Дисертації з теми "Extracorporeal perfusion"

Neurologic injuries are major causes of mortality and morbidity after cardiac surgery. This thesis aimed to investigate cerebral metabolism and perfusion abnormalities in pigs during hypothermic circulatory arrest, selective antegrade cerebral perfusion (SACP) and extracorporeal circulation following progressive venous stasis. Hypothermic circulatory arrest induced a metabolic pattern consistent with overt ischaemia, which was absent following SACP. In contrast, metabolism during SACP was influenced by the perfusate temperature, where a colder perfusate (20 °C) preserved cellular metabolism and membrane integrity better than a warmer perfusate (28 °C). The minimum SACP flow required to maintain metabolism during hypothermia at 20 °C was investigated with magnetic resonance imaging, protein S100β, near infrared spectroscopy and microdialysis. The findings suggested an ischaemic threshold close to 6 ml/kg/min in the present models. Furthermore, regional differences in perfusion with a hemispheric distribution were apparent at all flow levels and differed from earlier studies where the differences were uniform and followed a neuranatomical pattern. Venus stasis following superior vena cava congestion produced measurable signs of impaired cerebral perfusion and patterns of cerebral ischaemia were evident in individual animals. As venous pressure increased, the mean arterial pressure stayed more or less unchanged, generating reduced cerebral perfusion pressure and consequently an increased risk of ischaemia, which may impair cerebral perfusion, especially in cases of compromised arterial flow during extracorporeal circulation. In conclusion, cerebral metabolism and perfusion are influenced by temperature, SACP flow levels and venous congestion. In clinical practice, the regional differences in perfusion during SACP may be of pathogenic importance in focal cerebral ischaemia. Furthermore, the reduced superior vena cava cannula flow may pass undetected during bicaval cardiopulmonary bypass if the superior vena cava flow is not specifically monitored.

Introduction: A liver support device can bridge a patient in acute liver failure safely to transplant. An extracorporeal perfused porcine liver (ECLP) circumvents the limitations of hepatocyte based bioartificial liver, but its clinical application has been limited so far due to the potential risk of transmission of porcine endogenous retroviruses. Aim of this study was to develop an ECLP model that can provide artificial hepatic support across a semi-permeable membrane which should block porcine viruses due to its pore size. Methods: 50-60 Kg white landrace pigs treated with standard abattoir animal procedures were used as donors. The liver was perfused with normothermic autologous oxygenated blood using Medtronic BioMedicus BP560 driven centrifugal pump for 6 hours. This ECLP system was used to support a surrogate patient circulation across the filter Evaclio EC4A. Substances like galactose, ammonia, midazolam and para-aminobenzoic acid, were infused into the surrogate patient and their clearance was calculated. The study was designed as test (n=15) vs. control (n=5); with control experiments having no liver in the circuit. Results: After the optimization phase (n=23), we successfully perfused 15 porcine livers with the mean hepatic artery pressure of 87 mm Hg and flows of 1.2 L /min. Retention of Indocyanine green at 15 minutes was 11% in test and 96% in controls. Mean ammonia clearance of 945 mg/min/kg, galactose Vmax of 111.7 mg/min/Kg, hippurate ratio of 91% and a variable midazolam clearance was seen in the test experiments. Conclusion: The study was successful in proving the feasibility of an ECLP model based on abattoir animals that can be utilised for future research work. This model was able to provide adequate support to the surrogate patient across a hollow filter. Further work is needed to show that an ECLP system can be used in an anhepatic animal prior to application in human trials.

This thesis explored the potential of utilising Computational Fluid Dynamics simulations to design and improve a perfusion bioreactor for practical mesenchymal stromal cell experimentation. This method of simulations allowed for an in-depth analysis of the microfluidic nature within the custom-designed parallel plate flow chamber, creating the conditions the 3D PCL Scaffold carrying these cells would undergo. The focus on the simulated velocities and resulting shear stresses upon the scaffold surfaces (cells attachment site) ensures the cells survive. Further investigation was taken to improve cell retention on the PCL scaffold through plasma treating technique prior to seeding which was successful.

