PMC:6705338 / 7562-14130 JSONTXT

{"project":"2_test","denotations":[{"id":"31432994-26537141-396043","span":{"begin":2997,"end":2999},"obj":"26537141"}],"text":"Methods\nThe study respected the Brazilian legislation on the use of experimental animals (Lei Arouca no. 11.794/2008) and the standards of the Brazilian College of Animal Experimentation (COBEA). It was analyzed and approved by the Ethics Committee on the Use of Animals (CEUA) of Universidade Federal do Maranhão, registration no. 23115.011726/2016-51.\nSurgical procedures were performed at the Experimental Surgery Research Laboratory, Hospital Universitário, UFMA. Thirty Wistar rats (Rattus norvegicus albinus), adult males, with a mean weight of 307 ± 33 g, and 60 days of life, were selected from the Bioterium of UFMA. The animals were kept in a polypropylene cage under constant environmental conditions, receiving a ration for rats and water ad libitum for seven days for adaptation. There was noise control. The temperature was 22°C ± 2°C, the relative humidity was 40% to 60%, and the light/dark cycles were of 12/12 hours.\nRats were randomly assigned into three groups of ten animals (Fig. 1). A median laparotomy and the repair of a repaired abdominal wall defect were performed with a 4x3 cm mesh implanted intraperitoneally according to the selected group. Group 1: polypropylene mesh - OPTILENE® Mesh (B.Braun Surgical SA, Barcelona, Spain); group 2: polypropylene mesh with polyglecaprone - PHYSIOMESH® Flexible Composite Mesh (Ethicon, Somerville, NJ, USA); and group 3: a polyester mesh with collagen previously hydrated with 0.9% saline for one minute - SYMBOTEX® Composite Mesh (Covidien, Trévoux, France).\nFigure 1 Design of the experimental research comparing the intraperitoneal implant of three different types of meshes (polypropylene versus polypropylene with polyglecaprone versus polyester with porcine collagen) in Wistar rats.\nAfter a fasting of 12 hours, the rats were anesthetized with a mixture of 2% xylazine hydrochloride at a dose of 10 mg/kg and 10% ketamine hydrochloride at a dose of 100 mg/kg intramuscularly using a hypodermic needle of 13 mm x 4.5 mm on the posterior border of the left thigh. The evaluation of the efficacy of anesthesia was verified by the loss of the corneal-eyelid reflex and the reflex of the interdigital pressure. A manual epilation of the abdominal region was performed. The antisepsis was performed with polyvinyl-pyrrolidone-iodine, and then a fenestrated field was placed.\nThe animals were submitted to a laparotomy through a medial incision with 4 cm of extension immediately caudal to the xiphoid appendix, and dieresis planes with dissection between the cutaneo-adipose and musculoaponeurotic planes up to 2 cm on each side of the median line followed by opening of the abdominal cavity in the alba line measuring 2.5 cm with one suture point with polypropylene 4.0 (PROLENE® Ethicon, Somerville, NJ, USA) on each side of the incision, everting the edges of the abdomen rectum muscle, without covering the peritoneum, thus creating a defect with 2.5 x 1.5 cm (area = 3.75 cm2), without any need for abdominal wall resection12 (Fig. 2). According to the allocation, one of the synthetic meshes with 4 x 3 cm (area = 12 cm2) was implanted intraperitoneally by six transfixing “U” points in the musculoaponeurotic plane with a polypropylene 4.0 thread (PROLENE®, Ethicon, Somerville, NJ, USA) applied at the four corners of the mesh and at the midpoint between the caudal and cranial point on each side thereof. The nodes remained in the previously dissected subcutaneous space. The synthesis of the skin was performed with continuous transdermal suture not anchored with polyglactin 4.0 (NOVOSYN®, B.Braun Surgical S.A., Barcelona, Spain).\nFigure 2 Preparation of the defect in the abdominal wall (A) and fixation of the polypropylene mesh (B), polypropylene with polyglecaprone (C) and polyester with porcine collagen (D).\nThe analgesia in the immediate postoperative period was performed with paracetamol drops at a concentration of 200 mg/mL diluted in 100 mL of water and offered ad libitum. In post-operative, daily observations of the wound and of the general conditions of the animal were performed to identify and record possible post-operative complications (dehiscence, evisceration, seroma, hematoma, surgical site infection, and death).\nAfter 21 days, the rats were killed with a mixture of 2% xylazine hydrochloride at the dose of 40 mg/kg and 10% ketamine hydrochloride at the dose of 400 mg/kg intramuscularly. Death was characterized by respiratory arrest and complete absence of reflexes. A U-shaped incision was made involving all anatomical planes of the anterior abdominal wall, bordering the lateral borders of the abdominal wall (lateral borders) and the groin (lower border). The flap remained attached only to the costochondral border (Fig. 3). An analysis of the possible adhesions between the abdominal visceral structures and the visceral surface of the implanted meshes was carried out, in addition to an evaluation of the degree of adhesions according to Lamber et al.16(Table 1), as well as the determination of which organs were involved in this process and which sectors of the mesh were compromised, according to Figure 4. Each mesh was evaluated with a grid of nine quadrangular sectors: eight peripheral and one central sector.\nFigure 3 Reopening of abdominal wall in “U-shaped” (A and B).\nTable 1 Classification of the degree of adhesions between the abdominal viscera and the surface of the visceral face of intraperitoneally implanted meshes16.\nType of Adhesions Intensity of adhesions Definition\n0 None Absence of adhesions\n1 Little Fine adhesions for easy release\n2 Moderate Adhesions requiring a blunt dissection to be released\n3 Intense Firm adhesions, which require a higher force to release them, producing partial or total injury of the viscera involved.\nFigure 4 Adhesions with bilateral epididymal fat (A), omentum (B), liver (C), and lysis of adhesions between the mesh and the abdominal viscera (D).\nIn the analytical statistical evaluation, the Fisher’s exact test was used for the qualitative variables. The test was bilateral with a significance level of 5% (p value\u003c0.05). For analysis of quantitative variables, we used the ANOVA analysis of variance for parametric data and the Kruskal-Wallis test for non-parametric data. The test was bilateral with a significance level of 5%. The analysis of variance was performed by F test, and the normality test by Shapiro-Wilk test. The results of analytical statistics were presented as tables and box-plot graph. The software BioEstat®, version 5.3 (AnalystSoft), was used for statistical analysis."}