Detecting worsening heart failure based on fluid accumulation with respiratory confirmation

• US 8,632,473 B2
• Filed: 01/30/2009
• Issued: 01/21/2014
• Est. Priority Date: 01/30/2009
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Sowelam, Sameh
• Primary Examiner(s): Foley, Shanon A
• Application Number:
  US12/363,264
• Publication Number:
  US 20100198097A1
• Time in Patent Office: 1,817 Days
• Field of Search: None
• US Class Current: 600/538
• 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 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• 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 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61B 5/4878 Evaluating oedema
• 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: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/39622 Pacing therapy
• CPC Class Codes: G16H 40/63 for local operation
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment

Abstract

A medical device monitors a level of fluid accumulation, e.g., pulmonary edema, and one or more respiratory parameters of the patient to detect worsening heart failure. The medical device may use intrathoracic impedance measurements to monitor both the fluid accumulation and the one or more respiratory parameters. Respiration rate and volume, also referred to as the tidal volume, are examples of respiratory parameters. The medical device examines the one or more respiratory parameters after determining that the fluid accumulation indicates worsening heart failure. In this manner, the medical device uses the one or more respiratory parameters to confirm a determination of worsening heart failure that was made based on the fluid accumulation.

Claims

1. A method for confirming an indication of worsening heart failure in a patient, the indication based on monitoring a fluid index of the patient by means of intrathoracic impedance measurements made by a medical device, and the method comprising:

monitoring, with an activity sensor of the medical device, an activity level of the patient;

triggering respiration monitoring, in response to the indication of worsening heart failure, the respiration monitoring also by means of intrathoracic impedance measurements made by the medical device;

wherein the respiration monitoring accounts for an affect of the activity level as monitored by the activity sensor; and

when the respiration monitoring indicates increased respiration rates and decreased respiration volumes, the indication of worsening heart failure in the patient is confirmed.

2. The method of claim 1, further comprising:

continuing to monitor the fluid index of the patient, after triggering respiration monitoring; and

ceasing the respiration monitoring when, and if, the continued monitoring of the fluid index no longer indicates worsening heart failure.

3. The method of claim 1, wherein the medical device comprises an implantable medical device.

4. The method of claim 3, wherein the implantable medical device comprises at least one of a pacemaker, cardioverter, or defibrillator.

5. The method of claim 1, wherein the triggered respiration monitoring only commences when the monitored activity level indicates that the patient is at rest or otherwise below a threshold activity level.

6. The method of claim 1, wherein the activity sensor comprises one or more accelerometers.