Influence of injection rate of hyperbaric bupivacaine 0.75% on spinal anaesthesia in elderly patients with lower limb orthopaedic surgeries. A randomized controlled trial.

Abstract

To determine the effect of speed of hyperbaric bupivacaine (0.75%) injection on clinical characteristics of spinal anaesthesia in elderly patients undergoing lower limb orthopaedic surgeries. Study Design: Prospective, randomized, double-blind study. Setting: This study was conducted in the operating theatre of Fauji Foundation Hospital, Rawalpindi. Period: August 2018 - March 2019. Materials and Methods: 60 elderly patients undergoing lower limb orthopaedic surgery were randomized into two groups based on injection rate (fast and slow). 1.5 ml of 0.75% hyperbaric bupivacaine was injected over 5 seconds (fast group) and 50 seconds (slow group). Study was undertaken after taking permission from institutional ethical review committee. Level of sensory block, motor block, and systolic blood pressure were recorded at pre-specified intervals. Incidences of hypotensive episode, nausea, phenylephrine and antiemetic use were also documented. Results: Our study did not reveal any difference in maximum level of sensory block attained (fast = median T4, interquartile range [T4–T6] vs slow = T4 [T4–T6], P = 0.77). There was no difference in mean time (minutes) to reach T10 sensory level (fast = 2.5 ± 1.2 vs slow = 2.2 ± 0.8, P = 0.27); maximum sensory level (fast = 4.2 ± 1.5 vs slow = 3.8 ± 1.2, P = 0.26) and maximum motor block level (min) (fast = 5.9 ± 1.4 vs slow = 5.7 ± 1.2, P = 0.56). The rate of hypotension (fast = 8/30 vs slow = 4/30, P = 0.33), nausea (fast = 5/30 vs slow = 3/30, P = 0.99) and phenylephrine use (fast = 5/30 vs slow = 3/30, P = 0.71) and antiemetic requirement (fast = 1/30 vs slow = 2/30, P = 0.99) was also alike. Conclusion: There is no effect of injection speed of intrathecal (0.75%) bupivacaine on the clinical features of spinal anaesthesia in older patients undergoing lower limb orthopedic surgery.