RESUMEN
Objetivo: Estudar os efeitos do emprego de dois materiais consideravelmente diferentes quanto à origem e custo na correção intra-uterina da meningomielocele criada experimentalmente em feto de ovino. Métodos: Em 36 fetos de ovinos foi criado um defeito aberto de tubo neural, com 75 de dias de gestação. Os casos foram divididos em três grupos: o controle onde o defeito não foi corrigido, grupo corrigido A onde o material utilizado para cobrir a medula exposta foi a matriz dérmica humana acelular (MDHA) e o grupo corrigido B onde o material foi a celulose biossintética (CB). Após a correção realizada com 100 dias, os fetos eram mantidos intra-útero até o termo da gestação. Os sacrifícios foram realizados com 140 dias e a coluna fetal era submetida à análise macro e microscópica onde foi observada a aderência dos materiais à pele, medula ou tecido nervoso remanescente. Resultados: Na fase inicial (piloto), 11 fetos foram operados e 4 sobreviveram (37%). Na segunda fase (estudo) 25 fetos foram operados e 17 sobreviveram (68%). No grupo de estudo, 6 fetos não foram submetidos à correção (grupo controle), 11 casos foram corrigidos e ocorreu 1 perda fetal. Do total de 10 casos, 4 constituíram o grupo A e 6, o grupo B. À macroscopia observou-se deslizamento da pele e tecidos subjacentes sobre a CB em todos os casos onde ela foi empregada e isto não ocorreu em nenhum dos casos onde a MDHA foi utilizada. Para comparar a aderência, foram considerados 4 casos do grupo A e 4 do grupo B. A aderência, caracterizada pela migração de células do hospedeiro e proliferação de vasos para dentro da MDHA, foi observada em 100% dos casos do grupo A e em nenhum caso no grupo B (p < 0,05). No grupo B observou-se formação de uma camada de fibroblastos ao redor do material, protegendo a medula, caracterizando a formação de uma "neoduramater"...
Purpose: The aim of this study was to compare the effectiveness of two dura-mater substitutes, namely human acellular dermal matrix (HADM) and biosynthetic cellulose (BC), in repairing, in utero, surgically-induced meningomyelocele (MMC) in fetal sheep. Methods: A neural tube defect was created at 74-77 days gestation in 36 fetal sheep. They were divided into 3 groups, the control group that did not receive pre-natal corrective surgery, and the other two groups that received corrective surgery using HADM (Group A) or BC (Group B). Both materials were used as a dura-mater substitutes between the neural tissue and the sutured skin. Correction was performed at gestation day 100 and the fetuses were maintained in utero until term. Sheep were sacrificed on gestation day 140. The fetal spine was submitted to macro and microscopic analysis. At microscopy, adherence of the material to the skin and neural tissue was analyzed. Results: In the initial phase (pilot), experimentally-induced MMC was performed on 11 fetuses and 4 survived (37%). In the second phase (study), 25 fetuses received surgery and 17 survived (68%). In the study group, 6 fetuses did not undergo repair (control group), 11 cases were submitted to corrective surgery (experimental group) and one fetal loss occurred. Of the surviving cases in the experimental group, 4 constituted Group A and 6 in Group B. Macroscopically, skin and underlying tissues where easily displaced from the BC in all cases it was used; in contrast, HADM adhered to these tissues. To compare the adherence, 4 cases from Group A and 4 in Group B were studied. We observed adherence, host cell migration and vessel proliferation into the HADM all sections from Group A and this aspect was not present in any cases in Group B (p < 0.05). In Group B, we also observed that a new fibroblast layer formed around the BC thus protecting the medulla and constituting a "neoduramater"...
Asunto(s)
Animales , Celulosa/biosíntesis , Feto/cirugía , Meningomielocele , Ovinos/cirugía , Disrafia EspinalRESUMEN
BACKGROUND: Intrauterine surgical intervention for certain cardiac anomalies may have a therapeutic advantage over postnatal repair or palliation. However, it is essential to establish methods for intrauterine extracorporeal circulation and myocardial preservations which can maintain the hemodynamics and gas exchange in fetal lamb perioperatively. This study was aimed to observe the changes in hemodynamics and gas exchange according to the methods of fetal cardiac bypass. METHODS: Twelve fetal lambs (4.5 5.2 kg) at 120 to 150 days of gestation under ketamine anesthesia were subjected to cardiac bypass for 30 minutes. Six served as a group in which placenta was excluded from the extracorporeal circulation by clamping the umbilical cord during the bypass (the oxygenator group) and in the remaining six, the placenta worked as an in vivo oxygenator (the placenta group). The fetuses were observed every 10 minute during a 30-minute bypass and 30-minute post bypass period. The hemodynamic variables and fetal blood gases were measured at specific intervals. RESULTS: In the oxygenator group, mean arterial pressure (MAP), PaO2, heart rate and bypass flow rate were 62 to 74 mmHg, 220 to 282 mmHg, 169 to 182 /min and 134 to 164 ml/kg/min, respectively during bypass. But rapid deterioration of fetal cardiac and placental gas exchange function was observed following cessation of bypass. In the placenta group, MAP decreased from 61 to 34 mmHg and PaCO2 progressively increased from 56 to 74 mmHg during bypass. Flow rate was suboptimal (74 to 115 ml/kg/min) during bypass. All hearts of the placenta group was fibrillated immediately after discontinuation of bypass. CONCLUSION: The both methods of CPB, use of oxygenator and placenta as gas exchanger, under only ketamine anesthesia did not provide adequate hemodynamics and gas exchange without additional treatment for protection placental reaction. The methods of fetal cardiac bypass using either neonatal membrane oxygenator or placental as an in vivo oxygenator caused severe placental dysfunction and blood gas abnormalities.