U.S. patent application number 11/747382 was filed with the patent office on 2007-09-06 for electrosurgical generator.
This patent application is currently assigned to SMITH & NEPHEW, INC.. Invention is credited to Katherine A. Knudsen, Duane W. Marion, Andy H. Uchida, Ken Woodland.
Application Number | 20070208333 11/747382 |
Document ID | / |
Family ID | 35506985 |
Filed Date | 2007-09-06 |
United States Patent
Application |
20070208333 |
Kind Code |
A1 |
Uchida; Andy H. ; et
al. |
September 6, 2007 |
ELECTROSURGICAL GENERATOR
Abstract
An electrosurgical generator that can be used, for example, to
provide radio-frequency (RF) energy for localized tissue
coagulation, cutting, ablation, and to create lesions in nervous
tissue. The generator can provide controls for line power, RF
power, setting temperature and/or power, for selecting preset
temperature and power combinations, and for selecting programmed
treatment profiles. The generator can have a display to display the
desired probe and tissue temperature, measured probe impedance,
actual probe and/or tissue temperature, delivered power, treatment
time, mode setting, preset selection, and messages, and indicators
for RF Power On, Stimulation On, and Fault Condition. The generator
can include the ability to generate low frequency pulses to
stimulate nerves and to assist in the proper placement of the
electrosurgical probe in the location that is causing pain.
Inventors: |
Uchida; Andy H.; (Mountain
View, CA) ; Marion; Duane W.; (Santa Clara, CA)
; Woodland; Ken; (Wilmington, MA) ; Knudsen;
Katherine A.; (San Jose, CA) |
Correspondence
Address: |
FISH & RICHARDSON P.C.;SMITH & NEPHEW, INC.
150 Minuteman Road
Andover
MA
01810
US
|
Assignee: |
SMITH & NEPHEW, INC.
1450 Brooks Road
Memphis
TN
38116
|
Family ID: |
35506985 |
Appl. No.: |
11/747382 |
Filed: |
May 11, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10873289 |
Jun 23, 2004 |
7226447 |
|
|
11747382 |
May 11, 2007 |
|
|
|
Current U.S.
Class: |
606/34 |
Current CPC
Class: |
A61B 2018/00791
20130101; A61B 2018/00702 20130101; A61B 18/1206 20130101; A61B
2017/00084 20130101 |
Class at
Publication: |
606/034 |
International
Class: |
A61B 18/18 20060101
A61B018/18 |
Claims
1. An electrosurgical generator comprising: a probe recognizing
circuit configured to recognize an electrosurgical probe; a
processor configured to select a mode of the electrosurgical
generator based upon the recognized probe and to set a therapy
profile based upon the selected mode; a display configured to
display the therapy profile; and a user control configured to
modify the therapy profile.
2. The electrosurgical generator of claim 1 wherein the user
control comprises a soft key.
3. The electrosurgical generator of claim 1 wherein the user
control comprises an arrow key.
4. The electrosurgical generator of claim 1 wherein the user
control comprises a rotary encoder knob.
5. The electrosurgical generator of claim 1 wherein the display
comprises a visual display.
6. The electrosurgical generator of claim 5 wherein the visual
display comprises an LCD display.
7. An electrosurgical generator comprising: a. a processor
configured to: receive a target temperature; calculate a first set
temperature; command a first output power level until a measured
temperature is equal to or greater than the first set temperature;
calculate an updated set temperature based upon the target
temperature; command a second output power level until the measured
temperature is equal to or greater than the updated set
temperature; and determine whether the updated set temperature is
equal to the target temperature.
8. The electrosurgical generator of claim 7 wherein the processor
is configured to retrieve the target temperature from a storage
location.
9. The electrosurgical generator of claim 7 wherein the processor
is configured to receive the target temperature from a user
input.
10. The electrosurgical generator of claim 7 wherein the processor
is configured to calculate the first set temperature by subtracting
a predetermined value from the target temperature.
