Claims for Patent: 8,221,406

Summary for Patent: 8,221,406

Title:	Device for the electro-surgical sclerosing of body tissues
Abstract:	A high frequency current application apparatus for thermal sclerosing of body tissue, comprising a high frequency generator connected to at least two electrodes, one of which is to be introduced into body tissue. The apparatus includes a measuring and calculating device adapted to ascertain impedance (or ohmic resistance) between the two electrodes between which a respective therapeutic high frequency current flows. A control device is connected to the measuring and calculating device for varying the output power. During high frequency current application the measuring and calculating device forms the first derivative with respect of time of the impedance. The control device reduces output power when that derivative exceeds a positive threshold characteristic of a threat of tissue desiccation and restores output power to the original power when the first derivative exceeds in positive values a negative threshold characteristic of adequate rehydration of body tissue.
Inventor(s):	Desinger; Kai (Berlin, DE), Stein; Thomas (Teltow, DE), Roggan; Andre (Berlin, DE), Prezewowsky; Thomas (Teltow, DE)
Assignee:	Celon AG Medical Instruments (DE)
Application Number:	11/660,613
Patent Claims:	1. A high frequency current application apparatus for thermal sclerosing of body tissue, comprising a high frequency generator to which there are connected at least two electrodes of which at least one electrode is to be introduced into body tissue, and a measuring and calculating device which is adapted to ascertain from at least two of the parameters current strength, voltage, phase relationship and active power the impedance or the ohmic resistance between the two electrodes, between which a therapeutic high frequency current respectively flows, or to ascertain same by means of a measuring circuit independent of the therapeutic circuit, and a control device connected to the measuring and calculating device for varying the electrical output power of the high frequency generator, characterised in that the measuring and calculating device is adapted during a high frequency current application to form the first derivative from the characteristic in respect of time of the impedance or the ohmic resistance and to deliver a value dependent on the value of the first derivative, and the control device is adapted to significantly reduce the output power when the signal of the measuring and calculating device indicates that the derivative in respect of time of the impedance or the ohmic resistance exceeds a positive threshold which is characteristic for a threatening tissue desiccation and to restore the output power to the original power again when the signal of the measuring and calculating device indicates that the first derivative of the characteristic in respect of time of the impedance or ohmic resistance exceeds in the direction of positive values a negative threshold which is characteristic of adequate rehydration of the body tissue. 2. A high frequency current application apparatus as set forth in claim 1 characterised in that the measuring and calculating device is adapted to derive the parameters required for ascertaining impedance or ohmic resistance from a therapeutic high frequency current flowing between the electrodes. 3. A high frequency current application apparatus as set forth in claim 2 characterised in that the control device is adapted to reduce the output power to a value in the range of between 2% and 50% of the original output power when the signal of the measuring and calculating device indicates that the first derivative of the impedance or the ohmic resistance exceeds the positive threshold. 4. A high frequency current application apparatus as set forth in claim 1 characterised in that the measuring and calculating device is adapted to derive the parameters required for ascertaining impedance or ohmic resistance solely by means of a measuring circuit which is independent of the therapeutic circuit. 5. A high frequency current application apparatus as set forth in claim 4 characterised in that the control device is adapted to reduce the output power to a value in the range of between 0% and 50% of the original output power when the signal of the measuring and calculating device indicates that the first derivative of the impedance or the ohmic resistance exceeds the positive threshold. 6. A high frequency current application apparatus as set forth in claim 4 characterised in that the separate measuring circuit operates at a frequency different from the working frequency of the therapeutic high frequency current source. 7. A high frequency current application apparatus as set forth in claim 1 characterised in that the measuring and calculating device is adapted to form the first derivative in respect of time of the characteristic of the impedance or ohmic resistance from two measurement values which occur in succession in time of the impedance or the ohmic resistance. 8. A high frequency current application apparatus as set forth in claim 1 characterised in that the measuring and calculating device is adapted to calculate an average value of a number of measurement values which occur in succession in respect of time of the impedance or ohmic resistance and to form the first derivative in respect of time of the characteristic of the impedance or ohmic resistance from two measurement values which occur in succession in time of the impedance or the ohmic resistance. 9. A high frequency current application apparatus as set forth in claim 1 characterised in that the control device is adapted to reduce the output power when the signal of the measuring and calculating device indicates that the first derivative in respect of time of the characteristic of the impedance or ohmic resistance exceeds a value in the range of between 5 ohms/second and 50 ohms/second. 10. A high frequency current application apparatus as set forth in claim 1 characterised in that the control device is adapted to continuously reduce the output power over a short period of time. 11. A high frequency current application apparatus as set forth in claim 10 characterised in that the period of time is between 0.1 second and 5 seconds long. 12. A high frequency current application apparatus as set forth in claim 1 characterised in that the control device is adapted to maintain the reduced output power independently of the characteristic in respect of time of the impedance or resistance for a minimum time. 13. A high frequency current application apparatus as set forth in claim 12 characterised in that the minimum time is between 1 second and 10 seconds long. 14. A high frequency current application apparatus as set forth in claim 13 characterised in that the control device is adapted to use the first derivative of the characteristic in respect of time of the impedance or resistance for further control of power delivery again after expiry of the minimum time. 15. A high frequency current application apparatus as set forth in claim 1 characterised in that the control device is adapted to increase the output power again when the signal of the measuring and calculating device indicates that the first derivative in respect of time of the characteristic of impedance or ohmic resistance exceeds a value in the range of between minus 10 ohms/second and minus 0.1 ohm/second. 