Es wurde untersucht ob die normotherme extrakorporale Leberperfusion (NELP) als Methode geeignet ist, Lebern vor Transplantation zu konservieren, und ob sie warm ischämische Zellschäden beheben kann. Zum ersten Mal konnte experimentell gezeigt werden, daß eine erfolgreiche Transplantation nach 4 Stunden mit NELP möglich ist und sogar so zuverlässig, wie die Kaltkonservierung in der University of Wisconsin Lösung. Die NELP erhält die Leberfunktion und ermöglicht eine Regeneration warm ischämischer Schäden in Nicht-herzschlagenden Spendern. 36 Schweine der Deutschen Landrasse wurden in sechs Gruppen transplantiert. In der Gruppe 1 wurde direkt nach Organentnahme transplantiert, in Gruppe 2 nach 4 Stun-den Kaltkonservierung in der University of Wisconsin Lösung und in Gruppe 3 nach 4 Stunden NELP. In Gruppe 4 wurden die Lebern nach 60 Minuten warmer Ischämie direkt transplantiert, in Gruppe 5 nach 60 Minuten warmer Ischämie und 4 Stunden Kaltkonservierung und in Gruppe 6 nach 60 Minuten warmer Ischämie und 4 Stunden NELP. Alle Tiere deren Lebern vor Transplantation normotherm extrakorporal perfun-diert wurden (Gruppen 3 und 6) überlebten mit guter Organfunktion. Im Unterschied hierzu führte die Abfolge von 60 Minuten warmer Ischämie und 4 Stunden Kaltkonser-vierung unweigerlich zur primären Organ-Nichtfunktion innerhalb der ersten 24 Stun-den nach Lebertransplantation. Die Methode der NELP bietet die Chance eine Leber außerhalb des Körpers für Zeiträume von möglicherweise länger als 4 Stunden völlig funktionsfähig zu halten. Die NELP kann zur Organkonservierung vor Transplantation eingesetzt werden, aber auch dazu, Lebern von Nicht-Herzschlagenden Spendern zu nutzen.
Normothermic extracorporeal liver perfusion (NELP) was studied as a means to pre-serve livers for transplantation and to reverse warm ischemic injury. For the first time we provide experimental evidence that successful transplantation after 4h of normo-thermic extracorporeal liver perfusion is possible and as reliable as 4h of cold preser-vation in University of Wisconsin solution. NELP preserves liver function completely and is capable of reversing 60 min of warm ischemic injury in non heart beating do-nors. 36 German Landrace pigs were transplanted in six groups. Group 1 animals were transplanted directly, group 2 animals after 4h of cold preservation with University of Wisconsin solution and group 3 animals following 4h of normothermic extracorporeal liver perfusion. Group 4 animals sustained 1h of warm ischemia before transplantation of the liver. In group 5 animals were transplanted following 1h of warm ischemia and 4h of cold preservation, and in group 6 after 1h of warm ischemia and 4h of normo-thermic extracorporeal liver perfusion. All animals receiving livers treated by normo-thermic extracorporeal liver perfusion survived without liver failure (group 3 and 6). In contrast, all animals in group 5 developed primary graft non-function within 24 h after transplantation. The technique of NELP holds the potential to keep a mammalian liver outside the body completely functional, possibly for longer than 4h. NELP can be used for liver preservation prior to transplantation or to utilise organs from non-heart-beating donors.

O objetivo desta dissertação foi descrever em veterinária seqüência padrão de procedimentos que devem ser realizados nos períodos pré, trans e pós-circulação extracorpórea (CEC) para sua aplicação em cão, com base na literatura existente, e em observações levadas a efeito no Laboratório de Cirurgia Cardiotorácica, do Departamento de Cirurgia da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo. O referido trabalho concerne sobre a escolha do material, montagem e preparo da máquina ECOBEC ? Braile Biomédica - para circulação extracorpórea em cães, e descreve procedimentos básicos para entrada, condução, monitorização e saída de CEC, a fim de obter-se resultado técnico exeqüível no procedimento. Diante do exposto na literatura compulsada, baseado na metodologia e material proposto e com observações pessoais, é licito afirmar que esta é factível, desde que obedecidos os preceitos enumerados e descritos no presente trabalho para os períodos pré, trans e pós-circulação extracorpórea.
The purpose of this assay was to describe the standard basic procedures that should be followed before, during, and after cardiopulmonary bypass (CPB) in dogs, based on the existing literature and personal observations that took place in the Laboratory of Cardiothoracic Surgery, of the Surgical Department of the Faculdade de Medicina Veterinária e Zootecnia of the University of São Paulo. This assay reports how to choose the material, to prepare and to assemble the ECOBEC machine ? Braile Biomédica ? for cardiopulmonary bypass in dogs, and describes the basic procedures to start, conduct, follow up and finish it, in order to obtain a feasible technical results. Based on the literature, based on the methodology and material proposed and personal observations, it is reliable to state that this procedure can be accomplished since all paths described are followed before, during and after cardiopulmonary bypass.

