RESUMEN
BACKGROUND: Currently, absorbable meshes are used as temporary closure in case of laparostoma. Unfortunately the multifilament polyglycolic acid (PG) meshes with small pores reveal little elasticity acting rather as a fluid barrier than permitting drainage of intra-abdominal fluids. Therefore, a new mesh was constructed of absorbable polydioxanon monofilaments (PDS) with increased porosity and longer degradation time. MATERIAL AND METHODS: For evaluation of the tissue response the new PDS mesh was implanted as abdominal wall replacement in each five rats for 7, 21, or 90 days, respectively, and compared to a PG mesh. Histological analysis included HE staining with measurement of the size of the granuloma and immunoshistochemistry for TUNEL, Ki67, TNF-R2, MMP-2, YB1, FVIII, gas6, AXL. Parameters for neovascularization and nerve ingrowth were analyzed. RESULTS: The inflammatory and fibrotic tissue reaction is attenuated with PDS in comparison to PG, e.g., the size of the granuloma was smaller with less cell turnover, and less remodeling as represented by, e.g., reduction of apoptosis, expression of MMP-2, or TNF-R2. The number of ingrowing nerves and vessels explored via AXL, gas6, and factor VIII was increased in the PDS mesh. CONCLUSION: The results from the present investigation showed that a mesh can be constructed of monofilament PDS that induce significant less inflammatory and fibrotic reaction, however permits fluid drainage and preserves elasticity.
Asunto(s)
Materiales Biocompatibles , Polidioxanona , Ácido Poliglicólico , Mallas Quirúrgicas , Cicatrización de Heridas/fisiología , Animales , Colágeno Tipo I/metabolismo , Colágeno Tipo III/metabolismo , Granuloma de Cuerpo Extraño/patología , Masculino , Modelos Animales , Ratas , Ratas Sprague-DawleyRESUMEN
Abdominal hernia repair is the most frequently performed operation in surgery. Mostly due to lowered recurrence rates mesh repairs in hernia surgery have become an integral component despite increasing mesh-related complications. Current available mesh prosthesis are made of polypropylene (PP). polyethylene-terephtalat or polytetrafluorethylene. though all of them reveal some disadvantages. The introduction of new materials seems to be advisable. Caused by supposed advantageous textile properties and tissue response two mesh modifications made of polyvinylidene fluoride (PVDF) for abdominal hernia repair were developed. In the present study the PVDF meshes were compared to a common heavy weight PP-mesh (Prolene) in regard to functional consequences and morphological tissue response. After implantation in rats as inlay for 3, 14, 21, 42 and 90 days abdominal wall mobility was recorded by three-dimensional photogrammetry. Tensile strength of the suture zone and the mesh itself were determined. Explanted tissue samples have been investigated for their histological reaction in regard to the inflammatory infiltrate. vascularisation, connective and fat tissue ingrowth. Number of granulocytes, macrophages, fibroblasts, lymphocytes and foreign giant body cells have been evaluated to reflect quality of tissue response. The cellular response was grasped by measurement of DNA strand breaks and apoptosis (TUNEL), proliferation (Ki67) and cell stress (HSP70). Analyzing the results confirmed that construction of hernia meshes made of PVDF could be an advantageous alternative to the commonly used materials due to an improved biostability. lowered bending stiffness and a minimum tissue response.
