THORACIC IMPEDANCE DETECTION WITH BLOOD RESISTIVITY COMPENSATION
First Claim
1. A method comprising:
- obtaining a first blood resistivity quantity during a first time using at least one implanted intravascular or intracardiac electrode in a subject;
obtaining a second blood resistivity quantity during a second time using the at least one implanted intravascular or intracardiac electrode;
comparing the second blood resistivity quantity to the first blood resistivity quantity; and
declaring an indication or prediction of anemia to be present in the patient when the second blood resistivity quantity is less than the first blood resistivity quantity by at least a first amount.
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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.
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Citations
30 Claims
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1. A method comprising:
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obtaining a first blood resistivity quantity during a first time using at least one implanted intravascular or intracardiac electrode in a subject; obtaining a second blood resistivity quantity during a second time using the at least one implanted intravascular or intracardiac electrode; comparing the second blood resistivity quantity to the first blood resistivity quantity; and declaring an indication or prediction of anemia to be present in the patient when the second blood resistivity quantity is less than the first blood resistivity quantity by at least a first amount. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An implantable medical device comprising:
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a blood resistivity measurement circuit configured to provide a blood resistivity signal using first and second electrodes; a controller coupled to the blood resistivity measurement circuit, the controller configured to determine an indication or prediction of anemia by comparing a second blood resistivity quantity to an earlier first blood resistivity quantity; and a communication circuit coupled to the controller, the communication circuit configured to communicate the indication or prediction of anemia to an external interface device. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A system comprising:
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means for obtaining a first blood resistivity quantity during a first time using at least one implanted intravascular or intracardiac electrode in a subject; means for obtaining a second blood resistivity quantity during a second time using the at least one implanted intravascular or intracardiac electrode; means for comparing the second blood resistivity quantity to the first blood resistivity quantity; and means for declaring an indication or prediction of anemia to be present in the patient when the second blood resistivity quantity is less than the first blood resistivity quantity by at least a first amount. - View Dependent Claims (26, 27, 28, 29, 30)
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Specification