INTRODUÇÃO: A isquemia-reperfusão pulmonar e o uso do oxigenador de membranas são considerados fatores importantes na resposta inflamatória após a cirurgia cardíaca (CC) com utilização da circulação extracorpórea (CEC). Estudos anteriores que utilizaram os próprios pulmões dos pacientes como oxigenador em uma circulação extracorpórea biventricular (CECBV) em comparação à CEC convencional (CECC) mostraram efeitos benéficos na mecânica pulmonar e na reação inflamatória sistêmica. No entanto, a inflamação pulmonar ainda não foi totalmente esclarecida neste cenário. Os objetivos deste estudo foram observar o impacto da exclusão do oxigenador de membranas e da manutenção da ventilação e perfusão pulmonar na inflamação regional em porcos submetidos à CEC. MÉTODOS: Vinte e sete porcos ventilados mecanicamente foram submetidos à toracotomia e alocados randomicamente nos grupos: Controle (n=8), CECC (n=9) e CECBV (n=10). Os animais dos grupos CECC e CECBV foram submetidos respectivamente a uma CEC convencional ou a uma CEC biventricular com ventilação e perfusão pulmonar sem oxigenador de membranas por 90 minutos. As interleucinas (ILs) séricas foram avaliadas nos momentos: basal, após a CEC e 90 minutos após a CEC, e em momentos equivalentes no grupo Controle. As ILs do lavado broncoalveolar (LBA) foram medidas nos momentos basal e 90 minutos após a CEC. Amostras de tecido pulmonar foram coletadas da região ventral e dorsal do lobo pulmonar esquerdo para avaliação do número de polimorfonucleares (PMN) e quantificação do edema pela área de parênquima. Os dados foram avaliados através de ANOVA, considerando-se estatisticamente significante p<0,05. RESULTADOS: O grupo CECC apresentou uma maior inflamação, com um aumento no número de PMN, comparado ao grupo Controle (p < 0,001) nas regiões: ventral (2,8 x10-6± 0,7 x10-6 vs. 1,6 x10-6 ± 0,5 x10-6 , respectivamente) e dorsal (3,3 x10-6 ± 1,0 x10-6 vs. 1,9 x10- 6 ± 0,5 x10-6, respectivamente) e ao grupo CECBV (p = 0,006) nas regiões: ventral (2,3 x10-6 ± 0,7 x10-7) e dorsal (2,1 x10-6 ± 0,7 x10-6). Edema foi maior no grupo CECC comparado ao Controle nas regiões ventral e dorsal (2,4 x10-2 ± 3,5 x10-2 vs. 8,2 x10-4 ± 0,2 x10-4 e 5,7 x10 -2 ± 4,3 x10-2 vs. 0,3 x10-2 ± 1,0 x10-2, respectivamente, p = 0,016) e mais intenso na região dorsal em todos os grupos (p = 0,004). As IL 10 e IL6 do LBA foram maiores nos grupos submetidos à CECC (41,9 ± 12,2, p = 0,010 e 239,4 ± 45,2, p < 0,001, respectivamente) e à CECBV (40,7 ± 12,0, p = 0,016 e 174,8 ± 61,2, p = 0,004, respectivamente) comparadas ao Controle (21,0 ± 6,9 e 71,8 ± 29,8, respectivamente). As ILs séricas não diferiram entre os grupos (p > 0,05). O Grupo CECC, comparado ao grupo CECBV, mostrou um aumento maior com o tempo na IL6 do LBA (239,4 ± 45,2 vs. 174,8 ± 61,2, p = 0,027, respectivamente) e na IL8 sérica (193,1 ± 108,8 vs. 147,0 ± 59,4, p = 0,040, respectivamente). CONCLUSÕES: Em modelo experimental de circulação extracorpórea em porcos, a manutenção da perfusão e ventilação dos pulmões na CEC biventricular atenua a inflamação pulmonar em comparação à CEC convencional
