Intrathecal versus intravenous infusion of dexmedetomidine during subarachnoid block in lower abdominal surgeries

Background
Adjunct analgesic strategy is an alternative to prolong the analgesic duration and decrease the potential risk of side effects. The objective of this study was to evaluate the efficacy of dexmedetomidine as an adjuvant to subarachnoid anesthesia during lower abdominal surgeries compared with dexmedetomidine intravenous infusion.
Patients and methods
Forty patients, classified as American Society of Anesthesiologists I and II patients, aged 20–50 years, undergoing elective lower abdominal surgeries, were randomly allocated into two equal groups. Group I (=20) consisted of patients who received intrathecal 0.5% hyperbaric bupivacaine 15 mg (3 ml)+dexmedetomidine (10 µg) for subarachnoid block. Group II (=20) consisted of patients who received intravenous infusion of dexmedetomidine 0.5 μg/kg/h (without loading) after subarachnoid block. The onset and duration of sensory and motor block, the hemodynamic effects, the duration of analgesia and the incidence of side effects were recorded. Interleukin-6 level was estimated.
Results
Hemodynamic data were comparable between both groups. The mean time taken for the sensory block to reach T10 dermatome and motor block to reach B3 was significantly fast in group I as compared with group II. The time for two segment regressions and regression of sensory block to S2 dermatome and B0 motor block were significantly prolonged in group I compared with group II. The time to first rescue analgesic was prolonged, and the amount of analgesic/24 h was decreased significantly by the addition of dexmedetomidine to bupivacaine. Ramsay sedation scores were highly significant, being higher in group II. The level of interleukin-6 and the incidence of side effects were significantly lower in group I compared with group II.
Conclusion
In lower abdominal surgery, the use of intrathecal dexmedetomidine as an adjuvant to local anesthesia provides good motor and sensory blockade and is associated with mild sedation, decreased incidence of side effects, and inflammatory response compared with intravenous infusion.