IMPLANTABLE TISSUE PERFUSION SENSING SYSTEM AND METHOD

• US 20080208066A1
• Filed: 02/28/2008
• Published: 08/28/2008
• Est. Priority Date: 02/28/2007
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Cinbis, Can, Carney, James K.
• Granted Patent: US 8,170,650 B2
• Time in Patent Office: Days
• US Class Current: 600/504
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/14542 for measuring blood gases A61B5/14551 takes precedence
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence
• CPC Class Codes: A61B 5/361 Detecting fibrillation
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/7214 using signal cancellation, e.g. based on input of two identical physiological sensors spaced apart, or based on two signals derived from the same sensor, for different optical wavelengths
• CPC Class Codes: A61N 1/3925 Monitoring; Protecting

Abstract

A medical device for sensing cardiac events that includes a plurality of light sources capable of emitting light at a plurality of wavelengths, and a detector to detect the emitted light. A processor generates an ambient light measurement in response to ambient light detected by the detector, generates a plurality of light measurements in response to the emitted light detected by the detector, and adjusts the plurality of light measurements in response to the ambient light measurement.

Claims

1. A medical device for sensing cardiac events, comprising:

a plurality of light sources capable of emitting light at a plurality of wavelengths;

a detector to detect the emitted light; and

a processor to generate an ambient light measurement in response to ambient light detected by the detector, generate a plurality of light measurements in response to the emitted light detected by the detector, and adjust the plurality of light measurements in response to the ambient light measurement.

2. The device of claim 1, wherein the processor generates a first ambient light measurement prior to the generating of the plurality of light measurements and a second ambient light measurement subsequent to the generating of the plurality of light measurements.

3. The device of claim 1, wherein the processor generates a first ambient light measurement prior to a first light measurement of the plurality of light measurements, a second ambient light measurement subsequent to the first light measurement and prior to a second light measurement of the plurality of light measurements, and a third ambient light measurement subsequent to the second light measurement.

4. The device of claim 1, wherein the processor adjusts the generated plurality of light measurements in response to the relative timing of the plurality of light measurements to a first ambient light measurement and a second light measurement.

5. The device of claim 1, wherein the adjusting comprises subtracting an average of a first ambient light measurement and a second ambient light measurement from one or more of the plurality of light measurements.

6. The device of claim 1, wherein the processor adjusts a light source of the plurality of light sources in response to one of a first ambient light measurement and a second ambient light measurement being greater than the ambient threshold, and, in response to the one of the first ambient light measurement and the second ambient light measurement not being greater than the ambient threshold, stores the first ambient light measurement, the second ambient light measurement, and an intensity of light emitted by the light source of the plurality of light sources detected at the detector.

7. The device of claim 6, wherein the adjusting the light source of the plurality of light sources comprises increasing an amplitude and decreasing a pulse width of a light signal emitted by the light source of the plurality of light sources.

8. The device of claim 1, wherein the processor adjusts the detector in response to a first ambient light measurement not being less than an ambient threshold, and adjusts a first light source of the plurality of light sources in response to a first light measurement of the plurality of light measurements being greater than an upper limit threshold.

9. The device of claim 8, wherein the processor adjusts the first light source in response to an output corresponding to a second light measurement of the plurality of light measurements not being less than a lower limit threshold, the lower limit threshold being less than the upper limit threshold.

10. The device of claim 9, wherein the processor adjusts an output of the first light source in response to the adjusting of the detector and the first light source.

11. A method of adjusting sensing in a medical device, comprising:

determining ambient light received at a detector to generate a first ambient light measurement;

determining light emitted by a plurality of light sources and received at the detector to generate a plurality of light measurements at a plurality of wavelengths;

determining ambient light received at the detector to generate a second ambient light measurement; and

adjusting the generated plurality of light measurements in response to the first ambient light measurement and the second ambient light measurement.

12. The method of claim 11, wherein the first ambient light measurement is generated prior to the generating of the plurality of light measurements and the second ambient light measurement is generated subsequent to the generating of the plurality of light measurements.

13. The method of claim 11, further comprising determining ambient light received at the detector to generate a third ambient light measurement, wherein the first ambient light measurement is generated prior to a first light measurement of the plurality of light measurements, the second ambient light measurement is generated subsequent to the first light measurement and prior to a second light measurement of the plurality of light measurements, and the third ambient light measurement is generated subsequent to the second light measurement.

14. The method of claim 11, wherein the generated plurality of light measurements are adjusted in response to the relative timing of the plurality of light measurements to the first ambient light measurement and the second light measurement.

15. The method of claim 11, wherein the adjusting comprises subtracting an average of the first ambient light measurement and the second ambient light measurement from one or more of the plurality of light measurements.

16. The method of claim 11, further comprising:

determining whether one of the first ambient light measurement and the second ambient light measurement is greater than an ambient threshold;

adjusting a light source of the plurality of light sources in response to one of the first ambient light measurement and the second ambient light measurement being greater than the ambient threshold; and

storing the first ambient light measurement, the second ambient light measurement, and the determined light emitted by the light source of the plurality of light sources in response to the one of the first ambient light measurement and the second ambient light measurement not being greater than the ambient threshold.

17. The method of claim 16, wherein the adjusting the light source of the plurality of light sources comprises increasing an amplitude and decreasing a pulse width of a light signal emitted by the light source of the plurality of light sources.

18. The method of claim 11, further comprising:

determining whether the first ambient light measurement is less than an ambient threshold;

adjusting the detector in response to the first ambient light measurement not being less than the ambient threshold;

determining whether an output corresponding to a first light measurement of the plurality of light measurements is greater than an upper limit threshold; and

adjusting a first light source of the plurality of light sources in response to the first light measurement being greater than the upper limit threshold.

19. The method of claim 18, further comprising:

determining whether an output corresponding to a second light measurement of the plurality of light measurements is less than a lower limit threshold, the lower limit threshold being less than the upper limit threshold; and

adjusting the first light source in response to the second light measurement not being less than the lower limit threshold.

20. The method of claim 19, further comprising adjusting the output of the first light source in response to the adjusting of the detector and the first light source.