Implantable Cardiac Device With Dyspnea Measurement
First Claim
1. An implantable cardiac device, comprising:
- a housing configured for implantation in a patient;
an implantable sensor configured to sense transthoracic impedance;
an implantable activity sensor configured to make an activity measurement indicative of patient activity;
a memory provided in the housing and configured to store at least a pulmonary function index versus activity level profile comprising a plurality of index values associated with different ranges of patient activity levels;
a controller provided in the housing and coupled to the respective sensors and the memory, the controller configured to;
compute an index indicative of patient pulmonary function using the sensed transthoracic impedance by computing a ratio of multiple respiration parameters; and
detect an episode of dyspnea based on a parameter of the computed patient pulmonary function index exceeding an index value of the profile stored in the memory, the index value associated with an activity range of the profile which the patient activity level is calculated to be within; and
communication circuitry provided in the housing and configured to facilitate communication of information between the implantable cardiac device and a device external of the housing.
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Abstract
Cardiac monitoring and/or stimulation methods and systems employing dyspnea measurement. An implantable cardiac device may sense transthoracic impedance and determine a patient activity level. An index indicative of pulmonary function is implantably computed to detect an episode of dyspnea based on a change, trend, and/or value exceeding a threshold at a determined patient activity level. Trending one or more pulmonary function index values may be done to determine a patient'"'"'s pulmonary function index profile, which may be used to adapt a cardiac therapy. A physician may be automatically alerted in response to a pulmonary function index value and/or a trend of the patient'"'"'s pulmonary index being beyond a threshold. Computed pulmonary function index values and their associated patient'"'"'s activity levels may be stored periodically in a memory and/or transmitted to a patient-external device.
147 Citations
20 Claims
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1. An implantable cardiac device, comprising:
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a housing configured for implantation in a patient; an implantable sensor configured to sense transthoracic impedance; an implantable activity sensor configured to make an activity measurement indicative of patient activity; a memory provided in the housing and configured to store at least a pulmonary function index versus activity level profile comprising a plurality of index values associated with different ranges of patient activity levels; a controller provided in the housing and coupled to the respective sensors and the memory, the controller configured to; compute an index indicative of patient pulmonary function using the sensed transthoracic impedance by computing a ratio of multiple respiration parameters; and detect an episode of dyspnea based on a parameter of the computed patient pulmonary function index exceeding an index value of the profile stored in the memory, the index value associated with an activity range of the profile which the patient activity level is calculated to be within; and communication circuitry provided in the housing and configured to facilitate communication of information between the implantable cardiac device and a device external of the housing. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An implantable cardiac device, comprising:
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a housing configured for implantation in a patient; an implantable sensor configured to sense transthoracic impedance; an implantable activity sensor configured to make an activity measurement indicative of patient activity; a memory provided in the housing; a controller provided in the housing and coupled to the respective sensors and the memory, the controller configured to; compute an index indicative of patient pulmonary function using multiple respiration parameters developed from the sensed transthoracic impedance; and detect an episode of dyspnea based on a parameter of the computed index being beyond a threshold, the threshold based on a plurality of patient pulmonary function index values and associated patient activity levels; and communication circuitry provided in the housing and configured to facilitate communication of information between the implantable cardiac device and a device external of the housing. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification