Low cost, compact and pulsated constant current microcontroller based nerve locator

Regional anesthesia is preferred to global anesthesia when applicable due to its safety, low cost and patient preference. Successful regional anesthesia depends upon precise location of the peripheral nerve or nerve plexus. Locating peripheral nerves is usually done using nerve stimulation which is considered by many to be the current `gold standard´. In order to generate a nerve impulse by electrical means, a threshold stimulus of current must be applied to the nerve “rheobase”. The technique depends on stimulating muscular twitching at a close distance to the nerve without actually touching it. In this paper, a design for μcontroller-based nerve locator is introduced. The current delivered to the nerve is maintained constant in the proposed design for a wide range of load impedances. The device is tested and used to locate the nerves in the limbs of the animal. Moreover, the device tested successfully against IEC safety standards and compared to prior arts. The comparison is based on five characteristics which are waveform, current intensity, impulse duration, maximum load and functionality. Based on that rules the proposed design is able to achieve reasonably high scores that put it on the second place among 22 available nerve stimulators.