A comparative study of dexmedetomidine by two different routes as an adjunct to bupivacaine in usg guided supraclavicular block for upper limb surgeries-A prospective randomized placebo controlled triple blind study

The purpose of this study is to compare the onset andduration of sensory and motor blockade with two different routes ofdexmedetomidine viz. perineural and intramuscular as an adjuvant to 0.5% bupivacainein ultrasound guided supraclavicular brachial plexus block. Thestudy will be conducted for a period of 12 months. It will be a prospective,triple blind placebo control trial study. The patients will be allocated one ofthe three groups by block randomization. The study drug solution will be preparedby anesthesiologist not involved in the study. The anesthesiologist performingthe block and anesthesiologist observing the patient, both will be blinded tothe study groups. Data will be analyzed by the anesthesiologist who will beunaware of the group allocation.

The enrolled patients after fulfilling all theinclusion and exclusion criteria will be divided into 3 groups.(i) **Group B (n=30) Control Group –**20 ml of 0.5%Bupivacaine +1ml Normal Saline and 1ml Normal Saline intramuscular.(ii) Group BD (n=30) **Dexmedetomidine Group****–**20 ml of 0.5% Bupivacaine + 50µg Dexmedetomidine in 1ml Normal Saline and 1ml Normal Salineintramuscular.(iii)Group BDIM (n=30) Dexmedetomidine IM Group **–**20 ml of 0.5% Bupivacaine + 1ml Normal saline and 1µg/kg Dexmedetomidine intramuscular.(A total volume of 21ml will begiven in brachial plexus block)

Sensory and motor blockade will be assessed interritories of three nerves (radial, ulnar and median)  for every 3 min after completion of injectiontill 30 minutes and then for every 30 minutes after the end of surgery till thefirst 12 h, thereafter hourly until the block will have completely worn off.Sensoryblock (three nerve territories) will be assessed by pin prick test using a3-point scale: 0 = normal sensation, 1 = loss of sensation of pin prick(analgesia), and2 = loss of sensation of touch (anesthesia) on dorsum of handaround anatomical snuff box for radial nerve, on hypothenar eminence for ulnarnerve, on medial side of thenar eminence for median nerve.  Motor block will be determined by thumbabduction (radial nerve), thumb adduction (ulnar nerve), thumb opposition(median nerve). Further block assessment will be done at hourly intervals up to24 hours by a blinded anesthesiologist.

The primary outcome measure in this study will bethe time to first analgesic request.

The secondaryoutcome measures include the number of supplemental analgesic requirements, VASpain, nausea, patient satisfaction and onset and duration of sensory block andmotor block episode of hypotension and bradycardia.