Return electrode contact monitor
First Claim
1. A return e1ectrode contact monitor for electrosurgical apparatus including a RF power source coupled to an active electrode and a patient circuit including a return electrode for operative association with a patient, said monitor comprising:
- first means for producing an electric signal that varies with the resistance of a return part of the patient circuit, andcircuit means responsive to said electric signal, said circuit means establishing a preselected resistance value range beyond which an alarm output is produced, a manually operable set point actuator means, said circuit means including set point means responsive to said actuator means providing a threshold corresponding to the resistance at the last time said actuator means was actuated whereby upon a preselected fixed deviation of said resistance from said threshold and within said range an alarm output is produced.
2 Assignments
0 Petitions
Reexamination
Accused Products
Abstract
Apparatus for monitoring the resistance of the return part of the patient circuit of either a dual foil or single foil return electrode according to a user'"'"'s selection is disclosed. The apparatus measures the quality of the contact between the return electrode and the patient. A DC or AC converter provides a substantially DC voltage at its input that varies in relation to the resistance of the return part of the patient circuit at its AC output. Preferably, a constant current fed sinusoidal oscillator with a low pass filter at its DC output provides a substantially DC voltage related to the resistance at its AC input. An analog to digital converter converts the substantially DC voltage to a corresponding binary digital signal that is input to a programmed microprocessor. A manually operable set point switch coupled to the microprocessor is acatuated by the user which actuation establishes a resistance level with the pad (return electrode) in place on the patient. The microprocessor establishes preselected range between fixed maximum and minimum resistance values beyond which an alarm output is produced and establishes a threshold resistance value whereby upon a preselected fixed deviation, such as when the patient pad is partially detached, an alarm is produced and further an output so the RF power source will longer apply power to the active electrode.
-
Citations
17 Claims
-
1. A return e1ectrode contact monitor for electrosurgical apparatus including a RF power source coupled to an active electrode and a patient circuit including a return electrode for operative association with a patient, said monitor comprising:
-
first means for producing an electric signal that varies with the resistance of a return part of the patient circuit, and circuit means responsive to said electric signal, said circuit means establishing a preselected resistance value range beyond which an alarm output is produced, a manually operable set point actuator means, said circuit means including set point means responsive to said actuator means providing a threshold corresponding to the resistance at the last time said actuator means was actuated whereby upon a preselected fixed deviation of said resistance from said threshold and within said range an alarm output is produced. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
-
-
17. A return electrode contact monitor for electrosurgical apparatus including a RF power source coupled to an active electrode and a patient circuit providing a return load resistance including a return electrode for operative association with a patient, said monitor comprising:
-
detector means including a DC to AC converter in the form of a current fed push-pull sine wave oscillator and a low pass filter for producing a substantially DC voltage related to the resistance of the return part of the patient circuit, and circuit means including an analog to digital converter and a programmed microprocessor, said converter converting said substantially DC voltage to a corresponding binary digital signal that is input to said microprocessor, a manually operable set point switch coupled to said microprocessor, said microprocessor establishing preselected fixed maximum and minimum resistance value limits beyond which an alarm output is produced and said microprocessor further including set point means providing a threshold corresponding to the resistance at the instant of the last set point switch activation whereby upon a preselected fixed deviation of said resistance above said threshold and within said maximum and minimum value limits an alarm output is produced, said microprocessor providing an output to shut off the RF power source each time an alarm output is produced.
-
Specification