hepatobiliary surgery

BACKGROUND

With current emphasis on improving cost-quality relationship in medicine, it is imperative to evaluate cost-value relationships for surgical procedures. Previously the authors demonstrated comparable clinical outcomes for minimally invasive right hepatectomy (MIRH) and open right hepatectomy (ORH). MIRH had significantly higher intraoperative cost, though overall costs were similar.

METHODS

MIRH was decoded into its component critical steps using value stream mapping, analyzing each associated cost. MIRH technique was prospectively modified, targeting high cost steps and outcomes were re-examined. Records were reviewed for elective MIRH before (pre-MIRH n = 50), after (post MIRH n = 25) intervention and ORH (n = 98), between January 1, 2008 and November 30, 2016.

RESULTS

Average overall cost was significantly lower for post-standardization MIRH (post-MIRH $21 768, pre-MIRH $28 066, ORH $33 020; p < 0.001). Average intraoperative blood loss was reduced with MIRH (167, 292 and 509 mL p < 0.001). Operative times were shorter (147, 190 and 229 min p < 0.001) and LOS was reduced for MIRH (3, 4, 7 days p < 0.002).

CONCLUSIONS

Using a common quality improvement tool, the authors established a model for cost effective clinical care. These tools allow surgeons to overcome personal or traditional biases such as stapler choices, but most importantly eliminate non-value added interventions for patients.

A Novel Laparoscopic Surgery Model with a Device to Expand the Abdominal Working Space in Rats: The Influence of Pneumoperitoneum and Skin Incision Length on Postoperative Inflammatory Cytokines

PURPOSE

Experimental models of laparoscopic surgery generally use large animals owing to a sufficient abdominal working space. We developed a novel laparoscopic surgery model in rats. We performed intestinal anastomosis to demonstrate the feasibility and reliability of this model.

MATERIALS AND METHODS

We designed a device for rats that expanded the abdominal working space and allowed us to manipulate the intraperitoneal organs by hand under direct vision with pneumoperitoneum. We performed small bowel resection and intestinal anastomosis in rats using this model. To elucidate the effects of pneumoperitoneum and skin incision length, rats were randomly divided into four groups with differing surgical techniques: small incision group, large incision group, small incision + pneumoperitoneum group, and large incision + pneumoperitoneum group. Intraoperative abdominal pressure and postoperative cytokines were measured.

RESULTS

One experimenter completed small bowel resection and hand-sewn anastomosis under direct vision without any difficulties or assistance. Carbon dioxide pneumoperitoneum was maintained at 8-10 mmHg during surgery in both pneumoperitoneum groups. Necropsies revealed no evidence of anastomotic leakage at 24 h after surgery. The interleukin-6 and C-reactive protein concentrations were significantly greater in large incision group than in small incision group, but were not significantly different between small incision + pneumoperitoneum group and small incision group. These cytokines concentrations were the greatest in large incision + pneumoperitoneum group.

CONCLUSIONS

Our laparoscopic surgery model in rats is a simple and reliable experimental model. The length of skin incision might be a more influential determinant of surgical invasiveness than pneumoperitoneum.

Advanced training in laparoscopic abdominal surgery: a systematic review

BACKGROUND

Simulation has spread widely this last decade, especially in laparoscopic surgery, and training out of the operating room has proven its positive impact on basic skills during real laparoscopic procedures. Few articles dealing with advanced training in laparoscopic abdominal surgery, however, have been published. Such training may decrease learning curves in the operating room for junior surgeons with limited access to complex laparoscopic procedures as a primary operator.

METHODS

Two reviewers, using MEDLINE, EMBASE, and The Cochrane Library conducted a systematic research with combinations of the following keywords: (teaching OR education OR computer simulation) AND laparoscopy AND (gastric OR stomach OR colorectal OR colon OR rectum OR small bowel OR liver OR spleen OR pancreas OR advanced surgery OR advanced procedure OR complex procedure). Additional studies were searched in the reference lists of all included articles.

RESULTS

Fifty-four original studies were retrieved. Their level of evidence was low: most of the studies were case series and one fifth were purely descriptive, but there were eight randomized trials. Pig models and video trainers as well as gastric and colorectal procedures were mainly assessed. The retrieved studies showed some encouraging trends in terms of trainee satisfaction with improvement after training, but the improvements were mainly on the training tool itself. Some tools have been proven to be construct-valid.