11. The electrosurgical generator of claim 7 wherein the processor
is configured to calculate the first set temperature by retrieving
a pre-stored value.
12. The electrosurgical generator of claim 7 wherein the processor
is configured to calculate the updated set temperature by
subtracting a predetermined value from the target temperature.
13. The electrosurgical generator of claim 7 wherein the processor
is configured to calculate the updated set temperature by adding a
predetermined value to the first set temperature.
14. The electrosurgical generator of claim 7 wherein the processor
is configured to calculate the updated set temperature by
retrieving a pre-stored value.
15. The electrosurgical generator of claim 7 wherein the first
output power level is greater than the second output power
level.
16. The electrosurgical generator of claim 7 further comprising a
user control configured to modify the target temperature.
17. An electrosurgical generator comprising: a processor configured
to: receive a target temperature; command a first output power
level until a measured temperature is within a specified value of
the target temperature; calculate a second output power level when
the measured temperature is within the specified value of the
target temperature; command the second output power level; and
determine whether the measured temperature is equal to the target
temperature.
18. The electrosurgical generator of claim 17 wherein the processor
is configured to retrieve the target temperature from a storage
location.
19. The electrosurgical generator of claim 17 wherein the processor
is configured to receive the target temperature from a user
input.
20. The electrosurgical generator of claim 17 wherein the first
output power level comprises an output power level based upon an
identity of a surgical probe.
21. The electrosurgical generator of claim 17 wherein the first
output power level is greater than the second output power
level.
22. The electrosurgical generator of claim 17 further comprising a
user control configured to modify the target temperature.
23. An electrosurgical generator comprising: a processor configured
to: receive a target temperature; receive a first generator output
setting corresponding to a first generator output power; command
the first generator output setting when a difference between the
target temperature and a measured temperature is greater than a
specified value; calculate a second generator output setting if the
first generator output power is less than a maximum allowed
generator output power for an identified surgical probe and if the
difference between the target temperature and the measured
temperature is greater than the specified value, wherein the second
generator output setting corresponds to a second generator output
power that is greater than the first generator output power, and
command the second generator output setting; calculate a third
generator output setting if the first generator output power is
greater than the maximum allowed generator output power for the
identified surgical probe and the difference between the target
temperature and the measured temperature is greater than the
specified value, wherein the third generator output setting
corresponds to a third generator output power that is less than the
first generator output power, and command the third generator
output setting; and determine whether the difference between the
target temperature and the measured temperature is less than or
equal to the specified value.
24. The electrosurgical generator of claim 23 wherein the processor
is configured to retrieve the target temperature from a storage
location.
25. The electrosurgical generator of claim 23 wherein the processor
is configured to receive the target temperature from a user input.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 10/873,289 filed on Jun. 23, 2004. The disclosure of this
prior application is incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This description relates to electrosurgical generators.
[0004] 2. Related Art
[0005] Lower back pain is a common ailment and affects many people
at some point in their lives. Frequently, this pain is the result
of cracks or fissures that develop in the wall of the
intervertebral disc. These fissures are filled with small nerve
endings and blood vessels, and often are a chronic source of pain.
Additionally, the inner disc tissue (nucleus) frequently bulges
(herniates) into these fissures in the outer region of the disc,
likewise stimulating pain sensors within the disc.
[0006] Electrosurgical procedures provide minimally invasive
treatment options for treating lower back pain by applying thermal
energy (i.e., heat) to the affected area. Electrosurgical
procedures have been developed for use in other pain management
procedures, such as denervation procedures. An electrosurgical
generator provides electrical energy, such as, for example, high
frequency and radio frequency electrical energy. In particular, the
electrical energy provided by the electrosurgical generator is used
in pain management procedures to modify the structure of
tissue.
