title: 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.
  
  
  OBJECTIVE
  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.
  
  
  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.
  
  
  METHODS
  We included randomised clinical trials comparing veno-venous bypass during liver transplantation (irrespective of language or publication status).
  
  
  METHODS
  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.
  
  
  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).
  
  
  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.
authors.affiliation: Department of Surgery, Royal Free Campus, UCL Medical School, 9th Floor, Royal Free Hospital, Pond Street, London, UK, NW3 2QG.
authors.forename: Kurinchi Selvan
authors.initials: KS
authors.lastname: Gurusamy
authors.forename: Rahul
authors.initials: R
authors.lastname: Koti
authors.forename: Viniyendra
authors.initials: V
authors.lastname: Pamecha
authors.forename: Brian R
authors.initials: BR
authors.lastname: Davidson
mesh_terms: D001803:Blood Transfusion / Q000706:statistics & numerical data; D005112:Extracorporeal Circulation / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D008099:Liver / Q000098:blood supply; D016031:Liver Transplantation / Q000379:methods*; D011169:Portal Vein / Q000502:physiology; D016032:Randomized Controlled Trials as Topic; D051437:Renal Insufficiency / Q000209:etiology / Q000517:prevention & control; D014682:Vena Cava, Inferior / Q000502:physiology; D014683:Vena Cava, Superior / Q000502:physiology