A randomized trial of abdominal incision suture technique and wound strength in rats

The effect of different temporary abdominal closure techniques on fascial wound healing and postoperative adhesions in experimental secondary peritonitis

BACKGROUND

Secondary peritonitis causes considerable mortality and morbidity. New strategies have been introduced like relaparotomy and temporary abdominal closure in the management of such persistent intra-abdominal infections.

MATERIALS AND METHODS

Rats were divided into five groups each having ten animals. After induction of peritonitis, relaparotomies were done, and the abdomen was closed by different temporary abdominal closure techniques. After performing two relaparotomies during a 48-h period, all fascias closed primarily and incisional tensile strengths, hydroxyproline contents, and adhesions were measured on the following seventh day.

RESULTS

The median values of tensile strength and hydroxyproline concentrations were lowest in skin-only closure rats. Intraperitoneal adhesion scores were highest in Bogota bag closure group.

CONCLUSION

Primary, Bogota bag, and polyprolene mesh closures seem to be safe in terms of early fascial wound healing. Although it is easy to perform, skin-only closure technique has deleterious effects on fascial wound healing probably due to fascial retraction. Interestingly, Bogota bag has caused increased intraperitoneal adhesion formation.

Abdominal wall healing in reoperated rats

PURPOSE: Experimental evaluation of the abdominal wall healing in reoperations on the same surgical site, by means of macroscopic analysis, histological and breaking strength studies of the surgical scar. METHODS: Twenty-four rats were selected and divided in 3 groups (G1, G2 and G3). A medium longitudinal laparotomy was performed, followed by laparorrhaphy on two synthesis planes, using an interrupted suture technique. The reoperations were performed in the same way, on the same surgical site. On the first day of the study all the 24 rats were operated, on the 30th day the 16 animals belonging to G2 and G3 were reoperated, and finally, on the 60th day, the 8 rats from G3 were operated for the third and last time. After 30 days of the last laparotomy of each group, euthanasia was performed. Complications such as adhesions were evaluated during the resection of surgical site. The breaking strength study was performed next, followed by the microscopical collagen analysis, using for that histological cuts stained with picrosirius. RESULTS: The adhesions were prevalent in G2 and G3 (16% each) when compared to G1. No significant difference was found in the breaking strength study. Statistically significant difference was observed in collagen concentration analysis. It was found higher mature collagen (type I) as well as total collagen concentration in the groups operated more than once (G2 and G3). The highest concentration of mature collagen (p<0,0001) and total collagen (p<0,0021) were found in G3 followed by G2 and G1 (in this sequence). CONCLUSION: The highest mature collagen concentration on the experimental groups, points out the importance of inflammatory activity in the healing process; in the resutures of the abdominal wall the surgical scar maturity is faster acquired than in the primary sutures; in relation to the primary sutures, the resutures of the abdominal wall did not influence in the resistance of the surgical scar.

Avaliação fitoterápica da Jatropha gossypiifolia L. na cicatrização de suturas na parede abdominal ventral de ratos

INTRODUÇÃO: A espécie vegetal Jatropha gossypiifolia L., conhecida também como pião roxo, é utilizada na medicina popular como cicatrizante, anti-hipertensivo, purgativo e diurético. OBJETIVO: Avaliar a influência da administração intraperitoneal da Jatropha gossypiifolia L., na cicatrização de suturas da parede abdominal ventral de ratos, observando-se os seus aspectos macroscópicos, tensiométricos e microscópicos. MÉTODOS: Foram utilizados no procedimento 40 ratos da linhagem Wistar, machos, distribuídos em dois grupos de 20. Após incisão da parede e abertura da cavidade abdominal, foi instilado 1 ml/kg/peso de cloreto de sódio a 0,9% no grupo controle e no grupo Jatropha o extrato bruto etanólico da Jatropha gossypiifolia L., na concentração de 1 ml/kg/ peso. Realizou-se a sutura da parede abdominal com fio de polipropileno, com pontos separados. Os animais foram avaliados na sua evolução pós-operatória e mortos em dois subgrupos, no 3º e 7º dia. Analisou-se a parede abdominal ventral macroscopicamente, mediu-se a força de resistência a tensão e foram estudados os aspectos histológicos do reparo cicatricial. RESULTADOS: No exame macroscópico encontraram-se aderências mais intensas nos subgrupos Jatropha no 3º e 7º dia. A avaliação tensiométrica foi significantemente maior nos subgrupos Jatropha no 3º e 7º dia. A avaliação histológica comparativa entre os subgrupos demonstrou que o processo inflamatório agudo foi significantemente maior no subgrupo Jatropha no 3º e 7º dia; a neoformação capilar foi significantemente maior no 3º dia pós-operatório do subgrupo Jatropha sendo os outros parâmetros histológicos semelhantes. CONCLUSÃO: O uso do extrato bruto de Jatropha gossypiifolia L. intraperitoneal não demonstrou melhora significativa no processo de cicatrização da sutura da parede abdominal ventral de ratos com a dose e concentração utilizadas.

