ELECTRODE AND ELECTRODE POSITIONING ARRANGEMENT FOR ABDOMINAL FETAL ELECTROCARDIOGRAM DETECTION

• US 20110306862A1
• Filed: 06/12/2009
• Published: 12/15/2011
• Est. Priority Date: 06/13/2008
• Status: Active Grant

• Current Assignee: Monica Healthcare Limited (General Electric Company)
• Original Assignee: Monica Healthcare Limited (General Electric Company)
• Inventors: Pieri, Jean-Francois, Hayes-Gill, Barrie Robert, Barratt, Carl William
• Granted Patent: US 8,880,140 B2
• Time in Patent Office: Days
• US Class Current: 600/382
• CPC Class Codes: A61B 5/259 using conductive adhesive means, e.g. gels
• CPC Class Codes: A61B 5/282 Holders for multiple electrodes for introduction into the body A61B5/287
• CPC Class Codes: A61B 5/288 for foetal cardiography, e.g. scalp electrodes
• CPC Class Codes: A61B 5/4362 Assessing foetal parameters

Abstract

The invention relates to large area electrodes suitable for use in a fetal heart rate monitoring systems. The electrode comprises: a cutaneous gel contact (10) for sensing fetal electrocardiogram signals from a human pregnant subject; an electrical conductor (12) electrically connected to the gel contact (10) so as to define a first electrical contact region; a connector (14) in electrical contact with the electrical conductor (12) for connection to a lead wire; and a substructure (16) for attachment to a human pregnant subject. The gel contact (10) and the electrical conductor (12) are arranged on the substructure (16) to allow a contact surface (11) of the gel contact (10) to be in electrical communication with the skin of a human pregnant subject to define a second electrical contact region. The second electrical contact region has an area greater than 370 square millimetres. When arranged on a predefined electrode topology on the abdomen the success rate of fetal heart rate detection is significantly improved. The topology may be incorporated into a flat flexible cable which provides a comfortable and reproducible electrode arrangement allowing an untrained person to apply electrodes to a pregnant mother'"'"'s abdomen.

Claims

1. An electrode suitable for use in a fetal heart rate monitoring system, the electrode comprising:

a cutaneous contact for sensing fetal electrocardiogram signals from a human pregnant subject;

an electrical conductor electrically connected to the contact so as to define a first electrical contact region;

a connector in electrical contact with the electrical conductor for connection to a lead wire; and

a substructure for attachment to a human pregnant subject, the contact and the electrical conductor being arranged on the substructure to allow a surface of the contact to be in electrical communication with the skin of a human pregnant subject to define a second electrical contact region, wherein the second electrical contact region has an area greater than 370 square millimetres.

2. An electrode according to claim 1, wherein the electrode is a wet gel electrode and the contact is a gel contact.

3. An electrode according to claim 1, wherein the second electrical contact region is greater than 490 square millimetres.

4. An electrode according to claim 1, wherein the first electrical contact region is greater than 300 square millimetres.

5. An electrode according to claim 1 wherein the first electrical contact region is greater than 415 square millimetres.

6. An electrode according to claim 1, wherein the second contact region has a substantially rectangular, elongated or crescent shape.

7. An electrode according to claim 1, wherein the second contact region has a substantially circular shape.

8. An electrode according to claim 1, wherein the resistivity of the contact is between 1 and 20 ohm centimetres.

9. An electrode according to claim 1, wherein the resistivity of the gel contact is between 20 and 100 ohm centimetres.

10. An electrode according to claim 1, wherein the electrical conductor is a metal film.

11. An electrode according to claim 10 wherein the metal film is a silver/silver chloride film.

12. An electrode according to claim 2 wherein the contact includes a saline gel solution, the saline gel solution being held within a sponge and the sponge being secured on the substructure to permit electrical communication between the gel contact and the electrical conductor.

13. An electrode according to claim 1, wherein the substructure includes an adhesive capable of adherence to the skin of a pregnant subject.

15. A fetal heart rate monitoring system comprising at least one electrode according to claim 1.

14. (canceled)

16. A multi-electrode patch for use with a fetal heart rate monitor, the multi-electrode patch comprising:

a flexible substructure attachable to the skin of a pregnant subject;

at least three sensing electrodes positioned on the flexible substructure to approximate an arc, wherein the arc approximated by the at least three sensing electrodes is substantially the same in length and radius as the arc formed by the uterus fundus of a human pregnant subject; and

at least one connection port electrically connected to each sensing electrode and permitting electrical connection to a fetal heart rate monitor.

17. A multi-electrode patch according to claim 16 further including a common electrode, wherein the common electrode is electrically connected to the at least one connection port and is arranged on the flexible substructure, such that in use the distance between the at least three sensing electrodes and the common electrode is substantially the same as the distance between the uterus fundus and the symphis pubis of a pregnant subject.

18. A multi-electrode patch according to claim 16 further comprising a right leg driver electrode, wherein the flexible substructure includes a spur portion, the right leg driver electrode being located at the distal end of the spur portion.

19. A multi-electrode patch according to claim 16, wherein the at least three sensing electrodes include wet gel electrodes.

20. A multi-electrode patch according to claim 16, wherein the at least three sensing electrodes include electrodes which define an electrode contact region greater than 370 square millimetres.

