Comparison between Fentanyl as an Adjuvant to Bupivacaine Versus Bupivacaine alone among Patients undergoing Lower Abdominal Surgeries under Sub Arachnoid Block

Background and Aims: Postoperative pain management is one of the key issues among patients undergoing lower abdominal surgery under subarachnoid block. We decided to study the effect of intrathecal addition of 25 μg fentanyl to 0.5% bupivacaine in terms of quality of blocks and post-operative analgesia. Methods: A total of 80 ASA Grade I/II patients aged >18 years were enrolled in the study and were randomized to two groups: Group I (n=40) received 0.5% hyperbaric bupivacaine (3ml) with fentanyl 25 μg (0.5 ml) intrathecally whereas Group II (n=40) received 0.5% hyperbaric bupivacaine (3ml) diluted with 0.5 ml Normal Saline only. Hemodynamics, sensory block level, onset time and duration of motor/sensory block, adverse effects and Time for first rescue analgesic were noted. Data was compared using SPSS 21.0. Results: Both the groups were comparable demographically and for baseline hemodynamic parameters. No hemodynamic event took place in either of two groups. Median block level achieved was higher in Group I (T6) as compared to Group II (T8) (p<0.001). No significant difference between two groups was observed with respect to mean time taken for onset of sensory and motor blocks (p>0.05). However, mean duration of sensory and motor block was longer in Group I (229.50±56.16 and 163.38±35.15 min) as compared to that in Group II (158.50±50.93 and 116.05±37.66 min) (p<0.001). Time taken to first request for postoperative analgesia was also longer in Group I (288.0±90.37 min) as compared to that in Group II (196.25±59.21 min) (p<0.001). No significant difference in adverse effects was observed (p>0.05). Conclusion: Intrathecal adjuvant use of fentanyl potentiated the post-operative analgesic effect and prolong sensory blockade without affecting motor block.