Análise da cicatrização na Linha Alba com uso de extrato aquoso de Orbignya phalerata (babaçu): estudo controlado em ratos

INTRODUÇÃO: O mesocarpo do babaçu (Orbignya phalerata) tem sido utilizado em estudos experimentais para verificar a sua ação antiinflamatória. No Maranhão, é muito utilizado como alimento e como remédio popular para cicatrização de ferimentos. OBJETIVO: Avaliar macroscópica, histológica e tensiometricamente, a ação do extrato de Orbygnia phalerata no processo de cicatrização de laparotomias medianas em ratos. MÉTODOS: Quarenta ratos da linhagem Wistar, adultos, machos, foram utilizados em procedimento experimental que consistiu em uma incisão na linha alba e síntese em plano único com pontos separados de fio de polipropileno 5-0. Após esse procedimento comum, os animais foram distribuídos em dois grupos de 20. Ao grupo chamado controle, foi utilizado injeção intraperitoneal, em dose única de 1mL de soro fisiológico para cada quilo de peso. Ao grupo experimento, utilizou-se solução aquosa de babaçu na dose de 50 mg por quilo de peso. Os animais foram acompanhados e mortos após três e sete dias, procedendo-se, a seguir, à análise tensiométrica e histológica. RESULTADOS: O exame macroscópico não mostrou presença de aderências importantes entre a linha alba e os órgãos intra-abdominais nos grupos de estudo. A avaliação histológica mostrou efeito marginalmente significativo (p=0,086) para inflamação aguda nos grupos controle e experimento de três dias e efeito significativo (p=0,003) para a reação gigantocelular (p=0,003). Diferença significativa (p-=0,023) foi observada para inflamação aguda no grupos controle experimento de sete dias. Na análise intra-grupo (controle três e sete), foi observado efeito marginalmente significativo (p=0,094 e p=0,05) respectivamente para as variáveis inflamação aguda e crônica. Na análise somente entre os grupos experimentos, as variáveis reação gigantocelular (0,002) e colagenização (0,016) apresentaram resultado significativo. A avaliação tensiométrica mostrou diferença significativa em relação ao grupo experimento de sete dias, que ofereceu melhor resistência do que os outros grupos. CONCLUSÃO: As avaliações histológica e macroscópica não mostraram diferenças significativas entre o extrato e a solução salina; quanto à tensiométrica, o grupo experimento de sete dias apresentou diferença significativa em relação ao grupo controle de mesmo período de pós-operatório, sugerindo indícios de que o uso do extrato administrado intraperitonealmente favorece o processo de cicatrização.

