Implantable medical device with temperature measuring and storing capability

• US 8,055,338 B2
• Filed: 09/15/2008
• Issued: 11/08/2011
• Est. Priority Date: 03/30/2001
• Status: Expired due to Fees

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Amundson, Mark D., Von Arx, Jeffrey A., Linder, William J., Balczewski, Ron A.
• Primary Examiner(s): MANUEL, GEORGE C
• Application Number:
  US12/210,508
• Publication Number:
  US 20090012574A1
• Time in Patent Office: 1,149 Days
• Field of Search: 607/7, 607/21, 607/59, 607/60
• US Class Current: 607/6
• CPC Class Codes: A61B 5/0008 Temperature signals
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/7285 for synchronising or triggering a physiological measurement or image acquisition with a physiological event or waveform, e.g. an ECG signal A61B6/5205, A61B6/541, A61B8/5207, A61B8/543 take precedence
• CPC Class Codes: A61N 1/3655 controlled by body or blood temperature
• CPC Class Codes: G01K 13/20 Clinical contact thermometers for use with humans or animals

Abstract

An implantable medical device such as a cardiac pacemaker or implantable cardioverter/defibrillator with the capability of storing body temperature measurements taken periodically and/or when triggered by particular events.

Claims

1. A method, comprising:

configuring a medical device for implantation into a patient, wherein the medical device includes sensing and therapy circuitry interfaced to a controller contained within an implantable housing;

incorporating a temperature sensor for measuring temperature within the implantable housing, wherein the temperature sensor is interfaced to the controller; and

,

programming the controller to monitor and store temperatures before and after implantation of the device.

2. The method of claim 1 wherein the temperature sensor utilizes a proportional-to-absolute-temperature (PTAT) current source to generate a temperature signal.

3. The method of claim 2 wherein the temperature sensor further comprises:

a PTAT current source;

first and second oscillators;

a counter; and

,

wherein the PTAT current source feeds into the first oscillator in order to generate a clock signal with a frequency proportional to the PTAT current, and the counter compares the first oscillator clock frequency to a stable timebase generated by the second oscillator in order to generate a number that is proportional to temperature.

4. The method of claim 1 wherein the temperature sensor is a thermistor.

5. The method of claim 1 wherein the temperature sensor is a thermocouple.

6. The method of claim 1 further comprising programming the controller to not gather temperature measurements during periods when shock therapy is being delivered.

7. The method of claim 1 further comprising programming the controller to flag temperature measurements taken during periods when shock therapy is being delivered.

8. The method of claim 1 further comprising programming the controller to not gather temperature measurements during periods when a capacitor is being reformed.

9. The method of claim 1 further comprising programming the controller to flag temperature measurements taken during periods when a capacitor is being reformed.

10. The method of claim 1 further comprising programming the controller to store temperature measurements at specified times on a daily basis with an associated time stamp.

11. The method of claim 1 further comprising programming the controller to measure temperature periodically before implantation of the device.

12. The method of claim 1 further comprising programming the controller to set an alarm flag if the measured temperature ever leaves safe storage temperature limits.

13. The method of claim 1 further comprising programming the controller to announce the alarm flag when interrogated by an external programmer.

14. The method of claim 1 further comprising programming the controller to log minimum and maximum storage temperatures.

15. The method of claim 1 further comprising programming the controller to issue an alarm if the present device temperature is not inside safe operational temperature limits.

16. The method of claim 1 further comprising programming the controller to calibrate the temperature sensor by adjusting sensor measurements by an amount equal to the difference between an average temperature measurement and a nominal temperature assumed to be maintained by the patient'"'"'s body.

17. The method of claim 1 further comprising programming the controller to associate a temperature measurement with a simultaneously measured heart rate.

18. The method of claim 1 further comprising programming the controller to associate a temperature measurement with a simultaneously measured exertion level.