CONCLUSION

Higher-quality studies are required to appraise educational value in this field.

A new proposal for laparoscopic left colectomy in a rat model

PURPOSE

To evaluate the feasibility and safety of a new technique for laparoscopic segmental colectomy and primary anastomosis in the left colon of rats.

METHODS

Thirty rats were randomly assigned to three groups of ten animals each. All animals underwent segmental resection of the left colon and end-to-end anastomosis. In Group I, the animals underwent laparoscopic surgery with carbon dioxide pneumoperitoneum at a pressure of 5 mmHg. In Group II, the animals underwent pneumoperitoneum with carbon dioxide at a pressure of 12 mmHg. In Group III, the control group, the animals underwent open surgery. All animals were reopened on the 7th postoperative day and were evaluated for peritonitis, abscesses, anastomotic dehiscence and bowel obstruction, and the anastomosis bursting pressure was measured.

RESULTS

No obstructions, peritonitis or abscesses were found in any of the animals. An animal in Group I exhibited a blocked anastomosis leakage. The average anastomosis bursting pressure in the 30 animals was 187.02 ± 68.35 mmHg. There was no significant difference in the anastomosis bursting pressure among the groups (p = 0.503)

CONCLUSION

The laparoscopic experimental model was feasible and safe for segmental colectomy and anastomosis of the left colon in rats.

Percutaneous obliteration of patent processus vaginalis: a rat model for future inguinal hernia repair in children

PURPOSE

Inguinal hernia repair is one of the most common procedures performed by pediatric surgeons. A percutaneous technique could be the next advance in inguinal hernia repair in children. We used a rat model to study the utility of percutaneous inguinal hernia repair (PHR) using 2-octyl-cyanoacrylate (OCT).

METHODS

Four-week-old Lewis male rats were randomly divided into three groups: bilateral PHR group (BH) (n=15), unilateral PHR group (UH) (n=12), and sham group (n=14). After inducing a pneumoperitoneum, a 24-gauge cannula was advanced into the patent processus vaginalis (PPV) once air was aspirated. The canal is then obliterated by injecting 0.2 ml of 2-octyl-cyanoacrylate. Mating and herniography were performed at postoperative weeks 2 and 6, respectively. All rats were sacrificed at week 12.

RESULTS

Herniography revealed complete closure of PPV in (25/30) BH, (12/12) UH, and (0/28) of the sham group. All OCT-treated sides were found obliterated at the post-mortem gross examination. Histological analysis of the inguinal region revealed patent vase in all rats. However, mild to moderate foreign body reactions and fat necrosis were noticed at the injected sites. All rats demonstrated fertility at mating.

CONCLUSION

Percutaneous obliteration of PPV was feasible and safe in rats and potentially less invasive than the current techniques used in children. However, demonstrating long-term effectiveness, the need for pneumoperitoneum and the risk of OCT intraperitoneal spillage remain as challenges to overcome.

Laparoscopic surgery in a rat model

BACKGROUND

The rat is increasingly being used in laparoscopic research. Laparoscopic microsurgical training is critical in order to develop new surgical indications in pediatric patients. This report evaluates laparoscopic splenectomy and nephrectomy in a rat model.

MATERIALS AND METHODS

A Wistar rat (weight between 250 and 400 g) was placed in the supine position. Inhaled 3% halothane anesthesia was administered. A Veress needle is inserted in the right-upper abdomen. After establishing a pneumoperitoneum of 3-4 mm Hg, a 2- or 5-mm trocar was placed, according to the procedure. A 2-mm 0-degree endoscope was used. Two additional 2- or 5-mm trocars were then placed. Laparoscopic splenectomy involved two-handed dissection, intracorporeal ligation, and the division of gastrosplenic attachments and hilar and short gastric vessels. Laparoscopic nephrectomy was done by intracorporeal ligation and division of the renal vessels and the ureter after mobilization of the kidney.

RESULTS

Laparoscopic splenectomy was performed in 8 rats; laparoscopic nephrectomy was done in 4 rats. Operative time was 25-40 minutes for splenectomy and from 30 to 65 for nephrectomy. Postoperatively, 4 rats died from hemorrhage. No wound infections occurred at the port sites.

CONCLUSIONS

Laparoscopic splenectomy and nephrectomy in an experimental rat model is technically feasible and may provide an excellent training model for pediatric minimally invasive surgery.

