Addition of clonidine or lignocaine to ropivacaine for supraclavicular brachial plexus block: a comparative study

INTRODUCTION Clonidine is used with local anaesthetics to improve analgesia. However, the improvement conferred when clonidine is used together with ropivacaine is controversial. Thus, the present study aimed to evaluate the improvement in analgesia when clonidine is used together with ropivacaine for supraclavicular brachial plexus block. METHODS This was a prospective, randomised, double-blind controlled study. A total of 75 patients who were scheduled to undergo supraclavicular block were randomly assigned into three groups (i.e. clonidine, lignocaine and control groups) of 25. Patients in all three groups received 20 mL of 0.75% ropivacaine. In addition to that, patients in the clonidine group received 1 mL of clonidine (150 mu g) plus 9 mL of saline, patients in the lignocaine group received 10 mL of 2% lignocaine with adrenaline (1:200,000), and patients in the control group received 10 mL of saline. The characteristics of anaesthesia and analgesia for these three groups were assessed. RESULTS The addition of 2% lignocaine with adrenaline to ropivacaine led to earlier onset of the sensory block (by 4.88 mins), but no increase in the duration of analgesia when compared to analgesia using ropivacaine alone. The addition of clonidine to ropivacaine led to earlier onset of sensory and motor blocks (by 2.88 mins and 3.28 mins, respectively), as well as an increased duration of sensory and motor blocks (by 222.64 mins and 192.92 mins, respectively) when compared to analgesia using ropivacaine alone. The total duration of analgesia was increased by 208.24 mins with clonidine when compared to analgesia using ropivacaine alone. There were no significant differences in sedation score and no side effects in all three groups. CONCLUSION When compared to the use of ropivacaine alone, the addition of 150 mu g clonidine to ropivacaine for brachial plexus block achieved earlier analgesic onset and improved duration of analgesia, without unwanted side effects.