Author(s): Hari Kishore1, Rajagopal P.2, Binu Puthur Simon3, Karthika Asokan4
BACKGROUND: Brachial plexus blocks, alone or in combination with general anesthesia, has become one of the most important anesthesia techniques for surgeries in the upper limb. Prolongation of analgesia using perineural catheters are not yet popular, and we are in need for an adjuvant that can prolong the action of local anesthetics after single injection peripheral nerve blocks. Dexamethasone and clonidine are two commonly used adjuvants. This study was undertaken to compare the analgesic efficacy of dexamethasone and clonidine.
MATERIALS AND METHODS: Ninety adult patients fitting under the inclusion criteria were assigned to three groups of thirty each and received ultrasound guided supraclavicular brachial plexus block. They received either dexamethasone 8 mg (Group D) or clonidine 1mcg/kg (Group C) or saline 2 ml (Group S) with 15 ml of 0.5% bupivacaine. The onset of sensory and motor blocks, duration of analgesia and the duration of motor block were assessed.
RESULTS: The onset of sensory and motor block were comparable in all the three groups (17.50±2.86 minutes and 30.33±4.14 minutes; 17.17±3.13 minutes and 31.0±4.8 minutes; 18.33±3.55 minutes and 31.0±5.48 minutes for groups D, C and S respectively. The duration of analgesia and motor blockade was markedly prolonged in dexamethasone group (19.41±2.60 hours and 17.19±2.13 hours) and moderately prolonged clonidine group (11.49±1.66 hours and 10.41±1.18 hours) when compared to saline group (7.56±1.65 hours and 6.22±1.43 hours).
CONCLUSION: Dexamethasone proves to be a better adjuvant compared to clonidine, as it considerably prolongs analgesia and is devoid of significant side effects. But the prolonged motor block is still a matter of concern and the search for an adjuvant that selectively prolongs analgesia without impairing motor function continues.