SUMMARY OF THE INVENTION
[0007] An electrosurgical generator that can be used, for example,
to provide radio-frequency (RF) energy for localized tissue
coagulation, cutting, ablation, and to create lesions in nervous
tissue. The generator is, e.g., a line-powered radio-frequency
generator capable of delivering up to approximately 20 watts of
power. The generator can provide controls for line power, RF power,
setting temperature and/or power, for selecting preset temperature
and power combinations, and for selecting programmed treatment
profiles. The generator can have a display to display the desired
probe and tissue temperature, measured probe impedance, actual
probe and/or tissue temperature, delivered power, treatment time,
mode setting, preset selection, and messages, and indicators for RF
Power On, Stimulation On, and Fault Condition. The software for the
generator can be upgraded using a special card.
[0008] The generator can include the ability to generate low
frequency pulses to stimulate nerves and to assist in the proper
placement of the electrosurgical probe in the location that is
causing pain. For example, the generator may include the ability to
generate low frequency pulses of 0.1 to 3 ms in duration at a
frequency between approximately 2-50 hz.
[0009] Temperature and impedance monitoring can be used to assist
the surgeon by automatically adjusting energy delivery to maintain
effective tissue heating during temperature control applications.
Preset temperature and power settings can offer the convenience of
quickly configuring the generator for use. Programmed temperature
profiles can provide the convenience of selecting a treatment
setting for use with a particular type of probe, for example, the
Smith and Nephew SPINECATH.RTM. Intradiscal Catheter, the Smith and
Nephew Decompression Catheter, and the Smith & Nephew RF
Denervation Probe.
[0010] In one general aspect, a method includes recognizing an
electrosurgical probe coupled to an electrosurgical generator,
selecting a mode of the electrosurgical generator based upon the
recognized probe, setting a therapy profile based upon the selected
mode, and displaying the therapy profile. The generator can include
user inputs for modifying the therapy profile.
[0011] Implementations may include one or more of the following
features:
[0012] Setting the therapy profile includes automatically setting a
default parameters for the selected mode. The therapy profile
includes an automatic temperature profile, such as a temperature
rise from an initial temperature to a peak temperature and a dwell
time at the peak temperature. The temperature rise is, e.g., a
fixed rate of temperature rise such as one degree Celsius per
thirty seconds, one degree Celsius per six seconds, or one degree
Celsius per eighteen seconds. Alternatively, the temperature rise
is discontinuous. The rate of temperature rise is selected
automatically. The initial temperature, the peak temperature and/or
the dwell time at the peak temperature is selected automatically
and also can be manually overridden.
[0013] In one implementation, the therapy profile includes a
frequency parameter and a pulsewidth parameter. The therapy profile
also can include an adjustable voltage parameter. A rotary encoder
knob that is configured to adjust the voltage parameter can be
used.
[0014] In another implementation, the therapy profile is switched
between a first therapy profile and a second therapy profile. A
user modified parameter may be retained when switching between the
first therapy profile and the second therapy profile. The therapy
profile includes a temperature parameter and a time duration
parameter, and also can include a frequency parameter, a pulsewidth
parameter, and/or an amplitude parameter. The frequency parameter,
the pulsewidth parameter, and/or the amplitude parameter can be
adjusted to control a tissue temperature. The pulsewidth may be,
for example, 20 ms. In one implementation, the frequency parameter
and/or the amplitude parameter are adjusted to control tissue
temperature and the pulse width parameter is not adjustable.
[0015] The display of at least a portion of the display of the
therapy profile can be updated. The therapy profile can be
modified, and the modified therapy profile can be displayed.
[0016] In another general aspect, a computer program stored on a
computer readable medium includes instructions for recognizing an
electrosurgical probe coupled to an electrosurgical generator,
selecting a mode of the electrosurgical generator based upon the
recognized probe, setting a therapy profile based upon the selected
mode, and displaying the therapy profile. The generator can include
user inputs for modifying the therapy profile.
