Patients will be randomized to one of two groups:

1. Supraclavicular group: supraclavicular brachial plexus block performed with the aid of ultrasound;
2. Retroclavicular group: retroclavicular brachial plexus block performed with the aid of ultrasound.

The study will be proposed to all patients undergoing formarm or hand surgery under brachial plexus block. Patients will be randomized to one of two groups The first group - supraclavicular group - will receive an ultrasound-guided brachial plexus block via the supraclavicular approach, by injection of 30 ml of a mixture of ropivacaine 0.5 % + mepivacaine 1 %. The second group - retroclavicular group - will receive an ultrasound-guided brachial plexus block via the retroclavicular approach, by injection of 30 ml of a mixture of ropivacaine 0.5 % + mepivacaine 1 %. Primary outcome is success rate at 30 minutes after the injection defined as loss of sensation to pinprick in the forearm and hand. Secondary outcomes are: needling time, time to first analgesic request, postoperative opioid consumption, pain scores at 12 and 24 hours postoperatively, block-related complications, and patient satisfaction.

Inclusion Criteria:

• Adult patients who undergo forearm or hand surgery under brachial plexus block.

Exclusion Criteria:

• History of allergic reaction to local anaesthetics

  • Peripheral neuropathy
  • Renal or hepatic insufficiency
  • Coagulation disorders