Abstract

Background: Various adjuvants have been used with local anaesthetics in spinal
anaesthesia to prolong postoperative analgesia. Dexmedetomidine, the new highly
selective α2-agonist drug, is now being used as a neuraxial adjuvant. The aim of this
study was to evaluate the onset and duration of sensory and motor block, hemodynamic
effect, postoperative analgesia, and adverse effects of dexmedetomidine, or fentanyl
when given intrathecally with hyperbaric 0.5% bupivacaine.
Materials and Methods: Ninety patients classified in American Society of
Anaesthesiologists classes I and II scheduled for lower abdominal surgeries requiring
spinal anaesthesia were studied. Patients were randomly allocated to receive either 12.5
mg hyperbaric bupivacaine plus 10 μg dexmedetomidine (group D, n=30) or 12.5 mg
hyperbaric bupivacaine plus 25 μg fentanyl (group F, n=30) intrathecal. The control
group received 12.5 mg hyperbaric bupivacaine intrathecally (n=30).
Results: Patients in the dexmedetomidine group (D) had a significantly longer sensory
and motor block time than patients in the fentanyl group (F) and control group (B).
VAS score at rescue analgesia was significantly higher in the control group. Duration of
analgesia was significantly more in the dexmedetomidine, and fentanyl group as
compared to control. The total duration of analgesia was longer with dexmedetomidine
than fentanyl. Sedation scores were significantly higher in the Dexmedetomidine group.
No hemodynamic changes were noted in any group.
Conclusion: Intrathecal dexmedetomidine and fentanyl as adjuvants to hyperbaric
bupivacaine prolong sensory and motor block with minimal hemodynamic instability
and reduced demand for rescue analgesia. Intrathecal dexmedetomidine has a longer
duration of analgesia than fentanyl.