Enhanced tumour growth and impaired cellular antitumoural defense in hepatic colorectal carcinoma metastasis in rats after laparoscopy compared to open surgery

BACKGROUND

This study aims to assess postoperative hepatic growth of colorectal adenocarcinoma metastasis and peritumoural macrophage counts after laparoscopy in an experimental animal model.

METHODS

Thirty male syngenic WAG/Rij rats were randomised into two surgical groups: laparoscopy (LS; n = 15) using CO(2) at 12 mmHg and laparotomy (LT; n = 15; negative control) during an operating time of 90 min. At 45 min after setup, CC531s colon adenocarcinoma cells were injected into two liver lobes. Postoperative tumour volumes were determined by abdominal magnetic resonance imaging (MRI) and computed three-dimensional volumetry. Peritumoural macrophages were counted by local stereology using a confocal laser-scanning fluorescence microscope.

RESULTS

The median postoperative tumour volume was significantly higher after LS in both lobes (L): after 10, 15 and 20 days in L2 and L5: 24/12, 54/38, 275/62 mm(3) and 0/0, 15/11, 55/24 mm(3) (LS/LT). Significantly fewer peritumoural macrophages were found after LS at all postoperative time points (Mann-Whitney: p < 0.05).

CONCLUSIONS

Increased hepatic growth of colorectal adenocarcinoma metastasis and impaired cellular antitumoural defence after LS cast doubt on the use of LS in colorectal cancer and needs further clinical investigation.

A suitable animal model for laparoscopic hepatic resection training

BACKGROUND

There is a growing interest in using laparoscopy for hepatic resection. However, structured training is lacking in part because of the lack of an ideal animal training model. We sought to identify an animal model whose liver anatomy significantly resembled that of the human liver and to assess the feasibility of learning laparoscopic hepatic inflow and outflow dissection and parenchyma transection on this model.

METHODS

The inflow and outflow structures of the sheep liver were demonstrated via surgical dissection and contrast studies. Laparoscopic left major hepatic resections were performed.

RESULTS

The portal hepatis of all 12 sheep (8 for anatomic study and 4 for laparoscopic hepatic resection) resembled that of human livers. The portal vein (PV) was located posteriorly; the common hepatic artery (CHA) and the common bile duct (CBD) were located anterior medially and anterior laterally with respect to the portal hepatis. The main PV bifurcated into a short right and a long left PV. The extrahepatic right PV then bifurcated into right posterior and anterior sectoral PV. The CBD and CHA bifurcated into left and right systems. The cystic duct originated from the right hepatic duct. The cystic artery originated from the right HA in 11/12 animals. The left hepatic vein drained directly into the inferior vena cava (IVC). The middle and the right hepatic veins formed a short common channel before entering the IVC. Multiple venous tributaries drained directly into IVC. Familiarity with sheep liver anatomy allowed laparoscopic left hepatic lobe (left medial and lateral segments) resection to be performed with accuracy and preservation of the middle hepatic vein.

CONCLUSIONS

The surgical anatomy of sheep liver resembled that of human liver. Laparoscopic major hepatic resection can be performed with accuracy using this information. Sheep is therefore an ideal animal model for advanced surgical training in laparoscopic hepatic resection.

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.

Laparoscopy vs minilaparotomy and full laparotomy preserves circulatory but not peritoneal and pulmonary immune responses

PURPOSE

Laparoscopy has been associated with lower inflammatory responses. However, it has been postulated that minilaparotomy, in contrast to full laparotomy, is equally minimally invasive.

OBJECTIVE

The aim of this study was to investigate local, systemic, and distant organ immune responses after different surgical approaches to the abdominal cavity, such as minilaparotomy, full laparotomy, and laparoscopy, in a small animal model.

METHODS

Male Lewis rats received a permanent central venous catheter and were randomized to 4 groups (n = 6 per group). The animals were subjected to anesthesia alone (control), minilaparotomy (1 cm), full laparotomy (7 cm), or laparoscopy for 60 minutes. Blood was collected via the central venous catheter before as well as 1 hour and 6 hours after the start of intervention. Peritoneal and bronchoalveolar lavages, as well as heart puncture, were performed after 24 hours.

