Ultrasound-guided Supraclavicular Brachial Plexus Block in Elderly (US-SCB)

Effects of Age on Minimum Effective Volume of Local Anesthetic for Ultrasound-guided Supraclavicular Brachial Plexus Block (US-SCB)

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.

The study method is a step-up/step-down sequence model where the dose of local anesthetic for the following patient is determined by the outcome of the preceding block. The starting dose of 50:50 mixture of 0.5% levobupivacaine and 2% lidocaine is 30 mL. In the case of block failure, the dose will be increased by 5 mL. Conversely, block success will result in a reduction in dose by 5 mL. A blinded assistant will assess sensory and motor blockade in each nerve territory ( the median, radial, ulnar and musculocutaneous) at 5-min intervals up to 30 min after completion of US-SCB. Effective US-SCB will be defined as complete sensory blockade in the distribution of the radial, ulnar, median and musculocutaneous nerve.

Determining the minimum effective volume of a 50:50 mixture of levobupivacaine 0.5% and lidocaine 2% for successful supraclavicular brachial plexus block for hand surgery in 50% of elderly patients (MEAV50) and to calculate the effective volume in 95% of the elderly patients (MEAV95) as compared with control group (middle aged patients).

Sensory and motor block onset time and duration for each nerve (median, radial, ulnar and musculocutaneous) and for the group.

A blinded Assistant assess onset (in a 5-min intervals up to 30 minutes after completion of US-SCB) ) and duration of sensory and motor blockade (in a 30-min intervals after the completion of surgery).

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

Tomulic K, Pavicic Saric J, Acan I.Effect of age on anaesthetic volume for ultrasound guided supraclavicular brachial plexus block: 8AP2-8 June 2011 - Volume 28 - Issue - p 113 European Journal of Anaesthesiology