[0017] In another general aspect, a computer implemented method for
achieving a target temperature includes: a) receiving the target
temperature; b) calculating a first set temperature; c) commanding
a first output power level until a measured temperature is equal to
or greater than the first set temperature; d) calculating an
updated set temperature based upon the target temperature; e)
commanding a second output power level until the measured
temperature is equal to or greater than the updated set
temperature; and repeating d and e until the updated set
temperature is equal to the target temperature.
[0018] Implementations may include one or more of the following
features:
[0019] Receiving the target temperature can include retrieving the
target temperature from a storage location and receiving the target
temperature can include receiving a user input. Calculating the
first set temperature can include subtracting a predetermined value
from the target temperature or retrieving a pre-stored value. The
first power output level can be a maximum power output level, and
the second power output level can be a power output level less than
the maximum power output level. The maximum power output level can
be a maximum output power level for a particular probe being used.
In another implementation, the maximum output power level can be
the maximum power output level of the generator. In other
implementations, the maximum output power level can be a different
pre-determined value or a dynamically calculated value. The first
output power level can be an output power level based upon an
identity of a surgical probe. The first power output level can be
greater than the second power output level. Calculating the updated
set temperature can include subtracting a predetermined value from
the target temperature, adding a predetermined value to the first
set temperature, or retrieving a pre-stored value.
[0020] In another implementation, a proportional-integral routine
can be used to control to the target temperature by adjusting the
output voltage.
[0021] In another general aspect, a computer program stored on a
computer readable medium includes instructions for: a) receiving a
target temperature; b) calculating a first set temperature; c)
commanding a first output power level until a measured temperature
is equal to or greater than the first set temperature; d)
calculating an updated set temperature based upon the target
temperature; e) commanding a second output power level until the
measured temperature is equal to or greater than the updated set
temperature; and repeating d and e until the updated set
temperature is equal to the target temperature.
[0022] In another general aspect, an electrosurgical generator
includes means for recognizing an electrosurgical probe, means for
selecting a mode of the electrosurgical generator based upon the
recognized probe and for setting a therapy profile based upon the
selected mode, means for displaying the therapy profile, and means
for modifying the therapy profile.
[0023] Implementations can include one or more of the following
features:
[0024] The means for recognizing the electrosurgical probe can
include a probe recognition circuit. The means for selecting the
mode and for setting the therapy profile can include a processor.
The means for displaying the therapy profile can include a visual
display, such as, for example, an LCD display. The means for
modifying the therapy profile can include a user control, such as,
for example, a soft key, an arrow key, or a rotary encoder
knob.
[0025] In another general aspect, an electrosurgical generator
includes a probe recognizing circuit configured to recognize an
electrosurgical probe, a processor configured to select a mode of
the electrosurgical generator based upon the recognized probe and
to set a therapy profile based upon the selected mode, a display
configured to display the therapy profile, and a user control
configured to modify the therapy profile.
[0026] Implementations can include one or more of the following
features:
[0027] The display can include a visual display, such as, for
example, an LCD display. The user control may include, for example,
a soft key, an arrow key, or a rotary encoder knob.
[0028] In another general aspect, an electrosurgical generator
includes means for receiving a target temperature, calculating a
first set temperature, commanding a first output power level until
a measured temperature is equal to or greater than the first set
temperature, calculating an updated set temperature based upon the
target temperature, commanding a second output power level until
the measured temperature is equal to or greater than the updated
set temperature, and determining whether the updated set
temperature is equal to the target temperature, and means for
modifying the target temperature.
[0029] Implementations can include one or more of the following
features:
[0030] The means for receiving the target temperature, calculating
a first set temperature, commanding a first output power level
until a measured temperature is equal to or greater than the first
set temperature, calculating an updated set temperature based upon
the target temperature, commanding a second output power level
until the measured temperature is equal to or greater than the
updated set temperature, and determining whether the updated set
temperature is equal to the target temperature can include a
processor. In one implementation, the processor is configured to
retrieve the target temperature from a storage location. In another
implementation, the processor is configured to receive the target
temperature from a user input.
