Dexmedetomidine as an Additive to Spinal Anaesthesia in Orthopaedic Patients undergoing Lower Limb Surgeries: A Randomized Clinical Trial Comparing Two Different Doses of Dexmedetomidine

Abstract

Objective:

To compare the outcome of two different doses of dexmedetomidine (3 μg and 5 μg) given in combination with 0.5% hyperbaric bupivacaine via intrathecal route in patients undergoing lower limb orthopedic surgeries at LUMHS Jamshoro.

Methodology:

A randomized controlled trial done at LUMHS, Jamshoro, from March 2023 to March 2024. 114 patients (ASA ≤2) planned for lower limb orthopedic surgery were randomly allocated into two groups. Group A were given 12.5 mg of 0.5% hyperbaric bupivacaine plus dexmedetomidine (3 µg) intrathecally whereas group B received the same combination with 5 µg dexmedetomidine. The primary outcomes of this study were sensory and motor block assesment score, hemodynamic responses, and any complication associated during the perioperative period. The data was then statistically analyzed with SPSS version 26 and the level of significance (P <0.05).

Results:

Group A had a mean age of 37.38 ± 22.57 years, and group B, 41.40 ± 22.36 years. Group A had 72% males and 28% females, while group B had 56% males and 44% females. No intergroup differences were detected while comparing results for TTHSB, TTBS4 and TDOS (p = 0.612, p = 0.230 and p = 0.602 respectively). However, significant differences were observed for time to sensory block initiation (TTSI) (p = 0.003) and time to first rescue analgesia (TTFRA) (p = 0.0001), indicating variations in sensory block initiation and the time to first rescue analgesia between the groups.

Conclusion:

This study confirmed that supplementation of dexmedetomidine, usually at 5 µg, can be a useful adjuvant to hyperbaric bupivacaine for lower limb surgeries under spinal anesthesia. It is longer acting and has a prolonged time to first rescue with higher dose which makes it suitable for long duration procedures. Results of our study suggest that further investigations need to be carried out in order to detect a dose where these two parameters are a more balanced concomitant effect without causing hemodynamic instability.