Body-worn sensor for characterizing patients with heart failure
The invention provides a sensor for measuring both impedance and ECG waveforms that is configured to be worn around a patient's neck. The sensor features 1) an ECG system that includes an analog ECG circuit, in electrical contact with at least two ECG electrodes, that generates an analog ECG waveform; and 2) an impedance system that includes an analog impedance circuit, in electrical contact with at least two (and typically four) impedance electrodes, that generates an analog impedance waveform. Also included in the neck-worn system are a digital processing system featuring a microprocessor, and an analog-to-digital converter. During a measurement, the digital processing system receives and processes the analog ECG and impedance waveforms to measure physiological information from the patient. Finally, a cable that drapes around the patient's neck connects the ECG system, impedance system, and digital processing system.
1. A sensor for measuring both impedance and ECG waveforms and configured to be worn on a patient's torso, comprising:
(i) a first electrode patch module comprising at least first and second electrodes and a backing supporting the at least first and second electrodes; and
a second electrode patch module comprising at least third and fourth electrodes and a backing supporting the at least third and fourth electrodes,
wherein the first and second electrode patch modules are configured to be spatially separate and positioned on opposite sides of the medial axis of the patient's chest at approximately shoulder level below the collarbone;
(ii) a flexible electronics module comprising:
a digital processing system comprising a microprocessor and an analog-to-digital converter and a wireless transceiver;
a first sensor module configured to reversibly mate to the first electrode patch module and to electrically connect the first and second electrodes to the electronics module via a first conductor segment, and to operably connect a first electrical connector to the electronics module via a second conductor segment;
a second sensor module configured to reversibly mate to the second electrode patch module and to electrically connect the third and fourth electrodes to the electronics module via a third conductor segment, and to operably connect a second electrical connector to the electronics module via a fourth conductor segment; and
a battery module configured to reversibly mate to the first electrical connector and to the second electrical connector to electrically connect the battery module to the electronics module,
wherein
the electronics module, the first sensor module, the second sensor module, the first conductor segment, the second conductor segment, the third conductor segment, the fourth conductor segment, the first electrical connector, and the second electrical connector are of unitary construction;
the electronics module, the battery module, the first sensor module, and the second sensor module form an analog ECG circuit when the first sensor module is in electrical contact with the first electrode and the second sensor module is in electrical contact with the third electrode, the ECG circuit configured to generate an analog ECG waveform;
the electronics module, the battery module, the first sensor module, and the second sensor module form an analog impedance circuit when the first sensor module is in electrical contact with the first and second electrodes and the second sensor module is in electrical contact with the third and fourth electrodes, the impedance circuit configured to generate an analog impedance waveform; and
the digital processing system is configured to receive and process the analog ECG and impedance waveforms and to generate therefrom digital ECG and impedance waveforms, to determine therefrom on a continuous basis a heart rate (HR) value and a stroke volume (SV) value for the patient, and to transmit the HR and SV values to an external computer, and
further comprising a USB connector in electrical contact with a flash memory system.
2. The sensor of claim 1 , wherein the flexible electronics module comprises a plurality of conductors that electrically connect the electronics module, the battery module, the first sensor module, and the second sensor module.
3. The system of claim 1 , wherein the flexible electronics module comprises a flexible circuit that electrically connects the electronics module, the battery module, the first sensor module, and the second sensor module.
4. The system of claim 1 , wherein the flexible electronics module comprises at least two non-flexible circuit boards connected to each other with a flexible circuit board.
5. The system of claim 4 , wherein one of the non-flexible circuit boards comprises the ECG circuit, and the other comprises the digital processing system.
6. The system of claim 4 , wherein one of the non-flexible circuit boards comprises the impedance circuit, and the other comprises the digital processing system.
7. The system of claim 1 , wherein the second electrode is a current-injecting electrode, the fourth electrode is a current-injecting electrode, the first electrode is a voltage-measuring electrode, and the third electrode is a voltage-measuring electrode.
8. The system of claim 1 , wherein the wireless transceiver is one of a Bluetooth® transceiver and an 802.11-based transceiver.
9. A sensor for measuring both impedance and ECG waveforms and configured to be worn on a patient's torso, comprising:
(i) a first electrode patch module comprising at least first and second electrodes and a backing supporting the at least first and second electrodes; and
a second electrode patch module comprising at least third and fourth electrodes and a backing supporting the at least third and fourth electrodes,
wherein the first and second electrode patch modules are configured to be spatially separate and positioned on opposite sides of the medial axis of the patient's chest at approximately shoulder level below the collarbone;
(ii) a flexible electronics module comprising:
a digital processing system comprising a microprocessor and an analog-to-digital converter and a wireless transceiver;
a first sensor module configured to reversibly mate to the first electrode patch module and to electrically connect the first and second electrodes to the electronics module via a first conductor segment, and to operably connect a first electrical connector to the electronics module via a second conductor segment;
a second sensor module configured to reversibly mate to the second electrode patch module and to electrically connect the third and fourth electrodes to the electronics module via a third conductor segment, and to operably connect a second electrical connector to the electronics module via a fourth conductor segment; and
a battery module configured to reversibly mate to the first electrical connector and to the second electrical connector to electrically connect the battery module to the electronics module,
wherein
the electronics module, the first sensor module, the second sensor module, the first conductor segment, the second conductor segment, the third conductor segment, the fourth conductor segment, the first electrical connector, and the second electrical connector are of unitary construction;
the electronics module, the battery module, the first sensor module, and the second sensor module form an analog ECG circuit when the first sensor module is in electrical contact with the first electrode and the second sensor module is in electrical contact with the third electrode, the ECG circuit configured to generate an analog ECG waveform;
the electronics module, the battery module, the first sensor module, and the second sensor module form an analog impedance circuit when the first sensor module is in electrical contact with the first and second electrodes and the second sensor module is in electrical contact with the third and fourth electrodes, the impedance circuit configured to generate an analog impedance waveform; and
the digital processing system is configured to receive and process the analog ECG and impedance waveforms and to generate therefrom digital ECG and impedance waveforms, to determine therefrom on a continuous basis a heart rate (HR) value and a stroke volume (SV) value for the patient, and to transmit the HR and SV values to an external computer,
and further comprising a cable that comprises a USB connector in electrical contact with a flash memory system.
