The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 20, 1989
Filed:
Nov. 03, 1987
Francis M Charbonnier, McMinnville, OR (US);
Martin G Rockwell, Sherwood, OR (US);
Carl E Benvegar, Corvallis, OR (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A method and apparatus is disclosed for providing to the body of a patient a defibrillation pulse having a magnitude calculated to induce in that particular patient a desired defibrillation current. The patient's response to a defibrillation pulse is characterized in advance of defibrillation by repeatedly sampling the patient's transthoracic impedance to a small alternating current excitation signal. The sample having the lowest magnitude is taken to represent the patient's true transthoracic impedance. This lowest sampled impedance value is normalized to take into account the shape of the expected waveform and is then multiplied by the desired current to yield the target charge level to which an energy storage device must be charged to induce the desired current to flow in the patient on discharge. Charging of the energy storage device desirably begins before measurement of transthoracic impedance is completed and continues until the target charge is reached. Discharge of an energy storage device so charged causes the desired current to flow through the patient.