Asunto(s)
Membranas Artificiales , Polivinilos/química , Mallas Quirúrgicas , Animales , Fibroblastos/fisiología , Granulocitos/fisiología , Macrófagos/fisiología , Masculino , Presión , Ratas , Ratas Wistar , Relación Estructura-Actividad , Propiedades de Superficie , Resistencia a la Tracción , Textiles , Pesos y MedidasRESUMEN
BACKGROUND: Isoperistaltic colon is preferred to antiperistaltic colon for esophageal replacement, but experimental data do not exist to support this practice. METHODS: In 7 dogs a 20 cm long colon loop was interposed between the skin and the small bowel, isoperistaltically in 3 dogs and antiperistaltically in 4 dogs. Three months later five strain-gauges were implanted and evacuation was investigated by motility testing, barium studies, and scintigraphy. RESULTS: Motility recording showed normal colon motility in the excluded loops. Quiescent states (duration 40.2 +/- 13.6 minutes) were followed by contractile states (duration 7.5 +/- 2.4 minutes, frequency 3.3 +/- 0.6 per minute). The main peristaltic direction of isoperistaltic loops was isoperistaltic, and the main peristaltic direction of antiperistaltic loops was antiperistaltic. Evacuation took place exclusively during the contractile status. Half time emptying was more rapid in isoperistaltic loops (35 +/- 11 vs 69 +/- 16 minutes). The content of antiperistaltic loops was held back by antiperistaltic activity. Application of oatmeal porridge into the loops shortened the quiescent status from 40.2 to 13.2 +/- 4.8 minutes. CONCLUSIONS: The colon graft for esophageal replacement is an active system. Food is stored during the quiescent states and evacuated during the contractile states. The original peristaltic direction is preserved so that retroperistalsis in antiperistaltic loops may lead to patient discomfort and pulmonary complications.
Asunto(s)
Colon/fisiología , Colon/trasplante , Esófago/fisiología , Esófago/cirugía , Animales , Perros , Fluoroscopía , Peristaltismo , Procedimientos de Cirugía PlásticaRESUMEN
Two-third-resections of the proximal or distal small bowel with and without artificial valves were performed in rats. Intestinal adaptation led to a significant increase in bowel diameter, villus height and villus diameter and consequently in absorptive mucosal surface area per unit of serosal area. Additional artificial valve construction did not affect the calculated mucosal surface area after proximal resection, while it significantly decreased the absorptive area by the occurrence of large, plump villi after distal resection. There was no change in small-intestinal absorption of water, glucose and electrolytes per unit mucosa with valve construction. DNA cytometry showed that artificial valves led to mucosal hyperplasia without hypertrophy. These morphological changes coincided with a significant increase in basal and stimulated gastrin release. The body weight was unchanged or even worse in the valve groups than after resection alone, despite a significantly prolonged transit time. Therefore, in our study, artificial valves did not result in functional improvements after small intestinal resections.
Asunto(s)
Adaptación Fisiológica , Intestino Delgado/fisiopatología , Intestino Delgado/cirugía , Prótesis e Implantes , Síndrome del Intestino Corto/fisiopatología , Síndrome del Intestino Corto/cirugía , Animales , Gastrinas/metabolismo , Absorción Intestinal , Intestino Delgado/metabolismo , Intestino Delgado/patología , Masculino , Ratas , Ratas Sprague-Dawley , Síndrome del Intestino Corto/metabolismo , Síndrome del Intestino Corto/patologíaRESUMEN
In an animal experimental study we examined the postoperative recovery of the motility of the upper gastrointestinal tract after operative treatment of a benign gastric outlet obstruction. At 45 Days after induction, a duodenal stenosis was resected in six dogs, and resolved by Finney's duodenoplasty in another six dogs. Fourteen days after segmental resection, the gastric emptying was faster [half evacuation time (T1/2) for semisolid food = 44.4 +/- 16.8 min] than following duodenoplasty [T1/2 = 56.8 +/- 25.3). Here motor migrating complexes (MMCs) started in the antrum and could be traced down to the jejunum. After segmental resection we recognized MMC only distal to the anastomosis. The duration of the whole MMC cycle (69.0 +/- 18.6 min) as well as of the single phases was significantly shorter in the resection group than after duodenoplasty (108.0 +/- 15.1 min). At 28 days after operation the differences in the electromyographic findings were smaller (82.0 +/- 15.1 min vs. 111.4 +/- 11.2 min), but still significant. Obviously humoral transmitters and the extrinsic neural system lead to good propagation of the MMC across the anastomosis, even before the intramural pathways are reestablished. Concerning the fast recovery of the motility of the upper gastrointestinal tract, duodenoplasty is superior to segmental duodenal resection.
