Ventilation strategy and its influence on the functional performance of lung grafts in an experimental model of single lung transplantation using non-heart-beating donors.

OBJECTIVE: To compare the influence of two different ventilation strategies-volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV)-on the functional performance of lung grafts in a canine model of unilateral left lung transplantation using donor lungs harvested after three hours of normothermic cardiocirculatory arrest under mechanical ventilation. METHODS: The study comprised 40 mongrel dogs, randomized into two groups: VCV and PCV. Of the 20 recipients, 5 did not survive the transplant, and 5 died before the end of the post-transplant assessment period. The remaining 10 survivors (5 in each group) were evaluated for 360 min after lung transplantation. The functional performance of the grafts was evaluated regarding respiratory mechanics, gas exchange, and lung graft histology. RESULTS: There were no significant differences between the groups regarding respiratory mechanics (peak inspiratory pressure, plateau pressure, mean airway pressure, dynamic compliance, and static compliance) or gas exchange variables (PaO2, venous oxygen tension, PaCO2, venous carbon dioxide tension, and the arterial-venous oxygen content difference). The histopathological findings were consistent with nonspecific acute lung injury and did not differ between the groups. CONCLUSIONS: This model of lung transplantation showed that the functional performance of lung grafts was not influenced by the ventilation strategy employed during the first six hours after reperfusion.

Influência da estratégia ventilatória no desempenho funcional de enxertos pulmonares em um modelo experimental de transplante pulmonar unilateral de doadores após parada cardiocirculatória / Ventilation strategy and its influence on the functional performance of lung grafts in an experimental model of single lung transplantation using non-heart-beating donors

OBJETIVO: Comparar a influência de duas estratégias ventilatórias - ventilação controlada a volume (VCV) e ventilação controlada a pressão (VCP) - no desempenho funcional de enxertos pulmonares em um modelo canino de transplante pulmonar unilateral esquerdo, utilizando-se doadores cujos pulmões foram captados após três horas de parada cardiocirculatória em temperatura ambiente e sob ventilação mecânica. MÉTODOS: O estudo incluiu 40 cães mestiços randomizados nos grupos VCV e VCP. Dos 20 receptores, 5 não sobreviveram ao transplante, e 5 não sobreviveram ao período de avaliação pós-transplante. Os 10 receptores sobreviventes (5 em cada grupo) foram avaliados durante 360 min após o término do transplante pulmonar. O desempenho funcional dos enxertos foi estudado através da avaliação da mecânica respiratória, trocas gasosas e histologia do enxerto. RESULTADOS: Não houve diferenças significativas entre os grupos quanto às variáveis de mecânica respiratória (pressão de pico inspiratória, pressão de platô, pressão média de vias aéreas, complacência dinâmica e complacência estática) e de trocas gasosas (PaO2, pressão venosa mista de oxigênio, PaCO2, pressão venosa mista de CO2 e diferença arteriovenosa de oxigênio). As alterações histopatológicas foram compatíveis com o padrão de lesão pulmonar aguda não específica e não diferiram entre os grupos. CONCLUSÕES: Este modelo de transplante pulmonar mostrou que o desempenho funcional do enxerto não foi influenciado pela estratégia ventilatória utilizada até seis horas após a reperfusão.

OBJECTIVE: To compare the influence of two different ventilation strategies-volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV)-on the functional performance of lung grafts in a canine model of unilateral left lung transplantation using donor lungs harvested after three hours of normothermic cardiocirculatory arrest under mechanical ventilation. METHODS: The study comprised 40 mongrel dogs, randomized into two groups: VCV and PCV. Of the 20 recipients, 5 did not survive the transplant, and 5 died before the end of the post-transplant assessment period. The remaining 10 survivors (5 in each group) were evaluated for 360 min after lung transplantation. The functional performance of the grafts was evaluated regarding respiratory mechanics, gas exchange, and lung graft histology. RESULTS: There were no significant differences between the groups regarding respiratory mechanics (peak inspiratory pressure, plateau pressure, mean airway pressure, dynamic compliance, and static compliance) or gas exchange variables (PaO2, venous oxygen tension, PaCO2, venous carbon dioxide tension, and the arterial-venous oxygen content difference). The histopathological findings were consistent with nonspecific acute lung injury and did not differ between the groups. CONCLUSIONS: This model of lung transplantation showed that the functional performance of lung grafts was not influenced by the ventilation strategy employed during the first six hours after reperfusion.

