Midazolam in Supraclavicular Brachial Plexus Block
Status:
Completed
Trial end date:
2018-09-01
Target enrollment:
Participant gender:
Summary
An effective brachial plexus block (BPB) provides a useful alternative to general anesthesia
for upper arm surgery producing complete muscular relaxation. It provides surgical anesthesia
in upper extremity surgery, post-operative analgesia and chronic pain management. In addition
to surgical procedure on conscious patients and early eating after the procedure make
regional anesthesia more attractive.
Brachial plexus block also maintains stable intraoperative hemodynamic and associated
sympathetic block. The sympathetic block decreases postoperative pain, vasospasm and edema.
The nerve of brachial plexus may be blocked anywhere along its course. The approach for
blocking brachial plexus nerve is interscalene, supraclavicular, infraclavicular and axillary
approach.
Supraclavicular approach for blockade of the brachial plexus is the most commonly used
approach in providing surgical anesthesia. In recent years, the technique has gained
importance as regional anesthetic technique for surgical, diagnostic and therapeutic purposes
in interventional pain management. It includes blocking of the brachial plexus where it is
most compactly arranged, with fewer requirements of the anesthetic solution and rapid onset
of action. Supraclavicular nerve block is technically easy to perform because of reliable and
fixed landmark but association of pneumothorax is a profound complication.
The extent of blockade following injection into the sheath surrounding the brachial plexus
may depend on the volume and concentration of local anesthetic (LA) used. Because of
bupivacaine long duration of action, it is used most frequently among local anesthetics for
BPB.
Inevitably, the effects of single-injection BPB dissipate after several hours unmasking the
moderate-to-severe pain of the surgical insult. Efforts to prolong BPB duration by increasing
LA dose are limited by their narrow therapeutic window and indeed may not be effective as
recent studies have demonstrated equivalent analgesic duration with volumes as low as 5 ml.
Midazolam is known to produce antinociception and potentiate the effect of LA when given in
neuraxial block. It produces this effect by its action on Gamma Aminobutyric Acid-A (GABA-A)
receptors and also on the peripheral nerves which contain these receptors.
Several studies showed midazolam to be effective when used in intrathecal, epidural and
caudal blocks and now recently midazolam with bupivacaine has been found to improve analgesic
characteristics in peripheral blocks compared to bupivacaine alone. Due to the high blood
concentration of benzodiazepine through conventional routes and profound sedation, proper
assessment of analgesic effect was difficult to obtain. With the advent of the less toxic
water soluble benzodiazepine (midazolam), it became possible to use it directly over the
nerve tissues.