Assessment of the Sympathetic Nervous System Blockade of the Upper Limb After a Brachial Plexus Block in Patients With End Stage Renal Failure

Aim To quantify the degree of sympathetic blockade in the upper limb in patients with end stage renal failure produced during a regional anaesthetic technique, using laser Doppler flowmetry. Hypothesis Regional anaesthesia of the upper limb results in blockade of motor and sensory nerves, providing surgical and post-operative analgesia. Sympathetic nerves are also blocked resulting in local vasodilatation. This may be of benefit in surgery where enhanced blood flow is beneficial such as arterio-venous fistula creation. The degree and duration of sympathetic blockade produced by regional blocks however, has never been quantified. This study aims to quantify sympathetic blockade by measuring the changes in skin blood flow and skin temperature after placement of a brachial plexus block.