Intelligent electrocardiogram system

• US 5,042,498 A
• Filed: 04/06/1990
• Issued: 08/27/1991
• Est. Priority Date: 04/06/1990
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Company (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Dukes, John N.
• Primary Examiner(s): Jaworski, Francis
• Assistant Examiner(s): MANUEL, GEORGE C
• Application Number:
  US07/505,795
• Time in Patent Office: 508 Days
• Field of Search: 128/696, 128/639, 128/640, 128/641
• US Class Current: 600/509
• CPC Class Codes: A61B 5/276 Protection against electrode failure
• CPC Class Codes: A61B 5/28 for electrocardiography [ECG]
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure

Abstract

An Intelligent Electrocardiogram System that solves the problem of faulty electrical connections between a patient and an ECG instrument is disclosed. The electrode employed by the invention comprises a disposable insulative pad and a snap connector that includes an LED anchored in the top central portion of the snap connector. Wires from the LED run into a lead that extend to an ECG instrument. An adhesive attached to the pad enables the electrode to be secured on the skin of a patient. The electrode includes a metal post embedded in the center of pad. The post protrudes up from the insulative pad through the connector side, which is the side opposite the side that touches the patient'"'"'s skin. A spring contact surrounds the post and provides an electrical coupling to one of the wires inside the lead. The bottom portion of the post extends through and past a lower central surface of the pad that is capable of holding a volume of conductive jelly. A sensor circuit connected to the spring clip includes a current source, a comparator, and a current limiting resistor. A reference voltage Vr is applied to the comparator'"'"'s negative input, while the positive is linked to the spring contact. The output of the comparator flows through a resistor that is coupled to the LED. When a change in the impedance between the conductive portion of the electrode and the patient is detected, the sensor circuit activates the LED on the faulty electrode.

Claims

1. An apparatus for automatically detecting a failure of a connection placed on a patient by activating an alarm on said patient where said failure occurs comprising:

a conductive means for making an electrical connection to said patient;

a coupling means for making an electrical connection to said conductive means;

said coupling means having an end portion attached to said conductive means;

a detector means coupled to said conductive means for sensing when said conductive means becomes partially detached from said patient; and

an alarm means for indicating a failure when said detector means senses an inadequate connection between said conductive means and said patient;

said alarm means being affixed to said end portion of said coupling means;

said alarm means also being located generally next to said conductive means to precisely indicate the position of said failure.

2. An apparatus as claimed in claim 1, further comprising an insulative pad means for making an insulating connection to said conductive means;

said insulative pad means having a lower central surface;

said insulative pad means also having an adhesion means coupled to said conductive means for maintaining said conductive means in contact with said patient.

3. An apparatus as claimed in claim 2, in which said conductive means comprises

a generally cylindrical metal post which protrudes up from said insulative pad means from said lower central surface of said pad means;

said metal post including;

an upper, generally oblate spheroid portion,

a middle shank portion, and

a lower flange portion; and

a volume of conductive jelly held by contact with said lower central surface of said pad means;

said lower flange portion of said post extending into said volume of conductive jelly.

4. An apparatus as claimed in claim 1, in which said detector means measures a change in resistance between said conductive means and said patient.

5. An apparatus as claimed in claim 1, in which said alarm means is a light.

6. An apparatus as claimed in claim 1, in which said alarm means is an LED.

7. An apparatus as claimed in claim 1, in which said alarm means is an audible alarm.

8. An Intelligent Electrocardiogram System comprising:

an insulative pad having a contact side and a connector side;

a generally cylindrical metal terminal having an upper portion, a middle portion, and a lower portion;

said upper portion protruding from said connector side;

said terminal extending through said pad to said contact side;

a volume of conductive jelly in contact with said lower portion of said terminal;

a spring contact located around said middle portion of said metal terminal;

a lead connected to said spring contact;

an adhesive located on said contact side of said pad for maintaining attachment to a patient;

a detector that measures a change in electrical impedance between said metal terminal and said patient;

said detector including a DC current source, a comparator, and a current limiting resistor;

said current source being connected to said terminal;

said comparator being connected to said current source;

said resistor being connected to said comparator;

a lamp which illuminates when said detector senses said change in electrical impedance;

said lamp being connected to said comparator through said resistor;

an ECG amplifier coupled to said lead; and

an ECG display coupled to said ampliflier.

9. An Intelligent Electrocardiogram System comprising:

an insulative pad having a contact side and a connector side;

a generally cylindrical metal terminal having an upper portion, a middle portion, and a lower portion;

said upper portion protruding from said connector side;

said terminal extending through said pad to said contact side;

a volume of conductive jelly in contact with said lower portion of said terminal;

a spring contact located around said middle portion of said metal terminal;

a lead connected to said spring contact;

an adhesive located on said contact side of said pad for maintaining attachment to a patient;

an AC sensor circuit that measures a change in electrical impedance between said metal terminal and said patient;

said AC sensor circuit including

a voltage to current converter,

an AC voltage source,

a synchronous AC detector,

an AC voltage amplifier,

a comparator, and

a current limiting resistor;

said converter being connected to said terminal;

said AC voltage source being connected between said converter and said synchronous AC detector;

said AC voltage amplifier being connected between said converter and said synchronous AC detector;

said comparator being connected to said synchronous AC detector;

said resistor being connected to said comparator;

a lamp which illuminates when said detector senses said change in electrical impedance;

said lamp being connected to said comparator through said resistor;

an ECG amplifier coupled to said lead; and

an ECG display coupled to said amplifier.