Clonidine as an adjuvant in axillary brachial plexus block for below elbow orthopedic surgeries: A comparison between...

Axillary brachial plexus block for below elbow orthopedic surgery provides a safe and low-cost technique with the advantage of prolonged postoperative analgesia. Clonidine, with selective partial agonist activity on α2 adrenergic receptors, has significantly demonstrated its role in this regard as an adjuvant to local anesthetics. The current study compares the locally administered clonidine with systemically administered control group in terms of onset and duration of sensory block, motor block, and analgesia; hemodynamic variability; sedation; and other side effect profile.

Seventy patients (ASA I or II) scheduled for below elbow orthopedic surgeries were randomly allocated in equal numbers to receive either 30 ml of 0.5% plain bupivacaine with 150 μg (1 ml) of inj. clonidine locally in the axillary sheath and 1 ml of normal saline (NS) subcutaneously (Group L) or 30 ml of 0.5% plain bupivacaine with 1 ml of NS locally and 150 μg (1 ml) of inj. clonidine subcutaneously (Group S). Standard monitoring of vital parameters was done. Duration of sensory and motor block, analgesia, hemodynamic changes, and any adverse effects were observed and recorded for different duration up to 24 h.

Duration of sensory block (625 ± 35 min), motor block (690 ± 38 min), and analgesia (930 ± 45 min) was significantly longer in Group L than in Group S [sensory block (480 ± 30 min), motor block (535 ± 25 min), and analgesia (720 ± 30 min)] (P < 0.05). Significant alteration of heart rate, systolic blood pressure and diastolic blood pressure, and mean arterial pressure in Group S was observed compared to Group L (P < 0.05). Side effects like nausea and vomiting were comparable, but highly significant sedation score (χ(2) = 47.75 and 49.51 at 120 and 240 min, respectively; P < 0.01) was observed between the two groups.

Compared to systemic administration, local clonidine as an adjuvant in axillary block resulted in significant prolongation of duration of sensory and motor blockade, and analgesia without any hemodynamic alteration, probably by locally mediated mechanism of action.