Onset Time of Brachial Plexus Block Using Local Anaesthetic Diluted With 0.9% Saline vs 5% Dextrose

• Patients randomly assigned to receive either 0.5% ropivacaine diluted with NS or D5W.
• Randomization followed a computer-generated randomization table and patients are blinded as to their group allocation.
• Group allocations are concealed in a sealed opaque envelope and only known to an independent anaesthesia trainee who prepares 20mls 0.5% ropivacaine
• The anaesthesiologist involved in the performance of the supraclavicular brachial plexus block is blinded to group allocation
• All ultrasound-guided supraclavicular blocks are performed by 2 anaesthesiologists who are familiar with the technique.
• A trained anaesthesiology trainee who is blinded to group allocation evaluated sensory loss and motor blockade every 5 mins after injection of local anaesthetic.
• The extent of sensory loss is tested in the median, radial, ulnar, and musculocutaneous nerve distributions and evaluated using a 3-point score: 2 = normal sensation, 1 =loss of sensation to pinprick (ie, analgesia), or 0 = loss of sensation to light touch (ie, anesthesia). The extent of motor blockade is tested in the distribution of the radial (thumb abduction), ulnar (thumb adduction), musculocutaneous (flexion of the elbow in supination and pronation), and median nerves (thumb opposition) and evaluated using a 3-point scale where 2 = normal movement, 1 = paresis, and 0 = absent movement.
• Block success is defined as loss of sensation to pinprick (sensory score 1) in each of the radial, ulnar, median, and musculocutaneous nerve distributions measured 60 mins after the end of local anaesthetic injection. Patients in whom block success was not achieved after 60 mins were excluded from data analysis.
• During the postoperative recovery period, pain (verbal response score 4 or patient request for analgesic) is treated with IV tramadol 25-50 mg slow bolus with or without fentanyl 25mcg boluses every 5 minutes as needed.
• When oral intake is allowed, patients will receive oral paracetamol 1g with oral diclofenac 50 mg or celecoxib 200mg, if not contraindicated.
• The block duration is subsequently taken as time from complete analgesia to the time when the patient first feels the slightest pain from the operative site.
• Patients are followed up twice; once on post-operative day (POD) 1 and once between POD 7-10.
• They are seen in the ward or are contacted via telephone and asked for the presence of any pain, weakness, numbness, tingling, or any abnormal sensation in the operative extremity.
• If indicated, they are then told to come to hospital for further evaluation and management as necessary.

Inclusion criteria

• ASA I to III
• elective or emergency surgery of the hand, forearm and elbow

Exclusion criteria

• diabetes mellitus
• neurological deficit
• contraindications to supraclavicular brachial plexus blockade
• unable to give consent
• patient refusal