RESULTS

All surgical interventions led to a significant migration of polymorphonucleocytes into the abdominal cavity. Full laparotomy resulted in a significant increase in nitric oxide production by peritoneal macrophages as compared with control. Macrophage nitric oxide production after laparoscopy and minilaparotomy was not significantly different. A shift in the expression of OX-6 and CD54 was only detected after full laparotomy. Systemically, O(2)(-) release by circulating mononuclear cells was significantly increased after minilaparotomy and full laparotomy, but not after laparoscopy. The systemic levels of IL6 were significantly accelerated only after full laparotomy, with a maximum after 6 hours. In the lungs, function of alveolar macrophages was not altered in any group.

CONCLUSIONS

Any approach to the peritoneal cavity causes local inflammatory responses. Full laparotomy alters peritoneal macrophage functions more pronouncedly than does minilaparotomy or laparoscopy. Systemic inflammatory responses, such as free oxygen radical release, are significantly increased by both minilaparotomy and full laparotomy, whereas laparoscopy preserves systemic immune function. Our results may lead to further preference for the laparoscopic approach over minilaparotomy and full laparotomy.

Videolaparoscopic orchiectomy and nephrectomy: training model in rats

OBJECTIVE

Videolaparoscopic surgery conducted on small animals has proved to be of great importance for the improvement of surgical skills. This is a report utilizing an experimental model for laparoscopic orchiectomy and nephrectomy in training courses for urologists.

MATERIAL AND METHODS

Of 350 American Wistar rats enrolled, 319 animals underwent laparoscopic orchiectomy and nephrectomy under intraperitoneal general anesthesia. Graspers, dissectors, and a 0-degree telescope were introduced into the peritoneal cavity by two trocars of 5 mm and one of 10 mm, respectively.

RESULTS

Of 350 rats enrolled, 15 (4.2%) died due to anesthetic complications and 16 (4.5%) due to cannibalism and stress during transport. A total of 319 rats were operated on, 178 underwent bilateral orchiectomy, two per model (356 operations), and in 141 animals one nephrectomy per model (141 operations) was performed. A total of 497 operations were performed involving 140 urologists. The animals were easy to handle providing adequate practice without the occurrence of any major intraperitoneal lesion and hemorrhage.

CONCLUSION

Nephrectomy and orchiectomy are feasible in rats, and this model can be utilized for training videolaparoscopic surgeries.

Tissue adhesives for repairing inguinal hernia: a preliminary study

AIM

To investigate the efficacy of tissue adhesives for closing the orifice of the inguinal hernia sac (IHS) as an alternative method for treating inguinal hernia.

METHODS

Five-week-old male Lewis rats (n=4) were used, because Lewis rats have a large patent IHS. The rats were divided into 9 groups (n=6 in each) according to the type of tissue adhesive used: G1, fibrin glue (Beriplast); G1b, Beriplast plus blood; G2, microfibrillar collagen hemostat (Avitene); G2b, Avitene plus blood; G3, fibrinogen-based sealant (TachoComb); G3b, TachoComb plus blood; G4, synthetic absorbable sealant (Advaseal); G5, bilateral single port laparoscopic injection of octylcyanoacrylate (Dermabond); and G6, sham operation (control group). In G1-G4, surgery was performed through a midline lower abdominal incision. In G5, a 5-mm laparoscope was inserted in the epigastrium, a fine catheter was passed through the side port of the laparoscope into the right HIS, and 0.2 mL Dermabond was injected. The left IHS was treated in the same way. All rats were sacrificed 3 months after treatment, and IHS patency was examined macroscopically. All rats in G5 and G6 were mated 50 days after treatment to check fertility.

RESULTS

All rats survived until sacrifice. At sacrifice, all IHS were patent in G6. All IHS were also patent in G1-G4, but all IHS were closed at the internal ring in G5. In G5 there were no adhesions between the orifice of the closed sac and the small bowel in 5/6, and only minor adhesions in 1/6. G5 fertility (5/6: 83%) was the same as for the control group (G6).

CONCLUSION

Our results suggest that laparoscopic injection of Db into the IHS is simple, safe, reliable, virtually scarless, and may be a reasonable alternative to standard open surgical inguinal hernia repair.

Mini-laparotomy and full laparotomy, but not laparoscopy, alter hepatic macrophage populations in a rat model

BACKGROUND

Immune function is better preserved by laparoscopic versus conventional surgery. Numerous mediators of the systemic trauma response are synthesized and/or regulated by the liver. However, it has been stated that the advantages of laparoscopic surgery are no more obvious when conventional operations are performed via mini-laparotomy. We set out to compare the impact of laparoscopy and mini- and full laparotomy on the hepatic macrophage populations.

