NIGHT RESPIRATION RATE FOR HEART FAILURE MONITORING

• US 20090312649A1
• Filed: 06/01/2009
• Published: 12/17/2009
• Est. Priority Date: 06/17/2008
• Status: Active Grant

• Current Assignee: Biotronik SE & Company KG
• Original Assignee: Biotronik CRM Patent AG (Biotronik SE & Company KG)
• Inventors: Lian, Jie, Muessig, Dirk, de Voir, Christopher S., Lefkov, Sharon, Orlov, Michael V.
• Granted Patent: US 8,394,029 B2
• Time in Patent Office: Days
• US Class Current: 600/484
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/0809 by impedance pneumography
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/36585 controlled by two or more physical parameters
• CPC Class Codes: A61N 1/36592 controlled by the heart rate variability

Abstract

The invention refers to a monitoring device for monitoring and analyzing physiological signals. The monitoring device comprises a transthoracic impedance measurement unit and an evaluation unit connected to the transthoracic impedance measurement unit. The transthoracic impedance measurement unit is adapted to conduct a transthoracic impedance measurement and to generate a transthoracic impedance signal representing a measured transthoracic impedance at consecutive points in time. The evaluation unit being configured to process the transthoracic impedance signal received from the transthoracic impedance measurement unit and to thus generate a respiration signal and to generate therefrom an evaluation signal reflecting at least a diurnal pattern of the respiration rate.

Claims

1. A monitoring device for monitoring and analyzing physiological signals comprising:

an transthoracic impedance measurement unit;

an evaluation unit connected to said transthoracic impedance measurement unit;

said transthoracic impedance measurement unit configured to conduct a transthoracic impedance measurement and to generate a transthoracic impedance signal that represents a measured transthoracic impedance at consecutive points in time; and

,

said evaluation unit configured to process said transthoracic impedance signal received from said transthoracic impedance measurement unit and to thus generate a respiration signal and to generate therefrom an evaluation signal that reflects at least a diurnal pattern of a respiration rate.

2. The monitoring device of claim 1 wherein said evaluation unit is configured to perform a trending analysis of multiple physiological signals comprising said respiration signal.

3. The monitoring device of claim 1 wherein said evaluation unit is configured to detect an increase of a night respiration rate of a patient, and/or decrease of a daytime respiration rate of the patient, and/or decrease of a circadian variability of the respiration rate and to generate an alert signal upon detection of one or more of said increases or decreases.

4. The monitoring device of claim 2 further comprising:

a sensing unit configured to process an EGM signal that represents intracardiac myocardial electric potentials and determine therefrom a heart rate signal; and

,

wherein said evaluation unit is configured to perform a trending analysis of multiple physiological parameters, comprising a heart rate, and a heart rate variability.

5. The monitoring device of claim 1 further comprising:

a metal can;

wherein said transthoracic impedance measurement unit is connected or can be connected to a bipolar ventricular electrode lead having a tip electrode at its distal end and a ring electrode close to said tip electrode; and

,

wherein said transthoracic impedance measurement unit is configured to inject a current between said ring electrode and said metal can, and to measure a voltage between said tip electrode and said metal can.

6. The monitoring device of claim 5 wherein said transthoracic impedance measurement unit is configured to calculate an impedance as a ratio between a measured voltage and an injected current.

7. The monitoring device of claim 5 wherein said transthoracic impedance measurement unit is configured to measure an impedance signal with a sampling frequency of at least 8Hz.

8. The monitoring device of claim 5 wherein said transthoracic impedance measurement unit comprises:

a constant current source or a constant voltage source having current feed terminals that are connected or can be connected to electrodes for intracorporal placement and that is configured to generate measuring current pulses having a constant current strength or a constant voltage, respectively, configured to cause the current to be fed through a body via intracorporally placed electrodes;

a measuring unit configured to measure a voltage that corresponds to the current fed through the body by said constant current source or a current strength of the current fed through the body by said constant voltage source, respectively, to determine an impedance value for each measuring current pulse; and

,

an impedance value determination unit that is connected to said constant current source or said constant voltage source and the measuring unit.

9. The monitoring device of claim 1 further comprising a low-pass filter and wherein said evaluation unit is configured to process an impedance signal to remove high frequency cardiac components with the low-pass filter, to obtain the respiration signal.

10. The monitoring device of claim 1 wherein said evaluation unit is configured to process an impedance signal to determine a peak-to-peak interval of the respiration signal derived from an intrathoracic impedance signal that is a respiration cycle length.

11. The monitoring device of claim 1 wherein said evaluation unit is configured to process an impedance signal to determine an inflection at an end of expiration and a start of inspiration to determine a respiration cycle length of the respiration signal derived from an intrathoracic impedance signal.

12. The monitoring device of claim 1 further comprising a memory that is configured to store signals and/or data generated by said evaluation unit to further process.

13. The monitoring device of claim 1 wherein said evaluation unit is configured to determine overall statistics of a respiration rate signal.

14. The monitoring device of claim 13 wherein said evaluation unit is configured to determine separate day and night statistics of a measured respiration rate with user-programmable daytime and night time settings.

15. The monitoring device of claim 12 further comprising a telemetry unit that is configured for wireless transmission of data, wherein said monitoring device is configured to routinely transmit signals and/or data generated by said evaluation unit to a remote server.

16. The monitoring device of claim 13 wherein said evaluation unit is configured to determine a composite score from multiple physiological parameters.

17. The monitoring device of claim 16 wherein said evaluation unit is configured to determine said composite score as follows:

CS=a*rRR+b/dRR+c*rHR+d/HRV,

where a, b, c, and d are predefined non-negative coefficients, rRR is a resting respiration rate, dRR is a difference between day and night respiration rates, rHR is a resting heart rate, and HRV is an index of 24-hour heart rate variability.

18. The monitoring device of claim 17 where dRR is an index of 24-hour respiration rate variability.

19. The monitoring device of claim 17 wherein said evaluation unit is configured to generate an alert signal if the composite store exceeds a predefined threshold value, due to either an increase of rRR, or an increase of rHR, or a decrease of dRR, or a decrease of HRV, or their combinations.