Damage Detection in a Polymer Matrix Composite from 4D Displacement Field Measurements.

Standard Digital Volume Correlation (DVC) approaches enable quantitative analyses of specimen deformation to be performed by measuring displacement fields between discrete states. Such frameworks are thus limited by the number of scans (due to acquisition duration). Considering only one projection per loading step, Projection-based Digital Volume Correlation (P-DVC) allows 4D (i.e., space and time) full-field measurements to be carried out over entire loading histories. The sought displacement field is decomposed over a basis of separated variables, namely, temporal and spatial modes. In the present work, the spatial modes are constructed via scan-wise DVC, and only the temporal amplitudes are sought via P-DVC. The proposed method is applied to a glass fiber mat reinforced polymer specimen containing a machined notch, subjected to in situ cyclic tension and imaged via X-ray Computed Tomography. The P-DVC enhanced DVC method employed herein enables for the quantification of damage growth over the entire loading history up to failure.

Channeling Effect and Tissue Morphology in a Perfusion Bioreactor Imaged by X-Ray Microtomography.

BACKGROUND: Perfusion bioreactors for tissue engineering hold great promises. Indeed, the perfusion of culture medium enhances species transport and mechanically stimulates the cells, thereby increasing cell proliferation and tissue formation. Nonetheless, their development is still hampered by a lack of understanding of the relationship between mechanical cues and tissue growth. METHODS: Combining tissue engineering, three-dimensional visualization and numerical simulations, we analyze the morphological evolution of neo-tissue in a model bioreactor with respect to the local flow pattern. NIH-3T3 cells were grown under perfusion for one, two and three weeks on a stack of 2 mm polyacetal beads. The model bioreactor was then imaged by X-ray micro-tomography and local tissue morphology was analyzed. To relate experimental observations and mechanical stimulii, a computational fluid dynamics model of flow around spheres in a canal was developed and solved using the finite element method. RESULTS: We observe a preferential tissue formation at the bioreactor periphery, and relate it to a channeling effect leading to regions of higher flow intensity. Additionally, we find that circular crater-like tissue patterns form in narrow channel regions at early culture times. Using computational fluid dynamic simulations, we show that the location and morphology of these patterns match those of shear stress maxima. Finally, the morphology of the tissue is qualitatively described as the tissue grows and reorganizes itself. CONCLUSION: Altogether, our study points out the key role of local flow conditions on the tissue morphology developed on a stack of beads in perfusion bioreactors and provides new insights for effective design of hydrodynamic bioreactors for tissue engineering using bead packings.

Assessment of the interplay between scaffold geometry, induced shear stresses, and cell proliferation within a packed bed perfusion bioreactor.

By favoring cell proliferation and differentiation, perfusion bioreactors proved efficient at optimizing cell culture. The aim of this study was to quantify cell proliferation within a perfusion bioreactor and correlate it to the wall shear stress (WSS) distribution by combining 3-D imaging and computational fluid dynamics simulations.NIH-3T3 fibroblasts were cultured onto a scaffold model made of impermeable polyacetal spheres or Polydimethylsiloxane cubes. After 1, 2, and 3 weeks of culture, constructs were analyzed by micro-computed tomography (µCT) and quantification of cell proliferation was assessed. After 3 weeks, the volume of cells was found four times higher in the stacking of spheres than in the stacking of cube.3D-µCT reconstruction of bioreactors was used as input for the numerical simulations. Using a lattice-Boltzmann method, we simulated the fluid flow within the bioreactors. We retrieved the WSS distribution (PDF) on the scaffolds surface at the beginning of cultivation and correlated this distribution to the local presence of cells after 3 weeks of cultivation. We found that the WSS distributions strongly differ between spheres and cubes even if the porosity and the specific wetted area of the stackings were very similar. The PDF is narrower and the mean WSS is lower for cubes (11 mPa) than for spheres (20 mPa). For the stacking of spheres, the relative occupancy of the surface sites by cells is maximal when WSS is greater than 20 mPa. For cubes, the relative occupancy is maximal when the WSS is lower than 10 mPa. The discrepancies between spheres and cubes are attributed to the more numerous sites in stacking of spheres that may induce 3-D (multi-layered) proliferation.