[0031] In one implementation, the processor is configured to
subtract a predetermined value from the target temperature to
obtain the first set temperature. In another implementation, the
processor is configured to retrieve a pre-stored value of the first
set temperature. In one implementation, the processor is configured
to subtract a predetermined value from the target temperature to
obtain the updated set temperature. In another implementation, the
processor is configured to add a predetermined value to the first
set temperature to obtain the updated set temperature. In yet
another implementation, the processor is configured to retrieve a
pre-stored value of the updated set temperature. The first power
output level can be greater than the second power output level, and
the means for modifying the target temperature can include a user
control.
[0032] In another implementation, the set temperature is not ramped
to the target temperature. Instead, the measured temperature is
controlled directly to achieve the target temperature. The set
temperature is not changed or updated. A proportional-integral
routine, or other similar routine, can be used to control to the
target temperature by adjusting the output voltage.
[0033] In another implementation, a first output power can be
commanded if the measured temperature is less than a specified
value below the target temperature. Once the measured temperature
is within the specified value of the target temperature, a control
routine, such as a PID or a PI routine, can be used to calculate a
second output level for the generator.
[0034] In another general aspect, an electrosurgical generator
includes a processor configured to receive the target temperature,
calculate a first set temperature, command a first output power
level until a measured temperature is equal to or greater than the
first set temperature, calculate an updated set temperature based
upon the target temperature, command a second output power level
until the measured temperature is equal to or greater than the
updated set temperature, and determine whether the updated set
temperature is equal to the target temperature.
[0035] Implementations can include one or more of the following
features:
[0036] The processor can be configured to retrieve the target
temperature from a storage location or receive the target
temperature from a user input. The processor can configured to
calculate the first set temperature by subtracting a predetermined
value from the target temperature or by retrieving a pre-stored
value. The processor can be configured to calculate the updated set
temperature by subtracting a predetermined value from the target
temperature, by adding a predetermined value to the first set
temperature, or by retrieving a pre-stored value.
[0037] The first power output level can be greater than the second
power output level. The generator can include a user control
configured to modify the target temperature.
[0038] In another general aspect, a computer program stored on a
computer readable medium includes instructions for: a) receiving a
target temperature; b) commanding a first output power level until
a measured temperature is within a specified value of the target
temperature; c) calculating a second output power level when the
measured temperature is within the specified value of the target
temperature; d) commanding the second output power level; and
repeating c and d until the measured temperature is equal to the
target temperature.
[0039] Implementations can include one or more of the following
features:
[0040] The instructions for receiving the target temperature can
include instructions for receiving a user input. The first output
power level can include a maximum output power level. The maximum
output power level can include a maximum output power level based
upon an identity of a surgical probe. The second output power level
can include a output power level less than the maximum output power
level. The first output power level can be an output power level
based upon an identity of a surgical probe. The first output power
level can be greater than the second output power level. The
instructions for calculating the second output power level can
include instructions for using a PID algorithm or a PI algorithm to
calculate the second output power level. The instructions can also
include instructions for receiving an initial second output power
level. The instructions for receiving an initial second output
power level can include instructions for retrieving the initial
second output power level from a storage location. The initial
second output power level can be based upon an identity of a
surgical probe. The instructions for calculating the second output
power level c can include instructions for retrieving a pre-stored
value.
[0041] In another general aspect, a method for achieving a target
temperature includes: a) receiving a target temperature; b)
commanding a first output power level until a measured temperature
is within a specified value of the target temperature; c)
calculating a second output power level when the measured
temperature is within the specified value of the target
temperature; d) commanding the second output power level; and
repeating c and d until the measured temperature is equal to the
target temperature.
[0042] In another general aspect, an electrosurgical generator can
include means for receiving a target temperature, commanding a
first output power level until a measured temperature is within a
specified value of the target temperature, calculating a second
output power level when the measured temperature is within the
specified value of the target temperature, commanding the second
output power level, and determining whether the measured
temperature is equal to the target temperature and means for
modifying the target temperature.
