Patent ID: RE38695

Claim:
An electrode patch for use in a non-invasive device for detecting extravasation that may occur when a needle with a tip is inserted into a patient in order to introduce fluid into the vascular system of a patient, comprising: a body of the patch adapted to be affixed to the skin of a patient, an outer pair of elongated electrodes and an inner pair of elongate electrodes, the length of each of said electrodes being deployed along the body of said patch, said inner pair of electrodes being spaced from one another on either side of a center line, said inner pair defining a measuring zone, said measuring zone being shaped and dimensioned to encompass a needle tip within said zone, said zone being small enough to optimize sensitivity, said inner pair being long enough to facilitate placement of the patch over a needle tip inserted into a patient, each of said outer pair of electrodes being outward, relative to said center line, of a respective one of said inner electrodes, energization of said outer electrodes, when said patch is affixed to the skin of a patient, providing a field which induces a signal in said inner electrodes that is a function of the impedance of the tissue in said measuring zone.