BACKGROUND: Lung ischemia-reperfusion injury and the membrane oxygenator are considered important factors in the inflammatory response after cardiac surgery and cardiopulmonary bypass (CPB). Previous studies using the own lung as the oxygenator with a biventricular bypass demonstrated the beneficial effects of this technique. However, lung inflammation was not fully evaluated in this scenario. The aim of this study was to observe the impact of the exclusion of the membrane oxygenator and maintenance of lung perfusion on regional lung inflammation in pigs undergoing cardiopulmonary bypass. METHODS: Twenty-seven mechanically ventilated pigs were subjected to a thoracotomy and randomly allocated into Control (n=8), CPB (n=9) or Lung Perfusion (n=10) groups. Animals from the CPB group and Lung Perfusion group were subjected respectively to a conventional CPB or to a biventricular bypass with pulmonary ventilation and perfusion without a membrane oxygenator for 90 minutes. The systemic interleukins (ILs) were determined at baseline, after bypass and 90 min after bypass or at equivalent times in the Control group. ILs from bronchoalveolar lavage fluid (BAL) were evaluated at baseline and 90 min after bypass. Tissue samples were collected from the dorsal and ventral regions of the left lung for assessment of the number of polymorphonuclear leukocytes (PMN) per parenchyma area and edema. Data were evaluated using ANOVA and p< 0.05 was considered significant. RESULTS: The CPB group showed increased lung inflammation, with an increased PMN count compared to the Control (p<0,001) at ventral (2.8 x10-6± 0.7 x10-6 vs. 1.6 x10-6± 0.5 x10-6 , respectively) and dorsal regions (3.3 x10-6 ± 1.0 x10-6 vs. 1.9 x10-6 ± 0.5 x10-6, respectively) and to Lung Perfusion Group (p = 0.006) at ventral (2.3 x10-6 ± 0.7 x10-7) e dorsal regions (2.1 x10-6 ± 0.7 x10-6). Edema was higher in the CPB group compared to the Control at ventral and dorsal regions (2.4 x10-2± 3.5 x10-2 vs. 8.2 x10 -4± 0.2 x10-4 and 5.7 x10 -2 ± 4.3 x10-2 vs. 0.3 x10-2 ± 1.0 x10-2, respectively, p = 0.016) and increased in the dorsal region in all groups (p = 0.004). BAL IL10 and IL6 were higher in groups subjected to CPB group (41.9 ± 12.2, p = 0.010 e 239.4 ± 45.2, p<0.001, respectively) and to Lung Perfusion group (40.7 ± 12.0, p = 0.016 e 174.8 ± 61.2, p = 0.004, respectively) compared to Control group (21.0 ± 6.9 e 71.8 ± 29.8). Systemic interleukins did not differ between groups (p > 0.05). The CPB group compared to Lung Perfusion group showed a higher increase in BAL IL6 (239,4 ± 45,2 vs. 174,8 ± 61,2, p = 0,027, respectively) and in serum IL8 over time (193,1 ± 108,8 vs. 147,0 ± 59,4, p = 0,040, respectively). CONCLUSIONS: In a pig model of extracorporeal circulation, maintenance of lung perfusion and ventilation with biventricular bypass attenuates the pulmonary inflammation as compared to conventional CPB

