Onset Time of Brachial Plexus Block Using Local Anaesthetic Diluted With 0.9% Saline vs 5% Dextrose
Condition: Comparison of Onset Time
Study type: Interventional

Summary: 
      Regional anesthesia employs the use of local anesthetics (LA) to block specific nerves to
      enable pain free surgery to be performed, or for intra and post operative pain relief.
      Dilution of local anesthetics with normal saline (NS) is a common practice to enable larger
      volumes of LA to be given, for example, in instances where multiple nerve blocks are needed
      to be performed for optimal pain relief while avoiding toxic doses.

      A high sodium concentration is known to antagonize the analgesic effect of local anesthetics.
      5% dextrose (D5W) on the other hand is painless on injection and does not cause any long-term
      effects in animals or humans when injected around neurological tissue. In the literature,
      only one study using dextrose 5% as diluent to produce 0.5% ropivacaine for axillary brachial
      plexus block showed a statistically significant reduction in the onset time for sensory
      blockade when compared with dilution with NS.

      In this study, 0.5% ropivacaine diluted with D5W or NS is used for ultrasound guided
      supraclavicular brachial plexus block, and the time for complete sensory and motor blockade
      was compared. 0.5% ropivacaine is easily diluted and is a common concentration used at our
      centre for nerve blocks. The aim of this study is to assess if 0.5% ropivacaine diluted with
      D5W results in a shorter onset time for sensory block which may change the current practice
      of dilution with NS
    

Detailed description: 
      -  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.
    

Intervention name(s): 0.75% Ropivacaine; Normal saline; Dextrose 5%
Intervention type(s): Drug; Drug; Drug
Other intervention name(s): Naropin
Intervention MeSH terms: Ropivacaine
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: onset time; ultrasound-guided supraclavicular block; ropivacaine; normal saline; dextrose 5%