Comparison of Bursting Pressure of Abdominal wall Defects Repaired by Three Conventional Techniques

Still debated are the appropriate techniques for the repair of abdominal wall defects and the methods used to measure their strength. Although tension has been used in many studies to test wound strength, bursting pressure reflects more accurately the pathophysiology of wound dehiscence. The aim of the current study was to evaluate three different techniques for closure of abdominal wall defects using a new and more accurate device for bursting pressure measurements. Full thickness abdominal wall defects measuring 2 cm2 were created in 43 anesthetized rats randomly assigned to three groups: simple primary closure (n = 15), Mayo repair (n = 14), and primary closure reinforced with a mesh (n = 14). Thirty days after surgery, the rats were sacrificed. The abdominal wall was fully excised and placed over a bursting chamber made of a metal cylinder connected to a carbon dioxide source with a control valve and a manometer. Gas was gradually released while the pressure was recorded until bursting occurred. Disruption of all closures occurred at the point where the suture itself penetrated the tissue. The average bursting pressure was 1383 ± 299 mm Hg for the primary closure group, 1200 ± 409 mm Hg for the mesh reinforcement group, and 1607 ± 337 mm Hg for the imbrication repair (Mayo) group ( P < 0.03). The data suggests an advantage for the Mayo repair over the other two repairs. The bursting chamber tested is a new and more reliable method to study techniques and conditions influencing the strength of abdominal wall closure.

Comparison of PTFE, pericardium bovine and fascia lata for repair of incisional hernia in rat model, experimental study

Incisional hernia is a frequent complication of abdominal surgery developing in 11-20 % of patients undergoing an abdominal operation. Regarding morbidity and loss of manpower, incisional hernias continue to be a fundamental problem for surgeons. In this experimental study, three commonly used mesh materials (Goretex PTFE; Tutoplast Fascia lata; Tutopatch Pericardium bovine) were compared according to effectiveness, strength, adhesion formation, histological changes, and early complications. Three groups, each consisting of 14 rats, have been formed as group A: polytetrafluoroethylene (PTFE), group B: pericardium bovine and group C: fascia lata. Evaluations were achieved at the end of the first and second postoperative week, respectively. Adhesion formation, wound maturation, bursting pressure, and tensile strength were evaluated. No statistically significant difference regarding adhesion formation was observed between groups although adhesion formation was less significant in PTFE and pericardium bovine groups than in the fascia lata group. Bursting pressure and tensile strength values were significantly higher in PTFE group than in the fascia lata group ( P<0.05). No statistically significant difference was observed between groups regarding wound maturation. In this experimental model, PTFE and pericardium bovine were found to be superior to fascia lata in abdominal wall repair.

Fascial incisions heal faster than skin: a new model of abdominal wall repair

BACKGROUND

Optimal healing of the fascial layer is a necessary component of complete abdominal wall repair. The majority of acute wound healing studies have focused on the dermis. We designed a model of abdominal wall repair that, to our knowledge, for the first time simultaneously characterizes differences in the wound healing trajectories of the fascia and skin.

METHODS

Full-thickness dermal flaps were raised on the ventral abdominal walls of rats, and midline fascial celiotomies were completed. The dimensions of the flap were developed so as to have no detrimental effect on skin healing. The dermal flaps were replaced so that the fascial incisions would heal separately from the overlying skin incisions. Animals were killed 7, 14, and 21 days after operation and fascial and dermal wounds were harvested and tested for breaking strength. Fascial and dermal wounds were also compared histologically for inflammatory response, fibroplasia, and collagen staining.

RESULTS

Fascial wound breaking strength exceeded dermal wound breaking strength at all time points (9.16 +/- 2.17 vs 3.51 +/- 0.49 N at 7 days, P <.05). Fascial wounds also developed greater fibroblast cellularity and greater collagen staining 7 days after the incision. There was no difference in wound inflammatory response.

CONCLUSIONS

Fascial incisions regain breaking strength faster than simultaneous dermal incisions. The mechanism for this appears to involve increased fascial fibroplasia and collagen production after acute injury.

Comparison of incisional bursting strength of simple continuous and inverted cruciate suture patterns in the equine linea alba

OBJECTIVE

To determine the bursting strength of ventral median abdominal incisions closed by either simple continuous or inverted cruciate suture patterns.

STUDY DESIGN

Experimental.

ANIMAL OR SAMPLE POPULATION

Twelve equine cadavers.