Pancreas and islet transplantation are important treatment options for insulin dependent diabetes. However, one of the main challenges in pancreas and islet transplantation lies in organ (pancreas) preservation. Ischaemic injury post-retrieval causes significant damage the organ function and reduction in islet yield. It was hypothesised that extracorporeal normothermic perfusion of the pancreas would improve graft function post transplantation and pancreatic islet isolation when compared to traditional methods of organ preservation. The aims and objectives of the project included: • Conducting a systematic review of the literature in extracorporeal machine perfusion of the pancreas • Establishing an extracorporeal normothermic perfusion model of the porcine pancreas • Comparing the addition of kidney to the circuit of extracorporeal pancreas perfusion model A thorough systematic review of the available literature concluded the potential benefits of machine perfusion in pancreas preservation. Important insight into the experimental setup, perfusion parameters and vital outcome measures was also attained. A model of normothermic hemo-perfusion of the porcine pancreas with and without addition of the kidney as a dialysis organ was subsequently established. The organs were perfused for 120 minutes with stable perfusion parameters but sub-optimal acid-base environment. Addition of the kidney did not result in significant improvement of the acid-base environment.
Thesis (M.Phil.) (Research by Publication) -- University of Adelaide, School of Medicine, 2016.

碩士
中原大學
生物醫學工程研究所
100
By using an end-to-side vascular graft sutured to the right subclavian artery or right axillary artery as an arterial oxygenated blood perfusion conduit has become an alternative way of cardiopulmonary bypass setup, especially for aortic surgery and for surgery that cannot establish arterial access at the ascending aorta. During aortic arch surgery, physiological brain protection can be achieved by selective brain perfusion (with circle of Willis) via sending the oxygenated blood through the vascular graft to the right subclavian artery then to the right common carotid artery and right vertebral artery. However, the fraction of blood flow distribution to the brain and upper limb in this graft-subclavian perfusion has always been concern to the cardiovascular surgeons and perfusionists. In this study, by using reverse engineering to reconstruct a mock of aortic arch model based a health adult computer tomography image. Through in vitro study of hydrodynamic fluid test, the fractions of blood flow distribution under different included angle (15°, 30°, 45°, 60°, 75° and 90°, six included angles) between vascular graft (8 mm diameter) and right subclavian artery were calculated. Combining with previous publicized reference values of normal blood flow from physiological human vessels, we expect to obtain the ultimate included angle for suitable blood flow distribution and pressure for organ perfusion. As a result, perfusion to whole body mode (Bi-Ac mode), an angle of 30° is the most suitable included angle to maintain physiological tissue perfusion; and selected perfusion to head and upper limbs mode (Bi-ADEFc mode), an angle of 30° is also the most suitable included angle for brain protection. If the included angle is greater than 60°, hypo-perfusion of head and hyper-perfusion of right upper limb would occur. Once this ultimate included angle is established, it not only can be applied to aortic surgery, but also can be used in minimally invasive cardiac surgery, re-do cardiac operation and surgeries with severe calcified ascending aorta, with the result of this study, increasing safety of the cardiopulmonary bypass in terms of tissue protection and reducing operational complications can be achieved.

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2020
O melanoma maligno é um tipo de tumor cutâneo com origem nos melanócitos, localizados entre as células da camada basal da epiderme. A Perfusão Isolada do Membro (PIM) é uma técnica de circulação extracorporal, inicialmente utilizada na perfusão cardiovascular, com aplicação também na oncologia, nomeadamente no tratamento de neoplasias cutâneas, como o melanoma. Este trabalho final de mestrado foi realizado com o objetivo de compreender a abordagem de metástases em trânsito de melanoma, descrever a PIM no seu tratamento, rever a evolução histórica da técnica e os seus parâmetros de efetividade, refletir sobre as suas vantagens e limitações, assim como compreender o impacto desta terapêutica num contexto atual. Para tal foi feita uma revisão bibliográfica da literatura existente sobre a classificação e estadiamento do melanoma, para além da perfusão isolada de membro, e foi realizada a descrição da técnica com base na experiência do IPOFGLisboa. No melanoma maligno, a PIM aplica-se a doentes com estadiamento locorregional avançado, que apresentam metástases em trânsito dos membros, e tem como principais objetivos clínicos alcançar um elevado nível de remissão tumoral, evitar a amputação do membro atingido pela doença, assim como proporcionar uma melhor qualidade de vida. É uma terapêutica com mais de 50 anos de existência, apresentando elevadas taxas de resposta global com reduzidos níveis de toxicidades local e sistémica. Como principal limitação, a PIM não aumenta a sobrevivência global dos doentes e pode ocorrer recorrência das lesões em trânsito. Na era recente das terapias sistémicas para o melanoma, surge a questão provocadora sobre se a perfusão isolada de membro ainda desempenha um papel importante no tratamento de doentes com metástases em trânsito de melanoma.
Malignant melanoma is a cutaneous tumour originating from melanocytes, which are usually located in-between cells of the basal layer of the epidermis. Isolated Limb Perfusion (ILP) is a technique based on extracorporeal circulation which was initially used in cardiovascular perfusion and may have applications in oncology, namely in the treatment of some cutaneous neoplasms, such as melanoma. This paper aims to describe the role of ILP in the treatment of melanoma, to review its historical evolution its relevance and its parameters of effectiveness, to reflect on the advantages and limitations of ILP, as well as to understand the impact of this therapy in the recent age. For this purpose, a literature review and a detailed description of the technique were made based on IPOFG-Lisboa’s experience in this area. This technique is used in patients with advanced locoregional malignant melanoma, which are patients with in-transit metastasis of the limbs. The main clinical goals of ILP are to achieve a high level of tumour remission, to avoid limb amputation, as well as providing a better quality of life. It's a therapeutic practice used for more than 50 years. It shows high rates of overall response with reduced local and systemic toxicity levels. The main limitation of this technique is the fact that it does not increase patients’ overall survival and it may even lead to the recurrence of in-transit melanoma metastasis. In the recent era of systemic melanoma therapies, the provocative question arises as to whether isolated limb perfusion still plays an important role in the treatment of patients with in-transit melanoma metastasis.