[0043] Implementations can include one or more of the following
features:
[0044] The means for receiving a target temperature, commanding a
first output power level until a measured temperature is within a
specified value of the target temperature, calculating a second
output power level when the measured temperature is within the
specified value of the target temperature, commanding the second
output power level, and determining whether the measured
temperature is equal to the target temperature can include a
processor.
[0045] In another general aspect, an electrosurgical generator can
include a processor configured to receive a target temperature,
command a first output power level until a measured temperature is
within a specified value of the target temperature, calculate a
second output power level when the measured temperature is within
the specified value of the target temperature, command the second
output power level, and determine whether the measured temperature
is equal to the target temperature.
[0046] Implementations can include one or more of the following
features:
[0047] The processor can be configured to retrieve the target
temperature from a storage location. The processor can be
configured to receive the target temperature from a user input. The
first output power level can include an output power level based
upon an identity of a surgical probe. The first output power level
can be greater than the second output power level. The
electrosurgical generator can include a user control configured to
modify the target temperature.
[0048] In another general aspect, a computer program stored on a
computer readable medium includes instructions for: a) receiving a
target temperature; b) receiving a first generator output setting
corresponding to a first generator output power; c) commanding the
first generator output setting when a difference between the target
temperature and a measured temperature is greater than a specified
value; d) calculating a second generator output setting if the
first generator output power is less than a maximum allowed
generator output power for an identified surgical probe and if the
difference between the target temperature and the measured
temperature is greater than the specified value, wherein the second
generator output setting corresponds to a second generator output
power that is greater than the first generator output power, and
commanding the second generator output setting; e) calculating a
third generator output setting if the first generator output power
is greater than the maximum allowed generator output power for the
identified surgical probe and the difference between the target
temperature and the measured temperature is greater than the
specified value, wherein the third generator output setting
corresponds to a third generator output power that is less than the
first generator output power, and commanding the third generator
output setting; and f) repeating c through e until the difference
between the target temperature and the measured temperature is less
than or equal to the specified value.
[0049] Implementations can include one or more of the following
features:
[0050] The instructions for receiving the target temperature can
include instructions for receiving a user input. The instructions
for calculating the second generator output setting can include
instructions for adding a predetermined value to the first
generator output setting. The instructions for calculating the
third generator output setting can include instructions for
subtracting a predetermined value from the first generator output
setting.
[0051] The computer program can further include instructions for:
g) calculating a fourth generator output setting corresponding to a
fourth generator output power if the difference between the target
temperature and the measured temperature is less than or equal to
the specified value; and h) commanding the fourth generator output
setting. Instructions for calculating the fourth generator output
setting can include instructions for calculating the fourth
generator output setting using a control algorithm. The control
algorithm can include setting the fourth generator output setting
equal to a first constant multiplied by an integral of an error
value plus a second constant multiplied by the error value, wherein
the first constant and the second constant are defined for an
identified surgical probe and the error value equals the target
temperature minus the measured temperature.
[0052] The computer program can further include instructions for
limiting the fourth generator output control setting to a maximum
value. The maximum value can include the first generator output
control setting. The computer program can include instructions for
not integrating the error value when the fourth generator control
setting is equal to the maximum value. The computer program can
include instructions for limiting the fourth generator output
control setting to a minimum value. The minimum value can be
zero.
[0053] In another general aspect, a method for achieving a target
temperature includes: a) receiving a target temperature; b)
receiving a first generator output setting corresponding to a first
generator output power; c) commanding the first generator output
setting when a difference between the target temperature and a
measured temperature is greater than a specified value; d)
calculating a second generator output setting if the first
generator output power is less than a maximum allowed generator
output power for an identified surgical probe and if the difference
between the target temperature and the measured temperature is
greater than the specified value, wherein the second generator
output setting corresponds to a second generator output power that
is greater than the first generator output power, and commanding
the second generator output setting; e) calculating a third
generator output setting if the first generator output power is
greater than the maximum allowed generator output power for the
identified surgical probe and the difference between the target
temperature and the measured temperature is greater than the
specified value, wherein the third generator output setting
corresponds to a third generator output power that is less than the
first generator output power, and commanding the third generator
output setting; and f) repeating c through e until the difference
between the target temperature and the measured temperature is less
than or equal to the specified value.
