Comparison of dexmedetomidine & fentanyl as an adjuvant to levobupivacaine in peripheral nerve stimulator guided supraclavicular brachial plexus block

Brachial plexus block is one of the approaches to sensorimotor neural blockade by which surgical

anaesthesia of the upper limb may be achieved. It is preferred in upper limb surgeries because it has certain

advantages over general anaesthesia. It is safer in patients who are at high risk for general anaesthesia,

provides good postoperative analgesia and is economical.

The supraclavicular approach to brachial plexus block provides anaesthesia of the upper extremity in the

most consistent and time efficient manner. It has a high success rate and rapid onset of action. Peripheral

nerve blocks have an increasingly important role in ambulatory anaesthesia.

Local anaesthetic agents are compounds that have the ability to interrupt the transmission of the action

potential of excitable membranes by binding to specific receptors in the Na+ channels. Adjuvants have

been added to increase duration of analgesia and reduce total dose of local anaesthetic agents used

minimizing the risk for local anaesthetic agent toxicity.

Levobupivacaine is the newer local anesthetic agent introduced in clinical practice. It is the pure S(-)-

enantiomer of the racemic formulation bupivacaine. Whereas both the R- and S-enantiomers of bupivacaine

have anesthetic activity, preclinical studies suggested that levobupivacaine might be less cardiotoxic than the

racemic mixture. It acts by reversibly blocking neuronal intracellular Na+ channels, preventing

depolarization.

Dexmedetomidine (α2 adrenoceptor agonist) is being used for intravenous (IV) sedation and

analgesia for intubated and mechanically ventilated patients in Intensive Care Units. Its use in

peripheral nerve blocks has recently been described. When used as an adjuvant to local anaesthetic

agent it has been reported to have a rapid onset time, prolong the duration, and is safe in peripheral

nerve blocks.

Opiates are widely known to have an analgesic effect at the central and spinal cord level. However,

opioid analgesia can be initiated by activation of peripheral opioid receptors. Opioids such as

fentanyl have been used for regional nerve plexus blocks to improve the block duration and

quality. The peripheral administration of opioids provides prolonged analgesia without systemic

side effect.[4] Studies have shown better block duration and success rate of brachial plexus block

on addition of fentanyl.

Need for the study:

A number of studies have evaluated the efficacy of both the drugs, either independently or in

combination with other local anaesthetic agents. There are limited studies comparing the use of

fentanyl with levobupivacaine to dexmedetomidine with levobupivacaine. Considering the low

side effect and excellent postoperative analgesic efficacy of two drugs, it is essential to carry out

a comparative evaluation of two drugs for their adjuvant use with levobupivacaine in

supraclavicular block among patients undergoing upper limb orthopedic surgeries.