Circuit for testing cables for physiological signal sensing electrodes

• US 5,766,133 A
• Filed: 10/30/1995
• Issued: 06/16/1998
• Est. Priority Date: 10/28/1994
• Status: Expired due to Term

• Current Assignee: Sorin CRM USA (MicroPort Scientific Corp.)
• Original Assignee: Ela Medical S.A. (LivaNova Plc)
• Inventors: Faisandier, Yves
• Primary Examiner(s): Getzow, Scott M.
• Application Number:
  US08/550,444
• Time in Patent Office: 960 Days
• Field of Search: 600/509, 607/63, 607/28
• US Class Current: 600/509
• CPC Class Codes: A61B 5/276 Protection against electrode failure
• CPC Class Codes: A61B 5/333 Recording apparatus specially adapted therefor

Abstract

A test circuit and method for the integrity of electrode cables of a typical Holter machine for the recording of physiological signals, notably cardiac activity. This machine comprises: a plurality of signal terminals (16), which are ready to be connected each to a proximal extremity (20) of a cable (18) whose distal extremity (22) is connected to an external electrode (24) to be placed on the patient; amplifiers (30) receiving signals applied on the signal terminals; and circuit means for testing the integrity of the totality of electrical connections to the patient, comprising a current source (36), means (38, 40) to apply this current on terminals and means (34) to measure the voltage drop produced by the impedance of the circuit path (42) including the cable connected to the corresponding terminal and in which circulates the test current. The test means also includes in addition a pin (54) to test an individual cable, this pin being connected to a current source and being able to be put in contact with the distal extremity (22) of a given cable (18), whose proximal extremity (20) remains connected to its terminal (16), the test current circulating (58) between this terminal and the pin. Each of a number of individual cables in a bundle of cables can thus be manually tested by the device of the present invention to discriminate defective cables from electrodes that are poorly positioned on the patient.

Claims

1. Apparatus for the recording of a physiological signal collected by a plurality of external electrodes applied on a patient, comprising:

a plurality of signal terminals, each signal terminal being connectable to a proximal extremity of a cable, said cable having a distal extremity connectable to one of said plurality of external electrodes;

an amplifier having an input coupled to said plurality of signal terminals; and

circuit means for testing an electrical connection of each said plurality of signal terminals to the patient, said testing circuit means comprising;

a first current source having a test current output,

means for selectively applying on each one of said plurality of signal terminals said test current output, and

circuit means for measuring an impedance of a circuit path including a selective one signal terminal and the one of the plurality of cables connected to the selected signal terminal in response to said test current output applied to said circuit path;

wherein the apparatus further comprises;

a second current source having a second test current output; and

a pin, said pin being connected to the second current source and having a contact surface able to be put in contact with the distal extremity of one of said plurality of cables whose proximal extremity is connected to the corresponding signal terminal respectively, the second test current circulating between the corresponding signal terminal, one cable, and pin.

2. The apparatus of claim 1, in which the second current source is a continuous current source.

3. The apparatus of claim 1, in which the second current source is a source of alternating current.

4. The apparatus of claim 1, in which the second current source and the first current source are the same.

5. The apparatus of claim 1, in which the circuit testing means comprises means for measuring a voltage on the pin.

6. The apparatus of claim 5, in which the circuit testing means further comprises means for grounding the input of the amplifier.

7. The apparatus of claim 1, wherein the apparatus further comprises a case of a machine, a movable lid, said lid having a closed position in which the pin is blocked and an open position in which the pin is accessible.

8. The apparatus of claim 7, in which, in said closed position, the lid blocks the plurality of signal terminals to prevent disconnection of the proximal extremities of said plurality of cables from said signal terminals.

9. The apparatus of claim 7, wherein the apparatus further comprises an initialization button and in which, in said closed position, the lid blocks the initialization button from actuation.

10. The apparatus of claim 7, wherein the apparatus further comprises an extractable data support and in which, in said closed position, the lid blocks the extractable data support from removal.

11. The apparatus of claim 7, wherein the apparatus further comprises a connector of complementary data collection coming from the patient, and in which, in said closed position, the lid locks in position said connector of complementary data.

12. In a device for recording physiological signals using a plurality of cables and external electrodes on a patient to acquire said physiological signals, each of said cables having a proximal end connector and a distal end connector, the distal end being connectable to one of the plurality of external electrodes, a test circuit for testing continuity of said cables comprising:

a plurality of signal terminals, each terminal having an input to receive one of the proximal end connectors of one of the plurality of cables and a switch circuit element operable to connect said signal terminal to a ground;

an amplifier having an input coupled to the plurality of signal terminals and an output;

a measuring circuit coupled to the amplifier output operable to measure a voltage;

a current source having a test current output;

a test pin connected to the current source;

a multiplexor having an input connected to the current source and a plurality of outputs, said plurality of outputs being connected to said plurality of signal terminals, the multiplexor being operable in a first mode to apply said test current output to each one of said plurality of cables one cable at a time, wherein said measuring circuit measures a first voltage drop across a first circuit comprising said one cable and said cable signal terminal in response to the applied test current output, and in a second mode to apply said test current to selected ones of said plurality of cables one at a time, wherein said measuring circuit measures a second voltage drop across a second circuit comprising said selected one cable, said cable signal terminal, and test pin in response to the applied test current output, said first voltage being representative of whether or not the one cable is properly connected, the second voltage being representative of the continuity of the selected one cable.

13. The apparatus of claim 12 wherein each switch circuit element further comprises a static switch, the apparatus further comprising a logic control circuit operable to operate said plurality of signal terminal switch circuit elements to apply the test current output to the one cable in each of said first and second modes.

14. The apparatus of claim 12 wherein the switch circuit element further comprises a capacitor and the current source further comprises a high frequency current source.