A prospective randomized controlled double blind study of the effects of intravenous dexmedetomidine on subarachnoid block with hyperbaric bupivacaine for elective inguinal hernia repair in adult male patients

Abstract

Background and objectives: Intravenous (IV) dexmedetomidine is used as an adjuvant to general anesthesia due to its excellent analgesic and sedation properties. These properties may be useful to prolong the duration of sensory and motor block with spinal anesthesia. Hence, this study was designed to assess the effects of IV dexmedetomidine on the onset, duration and the hemodynamic characteristics of subarachnoid block (SAB) with hyperbaric bupivacaine 0.5% for elective inguinal hernia repair in adult male patients.

Methodology: This prospective randomized double blind study was conducted in 60 adult male patients belonging to American Society of Anesthesiologists (ASA) class I and II undergoing elective inguinal hernia repair. The enrolled patients were divided into 2 groups (n=30) to receive either 0.5 µg/kg dexmedetomidine intravenous bolus over 10 min (Group D) or saline infusion (Group C) prior to subarachnoid block with 0.5% hyperbaric bupivacaine 12.5 mg. Parameters assessed were the time of onset, highest level of sensory block, time to two segment sensory regression, total duration of analgesia, onset and duration of motor block, in addition to hemodynamic parameters at various intervals.

Results: Faster onset time of sensory block (1.29 ± 0.26 min vs. 3.38 ± 0.62 min), prolonged two segment sensory regression time (105.47 ± 8.71min vs. 71.3 ± 9.4 min) and prolonged duration of sensory block (249.5 ± 36.32 min vs. 154.17 ± 13.46 min) were observed in Group D compared to Group C. Similarly, rapid onset (2.92 ± 0.73 min vs. 6.52 ± 0.91 min) and prolonged duration of motor block (192 ± 28.44 min vs135.43 ± 12.64 min) were noted in Group D. Mean sedation score in Group D was 3.83 ± 0.379 vs. 1.83 ± 0.379 in Group C. Time of request for rescue analgesia was significantly prolonged in Group D compared to Group C. Hemodynamic parameters and incidence of side effects were similar in both the groups.

Conclusion: Premedication with single dose of intravenous dexmedetomidine 0.5 µg/kg prior to subarachnoid blockade with 0.5% hyperbaric bupivacaine hastens the onset and increases duration of sensory and motor block, with maintenance of stable hemodynamics and arousable sedation in infra umbilical surgeries in adult male patients.