Impedance monitor for discerning edema through evaluation of respiratory rate
First Claim
1. Implantable apparatus for detection of impedance measurement in a region of a living body'"'"'s tissue, having a plurality of electrodes exposed to said body tissue on an outer surface of a housing or on another support coupled to said body, said housing containing electrical energy pulse delivery means connected to at least one of said plurality of electrodes so as to create an electric field in said body in an area of tissue around and adjacent said one electrode and energy measurement means connected to at least one other of said plurality of said electrodes also located within said electric field, so that impedance measurements in the living body can be made in said field, said implantable device further characterized by having:
- timing circuit for timing the measurement of impedance to coincide with delivery of said energy pulse,memory circuit for storing a value representative of a dc value of said measured impedance at an instant in time,dc sampling offset circuit for determining a dc offset value of a next measurement of said impedance and connected to provide a dc offset value signal to said memory circuit,edema valuation and output circuit for generating output signals indicative of a level of edema related to the impedance values from in said memory circuit and said offset circuit, andwherein said memory circuit stores either said dc offset values or said dc values or both, over a period of days.
1 Assignment
0 Petitions
Accused Products
Abstract
An impedance monitor for discerning edema through evaluation of respiratory rate. Preferred embodiment includes edema monitor and trigger to initiate diagnostic reporting or corrective action when activated. Recording of Long Term Average and Short Term Average values for secondary edema measure based on DC signal level are described as are methods and apparatus for removing unwanted recurring noise.
693 Citations
36 Claims
-
1. Implantable apparatus for detection of impedance measurement in a region of a living body'"'"'s tissue, having a plurality of electrodes exposed to said body tissue on an outer surface of a housing or on another support coupled to said body, said housing containing electrical energy pulse delivery means connected to at least one of said plurality of electrodes so as to create an electric field in said body in an area of tissue around and adjacent said one electrode and energy measurement means connected to at least one other of said plurality of said electrodes also located within said electric field, so that impedance measurements in the living body can be made in said field, said implantable device further characterized by having:
-
timing circuit for timing the measurement of impedance to coincide with delivery of said energy pulse, memory circuit for storing a value representative of a dc value of said measured impedance at an instant in time, dc sampling offset circuit for determining a dc offset value of a next measurement of said impedance and connected to provide a dc offset value signal to said memory circuit, edema valuation and output circuit for generating output signals indicative of a level of edema related to the impedance values from in said memory circuit and said offset circuit, and wherein said memory circuit stores either said dc offset values or said dc values or both, over a period of days. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 23, 29, 30, 31, 32, 33)
-
-
14. Implantable apparatus for detection of impedance measurement in a region of a living body'"'"'s tissue, having a plurality of electrodes exposed to said body tissue on an outer surface of a housing or on another support coupled to said body, said housing containing electrical energy pulse delivery means connected to at least one of said plurality of electrodes so as to create an electric field in said body in an area of tissue around and adjacent said one electrode and energy measurement means connected to at least one other of said plurality of said electrodes also located within said electric field, so that impedance measurements in the living body can be made in said field, said implantable device further characterized by having:
-
timing circuit for timing the measurement of impedance to coincide with delivery of said energy pulse, memory circuit for storing a value representative of a dc value of said measured impedance at an instant in time, dc sampling offset circuit for determining a dc offset value of a next measurement of said impedance and connected to provide a dc offset value signal to said memory circuit, edema valuation and output circuit for generating output signals indicative of a level of edema related to the impedance values from in said memory circuit and said offset circuit, wherein said edema valuation and output circuit for generating comprises LTA/STA determining circuit means wherein a processor circuit derives a LTA signal value and a STA signal value based on the values of impedance stored over a predefined long term and short term, respectively for determining an LTA value and an STA value and memory means for storing said determined LTA and STA values and LTA/STA updating circuit means for updating said STA and LTA values based on new measurements of impedance.
-
-
15. An implantable device for chronic implant into a living body having at least one lead adapted for location in the heart of said body and means for generating electrical output pulses between said at least one lead and another electrode so as to enable the measurement of impedance between said at least one lead and said other electrode, the improvement comprising a
impedance determination means to determine the impedance of the thoracic cavity of the body based on the dc value of impedance measured between said lead and said electrode, edema evaluation means to determine values representing a level of edema based on said measurement at times over a course of days, and means for storing said value representing a level of impedance in said device for said times over said course of days.
-
27. Apparatus for implant into a living body having at least one lead adapted for location in the heart of said body and means for generating electrical output between said at least one lead and another electrode so as to enable the measurement of impedance between said at least one lead and said other electrode, the improvement comprising
means to determine the impedance of the thoracic cavity of the body based on the value of impedance measured between said lead and said electrode, and means to determine a value representing a level of edema based on said measurement wherein said means for interpreting comprises LTA/STA determining circuit means wherein a processor circuit derives a LTA signal value and a STA signal value based on the values of impedance stored over a predefined long term and short term, respectively for determining an LTA value and an STA value and memory means for storing said determined LTA and STA values and LTA/STA updating circuit means for updating said STA and LTA values based on new measurements of impedance.
-
28. Implantable apparatus and system having monitor means for determining edema values and to record such values and having at least one additional value monitor means for monitoring physiologic values from a list of physiologic parameters comprising:
activity, activity per unit of time, activity variability, heart rate, heart rate variability, respiration, minute ventilation, pulmonary edema, transthoracic edema, local edema, variability in edema, arrhythmia senses, frequency of arrhythmia senses, duration of arrhythmia episodes, long term values of preceding sense values, pressure values, blood oxygen, or patient activation temporal markers.
-
34. A method of determining patient pulmonary edema comprising:
-
measuring impedance between two electrodes implanted within a patient'"'"'s body a multiplicity of times throughout a chronic period greater than a day, filtering cyclic body effects on the impedance signal value from the signal to generate a DC signal value for each said measurement step, storing a history of filtered impedance changes representative of changes in said DC impedance signal value within said patient in an implanted device, and determining a level of edema based on said changes in said DC impedance signal values that have occurred during said monitored history.
-
-
35. An implantable medical device for chronic implant into a living body having at least two electrodes exposed to tissue within said body and pulse generator means for generating electrical output so as to provide for measurement of impedance between said at least two electrodes, the improvement comprising
impedance determination means to determine the impedance of the thoracic cavity of the body based on the dc value of impedance measured between said two electrodes, means to determine values representing a level of edema based on said measurement at times over a course of days, and means for storing said value representing a level of impedance in said device for said times over said course of days.
Specification