16. A high frequency current application apparatus as set forth in claim 9 characterised in that different threshold values can be selected for different kinds of tissue. 17. A high frequency current application apparatus as set forth in claim 1 characterised in that the control device is adapted to continuously return the output power to the original power over a short period of time. 18. A high frequency current application apparatus as set forth in claim 17 characterised in that the period of time is between 0.1 second and 5 seconds long. 19. A high frequency current application apparatus as set forth in claim 1 characterised in that the high frequency generator, the measuring and calculating device and the control device are disposed in a common housing. 20. A high frequency current application apparatus as set forth in claim 1 characterised in that the two electrodes between which impedance or ohmic resistance measurement is effected are arranged on a shank which is to be introduced into the body tissue. 21. A high frequency current application apparatus as set forth in claim 1 characterised in that the two electrodes between which impedance or ohmic resistance measurement is effected are arranged on two different shanks which are both to be introduced into the body tissue. 22. A high frequency current application apparatus as set forth in claim 1 characterised in that at least one of the two electrodes between which impedance or ohmic resistance measurement is effected is formed from a plurality of separate elements which are either arranged on the same shank or on different shanks and which are at the same electrical potential by an electrically conducting connection. 23. A high frequency current application apparatus as set forth in claim 1 characterised in that one of the two electrodes between which impedance or ohmic resistance measurement is effected is a neutral electrode which is to be applied to the surface of the skin. 24. A high frequency current application apparatus as set forth in claim 23 characterised in that the neutral electrode is formed from a plurality of separate elements which are to be applied to different surfaces of the skin and which are at the same electrical potential by an electrically conducting connection. 25. A high frequency application apparatus as set forth in claim 1 characterised in that the high frequency application apparatus has a control connection for an external pump connected to the electrodes which are introduced into the body tissue. 26. A high frequency application apparatus as set forth in claim 25 characterised in that the high frequency application apparatus is connected to a pump which is adapted to convey fluid into body tissue to be treated. 27. A high frequency application apparatus as set forth in claim 25 characterised in that the control device is adapted to cause the pump to be switched on when the control device detects a threat of tissue desiccation. 28. A high frequency application apparatus as set forth in claim 27 characterised in that the control device is adapted to actuate the external pump in such a way that fluid is conveyed into the treatment volume exclusively through those electrodes between which the control device has detected a threat of tissue desiccation. 29. A high frequency application apparatus as set forth in claim 27 characterised in that the control device is adapted to simultaneously cause the pump to be switched on and the output power to be reduced. 30. A high frequency application apparatus as set forth in claim 25 characterised in that the control device is adapted to actuate the pump in such a way that the pump conveys a previously defined amount of fluid into the treatment volume, wherein the amount of fluid is such that it approximately corresponds to the amount of previously vaporised tissue water. 31. A high frequency application apparatus as set forth in claim 26 characterised in that the pump is adapted to operate with a constant delivery and the control device is adapted to deactivate the pump again upon adequate tissue rehydration. 32. A high frequency application apparatus as set forth in claim 31 characterised in that the control device is adapted to cause deactivation of the pump and restoration of the output power to the original power at the same moment in time. 33. A high frequency application apparatus as set forth in claim 26 characterised in that the fluid is sterile physiological saline solution. 34. A high frequency application apparatus as set forth in claim 26 characterised in that the fluid is sterile water. 35. A high frequency current application apparatus for thermal sclerosing of body tissue, comprising a high frequency generator to which there are connected at least two electrodes which are configured for contact with body tissue, and a measuring and calculating device which is adapted to ascertain from at least two of the parameters current strength, voltage, phase relationship and active power the impedance or the ohmic resistance between the two electrodes, between which a therapeutic high frequency current respectively flows, or to ascertain same by means of a measuring circuit independent of the therapeutic circuit, and a control device connected to the measuring and calculating device for varying the electrical output power of the high frequency generator, characterised in that the measuring and calculating device is adapted during a high frequency current application to form the first derivative from the characteristic in respect of time of the impedance or the ohmic resistance and to deliver a value dependent on the value of the first derivative, and the control device is adapted to significantly reduce the output power when the signal of the measuring and calculating device indicates that the derivative in respect of time of the impedance or the ohmic resistance exceeds a positive threshold which is characteristic for a threatening tissue desiccation and to restore the output power to the original power again when the signal of the measuring and calculating device indicates that the first derivative of the characteristic in respect of time of the impedance or ohmic resistance exceeds in the direction of positive values a negative threshold which is characteristic of adequate rehydration of the body tissue. 36. A high frequency current application apparatus as set forth in claim 15 characterised in that different threshold values can be selected for different kinds of tissue.

Details for Patent 8,221,406

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Merck Sharp & Dohme Corp.	ZOSTAVAX	zoster vaccine live	For Injection	125123	05/25/2006		2024-08-20