Implantable cardiac device with dyspnea measurement

• US 8,954,146 B2
• Filed: 04/16/2014
• Issued: 02/10/2015
• Est. Priority Date: 02/28/2005
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Hopper, Donald L., Voegele, John, Hartley, Jesse W., Scheiner, Avram
• Primary Examiner(s): Koharski, Christopher D
• Assistant Examiner(s): Dinga, Roland
• Application Number:
  US14/254,464
• Publication Number:
  US 20140221853A1
• Time in Patent Office: 300 Days
• Field of Search: 600/484, 600/547, 607/17, 607/18, 607/19, 607/20
• US Class Current: 607/9
• CPC Class Codes: A61B 5/0022 Monitoring a patient using a global network, e.g. telephone networks, internet
• CPC Class Codes: A61B 5/0024 for multiple sensor units attached to the patient, e.g. using a body or personal area network
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/076 Permanent implantations telemetry using implanted circuitry A61B5/0031; implanted stimulators for therapy A61N1/3605, A61N1/362, A61N1/372
• CPC Class Codes: A61B 5/0809 by impedance pneumography
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/0826 Detecting or evaluating apnoea events A61B5/4818 takes precedence
• CPC Class Codes: A61B 5/085 Measuring impedance of respiratory organs or lung elasticity
• CPC Class Codes: A61B 5/091 Measuring volume of inspired or expired gases, e.g. to determine lung capacity
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/346 Analysis of electrocardiograms
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B
• CPC Class Codes: A61B 5/747 in case of emergency, i.e. alerting emergency services
• CPC Class Codes: A61N 1/3627 : for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/36585 : controlled by two or more physical parameters
• CPC Class Codes: A61N 1/3702 : Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371
• CPC Class Codes: A61N 1/3987 : characterised by the timing or triggering of the shock
• CPC Class Codes: G16H 50/20 : for computer-aided diagnosis, e.g. based on medical expert systems
• CPC Class Codes: G16H 50/30 : for calculating health indices; for individual health risk assessment

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.

Claims

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;

a controller provided in the housing and operatively coupled to the respective sensors and the memory, the controller configured to;

determine a patient index based at least part on the sensed transthoracic impedance;

detect a physiological condition based on the determined patient index being beyond a threshold, the threshold based at least in part on a plurality of previous patient index values and associated patient activity levels; and

provide an output based, at least in part, on the detected physiological condition.

2. The device according to claim 1, wherein the controller is configured to determine the patient index based at least in part on a ratio of a respiratory rate value and a tidal volume value for the patient.

3. The device according to claim 1, wherein the threshold is based on a profile developed by the controller using a plurality of previous patient index values and associated patient activity levels acquired over time.

4. The device according to claim 1, wherein the controller is configured to trend a plurality of patient index values to determine at least part of a patient profile, wherein the threshold is based at least in part on the patient profile.

5. The device according to claim 1, wherein the controller is configured to trend a plurality of patient index values and their associated patient activity levels to develop a patient index versus activity level profile, and wherein the threshold is based at least in part on the patient index versus activity level profile.

6. The device according to claim 5, wherein the controller is configured to detect the physiological condition using the threshold that is based at least in part on the patient index versus activity level profile.

7. The device according to claim 1, wherein the physiological condition relates to congestive heart failure (CHF).

8. The device according to claim 7, wherein the output relates to monitoring, diagnosis and/or therapy of congestive heart failure (CHF).

9. The device according to claim 1, comprising:

an implantable electrode arrangement; and

therapy circuitry provided in the housing and coupled to the controller and the implantable electrode arrangement, the therapy circuitry configured to deliver a therapy via the electrode arrangement based at least in part on the patient index and the associated patient activity.

10. The device according to claim 1, comprising:

an implantable electrode arrangement; and

therapy circuitry provided in the housing and coupled to the controller and the implantable electrode arrangement, the therapy circuitry configured to deliver a cardiac therapy via the electrode arrangement that changes a pacing rate by a predetermined amount when the physiological condition is detected.

11. The device according to claim 1, wherein:

the controller is configured to generate an alert in response to the patient index being beyond the threshold and a trend of the patient index indicative of worsening of congestive heart failure (CHF); and

the controller cooperates with communication circuitry to transmit the alert to an external device.

12. A system, comprising:

a sensor configured to sense transthoracic impedance;

an activity sensor configured to sense a patient activity level;

a memory;

a controller operatively coupled to the respective sensors and the memory, the controller configured to;

repeatedly determine a patient index value based at least in part on the sensed transthoracic impedance, and associate each of the patient index values with a corresponding activity level value detected at least in part by the activity sensor;

determine a patient index versus activity level profile based at least in part on one or more of the patient index values and corresponding activity level values; and

provide an output based, at least in part, on the patient index versus activity level profile.

13. The system of claim 12, wherein the patient index versus activity level profile includes a plurality of patient index values associated with different ranges of patient activity levels.

14. The system of claim 12, wherein the controller is configured to repeatedly determine a respiration rate (RR) and tidal volume (TV) of the patient based at least in part on the sensed transthoracic impedance and determine the patient index values based at least in part on the respiration rate (RR) and tidal volume (TV).

15. The system of claim 12 wherein the patient index values and the corresponding activity level values are stored in the memory.

16. The system of claim 12, wherein the controller trends the patient index values.

17. The system of claim 12, wherein the output adapts a therapy provided by the cardiac device.

18. The system of claim 17, wherein the output relates to monitoring, diagnosis and/or therapy of a congestive heart failure (CHF) therapy condition.

19. A system, comprising:

a sensor configured to sense transthoracic impedance;

an activity sensor configured to make an activity measurement indicative of patient activity;

a memory configured to store at least a patient index versus activity level profile that is based on a plurality of patient index values associated with different ranges of patient activity levels;

a controller operatively coupled to the respective sensors and the memory, the controller configured to;

determine a plurality of patient index values over time, each of the plurality of patient index values based at least part on the sensed transthoracic impedance;

determine a plurality of patient activity levels over time, wherein the plurality of patient activity levels are based at least in part on the activity sensor;

detect a physiological condition based on one or more patient index values exceeding a threshold of the patient index versus activity level profile, the threshold being associated with an activity range of the profile that the patient activity level is determined to be within; and

provide an output based, at least in part, on the detected physiological condition.

20. The system according to claim 19, wherein the controller is configured to determine the plurality of patient index values based at least in part on a ratio of a respiratory rate value and a tidal volume value for the patient.