Deceased brain liver donors were assessed for study eligibility to enroll overall number of 60 donors (30 in each group). Exclusion criteria were age less than 18 years and utilization of the procured graft for retransplantation or reduced size liver transplantation. Between November 2010 and December 2011 consecutive 67 deceased brain donors were assessed of whom 7 were excluded as they fell under exclusion criteria. Enrolled donors were randomized at the beginning of the procurement procedure into a sevoflurane group (inhaled anesthesia with sevoflurane) or a control group (without any volatile anesthetic). All other medication and surgical management was the same. The randomization sequence without any stratification was generated by computer and sealed with consecutively numbered envelopes providing concealment of random allocation. The study was approved by local ethics committee. Written informed consent was obtained from all recipients before liver transplantation.
At the beginning of procurement procedure all donors received bolus of 3μ
g/kg fentanyl to blunt spinal reflexes and bolus of 12
mg pipecuronium bromide for muscle relaxation. Electrocardiogram, arterial oxygen saturation, central venous pressure, and radial arterial blood pressure were monitored routinely. To maintain mean arterial pressure higher than 60
Hg infusion of norepinephrine 0,05–0,15μ
g/kg/min was administered as indicated. In sevoflurane group pharmacological preconditioning with end-expiratory sevoflurane of 2,0
volume% in mixture of oxygen and air (FiO2
= 0,4) was performed for the entire procedure of organ procurement. In control group donors inhaled only mixture oxygen and air (FiO2
= 0,4) without any volatile anesthetic.
All organ procurement procedures were performed in standardized manner by 3 experienced transplant surgeons, who were blinded to randomization. After laparotomy in all donors liver specimen was taken for evaluation for the presence of steatosis. Liver biopsies were evaluated by a single pathologist for the presence of macrovesicular steatosis. Using haematoxylin and eosin-stained sections, the degree of macrovesicular steatosis was graded as absent (0%), mild (1–30%), or moderate (31–60%) based on the percentage of hepatocytes with fat droplets.
All donor organ allografts were implanted by caval replacement technique with bicaval anastomoses. The anesthetic technique was the same in all recipients. Maintenance of anesthesia was obtained with sevoflurane (the minimal alveolar concentration was between 0,7 and 0,9). Fentanyl was given as continuous infusion. During a hepatic phase and after reperfusion norepinephrine 0,1–0,3μ
g/kg/min was used in all recipients to maintain mean arterial pressure at more than 60
Hg. Patients were ventilated with a fraction of inspired oxygen of 0,4 to 0,6, tidal volumes of 7 to 10
mL/kg, and a positive end-expiratory pressure of 0 to 5
O. Transfusion triggers were similar, with a target hematocrit of 25 to 30. Fresh frozen plasma, cryoprecipitate, and platelet concentrate were administered at the discretion of the attending anesthesiologist and according to results of thromboelastometry. All patients received intraoperative 500
mg methylprednisolone as induction of immunosuppression. Transplant surgeons and anesthesiologists were blinded to randomization.
Primary endpoint was postoperative liver injury assessed by peak serum values of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Secondary endpoint was incidence of early allograft dysfunction (EAD) defined as the presence of one or more of the following criteria: bilirubin greater or equal 10
mg/dL on day 7, international normalized ratio (INR) greater than or equal to 1,6 on day 7, and ALT or AST greater than 2000
IU/L within the first 7 days after liver transplantation [6
]. We performed limited number of subgroup analyses to assess the influence of degree of macrovesicular steatosis on protective effect of pharmacological preconditioning with sevoflurane.
Group sample size was calculated based on two assumptions. In our previous experience the mean postoperative peak levels of AST and ALT were 2532 ± 1013
IU/L and 1561 ± 625
IU/L, respectively. We expected that pharmacological preconditioning with sevoflurane could produce 30% reduction in peak levels of liver transaminases, as it was observed by Beck-Schimmer et al. [4
]. Thus, to achieve a 30% reduction in peak levels of transaminases with an α
error of 0,05 and a power 0,80, 29 patients were needed in both groups. The Shapiro-Wilk test was used to check for normal distribution. Nonparametric data were expressed as median (interquartile range) and parametric data as mean ± SD. Group means were compared using Mann-Whitney U
-test or Student's t
-test as appropriate. Categorical variables were compared using two-tailed Fisher's exact test. Significance was defined as P
< 0,05. Calculations were made using SPSS 18.0 software (SPSS Inc., Chicago, IL, USA).