Bi-level charge pulse apparatus to facilitate nerve location during peripheral nerve block procedures

A self-contained electrolocation apparatus comprising:

• an electrically conducting needle cannula having a proximal end, a distal end and a hollow bore therethrough;
• a non-conductive tube having a proximal end and a distal end, said tube mounted over said electroconductive needle so that said distal end of said non-conductive tube is proximal to said distal end of said needle cannula;
• a conductive layer on said non-conductive tube whereby said needle cannula and said conductive layer respectively define first and second conductors coaxially spaced from one another by said non-conductive tube;
• a grip fixedly attached to said needle cannula for manipulating said apparatus;
• and
• an electrical stimulus generator circuit including a battery within said grip and electrically connected to said first conductor and said second conductor, said stimulus generator circuit including an input device accessible by a practitioner's finger pressure to select an operating mode from a plurality of operating modes of said stimulus generator circuit, said stimulus generator being capable of applying a potential across said conductors sufficient to generate charge pulses, said circuit further including indications visible and audible to a practitioner of said preselected charge pulses, so that when said needle is positioned in a patient's tissue the practitioner can initiate and terminate one of said patterns of charge pulses and is informed of the status of said generator circuit, and wherein said charge pulses are sufficient to induce preselected constant currents between said distal end of said conductive layer and said distal end of said conductive needle through the patient's tissue, said currents being sufficient to induce a twitch response in the patient.

A method of locating a nerve comprising the steps of:

• providing an electrically conducting needle cannula having a proximal end, a distal end and a hollow bore therethrough;
• inserting the needle into a patient and towards the nerve;
• and
• alternatively generating charge pulses of electrical energy alternating between high and low charge pulses for stimulating the nerve and generating muscle twitches.