Comparative Study Between Two Adjuvant Drugs to Bupivacaine for Post-operative Epidural Analgesia in Abdominal Surgeries

The aim of the study is to evaluate the effect of dexmedetomidin and fentanyl as adjuvants to bupivacaine for postoperative epidural analgesia in abdominal surgeries regarding block characteristics, post-operative analgesia, hemodynamic changes and any anticipated side effects. * Type of Study: Prospective randomized comparative clinical study. * Study Setting: The operating theatres of Ain Shams University Hospitals * Study Period: One year * Sampling Method: Random sampling Patients randomly allocated by computer generated randomization and using opaque sealed envelopes to one of the three study groups according to the adjuvant drug used in postoperative analgesia. * Sample Size: Total 75 cases divided into 25 cases in each group. Kiran et al. (2018) reported a rather large effect size comparing onset to sensory block and time to maximum motor block. In a one-way ANOVA study, sample sizes of 25 cases per group in three groups whose means are to be compared. The total sample of 75 subjects achieves 80% power to detect differences among the means versus the alternative of equal means using an F test with a 0.0500 significance level. The size of the variation in the means is represented by the effect size = 0.4