Veno-venous bypass versus none for liver transplantation

 

Abstract

Background

Veno-venous bypass is used to overcome the effects of clamping of the inferior vena cava and portal vein during liver transplanation. The routine use of veno-venous bypass is, however, controversial.

Objectives

To compare the benefits and harms of veno-venous bypass (irrespective of open or percutaneous technique; heparin-coated or no heparin-coating) versus no veno-venous bypass during liver transplantation. To compare the benefits and harms of the different techniques of veno-venous bypass during liver transplantation.

Search methods

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded until December 2010.

Selection criteria

We included randomised clinical trials comparing veno-venous bypass during liver transplantation (irrespective of language or publication status).

Data collection and analysis

Two authors independently assessed trials for inclusion and independently extracted data. We analysed the data with both the fixed-effect and the random-effects models using RevMan Analysis. For continuous outcomes, we calculated the mean difference (MD) with 95% confidence intervals (CI) based on intention-to-treat or available case analysis. For binary outcomes, we used the Fisher's exact test since none of the comparisons of binary outcomes included more than one trial.

Main results

We identified three trials with high risk of bias which compared veno-venous bypass (n = 65) versus no veno-venous bypass (n = 66). None of the trials reported patient or graft survival. There were no significant differences regarding renal failure or blood transfusion requirements between the two groups. None of the trials reported on the morbidity related to veno-venous bypass or the requirement of veno-venous bypass in the control group.

We identified one trial with high risk of bias which compared percutaneous (n = 20) versus open technique (n =19) of veno-venous bypass. The patient or graft survival was not reported. There was no difference in veno-venous bypass related morbidity between the two groups. The operating time was significantly shorter in the percutaneous technique group (MD -59 minutes; 95% CI -102 to -16).

Authors' conclusions

There is no evidence to support or refute the use of veno-venous bypass in liver transplantation. There is no evidence to prefer any particular technique of veno-venous bypass in liver transplantation.

 

Plain language summary

Is routine veno-venous bypass necessary in liver transplantation?

During liver transplantation major veins are clamped (blocked using clamps) by the surgeon in order to complete the operation. This can decrease the blood returning to the heart which has the potential to decrease the blood pressure and the blood flow to the vital organs. To avoid this, diverting the blood flow through an external circuit bypassing the clamps and returning this blood to the heart (veno-venous bypass) has been advocated by some. However, the use of veno-venous bypass is associated with a risk of major life threatening complications and also minor complications. Thus, the use of veno-venous bypass is controversial.

We systematically searched various medical databases to determine whether veno-venous bypass is required routinely during liver transplantation. We identified a total of three randomised clinical trials with high risk of systematic error and high risk of random errors which compared veno-venous bypass (n = 65) with no veno-venous bypass (n = 66). None of the trials reported patient or graft survival. There were no differences regarding kidney failure or blood transfusion requirements between the two groups. None of the trials reported on the complications related to veno-venous bypass or the requirement of veno-venous bypass in the control group. We also identified one trial with high risk of systematic error and high risk of random errors which compared needle technique (percutaneous approach) (n = 20) with open technique (n =19) of veno-venous bypass. The patient or graft survival was not reported in this trial. There was no difference in veno-venous bypass related complications between the two groups. The operating time was shorter in the percutaneous technique group. There is currently no evidence to support the routine use of veno-venous bypass in liver transplantation.

 

Resumen

Antecedentes

Derivación venovenosa versus ninguna derivación para el trasplante hepático

La derivación venovenosa se utiliza para contrarrestar los efectos del pinzamiento de la vena cava inferior y de la vena porta durante el trasplante hepático. Sin embargo, el uso habitual de esta derivación es polémico.

Objetivos

Comparar los efectos beneficiosos y perjudiciales de la derivación venovenosa (independientemente de la técnica abierta o percutánea; cubierta de heparina o sin heparina) versus ninguna derivación venovenosa durante el trasplante hepático. Evaluar los efectos beneficiosos y perjudiciales de las diferentes técnicas de derivación venovenosa durante el trasplante hepático.

Estrategia de búsqueda

Se hicieron búsquedas en el Registro Especializado de Ensayos Controlados del Grupo Cochrane Hepatobiliar (Cochrane HepatoBiliary Group), Registro Cochrane Central de Ensayos Controlados (Cochrane Central Register of Controlled Trials, CENTRAL) en Cochrane Library, MEDLINE, EMBASE, y en Science Citation Index Expanded hasta diciembre 2010.

Criterios de selección

Se incluyeron ensayos clínicos con asignación aleatoria que compararon la derivación venovenosa durante el transplante hepático (independientemente del idioma o del estado de la publicación).

Obtención y análisis de los datos

Dos autores, de forma independiente, evaluaron los ensayos para su inclusión y extrajeron los datos. Los datos se analizaron con el modelo de efectos fijos y con el de efectos aleatorios mediante el análisis con el programa informático RevMan. Para los resultados continuos, se calculó la diferencia de medias (DM) con intervalos de confianza (IC) del 95% sobre la base del análisis de intención de tratar o de los análisis de casos disponibles. Para los resultados binarios, se utilizó la prueba exacta de Fisher ya que ninguna de las comparaciones de los resultados binarios incluyó más de un ensayo.

Resultados principales

Se identificaron tres ensayos con alto riesgo de sesgo que compararon la derivación venovenosa (n = 65) versus ninguna derivación venovenosa (n = 66). La supervivencia del injerto o de los pacientes no se informó en los ensayos. No hubo diferencias significativas en cuanto a la insuficiencia renal o a los requerimientos de una transfusión sanguínea entre ambos grupos. Ninguno de los ensayos informó morbilidad relacionada a la derivación venovenosa o el requerimiento de la misma en el grupo de control.

Se identificó un ensayo con alto riesgo del sesgo que comparó la técnica percutánea (n = 20) versus la técnica abierta (n = 19) para la derivación venovenosa. No se informó la supervivencia del paciente y del injerto. No hubo diferencias en la derivación venovenosa relacionada con la morbilidad entre ambos grupos. La duración de la cirugía fue significativamente menor en el grupo de técnica percutánea (DM −59 minutos; IC del 95%: −102 a −16).

Conclusiones de los autores

No se hallaron pruebas para apoyar o refutar el uso de la derivación venovenosa para el trasplante hepático. No existen pruebas para elegir alguna técnica específica de derivación venovenosa para el trasplante hepático.

Traducción

Traducción realizada por el Centro Cochrane Iberoamericano