Evaluation of the quality of electrode contact with a skin surface

• US 9,271,659 B2
• Filed: 05/05/2014
• Issued: 03/01/2016
• Est. Priority Date: 09/21/2012
• Status: Active Grant

• Current Assignee: Welch Allyn Incorporated
• Original Assignee: Welch Allyn Incorporated
• Inventors: Sunderland, Richard A.
• Primary Examiner(s): Gedeon, Brian T
• Assistant Examiner(s): TEJANI, ANKIT D
• Application Number:
  US14/269,933
• Publication Number:
  US 20140243643A1
• Time in Patent Office: 666 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/25 Bioelectric electrodes therefor
• CPC Class Codes: A61B 5/259 using conductive adhesive means, e.g. gels
• CPC Class Codes: A61B 5/276 Protection against electrode failure
• CPC Class Codes: A61B 5/282 Holders for multiple electrodes for introduction into the body A61B5/287
• CPC Class Codes: A61B 5/291 for electroencephalography [EEG]
• CPC Class Codes: A61B 5/296 for electromyography [EMG]
• CPC Class Codes: A61B 5/303 Patient cord assembly, e.g. cable harness
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence

Abstract

An instrument that utilizes body contact electrodes evaluates the quality of the connections made between the electrodes and the body. An electrode contact quality evaluation circuit performs the quality evaluation, such as by determining contact impedances for the electrodes. The corresponding contact quality of each electrode is conveyed to the user.

Claims

1. An instrument comprising:

a lead interface device configured to electrically communicate with at least three surface contact electrodes, the at least three surface electrodes comprising an injection electrode, a sense electrode, and a return electrode;

instrument electronics configured to detect electrical signals from the surface contact electrodes; and

electrode contact quality evaluation circuitry operable to determine a quality of electrical connections between the surface contact electrodes and a skin surface, the electrode contact quality evaluation circuitry including driven return circuitry coupled between the sense electrode and the return electrode, the driven return circuitry configured to generate a return current having opposite polarity to a test current that is supplied to the injection electrode.

2. The instrument of claim 1, further comprising:

electrode contact detection circuitry operable to determine whether two or more of the surface contact electrodes have been placed on the skin surface;

wherein the instrument controls the electrode contact detection circuitry and the electrode contact quality evaluation circuitry separately, so that the electrode contact quality evaluation circuitry operates after the electrode contact detection circuitry successfully detects at least three of the surface contact electrodes have been placed on the skin surface.

3. The instrument of claim 1, wherein the electrode contact quality evaluation circuitry is operable to determine a contact impedance indicative of the quality of the electrical connection between at least one of the surface contact electrodes and the skin surface with a single test operation.

4. The instrument of claim 3, wherein the determination of the contact impedance is independent of a magnitude of a DC offset present in at least one of the surface contact electrodes.

5. The instrument of claim 3, wherein the electrode contact quality evaluation circuitry is operable to simultaneously determine at least two separate contact impedances indicative of the respective qualities of the electrical connections between at least two of the surface contact electrodes and the skin surface with the single test operation.

6. The instrument of claim 5, wherein the electrode contact quality evaluation circuitry is operable to complete the single test operation when only three surface contact electrodes are placed on the skin surface.

7. The instrument of claim 1, wherein the instrument is an electrocardiograph, and wherein the instrument electronics include electrocardiograph acquisition electronics to receive and detect electrical signals from the heart.

8. The instrument of claim 1, wherein the instrument is selected from the group consisting of an electroencephalograph, and an electromyograph.

9. The instrument of claim 1, wherein the lead interface device, the instrument electronics, and the electrode contact quality evaluation circuitry are all contained within a single housing.

10. The instrument of claim 1, wherein the electrode contact quality evaluation circuitry includes a processing device, and wherein the processing device performs processing as part of determining the quality of electrical connections between the surface contact electrodes and a skin surface.

11. The instrument of claim 5, wherein the at least two separate contact impedances are determined for the injection electrode and the return electrode.