Advanced analyte sensor calibration and error detection

• US 9,808,190 B2
• Filed: 12/30/2013
• Issued: 11/07/2017
• Est. Priority Date: 04/15/2011
• Status: Active Grant

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Bohm, Sebastian, Rong, Daiting, Simpson, Peter C.
• Primary Examiner(s): JANG, CHRISTIAN YONGKYUN
• Application Number:
  US14/144,276
• Publication Number:
  US 20140114153A1
• Time in Patent Office: 1,408 Days
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 2560/0276 Determining malfunction
• CPC Class Codes: A61B 2560/04 Constructional details of apparatus
• CPC Class Codes: A61B 2562/085 combined with means for recording calibration data
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/14503 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors A61B5/1459, A61B5/1464, A61B5/1473, A61B5/1482, A61B5/14865 take precedence
• CPC Class Codes: A61B 5/1451 for interstitial fluid
• CPC Class Codes: A61B 5/14517 for sweat
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14535 for measuring haematocrit
• 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 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: A61B 5/14735 comprising an immobilised reagent
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase
• 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 5/15003 for venous or arterial blood
• CPC Class Codes: A61B 5/150992 Blood sampling from a fluid line external to a patient, such as a catheter line, combined with an infusion line; blood sampling from indwelling needle sets, e.g. sealable ports, luer couplings, valves tubing connectors and couplings A61M39/00
• CPC Class Codes: A61B 5/155 : Devices specially adapted for continuous or multiple sampling, e.g. at predetermined intervals devices loaded with multiple lancets simultaneously A61B5/15146
• CPC Class Codes: A61B 5/157 : Devices characterised by integrated means for measuring characteristics of blood
• CPC Class Codes: A61B 5/412 : Detecting or monitoring sepsis
• CPC Class Codes: A61B 5/4839 : combined with drug delivery
• CPC Class Codes: A61B 5/6848 : Needles
• CPC Class Codes: A61B 5/6849 : in combination with a needle set
• CPC Class Codes: A61B 5/6866 : Extracorporeal blood circuits, e.g. dialysis circuits
• CPC Class Codes: A61B 5/7257 : using Fourier transforms
• CPC Class Codes: A61B 5/7267 : involving training the classification device
• 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: A61B 5/743 : Displaying an image simultaneously with additional graphical information, e.g. symbols, charts, function plots
• CPC Class Codes: A61M 2005/14296 : Pharmacokinetic models
• CPC Class Codes: A61M 2230/201 : Glucose concentration
• CPC Class Codes: A61M 5/14 : Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
• CPC Class Codes: A61M 5/16804 : Flow controllers
• CPC Class Codes: A61M 5/1723 : using feedback of body parameters, e.g. blood-sugar, pressure measurement of body parameters A61B5/00
• CPC Class Codes: C12Q 1/001 : Enzyme electrodes
• CPC Class Codes: C12Q 1/006 : for glucose
• CPC Class Codes: G01D 18/00 : Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00
• CPC Class Codes: G01N 27/026 : Dielectric impedance spectroscopy electrochemical impedance spectroscopy for measuring corrosion G01N17/02
• CPC Class Codes: G01N 27/3274 : Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration coding of calibration information G01N33/48771
• CPC Class Codes: G01N 33/49 : Blood chemical methods for determining blood cell populations G01N33/5094; chemical analysis of blood groups or blood types G01N33/80
• CPC Class Codes: G16H 10/40 : for data related to laboratory analysis, e.g. patient specimen analysis
• CPC Class Codes: G16H 20/17 : delivered via infusion or injection
• CPC Class Codes: G16H 40/40 : for the management of medical equipment or devices, e.g. scheduling maintenance or upgrades
• CPC Class Codes: G16H 40/63 : for local operation
• CPC Class Codes: H05K 999/00 : dummy group
• CPC Class Codes: H05K 999/99 : dummy group
• CPC Class Codes: Y02A 90/10 : Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

Systems and methods for processing sensor data and self-calibration are provided. In some embodiments, systems and methods are provided which are capable of calibrating a continuous analyte sensor based on an initial sensitivity, and then continuously performing self-calibration without using, or with reduced use of, reference measurements. In certain embodiments, a sensitivity of the analyte sensor is determined by applying an estimative algorithm that is a function of certain parameters. Also described herein are systems and methods for determining a property of an analyte sensor using a stimulus signal. The sensor property can be used to compensate sensor data for sensitivity drift, or determine another property associated with the sensor, such as temperature, sensor membrane damage, moisture ingress in sensor electronics, and scaling factors.

