Comparison of Onset Time Clinical Trial
Official title:
Onset Time of Brachial Plexus Block Using Local Anaesthetic Diluted With 0.9% Saline vs 5% Dextrose
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
- 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.
;
Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Parallel Assignment, Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor), Primary Purpose: Treatment