Comparison of dexmedetomidine and clonidine as an adjuvant to intrathecal bupivacaine in lower limb surgery: A randomised, double-blind, placebo controlled trial

Abstract

Background: We compared the duration of analgesia and adverse effects along with the hemodynamic
changes, following intrathecal administration of dexmedetomidine or clonidine with bupivacaine.
Methodology: Seventy five patients of ASA grade I or II, ages between 20-50 years, were enrolled in
the study. Patients were randomly allocated to three equal groups, Group B received hyperbaric
bupivacaine (0.5%) 12.5 mg with normal saline as a placebo, group D received bupivacaine with 3 μg of
dexmedetomidine and Group C received bupivacaine with 30 μg of clonidine. All solutions were made
up to 3 ml with addition of normal saline and injected at L3-L4 using a 25G spinal needle. The onset and
duration of sensory and motor blockade, time to reach peak sensory and motor level and the sensory
and motor regression times were recorded. Hemodynamic changes and time to use first rescue analgesia,
diclofenac sodium 75 mg IM, were also recorded. In post anaesthesia care unit (PACU), pain scores were
recorded using visual analogue scale (VAS), initially every 30 minutes for 8 hours, then every 2 hours
till 24 hours. Descriptive statistics was used for describing frequencies, mean and standard deviation.
Analysis of variance (ANOVA) test was used to compare the quantitative variables in between the three
groups which were independent of each other. Chi square test was used to compare categorical variables.
All the data was analysed using SPSS vs. 17. P value < 0.05 was considered statistically significant.
Results: There was no significant difference in patients demographics or duration of surgery, in the time
to onset of sensory block but motor block was early in Group D and Group C as compared to Group B.
Duration of sensory and motor blockade was prolonged in Groups C and D, compared with Group B.
The mean regression time to S1 segment was 306.6 ± 52 min in Group D, 278.6 ± 27 min in Group C
and 199.8 ± 33 min in Group B. The regression of motor block to Bromage zero was 253.2 ± 38.40 min
in Group D, 229.00 ± 42.57 min in Group C and 175.00 ± 29 min in Group B. The time to analgesia was
significantly prolonged in Group D compared with Group C the latter being longer than Group B.
Conclusion: The addition of dexmedetomidine to intrathecal bupivacaine prolongs the motor and
sensory block and postoperative analgesia when compared to bupivacaine with or without clonidine,
with preserved hemodynamic stability in lower limb surgeries.