Claims

1. A method for identifying failure of an analyte sensor using a sensor system electronically coupled to the analyte sensor, the method comprising:

generating a data stream indicative of an analyte concentration of a host by applying a bias voltage to a first analyte sensor at least partially positioned within tissue of the host;

applying a stimulus signal to the first analyte sensor, wherein the stimulus signal is a time-varying signal;

measuring a signal response to the stimulus signal generated by the first analyte sensor;

determining, by the sensor system, that the signal response satisfies one or more predetermined sensor fault criteria associated with membrane damage; and

initiating an error routine via the sensor system in response to determining that the signal response satisfies the one or more predetermined sensor fault criteria.

2. The method of claim 1, wherein the error routine includes triggering one or more of an audible alarm and a visual alarm on a display screen.

3. The method of claim 1, wherein the stimulus signal has a predetermined frequency.

4. The method of claim 1, wherein the stimulus signal comprises a spectrum of frequencies.

5. The method of claim 1, further comprising calculating an impedance based on the signal response.

6. The method of claim 5, wherein the calculated impedance comprises a magnitude value and a phase value, and wherein the one or more predetermined criteria comprises a predefined impedance magnitude threshold and a predefined phase threshold.

7. The method of claim 5, wherein the calculated impedance is a complex impedance value.

8. The method of claim 1, wherein the error routine includes suspending display of sensor data generated from the data stream.

9. The method of claim 1, further comprising measuring a signal generated by a second analyte sensor, the second analyte sensor transcutaneously positioned within the host at the same time as the first analyte sensor, wherein the analyzing further includes correlating the signal generated by the second analyte sensor to the signal response and determining if the one or more predetermined criteria are satisfied based on the correlation.

10. A system for monitoring an analyte concentration of a host using an analyte sensor, the system configured to also identify failure of the analyte sensor, the system comprising:

an analyte sensor configured for transcutaneous implantation into a host; and

sensor electronics coupled to the analyte sensor, the sensor electronics configured to;

generate a data stream indicative of an analyte concentration of the host by applying a bias voltage to the analyte sensor,

apply a stimulus signal to the analyte sensor, wherein the stimulus signal is a time-varying signal,

measure a signal response to the stimulus signal generated by the first analyte sensor,

determine that the signal response satisfies one or more predetermined sensor fault criteria associated with membrane damage, and

initiate an error routine in response to determining that the signal response satisfies the one or more predetermined sensor fault criteria.

11. The system of claim 10, wherein the error routine includes triggering one or more of an audible alarm and a visual alarm on a display screen.

12. The system of claim 10, wherein the stimulus signal has a predetermined frequency.

13. The system of claim 10, wherein the stimulus signal comprises a spectrum of frequencies.

14. The system of claim 10, wherein the sensor electronics are further configured to calculate an impedance based on the signal response.

15. The system of claim 14, wherein the calculated impedance comprises a magnitude value and a phase value, and wherein the one or more predetermined criteria comprises a predefined impedance magnitude threshold and a predefined phase threshold.

16. The system of claim 14, wherein the calculated impedance is a complex impedance value.

17. The system of claim 10, wherein the error routine includes suspending display of sensor data generated from the data stream.

18. The system of claim 10, further a second analyte sensor coupled to the sensor electronics, the second analyte sensor configured for transcutaneously positioning within the host at the same time as the first analyte sensor, wherein the analyzing further includes correlating the signal generated by the second analyte sensor to the signal response and determining if the one or more predetermined criteria are satisfied based on the correlation.