Title: Efficacy of axillary versus infraclavicular brachial plexus block in preventing tourniquet pain.

Investigating team: David Brenner, Gabriella Iohom, Padraig Mahon, George Shorten

Background: Both axillary brachial plexus block and infraclavicular block (ICB) are commonly performed to facilitate upper limb surgery. One possible advantage of ICB is a lesser incidence of tourniquet pain. It is likely that the musculocutaneous, radial, medial cutaneous brachial (MCBN) and intercostobrachial (ICBN) nerves play a role in a patient’s perception of tourniquet pain. The skin of the medial and posterior aspect of the arm receives sensory innervation from the MCBN and ICB nerves. In the pyramid shaped infraclavicular space, the plexus cords usually lie close to each other and proximal to the point at which the MCBN arises; thus the likelihood of achieving MCBN block is greater with block in this region.

Objective: The main objective of the study was to compare Axillary and Infraclavicular Brachial Plexus Block in terms of incidence and severity of tourniquet pain.

Preliminary Results: Eighty two patients were recruited. The incidence, onset time and severity of tourniquet pain were similar in the two groups. The incidence of paraesthesia during block performance, and block performance time were greater in the axillary block group. The volume of local anaesthetic administered was greater in the infraclavicular block group. Infraclavicular block was associated with a greater degree of sensory block in the distributions of both the axillary nerve and the median cutaneous brachial nerve.

Current status: Accepted for publication.