10. A sensor for measuring both impedance and ECG waveforms and configured to be worn on a patient's torso, comprising:
(i) a first electrode patch module comprising at least first and second electrodes and a backing supporting the at least first and second electrodes; and
a second electrode patch module comprising at least third and fourth electrodes and a backing supporting the at least third and fourth electrodes,
wherein the first and second electrode patch modules are configured to be spatially separate and positioned at approximately shoulder level below the collarbone;
(ii) a flexible electronics module comprising:
a digital processing system comprising a microprocessor, an analog-to-digital converter and a wireless transceiver;
a first sensor module configured to reversibly mate to the first electrode patch module and to electrically connect the first and second electrodes to the electronics module via a first conductor segment, and to operably connect a first electrical connector to the electronics module via a second conductor segment;
a second sensor module configured to reversibly mate to the second electrode patch module and to electrically connect the third and fourth electrodes to the electronics module via a third conductor segment, and to operably connect a second electrical connector to the electronics module via a fourth conductor segment; and
a battery module configured to reversibly mate to the first electrical connector and to the second electrical connector to electrically connect the battery module to the electronics module,
wherein
the electronics module, the first sensor module, the second sensor module, the first conductor segment, the second conductor segment, the third conductor segment, the fourth conductor segment, the first electrical connector, and the second electrical connector are of unitary construction;
the electronics module, the battery module, the first sensor module, and the second sensor module form an analog ECG circuit when the first sensor module is in electrical contact with the first electrode and the second sensor module is in electrical contact with the third electrode, the ECG circuit configured to generate an analog ECG waveform;
the electronics module, the battery module, the first sensor module, and the second sensor module form an analog impedance circuit when the first sensor module is in electrical contact with the first and second electrodes and the second sensor module is in electrical contact with the third and fourth electrodes, the impedance circuit configured to generate an analog impedance waveform; and
the digital processing system is configured to receive and process the analog ECG and impedance waveforms and to generate therefrom digital ECG and impedance waveforms, to determine therefrom on a continuous basis a heart rate (HR) value and a stroke volume (SV) value for the patient, and to transmit the HR and SV values to an external computer,
and further comprising a serial connector in electrical contact with a flash memory system.
11. A sensor for measuring both impedance and ECG waveforms and configured to be worn on a patient's torso, comprising:
(i) a first electrode patch module comprising at least first and second electrodes and a backing supporting the at least first and second electrodes; and
a second electrode patch module comprising at least third and fourth electrodes and a backing supporting the at least third and fourth electrodes,
wherein the first and second electrode patch modules are configured to be spatially separate and positioned on the patient's torso;
(ii) a flexible electronics module comprising:
a digital processing system comprising a microprocessor, an analog-to-digital converter, and a wireless transceiver;
a first sensor module configured reversibly mate to the first electrode patch module and to electrically connect the first and second electrodes to the electronics module via a first conductor segment, and to operably connect a first electrical connector to the electronics module via a second conductor segment;
a second sensor module configured reversibly mate to the second electrode patch module and to electrically connect the third and fourth electrodes to the electronics module via a third conductor segment, and to operably connect a second electrical connector to the electronics module via a fourth conductor segment; and
a battery module configured to electrically connect to the electronics module,
wherein
the electronics module, the first sensor module, the second sensor module, the first conductor segment, the second conductor segment, the third conductor segment, the fourth conductor segment, the first electrical connector, and the second electrical connector are of unitary construction;
the electronics module, the battery module, the first sensor module, and the second sensor module form an analog ECG circuit when the first sensor module is in electrical contact with the first electrode and the second sensor module is in electrical contact with the third electrode, the ECG circuit configured to generate an analog ECG waveform;
the electronics module, the battery module, the first sensor module, and the second sensor module form an analog impedance circuit when the first sensor module is in electrical contact with the first and second electrodes and the second sensor module is in electrical contact with the third and fourth electrodes, the impedance circuit configured to generate an analog impedance waveform; and
the digital processing system is configured to receive and process the analog ECG and impedance waveforms and to generate therefrom digital ECG and impedance waveforms, to determine therefrom on a continuous basis a heart rate (HR) value and a stroke volume (SV) value for the patient, and to transmit the HR and SV values to an external computer, and further comprising a serial connector in electrical contact with a flash memory system.