THORACIC IMPEDANCE DETECTION WITH BLOOD RESISTIVITY COMPENSATION

• US 20080249433A1
• Filed: 06/16/2008
• Published: 10/09/2008
• Est. Priority Date: 08/19/2004
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Stahmann, Jeffrey E., Moon, Boyce, Hatlestad, John
• Granted Patent: US 7,672,718 B2
• Time in Patent Office: Days
• US Class Current: 600/547
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance

Abstract

This document discusses, among other things, a cardiac rhythm management device or other implantable medical device that uses thoracic impedance to determine how much fluid is present in the thorax, such as for detecting or predicting congestive heart failure, pulmonary edema, pleural effusion, hypotension, or the like. The thoracic fluid amount determined from the thoracic impedance is compensated for changes in blood resistivity, which may result from changes in hematocrit level or other factors. The blood-resistivity-compensated thoracic fluid amount can be stored in the device or transmitted to an external device for storage or display. The blood-resistivity-compensated thoracic fluid amount can also be used to adjust a cardiac pacing, cardiac resynchronization, or other cardiac rhythm management or other therapy to the patient. This document also discusses applications of the devices and methods for predicting or indicating anemia.

Claims

1. A method comprising:

detecting a thoracic impedance signal of a thorax of a subject;

detecting a blood resistivity signal; and

determining a thoracic fluid indication using the thoracic impedance signal, the determining the thoracic fluid indication including using the blood resistivity signal to reduce or eliminate an effect of a change in the blood resistivity on the thoracic fluid indication.