SYSTEM AND METHOD FOR MONITORING THORACIC FLUID LEVELS BASED ON IMPEDANCE USING AN IMPLANTABLE MEDICAL DEVICE
First Claim
1. A method for monitoring thoracic fluids within a patient having an implantable medical device, the method comprising:
- detecting thoracic impedance;
detecting cardiogenic impedance; and
monitoring thoracic fluids based on a combination of thoracic impedance and cardiogenic impedance.
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Accused Products
Abstract
Techniques are provided for monitoring thoracic fluid levels based on thoracic impedance (ZT) and cardiogenic impedance (ZC). In one example, the implantable device tracks the maximum time rate of change in cardiogenic impedance (i.e. max(dZC/dt)) to detect trends toward hypervolemic or hypovolemic states within the patient based on changes in heart contractility. The detection of these trends in combination with trends in thoracic impedance allows for a determination of whether the thoracic cavity of the patient is generally “too wet” or “too dry,” and thus allows for the titration of diuretics to avoid such extremes. In particular, a decrease in thoracic impedance (ZT) in combination with a decrease in max (dZC/dt) is indicative of the thorax being “too wet” (i.e. a fluid overload). Conversely, an increase in thoracic impedance (ZT) in combination with a decrease in max (dZC/dt) is indicative of the thorax being “too dry” (i.e. a fluid underload).
43 Citations
20 Claims
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1. A method for monitoring thoracic fluids within a patient having an implantable medical device, the method comprising:
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detecting thoracic impedance; detecting cardiogenic impedance; and monitoring thoracic fluids based on a combination of thoracic impedance and cardiogenic impedance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A system for monitoring thoracic fluids within a patient having an implantable medical device implanted therein, the system comprising:
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a thoracic impedance detector; a cardiogenic impedance detector; and a thoracic fluid monitor that monitors thoracic fluids based on a combination of thoracic impedance and cardiogenic impedance.
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20. A system for monitoring thoracic fluids within a patient having an implantable medical device implanted therein, the system comprising:
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means for detecting thoracic impedance; means for detecting cardiogenic impedance; and means for monitoring thoracic fluids based on a combination of thoracic impedance and cardiogenic impedance.
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Specification