Background and Goal of Study:
A growing number of patients undergo liver surgery using an enhanced recovery after surgery protocol. Epidural analgesia is widely used in such programs. However in liver surgery there are some safety concerns for epidural analgesia1 as major liver surgery may impair postoperative coagulation2. The aim of this study is to evaluate potential different effects of the surgical approach on INR during the first 4 post-operative days. 

Materials and Methods:
After ethical committee approval, the database of all liver surgery patients between 2010 and 2016 was screened for retrospective analysis of INR. Patients were divided into two groups depending on the method of surgery (laparoscopy versus laparotomy). Postoperative INR measurements were collected for the first 4 post-operative days and analyzed. Due to non-normality, non-parametric alternatives to ANOVA for repeated measures (Friedman test), mixed ANOVA and pairwise comparisons were used for statistical analyses.

Results and Discussion:
A total of 970 patients were screened. 248 patients were eligible for analysis, of which 172 underwent an open procedure and 76 a laparoscopic procedure. For the total group, INR significantly increased over time, peaking at postoperative day 2 (1.00 vs 1.35, p < 0.001). Overall values of INR were higher in the laparotomy group (p = 0.045).The pattern of perioperative changes, however, failed to reach significance (p =0.25) between the two surgical techniques (figure 1).

Conclusion(s):
In liver surgery, INR values alter over time, with the highest INR on postoperative day 2 for both laparoscopy and laparotomy. However the time course of postoperative INR values did not differ between both techniques. 

02 / Postoperative time course of INR values in laparoscopic and open liver surgery: a retrospective analysis.