Asunto(s)
Duodeno/cirugía , Obstrucción de la Salida Gástrica/cirugía , Motilidad Gastrointestinal/fisiología , Estómago/cirugía , Animales , Perros , Obstrucción Duodenal/cirugía , Electromiografía , Vaciamiento Gástrico/fisiología , Yeyuno/fisiología , Complejo Mioeléctrico Migratorio/fisiología , Procedimientos de Cirugía PlásticaRESUMEN
OBJECTIVE: To develop a new mesh for hernia repair that is adapted to the physiological forces. DESIGN: Animal experiment. SETTING: Surgical Department of the RWTH-Aachen. ANIMALS: Wistar rats MAIN OUTCOME MEASURES: Textile analysis, tensile strength, bending stiffness, histology and morphometry. RESULTS: After textile analysis of commercially available meshes in clinical use we defined the physiological forces and constructed a new mesh (Soft Hernia Mesh, SHM) based on a combination of non-absorbable polypropylene and absorbable polyglactin 910. The amount of non-absorbable material could be reduced to < 30% compared with Marlex while still guaranteeing the necessary pulling force of 16 N/cm. Improvements of the hosiery structure improved the symmetrical distribution of the retaining forces in all directions. Compared with the considerable restriction of the abdominal wall mobility by Prolene (polypropylene) and Mersilene (polyester) meshes there was no increase in the bending stiffness after the implantation of the new mesh. Histological examination showed a pronounced reduction of the inflammatory reaction in the tissues, and the collagen bundles were orientated merely around the mesh filaments instead of forming a scar plate that completely embedded the mesh. CONCLUSION: Different meshes caused specific histological reactions with changes of their mechanical properties after implantation in rodents. A new mesh with a reduced amount of polypropylene showed both less inflammation and less restriction in the mobility of the abdominal wall though it exceeded the required tensile strength of 16 N/cm.
Asunto(s)
Músculos Abdominales/fisiología , Hernia Ventral/cirugía , Prótesis e Implantes , Mallas Quirúrgicas , Animales , Materiales Biocompatibles , Masculino , Ensayo de Materiales , Tereftalatos Polietilenos/uso terapéutico , Polipropilenos/uso terapéutico , Diseño de Prótesis , Ratas , Ratas Wistar , Resistencia a la TracciónRESUMEN
OBJECTIVE: To assess the extent of shrinkage of meshes used for hernia repair. DESIGN: Experimental study in dogs. SETTING: University hospital, Germany and University Research Centre, Moscow. ANIMALS: 10 dogs had monofilament polypropylene meshes that weighed 95 g/m2 (Marlex) or multifilament reduced polypropylene meshes combined with polyglactin 910 that weighed 55 g/m2 (Soft Hernia Mesh) implanted for either 3 or 6 months. MAIN OUTCOME MEASURES: Histological appearance and radiological assessment of the position and area of the mesh. RESULTS: After 4 weeks the area of mesh in the monofilament group was reduced from to 139 (11) to 75 (8) cm2 (54%) and that of the multifilament from 116 (18) to 77 (20) cm2 (66%). The multifilament mesh with the reduced amount of polypropylene showed less inflammatory response and less shrinkage. The mesh did not seem to have moved. CONCLUSION: Meshes that contain a lot of polypropylene shrink to about 30%-50% of their original size after 4 weeks, requiring an overlap of at least 3 cm if implanted subfascially. Reduction in the polypropylene content decreases both the inflammatory response and the shrinkage. Meshes with big pores are less likely to fold and improve compatibility.
Asunto(s)
Polipropilenos , Mallas Quirúrgicas , Animales , Perros , Poliglactina 910RESUMEN
The use of biomaterials for closure of incisional hernias requires meshes adjusted to the physiological forces. The intraabdominal pressure is mainly influenced by the activity of the transverse muscles. The abdominal fascia of corpses withstands forces of 60-80 N/cm in horizontal and 20-30 N/cm in vertical direction; tearing of sutures occurs below 30 N/cm in horizontal direction. Assuming the abdominal cavity to be a thin hollow sphere, the rupture forces are approximately 4-16 N/cm for a diameter of 8-3 cm. The meshes currently in use are much stronger than this, rupturing at 40-100 N/cm. The curvature of the abdominal surface can be measured by 3D-photogrammetry and is highly significantly reduced following mesh implantation (t-test, 2-sided, P < 0.01). Reduction of the mesh material can decrease the rate of local wound complications and the stiffness of the abdominal wall.