METHODS

Male Lewis rats were subjected to anesthesia alone (control), mini-laparotomy (1 cm), full laparotomy (7 cm), or laparoscopy for 60 min. Endpoints were the total protein in the peritoneal lavage fluid, hepatic ED-1 cells (recruited monocytes), hepatic ED-2 cells (Kupffer cells), the expression of OX-6 in the liver, and C-reactive protein (CRP) in plasma.

RESULTS

Protein in the peritoneal lavage fluid increased significantly after all interventions. Full laparotomy was accompanied by an enhancement in ED-1-positive monocytes in the liver parenchyma compared to all other groups (p < 0.001). Mini- and full laparotomy led to an increase in ED-2-positive Kupffer cells (p < 0.001). Laparoscopy did not affect the number of monocytes/macrophages. There was no significant alteration of OX-6 expression in either group. No change in the cellular composition in the periportal fields was observed. The CRP plasma levels did not significantly differ between groups.

CONCLUSIONS

Laparoscopy completely prevents hepatic macrophage populations from expansion and normal cell disposition is preserved. Laparotomy, irrespective of incision size, increases the number of Kupffer cells. Moreover, full laparotomy, but not mini-laparotomy or laparoscopy, causes an increase in hepatic monocyte recruitment. The regulating pathways after surgery differ from other immunologic challenges, such as sepsis, in which immunocompetent cells accumulate and are stimulated in the periportal fields.

Laparoscopic injection of dermabond tissue adhesive for the repair of inguinal hernia: short- and long-term follow-up

PURPOSE

Is laparoscopic injection of 2-octyl-cyanoacrylate tissue adhesive (Dermabond: Db) into the inguinal hernia sac (IHS) effective for inguinal hernia repair?

METHODS

Thirty male 4-week-old Lewis rats were used as subjects for this study. In the right Db (R-Db) group (n = 10), a fine catheter was passed through an 18-guage indwelling intravenous cannula inserted in the right lower quadrant, and 0.2 mL Db was injected into the right IHS under laparoscopic control. The left side was not treated. Both IHSs were treated in the bilateral Db (B-Db) group (n = 10). In the no Db (N-Db or control) group (n = 10), only laparoscope insertion was performed. Herniography was performed before death. B-Db and N-Db rats were mated 50 days after treatment. Half of all rats were killed 2 months after treatment and the remaining half 12 months after treatment.

RESULTS

All rats survived until killing. Macroscopic findings postdeath confirmed herniography results; treated IHS were closed, and untreated IHS were patent. There were minor adhesions in 3 of 20 treated rats. Sperm were identified in the vaginas of all mated rats.

CONCLUSIONS

These results suggest that our new technique is simple, safe, and reliable as an alternative to standard operative repair for inguinal hernia.

Videoendoscopic endotracheal intubation in the rat: A comprehensive rodent model of laparoscopic surgery1,2

BACKGROUND

Peritoneal absorption of CO(2) during abdominal insufflation in laparoscopy may disrupt the acid-base equilibrium and alter the physiological response to stress. Current nonventilated rodent models of laparoscopy do not manage the CO(2) load of pneumoperitoneum, but ventilated surgical rodent models are invasive (tracheotomy) and may independently induce the inflammatory response.

MATERIALS AND METHODS

A comprehensive rodent model of laparoscopy was developed. Rats were randomized to receive anesthesia alone, anesthesia plus CO(2) pneumoperitoneum, or anesthesia plus CO(2) pneumoperitoneum with videoendoscopic intubation and mechanical ventilation. Arterial blood-gas analysis was performed at baseline and after 30 min of intervention.

RESULTS

Baseline pH, pCO(2), and HCO(3)(-) arterial blood gas parameters were normal for all rats. After 30 min, pCO(2) and pH changed slightly but remained normal among rats receiving anesthesia alone (pCO(2) = 46.5 +/- 1.9; pH = 7.365 +/- 0.009) whereas animals receiving anesthesia plus CO(2) pneumoperitoneum that were dependent on spontaneous respiration for ventilation developed significant hypercarbic acidosis (pCO(2) = 53.2 +/- 1.9, P < 0.05; pH = 7.299 +/- 0.011, P < 0.001). This acidosis was completely corrected with increased minute ventilation in intubated rats receiving mechanical ventilation (pCO(2) = 36.8 +/- 1.5, P < 0.001; pH = 7.398 +/- 0.011, P < 0.001).

