Comparison of ultrasound guided interscalene brachial plexus block using 0.2% ropivacaine with dexmedetomidine and 0.2% ropivacaine with dexamethasone - A prospective observational study

Introduction

Adding adjuvants to local anaesthetics in brachial plexus block is known to enhance the quality and duration of analgesia. This study was undertaken to compare 1 µg/kg of dexmedetomidine, or 100 µg/kg of dexamethasone added as adjuvants to 0.2% ropivacaine in ultrasound guided interscalene brachial plexus block for arthroscopic shoulder surgeries.

Subjects and methods

A prospective observational study in which 92 patients scheduled for arthroscopic shoulder surgery under ultrasound guided interscalene block with 15 ml of 0.2% ropivacaine and dexmedetomidine (Dexmed) or dexamethasone (Dexa) as adjuvants. Onset, duration of sensory and motor blockade, sedation score, time for rescue analgesia (duration of analgesia) were recorded and analysed.

Results

Demographic data and surgical characteristics were similar in both the groups. Sensorimotor blockade onset was earlier in group Dexmed (8.67 ± 3.06 min) as compared to group Dexa (14.61 ± 6.71 min) [P  < 0.001]. Blockade duration was longer in group Dexmed than group Dexa. Time of request for rescue analgesia was delayed in group Dexmed (930.0 ± 83.45 min) when compared to group Dexa (620.0 ± 125.54 min). Mild sedation was observed in group Dexmed.

Conclusion

Dexmedetomidine as an adjuvant to 0.2 % ropivacaine in ultrasound guided interscalene blockade is more efficacious than dexamethasone in hastening the onset, prolonging sensory blockade and delaying the time of request for rescue analgesia. Dexmedetomidine produces mild sedation compared to dexamethasone as an adjuvant.