Trauma hepático: análise do tratamento com balão intra-hepático em um hospital universitário de Curitiba / Hepatic trauma: analysis of the treatment with intrahepatic balloon in a university hospital of Curitiba

OBJETIVO: Discutir a estratégia cirúrgica para tratamento de lesões hepáticas penetrantes graves através de tamponamento com balão intra-hepático. MÉTODOS: Estudo retrospectivo com 18 pacientes com trauma hepático penetrante, tratados com balão, atendidos em um hospital de referência em trauma no sul do Brasil. Foram avaliados: idade, sexo, grau da lesão hepática, segmentos acometidos, quantidade de solução salina infundida no balão intra-hepático e seu tempo de permanência, lesões associadas, terapia nutricional, hemotransfusões, complicações, antibioticoterapia, necessidade de UTI e tempo de internamento. RESULTADOS: Todos os pacientes eram do sexo masculino com idade média de 22,5 anos (18-48). As feridas por arma de fogo foram mais prevalentes, sendo a localização mais comum a região torácica e a transição tóraco-abdominal. A lesão associada mais comum foi a do diafragma, e o segmento hepático mais acometido foi o VIII (29,6 por cento). Sete pacientes (38,9 por cento) sobreviveram e a complicação mais comum foi fístula biliar (42,8 por cento). Dos 11 (61,1 por cento) pacientes que foram a óbito, seis morreram no mesmo dia em que foram operados, três ficaram em média 18,6 dias internados e os demais morreram no 2° e 3° do pós-operatório. CONCLUSÃO: O tratamento das lesões hepáticas transfixantes costuma ser de difícil manejo cirúrgico e com alto índice de morbimortalidade. O uso do balão intra- hepático foi eficaz no tratamento dessas lesões, porém não é isento de complicações tendo suas indicações bem definidas.

OBJECTIVE: The authors discuss the surgical strategies in the management of complex penetrating hepatic lesions through liver balloon tamponade. METHODS: Eighteen patients who received care in a trauma referral center in southern Brazil over the last 5 years were selected retrospectively. Data and variables evaluated were age, sex, hepatic injury grade and location, amount of saline solution filling the balloon and the length of time it was kept in place, associated injuries, the nutritional therapy instituted, hem concentrate transfusion, complications, antibiotics use, ICU need and length of hospital stay. RESULTS: All patients were male with an average age of 22.5 years (18-48). Gunshot wounds were more prevalent than stab wounds and their most common locations were the thorax and thoraco-abdominal regions. The m most commonly associated injury was in the diaphragm, and Couinaud segment VIII was the most often injured hepatic region (29.6 percent). Seven patients (38.9 percent) survived and the most common complication were biliary fistulae (42.8 percent). From the eleven deceased patients (61.1 percent), 6 died on the day of admission, 3 stayed for 18.6 days in hospital and the others died on the 2nd and 3rd postoperative days. CONCLUSION: Transfixing hepatic lesions are usually difficult to manage and carry high morbidity and mortality rates. The use of intrahepatic balloon tamponade can be useful as a therapeutic tool, but not rid of complications, and for that reason it has specific and selected indications.

Hepatic trauma: analysis of the treatment with intrahepatic balloon in a university hospital of Curitiba.

OBJECTIVE: The authors discuss the surgical strategies in the management of complex penetrating hepatic lesions through liver balloon tamponade. METHODS: Eighteen patients who received care in a trauma referral center in southern Brazil over the last 5 years were selected retrospectively. Data and variables evaluated were age, sex, hepatic injury grade and location, amount of saline solution filling the balloon and the length of time it was kept in place, associated injuries, the nutritional therapy instituted, hem concentrate transfusion, complications, antibiotics use, ICU need and length of hospital stay. RESULTS: All patients were male with an average age of 22.5 years (18-48). Gunshot wounds were more prevalent than stab wounds and their most common locations were the thorax and thoraco-abdominal regions. The m most commonly associated injury was in the diaphragm, and Couinaud segment VIII was the most often injured hepatic region (29.6%). Seven patients (38.9%) survived and the most common complication were biliary fistulae (42.8%). From the eleven deceased patients (61.1%), 6 died on the day of admission, 3 stayed for 18.6 days in hospital and the others died on the 2nd and 3rd postoperative days. CONCLUSION: Transfixing hepatic lesions are usually difficult to manage and carry high morbidity and mortality rates. The use of intrahepatic balloon tamponade can be useful as a therapeutic tool, but not rid of complications, and for that reason it has specific and selected indications.