Technical modification of unilateral lung transplantation in rats.

The increasing demand in transplantation research requires efficient and less expensive animal models in order to obtain reliable results that are reproducible in larger animal models and, ultimately, applied clinically. The model of unilateral left lung transplantation in rats has proven to be a useful alternative for those purposes. We demonstrate a technical modification of this model, which consists of the isolation and ligation of the contralateral (right) pulmonary artery, allowing blood circulation exclusively in the transplanted lung. This model is feasible and reproducible. However, the short survival time restricts the assessment of the transplanted lung to a maximum period of three hours.

Modificação da técnica de alotransplante pulmonar unilateral em ratos / Technical modification of unilateral lung transplantation in rats

A crescente demanda de pesquisa em transplantes requer modelos eficientes e baratos que permitam resultados confiáveis para que, posteriormente, possam ser reproduzidos em animais de grande porte e, finalmente, aplicados clinicamente. O modelo de transplante pulmonar unilateral esquerdo em ratos tem demonstrado ser uma alternativa útil para estes propósitos. Apresentamos uma nova variante para esta técnica, a qual consiste no isolamento e ligadura da artéria pulmonar contralateral, permitindo a circulação do sangue somente no pulmão transplantado. Este modelo é exeqüível e reprodutível; no entanto, o tempo de sobrevida é relativamente curto, não permitindo avaliação do pulmão transplantado por períodos superiores a três horas.

The increasing demand in transplantation research requires efficient and less expensive animal models in order to obtain reliable results that are reproducible in larger animal models and, ultimately, applied clinically. The model of unilateral left lung transplantation in rats has proven to be a useful alternative for those purposes. We demonstrate a technical modification of this model, which consists of the isolation and ligation of the contralateral (right) pulmonary artery, allowing blood circulation exclusively in the transplanted lung. This model is feasible and reproducible. However, the short survival time restricts the assessment of the transplanted lung to a maximum period of three hours.

Partial liquid ventilation with perfluorodecalin following unilateral canine lung allotransplantation in non-heart-beating donors.

BACKGROUND: The purpose of this study was to evaluate canine lungs obtained from non-heart-beating donors after unilateral lung transplantation subjected to partial liquid ventilation with perfluorodecalin. METHODS: Twelve donor dogs were killed and kept under mechanical ventilation for 3 hours. Heart-lung blocks were harvested after retrograde pulmonary hypothermic flush with Perfadex. Left lung grafts were randomly transplanted into 12 weight-matched recipient animals. Animals were divided into 2 groups: control (standard mechanical ventilation, n = 6) and PLV (partial liquid ventilation, n = 6). Forty-five minutes after transplantation, the animals in the PLV group received perfluorodecalin (15 ml/kg) via orotracheal tube. All animals received volume-controlled ventilation (FIO2) 1.0, PEEP 5 cm H(2)O) over 6 consecutive hours. Thereafter, blood-gas analysis, ventilatory mechanics and hemodynamics were registered at 30-minute intervals. After 6 hours of reperfusion the animals were killed and the transplanted lungs were extracted to obtain the wet/dry weight ratio. RESULTS: There were significant differences in pulmonary arterial pressure, which were higher in control group animals (p < 0.009). The control animals also showed higher arterial PaO(2) than those in the PLV group (p < 0.00001), but lower PaCO(2) (p < 0.008). The peak and plateau pressures were higher in the PLV group (p < 0.00001). Neither static compliance nor wet/dry weight ratios were different in between groups. CONCLUSIONS: PLV with perfluorodecalin yields functional results compatible with life in this model. Nonetheless, pulmonary gas exchange and mechanics were superior after reperfusion in animals given conventional mechanical ventilation up to 6 hours after left lung allotransplantation.