A Study to Evaluate the Efficacy of Dexmedetomidine and Fentanyl as Adjuvant to Epidural Bupivacaine in Providing Post-Operative Analgesia to Patients Undergoing Total Knee Replacement.

Background: Knee osteoarthritis (OA) is the most common musculoskeletal condition affecting people worldwide. Peri-operative pain has been reported to be the major concern of patients in the post-operative period. There have been continuous searches for a pharmacological agent as an adjuvant which can prolong the analgesic action of local anaesthetic, so that the duration of analgesia can be prolonged in the post-operative period. Both dexmedetomidine and fentanyl have been used as an adjuvant to local anaesthetic delivered through epidural route for post-operative pain relief. Aim of the Study: We aim to compare the post-operative analgesic effects of dexmedetomidine and fentanyl as an adjuvant to epidural bupivacaine in patients undergoing total knee replacement. We will also note any side effects example nausea, vomiting, hypotension, bradycardia and pruritus for each of the study group. Setting and Design: This was a prospective randomized control trial in a tertiary hospital. Materials and Methods: Fifty consenting adult patients with physical status classes I and II, as determined by the American Society of Anaesthesiologists, scheduled to undergo elective total knee replacement, were randomly allocated to receive either Injection 0.5% Bupivacaine 10ml + Inj. Fentanyl 0.5 µg/kg in 2 ml NS (Group A) or injection 0.5% Bupivacaine 10ml + Inj. dexmedetomidine 0.5 µg/kg in 2 ml NS (Group B). The primary objective was to compare the post-operative analgesic effects of dexmedetomidine and fentanyl as an adjuvant to epidural bupivacaine in patients undergoing total knee replacement.. The secondary objective was to note any side effects example nausea, vomiting, hypotension, bradycardia and pruritus for each of the study group. Statistical Analysis Used: The results are discussed in the form of numerical values, percentages, mean and standard deviation. The α level for all analysis was set at 0.05 and p-value <0.05 was considered statistically signicant. Demographic data like sex, weight, age and as grades of both the groups were compared using chi-square test. Comparison of incidence of hypotension was done using Chi-Square test. The software used for statistical analysis was SPSS (statistical package for social sciences) version 21.0 Results: At 2 hours after the rst top-up dose, 15 out of 25 patients in Group B were having complete pain relief (i.e. NPRS 0) while this number in Group A was only 6. At 4 hours, none of the patients in Group A were having complete pain relief while there were 5 patients in Group B who had complete pain relief with NPRS 0. The trend of NPRS when observed at 6 hours exhibited the same pattern as at 4 hours. At 8 hours, in Group A there were just 2 patients which were having NPRS score 4 and rest of the 23 patients had complained of moderate pain with NPRS score 5. In Group B there were 7 patients with NPRS 3 at 8 hours and there were 13 patients with NPRS5. The mean time for NPRS 5 after rst top-up was found to be signicantly more in group B as compared to group A (p-value 0.004). study time required for second top-up was signicantly prolonged in group B (8.40 hours) as compares to group A (6.64hours). The incidence of hypotension is more commonly associated with dexmedetomidine as compared to fentanyl and the incidence of nausea & vomiting is more common when fentanyl is used as an adjuvant with isobaric bupivacaine. Conclusion: Isobaric bupivacaine in 0.5% concentration in combination with Dexmedetomidine as an adjuvant provides better analgesia for a longer duration of time as compared to Bupivacaine & Fentanyl combination.