Curva de aprendizado na fundoplicatura laparoscópica durante a residência médica em cirurgia geral / Learning curve in the laparoscopic fundoplication during the general surgery residency program

OBJETIVO: A fundoplicatura laparoscópica a 360° é o tratamento de escolha para pacientes com doença do refluxo gastroesofágico que não respondem bem ao tratamento clínico. Este artigo demonstra a curva de aprendizado durante a Residência Médica em Cirurgia Geral. MÉTODO: Foi realizada uma análise retrospectiva de 60 pacientes submetidos à fundoplicatura laparoscópica durante o período de março a outubro de 2005. Os pacientes foram divididos em dois grupos: 30 casos iniciais que foram comparados aos 30 casos subseqüentes. As variáveis analisadas incluíram: tempo operatório, taxa de conversão, complicações e tempo de hospitalização. RESULTADOS: A fundoplicatura laparoscópica foi realizada em 18 homens e 42 mulheres, com idade média de 48,3 anos. Comparando os dois grupos, houve diferença estatisticamente significativa no tempo operatório total (92,7 vs. 76,7 minutos, p=0,003), no tempo operatório para a operação de Nissen-Rossetti (86,7 vs. 68,4 minutos, p=0,00006) e no tempo para a liberação dos vasos gástricos curtos (22 vs. 13,1 minutos, p=0,00005). As complicações intra-operatórias foram maiores no primeiro grupo de pacientes, mas a diferença não foi estatisticamente significativa (p=0,2). Todos os procedimentos foram concluídos com sucesso por vídeo-laparoscopia em ambos os grupos, e a mortalidade foi nula nesta série. A alta hospitalar ocorreu em média no primeiro dia de pós-operatório em ambos os grupos (p=0,06). CONCLUSÃO: A fundoplicatura laparoscópica pode ser realizada com segurança por um cirurgião em formação, sob supervisão direta de um titular, com mínima morbidade para os pacientes. A curva de aprendizado foi demonstrada, avaliando-se principalmente, o tempo operatório do procedimento.

Papel da laparoscopia no trauma abdominal penetrante / The role of laparoscopy in penetrating abdominal trauma

OBJETIVO: O papel da laparoscopia na redução da taxa de laparotomias não-terapêuticas e da morbidade em pacientes vítimas de trauma abdominal penetrante tem sido amplamente discutido durante os últimos anos. O objetivo do presente estudo é relatar a experiência inicial de um hospital universitário no manejo laparoscópico de pacientes com trauma abdominal penetrante. MÉTODO: Durante um período de três anos, a laparoscopia foi realizada em 37 pacientes vítimas de trauma abdominal penetrante, hemodinamicamente estáveis. Os prontuários médicos foram revisados e os parâmetros analisados foram as indicações do procedimento, lesões associadas, necessidade de conversão, tempo de permanência hospitalar e complicações. RESULTADOS: Houve 18 (48,6 por cento) casos de laparoscopias diagnósticas (LD) positivas e 19 (51,4 por cento) negativas. Dos pacientes com LD positiva, oito (44,4 por cento) foram submetidos à laparotomia exploradora com finalidade terapêutica ou para melhor delineamento da lesão. Houve 10 (55,6 por cento) LD positivas nas quais não foi realizada conversão para cirurgia aberta. Quatro pacientes apresentaram lesões reparáveis laparoscopicamente, sendo realizado hepatorrafia (n=2) e frenorrafia (n=2). Os outros seis pacientes apresentavam lesões isoladas sem sangramento ativo, e a laparotomia não-terapêutica foi evitada. Os pacientes receberam dieta no primeiro dia de pós-operatório e o tempo médio de hospitalização foi de 3,8 dias. CONCLUSÕES: Nossa experiência inicial confirma que a laparoscopia é um bom método de avaliação e tratamento no trauma penetrante. A morbidade relacionada à laparotomias desnecessárias pode ser minimizada quando o procedimento é bem indicado, e o tratamento pode ser realizado com sucesso em casos selecionados.