Asunto(s)
Músculos Abdominales/cirugía , Hernia Ventral/fisiopatología , Complicaciones Posoperatorias/fisiopatología , Dehiscencia de la Herida Operatoria/fisiopatología , Músculos Abdominales/fisiopatología , Animales , Hernia Ventral/cirugía , Humanos , Presión Hidrostática , Procesamiento de Imagen Asistido por Computador , Fotogrametría , Complicaciones Posoperatorias/cirugía , Mallas Quirúrgicas , Dehiscencia de la Herida Operatoria/cirugía , Técnicas de Sutura , SuturasRESUMEN
The use of biomaterials for incisional hernia markedly reduces the recurrence rates. Disadvantages are high rates of local wound complications and restriction of mobility by the rigid "shell". The abdominal wall mobility after mesh implantation is analysed for eight different mesh materials. The initial textile testing reveals relevant differences in structure with marked asymmetry in the different directions. The materials are implanted as inlay in rats for 3, 7, 14, 21 and 90 days. The deformation of the abdominal wall following intraabdominal pressure of 0-70 mmHg (0-9.81 kPa) is documented by 3D-photogrammetry, the tensile strength by tearing of excised strips of mesh. Three commercial available materials and two laboratory modifications lead independently of their textile characteristics to a marked restriction of the rounded configuration of the abdominal wall. The tensile strength exceeds by far the physiologically necessary value of 16 N/cm. Three newly developed meshes made of multifilament polypropylene with reduced amounts of material (21% and 28% relative to Marlex) lead to no restriction of the abdominal wall configuration yet have uncompromised stability. It might be possible to reduce the rate of local wound complications by the use of these newly developed meshes.
Asunto(s)
Músculos Abdominales/cirugía , Procesamiento de Imagen Asistido por Computador/instrumentación , Contracción Isométrica/fisiología , Ensayo de Materiales/instrumentación , Fotogrametría/instrumentación , Polipropilenos , Mallas Quirúrgicas , Músculos Abdominales/patología , Músculos Abdominales/fisiopatología , Animales , Fenómenos Biomecánicos , Gráficos por Computador , Ratas , Resistencia a la TracciónRESUMEN
Clinical observations following laparoscopic surgery indicate a shorter period of postoperative ileus than after conventional surgery. The aim of our study was to verify disorders of postoperative motility of the small intestine by means of implanted electrodes after laparoscopic and conventional cholecystectomy (CHE) in an animal model. Four weeks after implantation of three electrodes on the jejunum, CHE was performed laparoscopically in 5 dogs and in an additional 5 dogs by laparotomy. Independent of the type of operation, normal motility (especially the migrating motility complex) was abolished during the early postoperative period. Electrical activity was characterized by the basic electrical rhythm. Time to the occurrence of the first postoperative activity front, indicating restoration of motility, varied significantly depending on the type of operation: It was 5.5 +/- 1.0 hours after laparoscopic CHE and 46 +/- 5 hours after conventional CHE. These results support the hypothesis that small peritoneal incisions and less manipulation of the intestine during laparoscopic surgery result in reduced abdominal trauma.
Asunto(s)
Colecistectomía Laparoscópica/efectos adversos , Motilidad Gastrointestinal , Complicaciones Posoperatorias , Animales , Colecistectomía/efectos adversos , Perros , Complejo Mioeléctrico MigratorioRESUMEN
First descriptions of clinical courses after laparoscopic cholecystectomy indicate a shorter period of postoperative ileus in comparison to conventional cholecystectomy. Early postoperative motility was registered in dogs (n = 10) by implanted serosal electrodes. Further on clinical signs of postoperative motility were documented in patients (n = 100) after laparoscopic and conventional cholecystectomy. In animal experiments a significantly reduced period of postoperative ileus (5.5 +/- 1 h) occurred after laparoscopic cholecystectomy in comparison with the conventional technique (46 +/- 5 h). Experimental data correlate well with earlier clinical signs of normal motility after laparoscopic cholecystectomy in patients. The shorter period of postoperative ileus is a further evidence for the minor abdominal trauma of laparoscopic techniques.