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

• US 8,843,187 B2
• Filed: 06/01/2010
• Issued: 09/23/2014
• Est. Priority Date: 08/22/2003
• Status: Expired due to Term

• 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:
  US12/791,791
• Publication Number:
  US 20100240976A1
• Time in Patent Office: 1,575 Days
• Field of Search: 600/345, 600/347, 600/365
• US Class Current: 600/347
• 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. A method for processing data from a glucose sensor, the method comprising:

applying a voltage to a working electrode of an electrochemical glucose sensor configured for invasive and/or minimally invasive subcutaneous implantation, invasive and/or minimally invasive transdermal implantation, or invasive and/or minimally invasive intravascular implantation, wherein the electrochemical glucose sensor is configured for measurement of a glucose concentration, wherein applying a voltage comprises at least one process selected from the group consisting of switching a voltage applied to the electrochemical sensor, cycling a voltage applied to the electrochemical sensor, and pulsing a voltage applied to the electrochemical sensor; and

detecting a signal artifact based on a signal response of the electrochemical glucose sensor to the switching, cycling, or pulsing of the applied voltage, wherein the signal artifact is associated with at least one condition selected from the group consisting of ischemia, a pH change, a temperature change, a change in available electrode surface area, and an interfering species.

2. The method of claim 1, further comprising replacing the detected signal artifact based on the signal response.

3. The method of claim 1, further comprising providing output based on the detected signal artifact.

4. The method of claim 1, further comprising providing output indicative of the glucose concentration in a host.

5. The method of claim 1, wherein measuring a signal response of the working electrode comprises measuring a current output of a working electrode of the glucose sensor.

6. A system for processing data from a glucose sensor, the system comprising:

an electrochemical glucose sensor comprising a working electrode, wherein the glucose sensor is configured for invasive and/or minimally invasive subcutaneous implantation, invasive and/or minimally invasive transdermal implantation, or invasive and/or minimally invasive intravascular implantation, wherein the glucose sensor is configured to measure a glucose concentration; and

electronic circuitry configured to apply a voltage to the working electrode over a time period of continuous implantation of at least a portion of the working electrode and to measure a signal response of the working electrode to the applied voltage, wherein the electronic circuitry is configured to detect a signal artifact based on the signal response, wherein the signal artifact is associated with at least one condition selected from the group consisting of ischemia, a pH change, a temperature change, a change in available electrode surface area, and an interfering species, wherein the electronic circuitry is configured to switch, cycle, or pulse the applied voltage.

7. The system of claim 6, wherein the electronic circuitry is configured to provide output based on the signal response.

8. The system of claim 6, wherein the electronic circuitry is configured to provide output indicative of the glucose concentration in a host.

9. The system of claim 6, wherein the signal response comprises a current output of the working electrode.

10. A method for detecting a signal artifact associated with a glucose sensor, the method comprising:

applying a voltage to an implantable electrochemical glucose sensor continuously over a time period of continuous implantation and measuring a signal response of the implantable electrochemical glucose sensor;

measuring a pH using a pH sensor; and

detecting a signal artifact based on the signal response and the measured pH.

11. A system for processing data from a glucose sensor, the system comprising:

an implantable electrochemical glucose sensor comprising a working electrode, wherein the glucose sensor is configured to continuously measure a glucose concentration of a host over a time period of continuous implantation;

a pH sensor configured to measure a pH in proximity to the glucose sensor during use of the glucose sensor; and

electronic circuitry configured to apply a voltage to the working electrode and to measure a signal response of the working electrode to the applied voltage, wherein the electronic circuitry is configured to detect a signal artifact based on the signal response and the measured pH.