摘要:
A method in electrical impedance tomography uses an adaptive repeated series of calculations and measurements to determine the best current pattern for a body having an initially unknown internal conductivity, for producing the best electrical impedance image for the body. Initially, an arbitrary current pattern and conductivity is utilized to generate a voltage pattern which is measured and compared with the theoretical voltage pattern based on the arbitrary conductivity and current patterns. When both the current pattern and the conductivity yielded by the process closely match values derived by measurements, the voltage pattern is used to produce the image.
摘要:
An apparatus for electrical impedance imaging of a body includes an array of multiple electrodes. Each is connected to an adjustable amplitude precision current source of fixed frequency and an oversampling type digital voltmeter. The current amplitudes are set to produce a series of spatial current patterns, all orthogonal to each other, and each applied for only a short time interval while voltages are measured. The voltage and current values are used to create real and reactive impedance images of the interior of the body.
摘要:
In an electrical impedance imaging system that is capable of forming images based on internal resistivity of a body, an array of electrodes is applied to the surface of the body and energized by a plurality of current generators. Each current generator is controlled to produce current patterns containing single fixed magnitudes. The current generators are also controlled to apply current to the respective electrode only when the current generator is at peak current value to minimize transient conditions and maximize the rate at which images can be produced.
摘要:
A self-contained electrolocation apparatus of the present invention includes an electrically conducting needle cannula having a proximal end, a distal end and a hollow bore therethrough. The invention further includes a non-conductive tube having a proximal end and a distal end, the tube being mounted over the needle cannula so that the distal end of the non-conductive tube is proximal to the distal end of the needle cannula. The non-conductive tube has a conductive layer thereon, whereby the needle cannula and the conductive layer respectively define first and second conductors coaxially spaced from one another by the non-conductive tube. There is a grip fixedly attached to the needle cannula for manipulating the apparatus. The grip has an electrical stimulus generator circuit within it that is electrically connected to the first conductor and the second conductor. The stimulus generator circuit is capable of applying a potential across the conductors so that when the needle is positioned in a patient's tissue and the electrical stimulus generator circuit is activated, the potential is sufficient to induce a preselected current thereby providing a charge pulse between the distal end of the conductive layer and the distal end of said needle cannula through the patient's tissue. The charge pulse is sufficient to induce a twitch response in the patient.
摘要:
An electrolocation apparatus is provided for locating a nerve to which anesthesia may be delivered. The apparatus includes a needle assembly having an electrically conductive needle cannula non-conductive tube secured over the needle cannula, and a conductive plating on the tube. The conductors are connected to a stimulator that generates alternating high and low charge pulses with a constant low current level. The high charge pulses generate noticeable muscle twitches immediately after insertion of the needle into the patient. Muscle twitches responsive to the high charge pulses will peak in magnitude, and muscle twitches responsive to the low charge pulses will become observable as the needle approaches the targeted nerve, and will be indistinguishable from the muscle twitches responsive to the high charge pulses when the needle is in a position for administration of anesthetic.