Effects of cold ischemia time on hepatic allograft function / Efeitos do tempo de isquemia fria sobre os enxertos hepáticos

ABSTRACT Background : Cold ischemia time is related to success of liver transplantation. Aim : To compare the impact of cold ischemia time on allografts locally collected to those collected distantly. Methods : Were evaluated 83 transplantations. The patients were divided in two groups: those who received liver grafts collected from cities out of Curitiba (n=42) and locally (n=41). From the donors were compared: cause of death, days at ICU, cardiac arrest, vasoactive drugs, lab exams, gender, age, and BMI. Were compared the subsequent information of receptors: cold ischemia time, warm ischemia time, length of surgery, lab exams, etiology of cirrhosis, MELD score, age, gender, histology of graft, use of vasoactive drugs, and blood components transfusion. Were evaluated the correlation between cold ischemia time and lab results. Results : The liver grafts collected from other cities were submitted to a longer cold ischemia time (500±145 min) compared to those locally collected (317,85±105 min). Donors from other cities showed a higher serum sodium level at donation (154±16 mEq/dl) compared to those from Curitiba (144±10 mEq/dl). The length of cold ischemia time was related to serum levels of ALT and total bilirubin. Conclusion : Liver grafts distantly collected underwent longer cold ischemia times, although it caused neither histologic injuries nor higher transfusion demands. There is a correlation between cold ischemia time and hepatic injury, translated by elevation of serum ALT and total bilirubin levels.

RESUMO Racional : O tempo de isquemia fria está relacionado ao sucesso do transplante hepático. Objetivo : Comparar o impacto do tempo dela sobre enxertos captados localmente com os distantes. Métodos : Avaliaram-se 83 transplantes. Os pacientes foram divididos em dois grupos: enxertos captados fora de Curitiba (n=42) e captados localmente (n=41). Dos doadores compararam-se causa do óbito, dias de UTI, parada cardíaca, drogas vasoativas, exames laboratoriais, gênero, idade e IMC. Dos receptores seguintes dados: tempos de isquemia fria e morna, tempo operatório, exames laboratoriais, causa da cirrose, MELD, idade na operação, gênero, biópsia do enxerto, uso de drogas vasoativas e necessidade de transfusões. Foi realizada avaliação de correlação entre o tempo de isquemia fria e os exames laboratoriais. Resultados : Os enxertos captados à distância foram submetidos a maior tempo de isquemia fria (500,3±145 min) quando comparados aos captados localmente (317,85±105 min). Os doadores de fora apresentaram níveis mais elevados de sódio no momento da doação (154±16 mEq/dl) comparados aos doadores de Curitiba (144±10 mEq/dl). Houve correlação entre o tempo de isquemia fria e os níveis de ALT e de bilirrubina total. Não houve diferenças ao comparar-se os demais dados. Conclusão : Enxertos captados à distância sofreram maior tempo de isquemia fria. Isso não refletiu nos prejuízos histológicos nem na demanda transfusional durante o pós-operatório. Houve correlação entre o tempo de isquemia fria e o grau de lesão hepática avaliada pela ALT e pela bilirrubina total.

Lyophilized allografts without pre-treatment with glutaraldehyde are more suitable than cryopreserved allografts for pulmonary artery reconstruction

Various methods are available for preservation of vascular grafts for pulmonary artery (PA) replacement. Lyophilization and cryopreservation reduce antigenicity and prevent thrombosis and calcification in vascular grafts, so both methods can be used to obtain vascular bioprostheses. We evaluated the hemodynamic, gasometric, imaging, and macroscopic and microscopic findings produced by PA reconstruction with lyophilized (LyoPA) grafts and cryopreserved (CryoPA) grafts in dogs. Eighteen healthy crossbred adult dogs of both sexes weighing between 18 and 20 kg were used and divided into three groups of six: group I, PA section and reanastomosis; group II, PA resection and reconstruction with LyoPA allograft; group III, PA resection and reconstruction with CryoPA allograft. Dogs were evaluated 4 weeks after surgery, and the status of the graft and vascular anastomosis were examined macroscopically and microscopically. No clinical, radiologic, or blood-gas abnormalities were observed during the study. The mean pulmonary artery pressure (MPAP) in group III increased significantly at the end of the study compared with baseline (P=0.02) and final [P=0.007, two-way repeat-measures analysis of variance (RM ANOVA)] values. Pulmonary vascular resistance of groups II and III increased immediately after reperfusion and also at the end of the study compared to baseline. The increase shown by group III vs group I was significant only if compared with after surgery and study end (P=0.016 and P=0.005, respectively, two-way RM ANOVA). Microscopically, permeability was reduced by ≤75% in group III. In conclusion, substitution of PAs with LyoPA grafts is technically feasible and clinically promising.

An outcome analysis and long-term viability of cryopreserved cultured epidermal allografts: assessment of the conservation of transplantable human skin allografts

PURPOSE: To assess the viability of cultured epithelium and preserved by freezing for periods varying from one month to one year. METHODS: Samples of cultured epithelium were incubated in cryoprotectant medium (Group A), packed in aluminum envelopes and packed in polystyrene boxes. The boxes were subjected to a temperature of-70ºC. After freezing for a period of time ranging from one to 12 months, cultured epithelial samples were assessed for their viability by vital staining (Trypan blue) and metabolic analysis based on glucose consumption and lactate production. Samples of not frozen cultured epithelium (Group B) were also tested for viability and the results obtained were used as comparison parameter for the variation of viability. RESULTS: Statistical analysis between the group A and B indicate that the mean age of the donors (p=0.51) and the culture time (p=1.18) showed no statistical difference. In 30 days we obtained 37% of the original viability of cultured epithelium, 25% at six months and one year, less than 15%. This trend was confirmed statistically with a reduction of approximately 1.8% of the original viability epithelium cultured every 30 days of storage. In the analysis by lactate production, similar results were observed. In the analysis by the glucose consumption results were not significant. The viability indices show statistically significant difference between the group A and B (p<0.0001). CONCLUSIONS: Although cryopreserved cultured epithelium showed significant reduction of viability, all samples remained viable. It was also found that the viability of cryopreserved cultured epithelial decreased as a function of storage time.