EP0558317A2
Expired / Lapsed
EP
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Cauterising apparatus
Assignee: G2 Design Ltd
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Filing: 1993-02-25
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Granted: —
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Expires: 2013-02-25
Abstract
Abstract Electrosurgical cauterising apparatus has a radio frequency generator with a power oscillator (12) which generates a bipolar cauterising output signal for application to a pair of cauterising electrodes. The oscillator carrier frequency varies according to the load resistance represented by tissue being cauterised and this variation is used to monitor the tissue resistance as cauterisation progresses. The apparatus generates a cauterisation termination signal according to progress of the tissue resistance on a resistance versus time curve characteristic of the tissue cauterisation process.
Inventors
- 👤 Nigel Mark Goble
- 👤 Colin Charles Owen Goble
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 04:16
CPC Classifications
A; A61; A61B; A61B18/00; A61B18/04; A61B18/12; A61B18/1206; A61B18/14; A61B18/1402; A61B2018/00636; A61B2018/00696; A61B2018/00702; A61B2018/00773; A61B2018/00845; A61B2018/00851; A61B2018/00875
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
87 words
Electrosurgical cauterising apparatus comprising a radio frequency generator having a pair of output terminals for the delivery of radio frequency power to a bipolar electrosurgical cauterising tool, characterised in that the generator includes means for sensing a property of tissue being cauterised by the tool during cautery, and control means operable to generate a cautery termination signal in response to the said property having reached a predetermined end point value, the signal being generated for terminating the delivery of cauterising radio frequency power to the cauterising tool.
Claim 2
Dependent Claim
14 words
Apparatus according to claim 1, characterised in that the said property is electrical resistance.
Claim 3
Dependent Claim
49 words
Apparatus according to claim 2, characterised in that the control means is operable to detect a minimum sensed tissue resistance following an initial stage of cautery during which the tissue resistance is falling and to generate the termination signal at least approximately at the time of reaching the minimum.
Claim 4
Dependent Claim
62 words
Apparatus according to claim 2, characterised in that the control means are operable to detect a maximum sensed tissue resistance following an initial stage of cautery during which the tissue resistance is falling and an intermediate stage of cautery during which the tissue resistance is rising, and to generate the termination signal at least approximately at the time of reaching the maximum.
Claim 5
Dependent Claim
73 words
Apparatus according to claim 2, characterised in that the control means are operable to detect an initial period of falling tissue resistance followed by an intermediate period of rising tissue resistance and to generate the termination signal when the sensed tissue resistance has reached a value during one or either of the said periods which value has a predetermined relationship with the sensed tissue resistance at the beginning of the relevant said period.
Claim 6
Dependent Claim
124 words
Apparatus according to claim 2, characterised by a cautery level setting device, and characterised in that the control means are operable to store an initial tissue resistance value sensed at the beginning of cautery, and to detect a minimum sensed tissue resistance following an initial stage of cautery during which the tissue resistance is falling and a maximum sensed tissue resistance following an intermediate stage of cautery during which the tissue resistance is rising, and in that the control means are further operable to generate the termination signal at any of a plurality of predetermined tissue resistance values occurring at different times during the initial period, the intermediate period, and a final period of cautery according to the setting of the level setting device.
Claim 7
Dependent Claim
51 words
Apparatus according to claim 6, characterised in that the control means are arranged such that each of at least some of the tissue resistance values are predetermined by having a particular ratio with respect to the last preceding one of the initial resistance value, the minimum resistance and the maximum resistance.
Claim 8
Dependent Claim
36 words
Apparatus according to any preceding claim, characterised in that the generator includes a switching device (16) coupled to the control means and operable to stop delivery of radio frequency power in response to the termination signal.
Claim 9
Dependent Claim
57 words
Apparatus according to any of claims 2 to 7, characterised in that the generator includes a power control circuit (14) coupled to the control means, and the control means are operable to feed a power setting signal to the power control circuit to set the output power of the generator according to an initial sensed tissue resistance.
Claim 10
Dependent Claim
54 words
Apparatus according to claim 9, characterised in that the control means are operable to feed a further power setting signal to the power control circuit (14) when the sensed tissue resistance approaches the predetermined end point value in order to reduce the output power of the generator until the end point value is reached.
Claim 11
Dependent Claim
56 words
Apparatus according to any of claims 2 to 7, 8 and 9, characterised in that the generator includes a power oscillator (12) coupled to the output terminals and having an automatic output impedance adjusting circuit operable to alter the oscillator carrier frequency according to load resistance, and in that the sensing means comprise a frequency counter.
Claim 12
Dependent Claim
33 words
Apparatus according to claim 11, characterised in that the control means comprise a microprocessor (18) and a memory (20) for storing a table allowing conversion of frequency counter values to tissue resistance values.
Claim 13
Dependent Claim
23 words
Apparatus according to claim 11 or claim 12, characterised in that the carrier frequency is in the range of from 300kHz to 5MHz.
Claim 14
Dependent Claim
33 words
Apparatus according to any preceding claim, characterised by further comprising a surgical tool (10) having a pair of cauterising electrodes each connectible to a respective one of the output terminals of the generator.
Claim 15
Dependent Claim
17 words
Apparatus according to claim 14, characterised in that the surgical tool (10) is a pair of forceps.
Claim 16
Independent Claim
74 words
A method of operating electrosurgical cauterising apparatus having a radio frequency generator and a bipolar cauterising tool with cauterising electrodes coupled to the generator, characterised by the steps of applying radio frequency power to the electrodes, automatically sensing a property of tissue being cauterised between the electrodes during cautery, generating a cautery termination signal in response to the said property having reached a predetermined end point value, and ceasing application of radio frequency power.
Claim 17
Dependent Claim
30 words
A method according to claim 16, characterised in that the radio frequency power is applied as a stream of carrier pulses and in that the said property is repeatedly sensed.
Claim 18
Dependent Claim
14 words
A method according to claim 16, characterised in that the property is tissue resistance.
Claim 19
Dependent Claim
64 words
A method according to claim 18, characterised by detecting a minimum sensed tissue resistance following an initial stage of cautery during which the tissue resistance is falling, and a maximum sensed tissue resistance following an intermediate stage of cautery during which the tissue resistance is rising, and generating the termination signal at least approximately when one of the said minimum and maximum is reached.
Claim 20
Dependent Claim
92 words
A method according to claim 18, characterised by monitoring the sensed tissue resistance during at least one of initial, intermediate and final stages of cautery associated respectively with rising, falling and rising tissue resistance, storing tissue resistance values corresponding to the commencement of at least one of the said stages of cautery, and generating the termination signal when the sensed tissue resistance value has reached a predetermined relationship during a selected one of the said cautery stages with respect to the stored resistance value corresponding to the commencement of the selected stage.
Claim 21
Dependent Claim
35 words
A method according to claim 18, characterised in that the termination signal is generated in response to the sensed tissue resistance reaching a predetermined point on a resistance versus time curve characteristic of tissue cauterisation.
References Cited (Backward Citations)
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