Dexamethasone & Bupivacaine vs Bupivacaine Alone in Combined Femoral and Sciatic Nerve Block for Perioperative Analgesia in Patients Undergoing Lower Limb Surgeries

In regional anesthesia local anaesthetics alone provide analgesia for not more than 4-8 hours. Increasing the duration of local anaesthetic action is often desirable because it prolongs surgical anaesthesia and analgesia. Different additives have been used to prolong regional blockade. Vasoconstrictors can be used to constrict vessels, thereby reducing vascular absorption of the local anaesthetic. Additives like opioids, clonidine and verapamil were added to local anaesthetics, but the results are either inconclusive or associated with side effects. Steroids when used intrathecally are reported to cause arachnoiditis, but there is no evidence suggesting any neuritis when steroids are used in low concentration in peripheral nerve blocks.

Steroids have powerful anti-inflammatory as well as analgesic properties. Perineural injection of steroids is reported to influence postoperative analgesia. They relieve pain by reducing inflammation, and blocking transmission of nociceptive C-fibres and by suppressing ectopic neural discharge. The addition of 5 mg of dexamethasone to 10 ml of 0.5% levobupivacaine in interscalene brachial plexus block showed improvement of postoperative analgesia for arthroscopic shoulder operation without any specific complications.

The objective of this study is to compare the effects of combining of dexamethasone and bupivacaine versus bupivacaine alone in combined femoral and sciatic nerve block in patients undergoing lower limb vascular surgeries. The effects will be studied in terms of:

* Onset of sensory blockade and motor blockade * Duration of analgesia / first request for analgesic * Duration of motor blockade