21. A multi-electrode patch according to claim 16, wherein the at least three sensing electrodes include electrodes which define an electrode contact region greater than 490 square millimetres.

22. A multi-electrode patch according to claim 16, wherein the at least three sensing electrodes include electrodes which each define a substantially rectangular, elongated or crescent electrode contact region.

23. A multi-electrode patch according to claim 16, wherein the at least three sensing electrodes include electrodes which each define a substantially circular electrode contact region.

24. A multi-electrode patch according to claim 16, wherein the at least three sensing electrodes are equispaced along the length of the arc.

25. A multi-electrode patch according to claim 24 wherein the spacing of the at least three sensing electrodes is between 80 mm and 100 mm.

26. A multi-electrode patch according to claim 24 wherein the spacing of the at least three sensing electrodes is between 130 mm and 150 mm.

27. A multi-electrode patch according to claim 24 wherein the spacing of the at least three sensing electrodes is between 155 mm and 175 mm.

28. A multi-electrode patch according to claim 24 wherein the spacing of the at least three sensing electrodes is between 230 mm and 250 mm.

29. A multi-electrode patch according to claim 24 including at least one additional sensing electrode positioned on the line of the arc defined by the at least three sensing electrodes and spaced from a central electrode of the at least three sensing electrodes at a distance different to the spacing of the at least three sensing electrodes.

30. A multi-electrode patch according to claim 29 wherein the at least one additional electrode is spaced from a central electrode of the at least three sensing electrodes by one or more of between 80 mm and 100 mm, between 130 mm and 150 mm, between 155 mm and 175 mm and between 230 mm and 250 mm.

31. A multi-electrode patch according to claim 16, wherein the at least three sensing electrodes are electrically connected to the connection port by shielded wiring.

32. A multi-electrode patch according to claim 31 wherein the flexible substructure and shielded wiring form a flexible flat cable.

33. A multi-electrode patch according to claim 16, wherein the flexible substructure includes an adhesive capable of adherence to the skin of a pregnant subject.

34. A multi-electrode patch according to claim 16, including integrated circuitry configured to amplify and filter a detected fetal electrocardiogram signal.

35. A method for taking fetal ECG measurements comprising the steps of:

a) providing a multi-electrode patch according to claim 16;

b) establishing a first line on the skin of a pregnant subject to approximate the line of the uterus fundus;

c) placing the multi-electrode patch on the skin of the pregnant subject such that the at least three sensing electrodes are positioned along a line approximating the first line; and

d) placing a common electrode on the skin of the pregnant subject at a location opposing the location of the at least three sensing electrodes such that a line taken between the common electrode and each of the sensing electrodes passes through the womb of the pregnant subject; and

e) taking an fECG measurement using any combination of the said at least three sensing electrodes referenced against the common electrode.

36. A method according to claim 35 wherein step d) includes placing the common electrode at a location approximating the symphis pubis of the pregnant subject.

37. A method according to claim 35 wherein step d) includes placing the common electrode on the back of the pregnant subject.

38. A method according to claim 35 including, after step d), the sub-step of:

placing a right leg driver electrode on the back or abdominal side of a pregnant subject.

39. A method according to claim 35 wherein step c) includes establishing a second line on a pregnant subject, the second line being parallel to the first line and passing through the Xiphoid Process, and placing the multi-electrode patch on the skin of a pregnant subject such that the at least three sensing electrodes are positioned between the first line and the second line.

40. A method according to claim 39 wherein step c) further includes establishing a third line on a pregnant subject, the third line being parallel to the first line and located up to 100 mm away from the first line, and placing the multi-electrode patch on the skin of a pregnant subject such that the at least three sensing electrodes are positioned between the third line and the second line.

41. A method according to claim 35 wherein the electrodes arranged on the multi-electrode patch define a substantially rectangular, elongate or crescent electrode contact area and wherein step c) includes aligning the at least three sensing electrodes such that the longitudinal axis of each electrode contact area is transverse to the abdominal muscle of the subject.

42. A method according to claim 35 wherein the electrodes arranged on the multi-electrode patch define a substantially circular electrode contact area.

45. A multi-electrode patch according to claim 16 further including a common electrode positioned on the flexible substructure, the common electrode being spaced from a centremost one of the sensing electrodes by a distance of between 14 and 20 cm on the concave side of the arc.

43. (canceled)

44. (canceled)

46. A method for taking fetal ECG measurements comprising the steps of:

a) providing a multi-electrode patch having;

a flexible substructure attachable to the skin of a pregnant subject;

at least three sensing electrodes positioned on the flexible substructure to approximate an arc, wherein the arc approximated by the at least three sensing electrodes is substantially the same in length and radius as the arc formed by the uterus fundus of a human pregnant subject

at least one connection port electrically connected to each sensing electrode and permitting electrical connection to a fetal heart rate monitor;

a common electrode positioned on the flexible substructure, the common electrode being spaced from a centremost one of the sensing electrodes by a distance of between 14 and 20 cm on the concave side of the arc;

b) placing the multi-electrode patch on the skin of the pregnant subject such that the common electrode is positioned between approximately 0 and 5 cm above the symphis pubis;

c) placing the sensing electrodes such that a centremost sensing electrode is positioned above the umbilicus; and

d) taking an fECG measurement using any combination of the said at least three sensing electrodes referenced against the common electrode.