Multiple RF return pad contact detection system
First Claim
1. A return pad contact detection system for use with at least two pairs of patient return pads adapted for contacting a patient, each pair of said at least two pairs of patient return pads having two conductors attached to a corresponding patient return pad for connecting the pad to a source of a.c. energy passing through the pad, said return pad contact detection system comprising:
- at least two signal sources for generating an operating current for a corresponding pair of said at least two pairs of patient return pads;
means for applying the operating current through said conductors to said at least two pairs of patient return pads; and
at least two resonant circuits each corresponding to at least one pair of patient return pads and one of said at least two signal sources, each of said at least two resonant circuits responsive to said current for producing a signal which is a function of the impedance between said two corresponding patient return pads, said at least two resonant circuits being tuned to different frequencies and being tuned to the substantially the same frequency as the corresponding signal source for substantially minimizing measurement interaction between the at least two pairs of patient return pads when said operating currents are simultaneously applied to said corresponding pairs of patient return pads.
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Accused Products
Abstract
A multiple RF return pad contact detection system is provided which is adaptive to different physiological characteristics of patients without being susceptible to electrosurgical current interference (e.g., interference or measurement interaction between components of the detection system). The detection system can measure or sense the contact resistance or impedance between the patient and pairs of RF return pads or return electrodes where multiple pairs of RF return pads are utilized due to the high current frequently needed during electrosurgery while eliminating or minimizing the risk of measurement interaction between the RF return pad pairs. The system allows for the independent and simultaneous measurement of the pad contact impedance for each pair of RF return pads. If the impedance of any pad pair is above a predetermined limit, the system turns off or reduces the electrosurgical output of the electrosurgical generator to prevent excess heating. The system eliminates or minimizes interference or measurement interaction between the pad pairs by providing a different signal source frequency for each pad contact pair, but a frequency which matches an associated series resonant network frequency. The current that flows in the series resonant network is a direct reflection or function of the pad impedance of the corresponding pad pair.
88 Citations
22 Claims
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1. A return pad contact detection system for use with at least two pairs of patient return pads adapted for contacting a patient, each pair of said at least two pairs of patient return pads having two conductors attached to a corresponding patient return pad for connecting the pad to a source of a.c. energy passing through the pad, said return pad contact detection system comprising:
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at least two signal sources for generating an operating current for a corresponding pair of said at least two pairs of patient return pads;
means for applying the operating current through said conductors to said at least two pairs of patient return pads; and
at least two resonant circuits each corresponding to at least one pair of patient return pads and one of said at least two signal sources, each of said at least two resonant circuits responsive to said current for producing a signal which is a function of the impedance between said two corresponding patient return pads, said at least two resonant circuits being tuned to different frequencies and being tuned to the substantially the same frequency as the corresponding signal source for substantially minimizing measurement interaction between the at least two pairs of patient return pads when said operating currents are simultaneously applied to said corresponding pairs of patient return pads. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A return pad contact detection system for use with at least two pairs of patient return pads adapted for contacting a patient, each pair of said at least two pairs of patient return pads having two conductors attached to a corresponding patient return pad for connecting the pad to a source of a.c. energy passing through the pad, said return pad contact detection system comprising:
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means for producing and applying a corresponding current signal for each of said at least two pairs of patient return pads;
resonant circuitry means responsive to the impedance between said at least two pairs of patient return pads for producing at least one signal which is a function of said impedance; and
measurement means for receiving said at least one signal for determining the impedance between said at least two pairs of patient return pads, wherein the frequency of said corresponding current signal for each of said at least two pairs of patient return pads is substantially equal to the frequency of at least a portion of said resonant circuitry means. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification