System and method for automated fluid monitoring
First Claim
1. A method of operating an implantable cardiac device (ICD) to monitor a patient, the method comprising:
- monitoring a position of the patient and making a determination of when the patient assumes a predetermined repose position for at least a predetermined period of time;
initiating a plurality of measurements of thoracic impedance after making said determination that the patient is in said predetermined repose position;
obtaining said plurality of measurements of thoracic impedance by transmitting a signal on at least one ICD lead and sensing a received signal at a point separated from said ICD lead; and
using said measurements to calculate at least one quantity related to thoracic impedance.
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Accused Products
Abstract
An implantable cardiac device and method monitors a patient'"'"'s body impedance so as to diagnose medical problems, such as fluid balance problems in congestive heart failure patients. The device monitors the patient'"'"'s position and determines an appropriate time for collecting body impedance data when the patient is in repose. The device then obtains a series of measurements of thoracic impedance by transmitting a signal on at least one lead, which may be a standard pacemaker lead, and sensing a signal received at a different point. The series of measurements are combined to obtain desired representations of thoracic impedance. In an embodiment, impedance is represented by an extracellular water (ECW) resistance value and an intracellular water (ICW) resistance value determined using a Cole calculation method.
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Citations
32 Claims
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1. A method of operating an implantable cardiac device (ICD) to monitor a patient, the method comprising:
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monitoring a position of the patient and making a determination of when the patient assumes a predetermined repose position for at least a predetermined period of time;
initiating a plurality of measurements of thoracic impedance after making said determination that the patient is in said predetermined repose position;
obtaining said plurality of measurements of thoracic impedance by transmitting a signal on at least one ICD lead and sensing a received signal at a point separated from said ICD lead; and
using said measurements to calculate at least one quantity related to thoracic impedance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A system for monitoring a patient using an implantable cardiac device (ICD), comprising:
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monitoring means for sensing a position of the patient and making a determination of when the patient assumes a predetermined repose position for at least a predetermined period of time;
control means for initiating a plurality of measurements of thoracic impedance after making said determination that the patient is in said predetermined repose position;
impedance measuring means for obtaining said plurality of measurements of thoracic impedance by transmitting a signal on at least one ICD lead and sensing a received signal at a point separated from said ICD lead; and
processing means for calculating, using said measurements, at least one quantity related to thoracic impedance. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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Specification