Comparison between intrathecal isobaric ropivacaine 0.75% with hyperbaric bupivacaine 0.5%: A double blind randomized controlled study

Background: To compare the sensory and motor loss and duration of analgesia in patients undergoing lower abdominal and lower limb surgeries when isobaric ropivacaine or bupivacaine were used in spinal anesthesia. Methodology: One hundred ASA grades I & II patients of either sex in the age range of 20-60 years undergoing lower abdominal and lower limb surgery were randomly divided into two equal groups: in Ropivacaine Group, patients received 22.5 mg of inj. ropivacaine for spinal analgesia and in Bupivacaine Group; 15 mg of inj. bupivacaine was used for spinal analgesia. Parameters observed were onset of sensory and motor block, two segments regression and duration of motor blockade. Results: The sensory onset was significantly delayed in the Ropivacaine Group (42.6 ± 11.39 min) compared to the Bupivacaine Group (18.4 ± 6.53 min), P<0.001. The motor onset was also significantly delayed in Ropivacaine Group (55.54 ± 13.01 min) compared to Bupivacaine Group (27.5 ± 8.03 min), P<0.001. The peak sensory time was significantly delayed in the Ropivacaine Group (10.92± 2.60 min) compared to Bupivacaine Group (7.38 ± 1.69 min), P<0.001. The peak motor time was also significantly delayed in the Ropivacaine Group (8.92 ± 2.41 min) compared to the Bupivacaine Group (4.82 ± 1.22 min), P<0.001.The two dermatomal sensory segment regression was significantly prolonged in Ropivacaine Group (117.2 ± 12.5 min) compared to Bupivacaine Group (108.5 ± 10.61 min), P<0.001. The duration of motor blockade was significantly prolonged in the Bupivacaine Group (190.2 ± 28.37 min) compared to the Ropivacaine Group (149.7±8.60 min), P<0.001.The duration of post-operative analgesia was similar in both the groups and was statistically insignificant. There was no significant difference in the comparison of heart rate, blood pressure nor significant respiratory side effects between the groups. The quality of sedation was better in Ropivacaine Group (1.16±0.37) as compared to Bupivacaine Group (0.96±0.49) but statistically insignificant. Conclusion: Intrathecal plain ropivacaine might be superior to bupivacaine in terms of a longer sensory block, and a shorter motor block duration. Therefore 0.75% isobaric ropivacaine can be safely used in lower limb and lower abdominal surgeries, especially in cases where early ambulation is desired.