BACKGROUND: The role of laparoscopy in reducing the rate of non-therapeutic laparotomies and the morbidity in patients sustaining penetrating abdominal trauma has been widely discussed over the last years. The aim of this article is to report the initial experience from a university hospital in the laparoscopic management of penetrating abdominal traumas. METHODS: In a 3-year period, laparoscopy was performed in 37 patients who were hemodynamically stable and sustained penetrating abdominal trauma. Medical records were reviewed and the evaluation was conducted to determine indications for laparoscopy, associated injuries, the need for exploration, lenght of hospital stay and complications. RESULTS: There were 18 (48.6 percent) positive and 19 (51.4 percent) negative diagnostic laparoscopies (DL). In patients with positive DL, 8 (44.4 percent) underwent exploratory laparotomy. In this group, all of them had either therapeutic laparotomy or laparotomy for better lesion identification. There were 10 (55.6 percent) positive DLs, in whom laparotomy was not performed. Four of them had their injuries repaired laparocopically, hepatorraphy (n=2) and diaphragmatic repairs (n=2). The other ones had isolated nonbleeding injuries, and nontherapeutic laparotomy was successfully avoided. Patients were allowed a diet in the first postoperative day and the mean postoperative hospital stay was 3.8 days. CONCLUSION: Our initial experience confirms that laparoscopy is a good method of evaluation and treatment for penetrating trauma. The morbidity from an unnecessary laparotomy may be minimized when the procedure is well indicated, and treatment can be performed successfully in selected cases.

Fatores prognósticos em pacientes submetidos à cirurgia por trauma pancreático / Prognostic factors in patients undergoing surgery for pancreatic trauma

OBJETIVO: As lesões traumáticas pancreáticas são pouco freqüentes após trauma abdominal fechado ou penetrante. O objetivo deste estudo retrospectivo é analisar a experiência de um serviço universitário e relatar os fatores prognósticos e o tratamento cirúrgico instituído. MÉTODO: Foram selecionados e revisados os prontuários dos pacientes portadores de trauma pancreático durante um período de nove anos em um hospital universitário nível terciário de trauma e os parâmetros analisados foram: mecanismo do trauma, presença de choque na admissão, grau da lesão pancreática, escore de trauma, tratamento cirúrgico, complicações e mortalidade. RESULTADOS: Oitenta e nove pacientes foram identificados e o diagnóstico foi realizado durante a laparotomia em todos os casos. Os traumas abdominais penetrantes foram responsáveis por 67,4 por cento dos casos. Utilizando a Escala de Lesões de Orgãos, as lesões grau II e III foram as mais comuns e o tratamento foi definido de acordo com o grau e o local da lesão. A mortalidade global foi de 21,3 por cento e significativamente maior nos pacientes que apresentaram choque na admissão, lesões pancreáticas grau IV e V, e Escore de Gravidade da Lesão (ISS) elevado. CONCLUSÕES: A lesão pancreática é um fenômeno raro, porém com elevada mortalidade, que está intimamente relacionada à presença de choque na admissão, ao grau da lesão pancreática e ao escore de trauma.

BACKGROUND: Traumatic lesions of the pancreas following blunt or penetrating abdominal trauma are infrequent. The aim of this retrospective study on traumatic pancreatic injuries was to assess the experience of an academic center and to report prognostic factors and surgical treatment. METHODS: Patients with pancreatic injuries were identified during a 9-year period from the registries of a level I trauma center and medical records were reviewed. Parameters analyzed were mechanism of injury, presence of shock, degree of injury, trauma score, operative management, outcome, morbidity and mortality. RESULTS: Eighty-nine patients sustaining pancreatic injuries were identified and diagnosis was made during laparotomy in all cases. Penetrating abdominal trauma was observed in 67.4 percent of the cases. Using the Organ Injury Scale, grade II and III wounds were more common and management was defined according to the degree and site of injury. Mortality was 21.3 percent and it was significantly higher in patients presenting shock on admission, pancreatic injury grades IV and V and higher Injury Severity Score (ISS). CONCLUSION: Pancreatic injury is a rare but deadly phenomenon and mortality rate is related to the presence of shock on admission, degree of pancreatic injury and trauma scores.

