ELECTROSURGERY SAFETY CIRCUIT

• US 3,683,923 A
• Filed: 09/25/1970
• Issued: 08/15/1972
• Est. Priority Date: 09/25/1970
• Status: Expired due to Term

• Current Assignee: Robert K. Anderson
• Original Assignee: Robert K. Anderson
• Inventors: Anderson, Robert K.
• Primary Examiner(s): Pace, Channing L.
• Application Number:
  US05/075,358
• Time in Patent Office: 690 Days
• Field of Search: 128/2.1,303.14,303.17,303.18
• US Class Current: 606/35
• CPC Class Codes: A61B 18/1233 with circuits for assuring patient safety
• CPC Class Codes: A61B 18/16 Indifferent or passive electrodes for grounding
• CPC Class Codes: A61B 2018/165 Multiple indifferent electrodes
• CPC Class Codes: H02H 3/33 using summation current transformers H02H3/347 takes precedence
• CPC Class Codes: Y10S 128/908 Patient protection from electric shock

Abstract

A safety circuit suitable for use in electrosurgery apparatus to prevent electrical burns is described herein. A current sensing transformer having a pair of primary windings and a single secondary or sense winding is provided. The primary windings are connected so as to compare the input current applied to an active electrode with the output current from an indifferent plate. When the comparison is unequal, the sense winding generates an error signal that warns the operator of the electrosurgery apparatus of a possible electrical burn situation. Alternatively, the primary windings are connected so as to sense the equality of output currents from two indifferent plates. Lack of equality causes an error signal to be generated to warn the operator.

Claims

1. A safety circuit suitable for use in determining the occurrence of a break in the ground side of an electrical energy source having an active side and a ground side, the active side of said electrical energy source being adapted to apply current to an active electrode and the ground side of said electrical energy source being adapted to receive return current in equal amounts from two indifferent electrodes, said safety circuit comprising:

a current sensing transformer including;

a first primary winding connected between the ground side of said electrical energy source and one of said indifferent electrodes;

a second primary winding connected between the ground side of said electrical source and the other of said indifferent electrodes, said first and second windings being connected so that current passing through them generate opposing magnetic fields; and

, a sense winding connected so as to sense when the magnetic fields generated by said first and second primary windings are unbalanced; and

, an alarm connected to said sense windings so as to provide an indication when said sense winding senses that the magnetic fields generate by said first and second primary windings are unbalanced.

2. A safety circuit as claimed in claim 1 wherein said alarm includes a means for preventing the further application of power from said electrical energy source when said sense winding sense that the magnetic fields generated by said first and second primary windings are unbalanced.

3. In an electrosurgical apparatus wherein electrical energy from a radio frequency source having an active side and a ground side is applied via an active cable to an active electrode, suitable for operating on a patient, and returns via at least one indifferent electrode and a ground cable, a improvement comprising a safety circuit suitable for sensing a discontinuity in the return portion of said electrosurgical apparatus, said safety circuit being connected between said radio frequency source and said electrodes.

4. The improvement claimed in claim 3 wherein said safety circuit comprises:

a current sensing transformer having a pair of primary windings connected so as to be balanced when said electrosurgical apparatus is operating in a normal manner and connected so as to be unbalanced when a break occurs in said portion; and

, an alarm connected to said current sensing transformer so as to be activated when said current sensing transformer is unbalanced because of said break in said return portion.

5. The improvement claimed in claim 4 wherein said current sensing transformer has first and second primary windings, said first primary winding being connected between the active side of said radio frequency source and said active electrode, said second primary winding being connected between the ground side of said radio frequency source and said at least one indifferent electrodE, said first and second primary windings being connected so that current passing through them generates opposing magnetic fields, said current sensing transformer further including a sense winding connected so as to sense when the magnetic fields generated by said first and second primary windings are unbalanced, said sense winding being connected to said alarm.

6. The improvement claimed in claim 5 wherein said alarm includes means for preventing the application of power from said radio frequency source to said active electrode when said sense winding senses said unbalanced condition.

7. The improvement claimed in claim 6 wherein said alarm includes an alarm device and a triggerable solid state device that is activated to pass current to said alarm device when said sense winding senses said unbalanced condition.

8. The improvement claimed in claim 4 wherein said electrical energy returns via two indifferent electrodes and wherein said transformer includes first and second primary windings, said first primary winding being connected between one of said indifferent electrodes and the ground side of said radio frequency source, said second primary winding being connected between the other of said indifferent electrodes and the ground side of said radio frequency source, said first and second primary windings being connected so that currents passing through them generate opposing magnetic fields, said current sensing transformer further including a sense winding connected so as to sense when the magnetic fields generated by said first and second primary windings are unbalanced, said sense winding being connected to said alarm.

9. The improvement claimed in claim 8 wherein said alarm includes means for preventing the application of power from said radio frequency source to said active electrode when said sense winding senses said unbalanced condition.

10. The improvement claimed in claim 9 wherein said alarm includes an alarm device and a triggerable solid state device that is activated to pass current to said alarm device when said sense winding senses said unbalanced condition.