METHODS

A 25 cm ventral median incision was made through the linea alba and a 200 L polyurethane bladder was placed within the abdomen. Either a simple continuous or an inverted cruciate pattern using 3 polyglactin 910 with a bite size and suture interval of 1.5 cm was used to close linea incisions. Closure time was recorded for each pattern. The bladder was inflated with air at 40 L/min, and the pressure at body wall failure recorded. The length of suture used for wound closure and the wound failure modes were recorded. Deviation from the linea (cm), total suture length (cm), suture length to wound length ratio (SL:WL), closure time (min), bursting pressure (mm Hg), and failure modes were compared between groups using Welch-Aspin t-tests. The effects of independent subject variables were assessed for possible effects on bursting strength using analysis of covariance.

RESULTS

Mean bursting pressure was significantly greater for the simple continuous pattern than for the inverted cruciate pattern (P = .01). Significantly less suture material (P = .0002) was required with the continuous pattern than with the inverted cruciate pattern. Mean closure time, SL:WL, deviation from the linea, and failure modes were not significantly different between groups. No significant effects were noted for independent variables in both groups on bursting strength.

CONCLUSIONS

In this model, a simple continuous closure pattern for ventral median abdominal incisions was stronger than an inverted cruciate pattern. A simple continuous pattern leaves less foreign material in the wound, which may be of benefit in reducing incisional complications.

CLINICAL RELEVANCE

Use of a continuous closure pattern for the linea alba may offer greater wound security during episodes of increased intra-abdominal pressure in horses.

Suporte para pontos totais de segurança: modelo mk vs. modelo vs. convencional

Os autores comparam um modelo convencional de suporte para pontos totais de segurança da parede abdominal com um novo modelo desenvolvido pelo Instituto de Bioengenharia Erasto Gaertner (IBEG) - o modelo MK, avaliando sua efetividade, ocorrência de complicações, aspecto estético, dor na cicatriz cirúrgica e viabilidade econômica. Foram estudados 66 pacientes submetidos a cirurgia abdominal em dois hospitais de Curitiba (Hospital Erasto Gaertner e Hospital de Clínicas da Universidade Federal do Paraná), no período de maio a julho de 1996. Os pacientes foram divididos em dois grupos: no primeiro grupo foi utilizado o modelo MK, enquanto no segundo utilizou-se o modelo convencional. O modelo MK demonstrou menor índice de complicações, entre as quais: hematoma (p=0,01), coleção sero-hemática (p=0,01), abscesso subcutâneo (p=0,01) e úlcera decorrente dos pontos totais (p=0,02). No que diz respeito à dor, o modelo MK foi mais bem tolerado pelos pacientes, com diferença estatisticamente significativa (p=0,004). O resultado estético e a ocorrência de deiscência, evisceração, hérnia incisional e infecção não mostraram diferença significativa entre os dois grupos. O modelo MK mostrou ser efetivo como suporte para pontos totais de segurança, com uma menor incidência de complicações e menor índice de dor local.

Síntese da parede abdominal: sutura contínua ou com pontos separados? Revisão da literatura

Uma revisão da literatura foi realizada para atualização sobre o fechamento da parede abdominal. São relatados historicamente as controvérsias inerentes ao tema. Atualmente considera-se que o fechamento em massa do plano peritônio-músculo-aponeurótico é o mais adequado, com menor risco de complicações do que o fechamento por planos anatômicos. O tipo de fio utilizado, apesar de existirem várias opções, também está estabelecido, sendo melhor empregado os fios inabsorvíveis, ou os absorvíveis de longa duração, preferencialmente monofilamentares. Quanto fechar as laparotomias com sutura contína ou sutura com pontos separados, permanecem divergências, sendo que várias publicações, com diferentes amostras e meios de avaliação, referem vantagens para uma ou outra técnica, ou concluem pela similaridade de resultados entre elas. Sobre essas divergências, os autores discutem a sutura contínua e a sutura com pontos separados no fechamento da parede abdominal, abordando os aspectos técnicos de ambas.

Acute wound failure

The causes and treatment of acute failure of the abdominal incision are reviewed, along with a summary of studies on fascial healing. Emphasis is placed on taking large bites of tissue during closure to prevent dehiscence. Patient-related risk factors are viewed as less important in the causation of wound failure.