The aim of this study is to determine the minimum effective volume of local anesthetic (50:50 mixture of 0.5% levobupivacaine and 2% lidocaine) required to produce an effective US-SCB for surgical anesthesia in 50% of patients and to calculate the effective volume required to produce an effective US-SCB in 95% of the patients (MEAV95) in elderly group (>65 years) and in middle aged group (<45years) of patients.

We believe that known data regarding the minimum anesthetic volume required for effective US-SCB from middle age population can not be applicable to the elderly population since our preliminary data, presented at Euroanesthesia meeting in Amsterdam, 2011, and published in abstract form in the European Journal of Anaesthesiology, showed that involutional changes of brachial plexus in elderly, assessed by measuring the cross-sectional area (CSA) of brachial plexus at the first rib, allowed a 35% reduction in local anesthetic volume for an effective US-SCB for surgical anesthesia in elderly patients in comparison with the younger patients.

Inclusion Criteria:

• ASA 1 - 3 elderly patients (>65 years) scheduled for hand surgery
• ASA 1-3 middle aged patients (<45 years)

Exclusion Criteria:

• Cognitive impairment
• Coagulopathy
• Allergy to local anesthetics
• Infection at the puncture site,
• Body mass index > 35 kg/m2