British Journal of Anaesthesia, 1992, Vol. 69, No. 4 411-413
© 1992 The Board of Management and Trustees of the British Journal of Anaesthesia
research-article |
A METHOD TO FACILITATE REGIONAL ANAESTHESIA BY DETECTION OF MIXED NERVE ACTION POTENTIALS
Department of Anaesthesia, Frenchay Hospital Frenchay, Bristol BS16 1LE.
Burden Neurological Institute Stoke Lane, Stapleton, Bristol BS16 1QT.
We have studied conduction anaesthesia of the median and ulnar nerves at the axilla using mixed nerve action potentials (MNAP) as a guide to needle position in three volunteers. The median and ulnar nerves were stimulated distallv at the wrist using surface electrodes and MNAP were detected proximally in the axilla using an insulated needle electrode. The increase in amplitude of MNAP to maximum as the insulated needle electrode approached the nerve trunk was taken as an indication that the tip of the needle was in close proximity to the nerve trunk. Instillation of 1% lignocaine plain 4 ml decreased the amplitude of the MNAP with the onset of nerve block. We conclude that this method may be of potential use as an aid to peripheral regional anaesthesia by allowing accurate localization of needle position close to specific nerve trunks.
*Present address, for correspondence: Department of Anaesthesia, Poole General Hospital, Longfleet Road, Poole BH15 2JB.