[0054] In another general aspect, an electrosurgical generator
includes: means for receiving a target temperature, receiving a
first generator output setting corresponding to a first generator
output power, commanding the first generator output setting when a
difference between the target temperature and a measured
temperature is greater than a specified value, calculating a second
generator output setting if the first generator output power is
less than a maximum allowed generator output power for an
identified surgical probe and if the difference between the target
temperature and the measured temperature is greater than the
specified value, wherein the second generator output setting
corresponds to a second generator output power that is greater than
the first generator output power, and commanding the second
generator output setting, calculating a third generator output
setting if the first generator output power is greater than the
maximum allowed generator output power for the identified surgical
probe and the difference between the target temperature and the
measured temperature is greater than the specified value, wherein
the third generator output setting corresponds to a third generator
output power that is less than the first generator output power,
and commanding the third generator output setting and determining
whether the difference between the target temperature and the
measured temperature is less than or equal to the specified value;
and means for modifying the target temperature.
[0055] In another general aspect, an electrosurgical generator
includes a processor configured to: receive a target temperature;
receive a first generator output setting corresponding to a first
generator output power; command the first generator output setting
when a difference between the target temperature and a measured
temperature is greater than a specified value; calculate a second
generator output setting if the first generator output power is
less than a maximum allowed generator output power for an
identified surgical probe and if the difference between the target
temperature and the measured temperature is greater than the
specified value, wherein the second generator output setting
corresponds to a second generator output power that is greater than
the first generator output power, and command the second generator
output setting; calculate a third generator output setting if the
first generator output power is greater than the maximum allowed
generator output power for the identified surgical probe and the
difference between the target temperature and the measured
temperature is greater than the specified value, wherein the third
generator output setting corresponds to a third generator output
power that is less than the first generator output power, and
command the third generator output setting; and determine whether
the difference between the target temperature and the measured
temperature is less than or equal to the specified value.
[0056] Implementations can include one or more of the
following:
[0057] The processor can be configured to retrieve the target
temperature from a storage location. The processor can be
configured to receive the target temperature from a user input.
[0058] Other features will be apparent from the description and
drawings, and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0059] FIG. 1 is a perspective view of an electrosurgical
generator.
[0060] FIG. 2 is a plan view of a front panel of the
electrosurgical generator of FIG. 1.
[0061] FIG. 3 is an exemplary standby mode interface implemented by
the electrosurgical generator of FIG. 1 while executing the
processes of FIGS. 4, 11, 12, and 13.
[0062] FIGS. 4, 11, 12, and 13 are flow charts of exemplary
processes implemented by the electrosurgical generator of FIG.
1.
[0063] FIG. 5 is an exemplary SPINECATH.RTM. AUTOTEMP.RTM. mode
interface implemented by the electrosurgical generator of FIG. 1
while executing the processes of FIGS. 4, 11, 12, and 13.
[0064] FIG. 6 is an exemplary Decompression AUTOTEMP.RTM. mode
interface implemented by the electrosurgical generator of FIG. 1
while executing the processes of FIGS. 4, 11, 12, and 13.
[0065] FIG. 7 is an exemplary Sensory Stimulate mode interface
implemented by the electrosurgical generator of FIG. 1 while
executing the processes of FIGS. 4, 11, 12, and 13.
[0066] FIG. 8 is an exemplary Motor Stimulate mode interface
implemented by the electrosurgical generator of FIG. 1 while
executing the processes of FIGS. 4, 11, 12, and 13.
[0067] FIG. 9 is an exemplary RF Lesion mode interface implemented
by the electrosurgical generator of FIG. 1 while executing the
processes of FIGS. 4, 11, 12, and 13.