CONCLUSIONS

CO(2) pneumoperitoneum induces significant hypercarbic acidosis in nonventilated rats. Noninvasive endotracheal intubation is feasible in the rat with videoendoscopic assistance. Our noninvasive rodent model of laparoscopic surgery controls for anesthesia- and capnoperitoneum-related acid-base changes and provides an environment in which the biological response to pneumoperitoneum can be studied precisely.

Modelo experimental de esplenectomia laparoscópica em ratos

OBJETIVO: Desenvolver um modelo de esplenectomia laparoscópica em ratos. MÉTODOS: Foram utilizados trinta e cinco ratos machos ( Rattus Norvegicus Albinus, linhagem Wistar),pesando 250 +/- 50 g .Os animais foram anestesiados com cetamina e xylazina e foi estabelecido pneumoperitônio de CO2 com pressão de 7 mmHg, através da agulha de Veress. Após pneumoperitônio, dois trocateres de 5 mm e um de 11mm foram alocados na parade abdominal obedecendo a triangulação. O ligamento gastroesplênico foi dissecado para mobilização do baço. Os vasos hilares foram dissecados e eletrocoagulados utilizando a pinça "Maryland" e o gancho "HooK". Um "endobag" adaptado, foi utilizado para retirar o orgão da cavidade abdominal. RESULTADOS: Um animal (2,86%) morreu na indução anestésica. Após um período de observação de oito dias, trinta animais sobreviveram (85,7 %) e quatro (11,42%) Morreram no pós-operatório imediato. Em relação às complicações, Aderências intra-abdominais foram encontradas em 25,71% dos animais (n=9). CONCLUSÃO: A esplenectomia laparoscópica é um modelo factível por conta da baixa taxa de mortalidade além do baixo custo para treinamento da técnica.

Modelo experimental de vasectomia laparoscópica em ratos

OBJETIVO: Descrever um modelo experimental de vasectomia laparoscópica em ratos. MÉTODOS: Foram utilizados 35 ratos Rattus norvegicus albinus da linhagem Wistar. Após a anestesia, os ratos foram submetidos ao pneumoperitôneo através da agulha de Veress com PCO2 de 7mmHg. Depois, foram transpassados pela parede abdominal um trocater de 11mm de espessura e dois trocateres com 5 mm de espessura. Através destes foram introduzidos na cavidade abdominal à ótica (10mm) e as pinças utilizadas na dissecção, cauterização e secção do canal deferente e seus vasos. RESULTADOS: Durante o ato operatório dois animais (5,74%) apresentaram sangramento, contido com cauterização. Ocorreu um óbito na indução anestésica (2,85%) e outro (2,85%) no quarto dia pós-operatório de causa não identificada. Após 08 dias havia 33 ratos vivos (94,28%). CONCLUSÃO: Neste modelo, o material cirúrgico é o mesmo utilizado em humanos e são aplicados todos os procedimentos básicos da cirurgia laparoscópica, tornando-o factível para o treinamento de acadêmicos, médicos residentes e cirurgiões.

The impact of carbon dioxide and helium insufflation on experimental liver metastases, macrophages, and cell adhesion molecules

BACKGROUND

Laparoscopic insufflation, proposed to reduce hepatic perfusion, may enhance hepatic tumor spread. It is unknown whether intraabdominal pressure or the gas itself influences hepatic tumor growth. In contrast to carbon dioxide, the alternative gas helium is believed to reduce malignant cell growth.

METHODS

For this study, 36 WAG/Rij rats were randomized in two experimental groups. The animals were laparoscopically insufflated with carbon dioxide ( n = 19) or helium gas ( n = 17). Liver metastases were induced by laparoscopic injection of 50,000 CC531 cells into the portal vein. Macroscopic and microscopic analyses of CC531 tumor cell growth, macrophages, and CD44v5, v6 were performed. Data were analyzed by Kruskal-Wallis, Dunn, and Holm tests.

RESULTS

No significant differences in macroscopic and microscopic analyses were found between carbon dioxide and helium gas insufflations ( p > 0.05).

CONCLUSIONS

Recent studies have shown that insufflation with carbon dioxide may result in increased hepatic tumor growth. The current study comparing carbon dioxide and helium insufflations could show for the first time either oncologic nor immunologic differences in relation to the liver between two different gases. In conclusion, elevated intraabdominal pressure during gas insufflation is responsible for hepatic disadvantages during pneumoperitoneum, not carbon dioxide gas itself.

