Brachial Plexus Block Duration Clinical Trial
Official title:
A Randomized Comparison Between Intravenous and Perineural Dexamethasone for Ultrasound-Guided Axillary Blocks
Dexamethasone prolong the duration of brachial plexus blocks, but the optimal route,
intravenous (IV) or perineural (PN), remains controversial.
This Multi-centric trial compare IV and PN dexamethasone for ultrasound-guided axillary
brachial plexus blocks (AXBs). Research hypothesis is that PN modality will outlast its IV
counterpart. Since analgesic duration and sensory duration can be influenced by intake of
pain medications and surgical trauma to small cutaneous nerves, the investigators will
select motor block duration as the main outcome.
After Ethics Committee of the McGill University Health Centre, a total of 150 patients
undergoing upper extremity surgery (below the elbow) will be recruited.
All AXBs will be supervised by one of the coauthors and conducted preoperatively in an
induction room. This area will have full access to an oxygen source, resuscitative equipment
and drugs.
All patients will have fasted for at least eight hours. An IV cannula will be placed prior
the block and will be monitored and given oxygen at 2-4 L/min through nasal cannulas.
Light sedation will be provided for patient comfort if needed.Patients will be placed supine
with the shoulder abducted and the elbow flexed. The AXB will have a puncture site superior
to the axillary artery. After skin disinfection and draping, a skin wheal will be raised
with 3 mL of lidocaine 1.5%.
In both groups, 30 mL of lidocaine 1.0%-bupivacaine 0.25% with epinephrine 5 µ/mL will be
used. A 22-gauge, 5 cm block will be advanced under direct US vision toward the
musculocutaneous nerve. Six mL of LA will be deposited in this location. The needle will
then be directed posterior to the artery, at 6 o'clock position and twenty-four mL of LA
will be deposited to obtain a spread around the artery.
Patients will be randomized to receive 8 mg of IV or PN dexamethasone. In the IV group,
patients will receive 0.8 mL of dexamethasone (10 mg/mL) intravenously and 0.8 mL of normal
saline will be added to the injectate through the block needle. In the PN group, patients
will receive 0.8 mL of normal saline intravenously and 0.8 mL of dexamethasone (10 mg/mL)
will be added to the injectate through the block needle.
A research assistant will prepare the IV and PN injectates. The operator, patient and
investigator assessing the block will be blinded to group allocation.
If placement of the needle tip in the desired location is unsuccessful after 15 minutes, the
procedure will be stopped and the patient excluded from the study. Brachial plexus blockade
will be carried out using an alternative method. If the alternative method fails as well,
the patient will be given general anesthesia and intravenous narcotics will be used for
postoperative analgesia
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