The Protective Value Of Venovenous Bypass On Postoperative Acute Kidney Injury In Patients Undergoing Liver Transplantation

ObjectiveThe aims of this study were to determine if venovunous bypass (VVB) can reduce the incidence of acute kidney injury (AKI) after classic liver transplantation and to investigate the risk factors of postoperative AKI and impact of AKI on postoperative outcomes.MethodsAdult patients who underwent liver transplantation between January 2004 and May 2014 at a tertiary hospital were identified. AKI was determined by Acute Kidney Injury Network (AKIN) criteria (a percentage increase in creatinine (Cr) by≥1.5-fold from preoperative level or an absolute increase in Cr>0.3mg/dL within 48 hours after liver transplantation). Patients with and without intraoperative VVB were compared. Propensity matching was used to control preoperative confounding factors. Logistic regression was used to identify risk factors of postoperative AKI following liver transplantation, and survival analysis was conducted to investigate the impact of AKI on graft survival and patient survival.ResultsOf 1037 patients,247 (23.8%) received VVB and the rest did not. Preliminary analysis showed many preoperative variables were significantly different between the two groups. A propensity score for each patient was generated by a Logistic regression model. The two groups were matched with a 1:1 ratio. After the matching, there were 221 patients in each group.The pre-matching differences disappeared after the matching. The incidence of AKI in the non-VVB group was higher compared with the VVB group, but there was no statistical significance (51.1% in the VVB group vs.55.2% in the non-VVB group; p=0.393). Then the matched patients were further divided into 2 patient populations:normal pretransplant renal function (defined as Cr<1.2mg/dL) and compromised pretransplant renal function (defined as Cr>1.2mg/dL).Analysis showed the incidence of postoperative AKI was significantly higher in non-VVB patients compared with the VVB group (50.8% in the VVB group vs.37.2% in the non-VVB group; P=0.033) in patients with compromised pretransplant renal function. In patients with normal pretransplant renal function, the incidence of AKI was not significantly different. Further analysis by controlling important intraoperative variables confirmed the protective value of VVB on AKI (odds ratio,0.11; 95% confidence interval,0.03 to 0.41; P<0.001) in the specific population. Risk factors of AKI included hypertension (odds ratio,1.41; 95% confidence interval,1.04-1.91; P=0.029), increased body mass index (odds ratio,1.06; 95% confidence interval,1.03-1.09; P<0.001), intraoperative administration of antifibrinolysis (odds ratio,1.39; 95% confidence interval,1.02-1.90; P=0.037) and intraoperative administration of vasopressors (odds ratio,1.43; 95% confidence interval,1.07-1.91; P=0.015). Postoperative AKI was associated with worse outcomes, including prolonged stay in hospital and in intensive care unit, increased incidence of postoperative dialysis (odds ratio,2.70; 95% confidence interval,1.60-4.53; P<0.001), poorer graft survival (hazard ratio,2.04; 95% confidence interval,1.20-3.46; P=0.009), but not patient survival (P>0.05).ConclusionsOur study showed that posttransplant AKI was common and VVB was associated with significantly lower incidence of posttransplant AKI in certain patient population. Risk factors of postoperative AKI included hypertention, increased body mass index, intraoperative administration of vasopressors and intraoperative administration of antifibrinolysis. And AKI was associated with worse postoperative outcomes, including increased incidence of postoperative dialysis and graft failure.