Modelo experimental de hepatectomia parcial laparoscópica em ratos

OBJETIVO: Descrever um modelo experimental de hepatectomia parcial laparoscópica em ratos. MÉTODOS: Foram utilizados 35 ratos Rattus Norvegicus albinus da linhagem Wistar todos machos pesando 250+/-50g. Os animais foram anestesiados com cetamina e xilasina, e submetidos à insuflação através da agulha de Veress com PCO2 de 7mmHg. Após o pneumoperitôneo foram transpassados pela parede abdominal dois trocateres com 5 e um com 11 mm de espessura, de tal modo a formarem uma figura geométrica triangular. A ligadura de três lobos hepáticos (esquerdo, central esquerdo e central direito) foi feita utilizando-se o "endoloop" e a eletrocoagulação dos pontos hemorrágicos através do "hook". Os animais foram sacrificados após um período de observação de oito dias. RESULTADOS: Três animais (8,6%) morreram na indução anestésica. Após um período de observação de oito dias 30 animais sobreviveram (85,7%), e apenas 2 (5,7%) vieram a óbito no pós-operatório imediato. Quanto às complicações, a presença de granuloma foi observada em 54,3% dos ratos (n=19). Nenhuma conversão para a cirurgia aberta foi necessária. CONCLUSÃO: O modelo de hepatectomia parcial laparoscópica em ratos utilizando material cirúrgico semelhante ao usado em humanos é factível para o treinamento e aprimoramento de novos cirurgiões.

Impact of dopamine and endothelin-1 antagonism on portal venous blood flow during laparoscopic surgery

BACKGROUND

Recent data indicate that pneumoperitoneal carbondioxide (CO2) insufflation impairs hepatic macro- and microcirculation. Whether dopamine and endothelin-1 (ET-1) antagonists might restore liver blood during laparoscopic surgery has not yet been investigated.

METHODS

For this study, 30 male WAG/Rij rats were randomized into two groups to obtain pneumoperitoneum with CO2 (n=15) or helium (n = 15). All the animals were implanted with a polyethylene-50 cannula into the right vena jugularis and a Doppler ultrasound flow probe around the portal vein. In each group, the rats were administered dopamine (n = 5); JKC-10, JKC-301, which is a selective endothelin-1 (ET-1) antagonist (n = 5), or sodium chloride as a control (n = 5). Portal blood flow was measured during intraabdominal pressures 2 to 12 mmHg. Data were analyzed using the Kruskal-Wallis h-test.

RESULTS

The application of dopamine and ET-1 antagonists significantly improved portal blood flow over that of the control animals (p <0.05). No significant differences were found between CO2 and helium insufflation (P > 0.05).

CONCLUSIONS

Dopamine and ET-1 antagonism restore portal blood flow during laparoscopic surgery independently of the insufflation gas. Whether improved hepatic perfusion might have beneficial effects on liver function needs further investigation.

Impact of laparoscopic surgery on experimental hepatic metastases

BACKGROUND

Metastatic disease to the liver is one of the major factors determining outcome after colonic resection with curative intention. The influence of laparoscopic surgery on metastatic disease in the liver is still largely unknown.

METHODS

An intrasplenic tumour cell inoculation was performed in 30 WAG-Rij rats. After 7 days the rats were randomized into three operative groups: laparotomy (n = 10), laparoscopy with 7 mmHg carbon dioxide pneumoperitoneum (n = 10) and gasless laparoscopy (n = 10). A small bowel segmental resection was carried out in all rats. Some 21 days later the rats were evaluated for number and diameter of tumour nodules and cancer index score at eight different abdominal sites.

RESULTS

Hepatic tumour growth scored with the cancer index was significantly reduced in the gasless laparoscopy group compared with that in the carbon dioxide laparoscopy group (P = 0.04) and the laparotomy group (P = 0.02). Tumour growth at the port site and total tumour load were significantly reduced in the gasless group compared with the laparotomy group (P < or = 0.04).

CONCLUSION

Laparoscopy with carbon dioxide insufflation seems to stimulate the growth of dormant tumour cells into overt liver metastases. Gasless laparoscopy on the other hand may have a protective effect against metastatic disease in the liver. The promoting and inhibiting effects of laparoscopic procedures on growth of liver metastases need further evaluation.