Quilotórax traumático por ferimento penetrante do tórax / Traumatic chylothorax by Gunshot wound of thorax

The authors report two cases of traumatic chylothorax. They were caused by gunshot wounds producing thorax transfixing injuries and the chilothorax was subsequently diagnosed during the thoracic drainage follow-up, a chilous color was noticed in the drainage output. This was confirmed with a Sudam III stain. Both cases were treated conservatively with Total Parenteral Nutrition according to the current literature. One of the cases, in its evolution, required surgical treatment due to a persistent high output fistulae

Clampeamento da aorta torácica: experiência de um Hospital de Emergência / Aortic cross-clamping: experience in an emergency hospital

A oclusäo temporária da aorta descendente, tanto antes quanto depois do procedimento cirúrgico pelas lesöes traumáticas, visa a redistribuiçäo do fluxo sanguíneo para o coraçäo e para o cérebro e também minimizar a perda sanguínea. Este estudo descreve a experiência dos autores na realizaçäo da toracotomia antero-lateral esquerda com oclusäo temporária da aorta descendente no manejo de pacientes com perda sanguínea maciça. Analisou-se retrospectivamente onze pacientes vítimas de trauma torácico e abdominal fechado e/ou penetrante, admitidos no Hospital Universitário Cajurú, da Pontifícia Universidade Católica do Paraná, de fevereiro à novembro de 1996. Todos os pacientes foram submetidos ao clampeamento da aorta torácica. Os onze pacientes eram do sexo masculino, com idade média de 22,2 anos. A causa mais comum de trauma foi ferida por arma de fogo, representando 72,7 por cento de todos os casos. ORTs era 4,11 + - 1,97. O local mais frequentemente envolvido foi o abdome (63,6 por cento) e 81,8 por cento pacientes apresentavam lesöes nos grandes vasos tóraco-abdominais. O clampeamento aórtico foi realizado antes da abordagem das lesöes traumáticas em sete pacientes. O índice de mortalidade no pós-operatório imediato foi 63,6 por cento. Somente dois pacientes sobreviveram na amostra global e um deles desenvolveu uma acidose metabólica. O clampeamento da aorta representa um risco imediato de morte devido às severas lesöes hemorrágicas que o precedem. Em relaçäo à literatura, retardamos o clampeamento da aorta torácica, visto que näo há uma hora oportuna para proceder com o clampeamento da aorta. O clampeamento aórtico apresenta-se como um procedimento desafiador, sendo raramente realizado e está associado a um elevado índice de mortalidade, devido a gravidade das lesöes associadas(AB)

Effect of streptokinase in the prevention of intra-abdominal adhesions in the rat

The objective of the present study was to assess the action of streptokinase, a streptococcal derivative with fibrinolytic capacity, in the prevention of intraperitoneal adhesions in rats. Eighty animals were divided into four groups of 20 each; group A (control) received isotonic saline by the intraperitoneal route, group B received streptokinase by the intraperitoneal rout at the dose of 60.000 units/kg body weight diluted in 2 ml isotonic saline, group C received 60.000 streptokinase units diluted in 1 ml isotonic saline by the intravenous route, and group D received 30.000 streptokinase units in 2 ml isotonic saline by the intraperitoneal route and 30.000 streptokinase units diluted in 1 ml isotonic saline by the intravenous route. The animals were submitted at random to median laparotomy for the preparation of stitches inducing adhesions of the ischemic type according to the model of FERRAZ-NETO et al. (1991) modified, and sacrificed with a lethal dose of sulfuric ether on the 3rd and 7th postoperative day. Streptokinase was found to be effective in the prevention of adhesions when used by the intraperitoneal route (p=0,0349) or when administered both intraperitoneal and intravenously (p=0,0073). Comparison of the 3rd and 7the posteperative day within the same group showed no significant difference, suggesting that the drug acts during the early period of the healing process. We conclude that streptokinase is effective in the prevention of adhesion formation when used by the intraperitoneal route or by the combined intraperitoneal and intravenous routes at the dose employed in rats.

Síndrome de Zollinger-Ellison e neoplasia endócrina múltipla: relato de caso / Zollinger-Ellison syndrome and multiple endocrine neoplasia: a case report

A síndrome de Zollinger-Ellison (SZE) e a neoplasia endócrina múltipla (NEM) é uma condiçäo relativamente rara. Neste trabalho apresentamos e discutimos os achados clínicos, laboratoriais e diagnóstico de um caso de SZE