Efficacy and safety of dexmedetomidine as an intrathecal agent: a dose finding clinical study
Abstract
Background and Objectives: Dexmedetomidine is increasingly being used in regional anesthesia as an adjuvant but there is no consensus on exact minimal and safe dose when used intrathecally. The present study was conducted to evaluate the efficacy of three different doses of dexmedetomidine when given intrathecally as an adjuvant to bupivacaine in patients undergoing lower abdominal surgery.
Methodology: After taking ethical committee approval, and obtaining patients consent, 60 American Society of Anesthesiologist (ASA) physical status I and II patients in the age group of 25-60 years undergoing lower abdominal surgeries were divided randomly into three groups in this randomized double blind study. An intrathecal dose of 2.5 ml of 0.5% hyperbaric bupivacaine was administered to all patients supplemented with dexmedetomidine. In Group A 5 mg, Group B 7.5 mg and in Group C 10 mg of dexmedetomidine was administered with a volume of 3ml of study drug in each group. The onset time, time to peak sensory level, motor blockade, sedation, duration of motor block, analgesia and any adverse effects were noted. At the end of the study, data were compiled and analyzed with appropriate statistical tests.
Results: Demographic profile was comparable in all the three groups. The time to onset of sensory block in Group C (1.55 ± 0.510 min) was significantly lower than Group A (2.15 ± 0.745 min) and Group B (2.20 ± 0.410 min). Sensory regression by two segments was significantly higher in Group C (220.65 ± 25.86 min) as compared to Group A (104.7 ± 25.5min) and Group B (145.10 ± 24.54 min). (p < 0.05) The duration of motor block was shortest in Group A (243.8 ± 22.0 min) as compared to Group B (305.4 ± 35.8 min) and Group C (387.0 ± 39.4 min). The visual analogue scale score for pain was lesser in Group C as compared to the other two groups.
Conclusion: Optimal dose of dexmedetomidine is difficult to define especially with prolonged duration of sensory and motor blockade in a dose dependent manner with minimal increase in side effects with higher doses. However, we conclude that 7.5 mg seems to be just optimal intrathecal dose of dexmedetomidine and can be used safely and effectively in lower abdominal surgeries.