Retroperitoneal minilaparoscopic nephrectomy in the rat model

OBJECTIVES

Development of small animal models for laparoscopic surgery is important for basic pathophysiologic and oncologic studies, instrument development, and surgical training. Although transperitoneal laparoscopy has been described in the rat, the technical feasibility of the retroperitoneoscopic approach for major renal surgery has not been reported previously. Herein, we describe the development of a rat model for retroperitoneal minilaparoscopic nephrectomy.

METHODS

Sixteen male Sprague-Dawley rats underwent a three-port bilateral retroperitoneoscopic nephrectomy using 2 and 3-mm instruments and optics exclusively. After developing the technique in 10 animals, the study was conducted in 6 animals. Following retroperitoneal balloon dilation and CO(2) pneumoretroperitoneum (mean 4.5 mm Hg), nephrectomy was accomplished by intracorporeal en bloc ligation of the renal pedicle. To prevent peritoneal entry, the anterior surface of the kidney was mobilized subcapsularly. Volume of the created retroperitoneal space and peritoneal integrity were confirmed by a contrast x-ray study. Intraperitoneal pressure was monitored constantly during the procedure.

RESULTS

Mean surgical time was 74.5 minutes (range 60 to 95) and estimated blood loss was less than 1 mL. Mean volume of the retroperitoneal space was 8.4 mL after initial balloon dilation, and 11.5 mL after nephrectomy. Mean weight of the excised kidneys was 1. 4 g. Inadvertent peritoneotomy occurred during 3 of 12 study nephrectomies. Complications included renal artery hemorrhage leading to death in 1 animal and renal vein injury in 1 animal.

CONCLUSIONS

Laparoscopic retroperitoneal nephrectomy in the rat model is technically feasible. This novel small animal model can be used for further studies of the retroperitoneal laparoscopic approach.

Carbon dioxide pneumoperitoneum is associated with increased liver metastases in a rat model

BACKGROUND

In patients with primary colorectal cancer, liver metastases are the most important indicators of prognosis and survival; the effect of laparoscopic surgery on the development of hepatic tumor spread is still largely unknown.

METHODS

Thirty WAG/Rij rats were randomly divided into 3 operative groups for intraportal tumor cell inoculation: carbon dioxide pneumoperitoneum (group I, n = 10), gasless laparoscopy (group II, n = 10) and open laparotomy (group III, n = 10). The total operating time was 90 minutes with tumor cell injection (50,000 CC531 colon carcinoma cells/mL) performed 45 minutes after the start of the procedure. Hepatic tumor growth and the total tumor load were evaluated 28 days after surgery.

RESULTS

Hepatic tumor growth and total tumor load were significantly reduced in the gasless laparoscopy group (group II) as compared with the carbon dioxide pneumoperitoneum group (group I) and the open laparotomy group (group III) (P < .05). No significant difference was found between the carbon dioxide and the open laparotomy groups.

CONCLUSIONS

Insufflation of carbon dioxide may actually stimulate metastatic disease of the liver. Gasless laparoscopy seems to preserve hepatic resistance against tumor growth.

Impact of laparoscopic colonic resection on tumour growth and spread in an experimental model

BACKGROUND

The influence of surgical manipulation and carbon dioxide pneumoperitoneum on intraperitoneal tumour growth and port-site metastasis during laparoscopic colon resection is still unknown.

METHODS

Some 33 male WAG/Rij rats were randomized into three experimental groups: a laparoscopy group with carbon dioxide pneumoperitoneum (n = 11), a gasless laparoscopy group (n = 11) and a laparotomy group (n = 11). After transanal injection of a tumour cell suspension (1 x 106 CC 531 cells) into the distal colon, a colon segment resection and an end-to-end anastomosis (laparoscopy; intra-abdominal technique) were performed. Tumour growth was scored semiquantitatively 24 days after the operation. Data were analysed by the Kruskal-Wallis test.

RESULTS

The tumour indices from the four locations with the greatest tumour growth were significantly decreased in the laparoscopy group with carbon dioxide pneumoperitoneum compared with the gasless laparoscopy and laparotomy groups (P < 0.01). Port-site metastases were significantly decreased in the carbon dioxide pneumoperitoneum group compared with the gasless laparoscopy group (P = 0.05).

CONCLUSION

A full laparotomy incision promotes greater tumour growth than does carbon dioxide pneumoperitoneum. Surgical manipulation stimulates local tumour spread more than the establishment of a carbon dioxide pneumoperitoneum.