To Compare the Effects of Different Doses of Dexmedetomidine on Intrathecal Bupivacaine in Infraumbilical Surgeries: A Prospective, Randomized, Double-blind Clinical Study.

Introduction: Spinal anesthesia is preferred technique of choice in infraumbalical surgeries. Limitation of this technique is shorter duration of analgesia, so various adjuvants have been used with intrathecal bupivacaine such as fentanyl, clonidine, and dexmedetomidine. Dexmedetomidine is a highly selective alpha 2 adrenergic agonist. The aim of our study was to know the effect of different doses of dexmedetomidine on intrathecal bupivacaine.

Materials and Methods: The prospective, randomized, double-blind study was conducted in tertiary health care center, on ninety patients of the American Society of Anesthesiology Class I and II, of age group 18-60 years of either sex. They were randomly allocated into three groups. Group BD5 ( n = 30): intrathecal bupivacaine 12.5 mg (2.5 ml) + dexmedetomidine 5 μg (0.5 ml), Group BD10 ( n = 30): intrathecal bupivacaine 12.5 mg (2.5 ml) + dexmedetomidine 10 μg (0.5 ml), Group BD15 ( n = 30): intrathecal bupivacaine 12.5 mg (2.5 ml) + dexmedetomidine 15 μg (0.5 ml) administered intarthecally. The onset and maximum level of sensory block, time to reach maximum level of sensory block, time of two-segment sensory regression, the total duration analgesia, time of rescue analgesia, onset and duration of motor block and heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure, respiratory rate, and oxygen saturation were recorded at various intervals. Moreover, any adverse effects such as bradycardia, hypotension, nausea, vomiting, and sedation were recorded.

Results: The onset time of sensory block in Group D5 -2.76 ± 1.32, Group D10 -2.45 ± 1.50, and Group D15 -1.86±0.93, which is statistically significant ( P = 0.025). The time taken for two-segment sensory regression Group D5 -96.66 ± 33.67, Group D10 -116.80 ± 36.27, and Group D15 120.96 ± 30.24, ( P = 0.014). The time taken for complete sensory recovery in Group D5 -319.83 ± 61.41, Group D10 -336.13 ± 61.38, and Group D15 -415.20 ± 96.6, which is statistically highly significant ( P = 0.000). Time for rescue analgesia in Group D5 -377.46 ± 60.05, in Group D10 -401.60 ± 61.11, and in Group D15 -517.96 ± 97.30, which is statistically highly significant ( P < 0.000).

Conclusion: We concluded that there was decrease in onset of sensory and motor blockade with the prolongation of duration of anesthesia and analgesia in a dose-dependent manner.