Systems and methods for replacing signal artifacts in a glucose sensor data stream

• US 8,790,260 B2
• Filed: 10/14/2009
• Issued: 07/29/2014
• Est. Priority Date: 08/22/2003
• Status: Active Grant

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Goode, Paul V. Jr., Brauker, James H., Kamath, Apurv U., Thrower, James Patrick, Carr-Brendel, Victoria
• Primary Examiner(s): D'Angelo, Michael
• Assistant Examiner(s): JANG, CHRISTIAN YONGKYUN
• Application Number:
  US12/579,357
• Publication Number:
  US 20100036215A1
• Time in Patent Office: 1,749 Days
• Field of Search: 600/345, 600/347, 600/365
• US Class Current: 600/365
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/0271 Thermal or temperature sensors
• CPC Class Codes: A61B 2562/08 Sensors provided with means for identification, e.g. barcodes or memory chips
• CPC Class Codes: A61B 5/0004 characterised by the type of physiological signal transmitted
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14539 for measuring pH
• CPC Class Codes: A61B 5/14542 for measuring blood gases A61B5/14551 takes precedence
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: A61B 5/7475 User input or interface means, e.g. keyboard, pointing device, joystick

Abstract

Systems and methods for minimizing or eliminating transient non-glucose related signal noise due to non-glucose rate limiting phenomenon such as ischemia, pH changes, temperatures changes, and the like. The system monitors a data stream from a glucose sensor and detects signal artifacts that have higher amplitude than electronic or diffusion-related system noise. The system replaces some or the entire data stream continually or intermittently including signal estimation methods that particularly address transient signal artifacts. The system is also capable of detecting the severity of the signal artifacts and selectively applying one or more signal estimation algorithm factors responsive to the severity of the signal artifacts, which includes selectively applying distinct sets of parameters to a signal estimation algorithm or selectively applying distinct signal estimation algorithms.

Claims

1. In a glucose sensing system comprising a glucose sensor configured for producing an output representative of glucose concentration in a host and processing circuitry configured to process the output, a method for processing data from the output, the method comprising:

generating a glucose sensor data point from the glucose sensor output;

detecting a signal loss associated with the glucose sensor data point;

filtering the glucose sensor data point with a filter whereby a filtered glucose sensor data point is generated; and

adjusting, using a processor, the filtered glucose sensor data point to reduce effects associated with the signal loss.

2. The method of claim 1, wherein filtering comprises pass band or stop band filtering.

3. The method of claim 1, wherein filtering comprises recursive filtering.

4. The method of claim 1, wherein filtering comprises infinite impulse response filtering.

5. The method of claim 1, further comprising converting the adjusted sensor data point into a substantially real-time estimated glucose value;

and outputting information representative of the substantially real-time estimated glucose value via a user interface.

6. The method of claim 1, further comprising receiving a data stream generated by the continuous glucose sensors continuously during a time period of continuous glucose sensing of the glucose sensor;

detecting a signal loss associated with the data stream; and

generating an estimated data stream by filtering the data stream continuously in real time and adjusting at least a portion of the filtered data stream associated with the detected signal loss in real time to reduce effects associated with the detected signal loss, wherein the data stream includes the glucose sensor data point.

7. The method of claim 6, further comprising selectively outputting via a user interface glucose concentration information based on the data stream or the estimated data stream responsive to a detection of signal artifacts in the data stream.

8. The method of claim 1, further comprising outputting via a user interface information representative of a substantially real-time glucose concentration of a host, the substantially real-time information based at least in part on the adjusted data point.

9. A glucose sensor system for monitoring a glucose concentration in a host, the system comprising:

a continuous glucose sensor configured to produce a data stream; and

a processor configured to receive the data stream, wherein the processor is configured to generate an estimated data stream based at least in part on applying the data stream to a recursive filter and adjusting the filtered data stream to reduce effects associated with a signal loss.

10. The system of claim 9, wherein the processor further comprises a pass band filter, and wherein the processor is configured to generate the estimated data stream based additionally on applying the data stream to the pass band filter.

11. The system of claim 10, wherein the processor further comprises an infinite impulse response filter, wherein the processor is configured to generate the estimated data stream based additionally on applying the data stream to the infinite impulse response filter.

12. The system of claim 9, wherein the processor is housed in at least one of a sensor electronics housing or a receiver electronics housing.

13. The system of claim 9, wherein the data stream comprises information indicative of a glucose sensor data point, wherein the processor is configured to detect a signal loss associated with the data point, wherein applying the recursive filter to the data stream comprises applying the recursive filter to the data point to generate a filtered data point, and wherein augmenting the data stream comprises augmenting the filtered data point to generate an estimated data point to reduce the effects of the detected signal loss.

14. The system of claim 13, further comprising a calibration module configured to convert the estimated data point into a substantially real-time estimated glucose value.

15. The system of claim 9, wherein the processor receives the data stream continuously during a time period of continuous glucose sensing of the glucose sensor and generates the estimated data stream continuously in real time during the time period.

16. The system of claim 15, further comprising an output module configured to output via a user interface information representative of a real-time glucose concentration of a host, wherein the information is based at least in part on the estimated data stream.

17. The system of claim 9, further comprising an output module configured to selectively output via a user interface information representative of the data stream or information representative of the estimated data stream responsive to a detection of signal artifacts in the data stream.