Test and control device for electrosurgical apparatus

• US 3,933,157 A
• Filed: 10/23/1973
• Issued: 01/20/1976
• Est. Priority Date: 10/23/1973
• Status: Expired due to Term

• Current Assignee: ABet Stille-Werner
• Original Assignee: ABet Stille-Werner
• Inventors: Jacobson, Nils Bertil, Bjurwill, Per Henrik
• Primary Examiner(s): Michell, Robert W.
• Assistant Examiner(s): Cohen, Lee S.
• Application Number:
  US05/408,535
• Time in Patent Office: 819 Days
• Field of Search: 128/303.14, 128/303.17, 128/303.18, 128/2.1 P, 128/419 R, 128/423, 128/303.13, 317/18 B, 317/18 A, 317/18 D, 317/31
• 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

Abstract

An electrosurgical apparatus having a diathermy current generator connected to an active electrode and a two-segment inactive electrode in surface engagement with the patient includes a test and control device automatically sensing the sum of the contact impedances of the two inactive electrode segments and inhibiting the passage of the diathermy current through the patient if the sensed impedance value is too high or too low. The sensing of the contact impedances is effected at intervals during periods when no diathermy current flows and is accomplished by means of alternating current.

Claims

1. A test and control device for an electrosurgical diathermy current circuit of the type having a high-frequency diathermy current generator, an active electrode connected to the diathermy current generator and an inactive electrode comprising two spaced electrode segments connected in parallel to the diathermy current generator, said test and control device comprising:

a. a sensing circuit means for being connected in series through the spaced electrode segments as bridged by a patient'"'"'s body including a source of alternating test current and an impedance, said sensing means comprising;

1. a free-running multivibrator having two operating states, and

2. a relay having a coil connected to and controlled by said multivibrator and a two-position switch arranged to disconnect the spaced electrode segments from the diathermy current circuit in one position;

b. means for automatically and repetitively sensing the resulting voltage drop across the electrode segments;

c. means connected to said sensing means and adapted to be connected to the diathermy current circuit and responsive to such voltage drop for inhibiting the passage of diathermy current whenever said voltage drop exceeds a predetermined maximum, or is less than a predetermined minimum said inhibiting means adapted to be connected to said electrode segments through the second position of the two-position switch; and

d. circuit means controlled by said inhibiting means for applying said alternating test current to said multivibrator to hold it in that state by which said relay coil is deenergized.

2. A test and control device for an electrosurgical diathermy current circuit of the type having a high-frequency diathermy current generator, an active electrode connected to the diathermy current generator and an inactive electrode comprising two spaced electrode segments connected in parallel to the diathermy current generator, said test and control device comprising:

a. a sensing circuit means for being connected in series through the spaced electrode segments as bridged by a patient'"'"'s body including a source of alternating test current and an impedance;

b. means for automatically and repetitively sensing the resulting voltage drop across the electrode segments; and

c. means connected to said sensing means and adapted to be connected to the diathermy current circuit and responsive to such voltage drop for inhibiting the passsage of diathermy current whenever said voltage drop exceeds a predetermined maximum, or is less than a predetermined minimum, said inhibiting means including;

3. a relay having switch contacts adapted to be connected in the diathermy current circuit, and a coil, anda pair of normally conducting electron switches each having a gate, and connected in series with said coil, one of said gates being connected to said impedance for opening its switch when said voltage drop exceeds said maximum, and the other of said gates being adapted to be connected to said electrode segments for opening its switch when said voltage drop is less than said minimum.

5. A test and control device according to claim 3 in which said first of said circuit means includes a normally conducting silicon controlled rectifier controlling said electrically controlled means and having a gate connected to said impedance whereby said rectifier is rendered non-conductive in response to an excessive voltage drop across said electrode segments.

6. A test and control device according to claim 3 in which said other of said circuit means includes a normally conducting silicon controlled rectifier controlling said electrically controlled means and having a gate, an electronic switch interconnecting said source of test current with said gate and having a gate of its own adapted to be connected to the lower voltage side of said electrode segments, whereby said rectifier is rendered non-conductive in response to the absence of a voltage drop across said segments sufficient to activate said electronic switch.

4. A test and control device for an electrosurgical diathermy current circuit of the type having a high-frequency diathermy current generator, an active electrode connected to the diathermy current generator and an inactive electrode comprising two spaced electrode segments connected in parallel to the diathermy current generator, said test and control device comprising:

a. a sensing circuit means for being connected in series through the spaced electrode segments as bridged by a patient'"'"'s body including a source of alternating test current and an impedance;

b. means for automatically and repetitively sensing the resulting voltage drop across the electrode segments; and

c. means connected to said sensing means and adapted to be connected to the diathermy current circuit and responsive to such voltage drop for inhibiting the passage of diathermy current whenever said voltage drop exceeds a predetermined maximum, or is less than a predetermined minimum, said inhibiting means including;

1. electrically controlled means having a switch adapted to be connected in the diathermy current circuit, and

2. a pair of circuit means powered by said alternating test current and normally jointly effecting energizing of said electrically controlled means, a first of said circuit means being responsive to a too low voltage on said impedance and the other of said circuit means being responsive to a too low voltage across said electrode segments.