Transient sensor response to posture as a measure of patient status

• US 9,993,165 B2
• Filed: 04/08/2015
• Issued: 06/12/2018
• Est. Priority Date: 04/08/2011
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Thakur, Pramodsingh Hirasingh, Patangay, Abhilash, Hatlestad, John D., Beck, Kenneth C.
• Primary Examiner(s): Lin, Jerry
• Application Number:
  US14/681,267
• Publication Number:
  US 20150208928A1
• Time in Patent Office: 1,161 Days
• Field of Search: 702 19
• CPC Class Codes: A61B 2560/0462 Apparatus with built-in sensors
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• 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 5/02405 Determining heart rate variability
• 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 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61B 5/4848 Monitoring or testing the effects of treatment, e.g. of medication
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61B 5/7246 using correlation, e.g. template matching or determination of similarity
• 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 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: A61N 1/36535 controlled by body position or posture
• CPC Class Codes: G16H 20/40 relating to mechanical, radiation or invasive therapies, e.g. surgery, laser therapy, dialysis or acupuncture
• CPC Class Codes: G16H 40/63 for local operation

Abstract

Patient posture information can be received, such as to indicate a change in patient posture by at least a threshold amount. A transient response signal indicative of a change in a physiological parameter can be received at multiple instances near a change in patient posture. Waveform morphology features can be extracted from a transient response signal and used to provide an indication of a cardiac status, such as a heart failure status.

Claims

1. A system, comprising:

a first sensor configured to detect a change in posture status;

a second sensor configured to sense a transient response signal of a physiological parameter during the change in posture status;

a processor circuit, configured to generate a cardiac status based on the transient response signal of the physiological parameter, the transient response signal occurring during the change in posture status; and

a monitoring circuit configured to provide an indication of the cardiac status.

2. The system of claim 1, wherein the second sensor is configured to sense a transient response of a heart rate (HR) signal before and during the change in posture status, the transient response of the HR signal including on or more of:

a transient increase in HR from a baseline HR prior to the posture change to a peak HR during the change in posture status;

a decrease in HR from the peak HR to a first HR trough after the peak HR during the change in posture status;

a duration for the HR to rise from the baseline HR to the peak HR during the change in posture status;

or

a duration of an initial HR transient from the baseline HR to the first HR trough.

3. The system of claim 1, wherein the processor circuit is configured to generate the cardiac status based on waveform morphology of at least a portion of the transient response signal.

4. The system of claim 3, wherein the waveform morphology includes a rise time, a decay time, or a duration of the at least a portion of the transient response signal.

5. The system of claim 3, wherein:

the first sensor is configured to determine the detected change in posture status as one of a plurality of classes of posture changes including a step change or an azimuthal change in posture; and

the processor circuit is configured to generate the cardiac status based at least on the determined class of change in posture status.

6. The system of claim 5, wherein the plurality of classes of postural changes include a change between recumbent and upright postures, or a change between recumbent and supine postures.

7. The system of claim 1, wherein the processor circuit is configured to generate the cardiac status based on one or more characteristic parameters of a signal model representing the transient response signal.

8. The system of claim 7, wherein:

the signal model includes a first or second order system approximation of a waveform morphology of the transient response signal; and

the one or more characteristic parameters include at least one of a delay duration, a decay duration, a natural frequency of oscillation, or a magnitude change extracted from the signal model.

9. The system of claim 1, wherein the first sensor includes at least one of a tilt switch, a single axis accelerometer, or a multi-axis accelerometer.

10. The system of claim 1, wherein:

the processor circuit is configured to extract from the transient response signal one or more signal features occurring during the change in posture status, and to establish respective trends of the one or more signal features over a specified period of time, each of the respective trends indicating worsening or improving patient health status; and

the monitoring circuit is configured to display the respective trends.

11. The system of claim 1, wherein the processor circuit is configured to generate respective cardiac status before and after delivery of one of a cardiovascular therapy, an autonomic modulation therapy, or a drug therapy.

12. The system of claim 1, further comprising a therapy delivery circuit configured to deliver a therapy based at least on the cardiac status.

13. A method, comprising:

detecting a change in posture status of a patient;

sensing a transient response signal of a physiological parameter during the change in posture status;

generating a cardiac status based on the transient response signal of a physiological parameter, the transient response signal occurring during the change in posture status; and

providing an indication of the cardiac status.

14. The method claim 13, wherein sensing the transient response signal includes sensing a transient response of a heart rate (HR) signal before and during the change in posture status, the transient response of the HR signal including on or more of:

a transient increase in HR from a baseline HR prior to the posture change to a peak HR during the change in posture status;

a decrease in HR from the peak HR to a first HR trough after the peak HR during the change in posture status;

a duration for the HR to rise from the baseline HR to the peak HR during the change in posture status;

or

a duration of an initial HR transient from the baseline HR to the first HR trough.

15. The method of claim 13, wherein generating the cardiac status includes generating the cardiac status based on waveform morphology of at least a portion of the transient response signal.

16. The method of claim 13, wherein:

detecting the change in posture status includes classifying the detected posture change as one of a plurality of classes of posture changes including a step change or an azimuthal change in posture; and

generating the cardiac status includes generate the cardiac status based at least on the determined class of change in posture status.

17. The method of claim 13, wherein generating the cardiac status includes creating a signal model to represent the transient response signal, and generating the cardiac status based on one or more characteristic parameters of the signal model.

18. The method of claim 17, wherein:

the signal model includes a first or second order system approximation of a waveform morphology of the transient response signal; and

the one or more characteristic parameters include at least one of a delay duration, a decay duration, a natural frequency of oscillation, or a magnitude change extracted from the signal model.

19. The method of claim 13, further comprising:

extracting from the transient response signal one or more signal features occurring during the change in posture status;

establishing respective trends of the one or more signal features over a specified period of time, each of the respective trends indicating worsening or improving patient health status; and

displaying the respective trends.

20. The method of claim 13, wherein generating the cardiac status includes generating respective cardiac status before and after delivery of a therapy including a cardiovascular therapy, an autonomic modulation therapy, or a drug therapy, the cardiac status indicating an efficacy of the delivered therapy.