[0068] FIG. 10 is an exemplary Pulsed RF mode interface implemented
by the electrosurgical generator of FIG. 1 while executing the
processes of FIGS. 4, 11, 12, and 13.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0069] As shown in FIG. 1, an electrosurgical generator 100
includes a chassis 105, and a front panel 110. The front panel 110
includes a display 115, soft keys 120, arrow keys 125, status
indicators 130, an RF output on/off control button 135, a grounding
pad receptacle 140, a probe receptacle 145, and a rotary encoder
knob 150. Probe receptacle 145 receives a probe 165 via a cable
plug 160, a cable 155, and a cable plug 162. The display 115 is,
for example, an LCD screen that displays certain information during
a surgical procedure, as will be discussed in more detail below
with respect to FIGS. 2-3 and 5-10.
[0070] Generator 100 can be used with probes such as, for example,
the Smith and Nephew SPINECATH.RTM. Intradiscal Catheter, the Smith
and Nephew Decompression Catheter, and the Smith & Nephew RF
Denervation Probe. The electrosurgical generator 100 is capable of
therapy profiles through several modes of operation, including
SPINECATH.RTM. AUTOTEMP.RTM.. (automatic temperature) mode,
Decompression AUTOTEMP.RTM. mode, stimulation mode, RF lesion mode,
and Pulsed RF mode. When using the Smith & Nephew RF
Denervation Probe, the generator initially enters the stimulation
mode, and the RF lesion mode or Pulse RF mode is accessed through
the stimulation mode.
[0071] During a disc denervation procedure, the rotary encoder knob
150 is used to turn on/off the stimulation mode output voltage and
adjust the stimulation mode output voltage for motor and sensory
stimulus prior to applying RF energy to treat tissue. The rotary
encoder knob is pushed to turn the stimulation mode power on or
off. With the stimulation mode power on, the rotary encoder knob
150 can be rotated clockwise to increase the stimulation mode
output voltage and counter clockwise to decrease the stimulation
mode output voltage.
[0072] In all modes other than stimulation mode, the RF output
on/off control button 135 is used to start or stop RF power
delivery. The button 135 is pressed, or alternatively, a foot
switch (not shown) is pressed, to start and stop RF power delivery.
If the RF output on/off control button 135 is pressed in
succession, then RF power delivery toggles on and off.
[0073] Referring to FIG. 2, the status indicators 130 include an
indication for "RF On" such as an LED 240 that is illuminated when
the electrosurgical generator 100 is delivering RF power in all
modes but the stimulation mode, a "Stimulation On" indication such
as an LED 245 that is illuminated when the generator 100 is
delivering stimulation power, and a fault indication such as an LED
250 that is illuminated when a fault condition is detected. The
arrow keys 125 and soft keys 120 are used to control different
parameters for different modes of operation of the generator 100.
The soft keys and arrow keys are associated with controls shown in
the display 115. The operator manipulates a control by operating
the soft key or arrow key corresponding to the control. Typically,
the function associated with the soft key can change as the display
is changed, and the arrow keys are used to adjust a particular
parameter up or down.
[0074] As shown, the soft keys 120 include three separate soft keys
205, 215, and 220. Soft key 205 operates on control 260 and soft
key 215 operates on control 265. In the implementation shown in
FIG. 2, soft key 220 does not have a corresponding control shown in
the display 115. Arrow keys 125 include three sets of arrow keys
225, 230, and 235. Arrow keys 225 include a down arrow key 225a and
an up arrow key 225b. Arrow keys 230 include a down arrow key 230a
and an up arrow key 230b. Arrow keys 235 include a down arrow key
235a and an up arrow key 235b. The arrow keys 225, 230, and 235
operate on controls 280, 275, and 270 of display 115,
respectively.
[0075] When line power is initially applied to the generator 100,
the generator performs a system self-test to determine if it is
performing properly. After the self-test, the generator 100 enters
a standby mode in which RF power cannot be delivered. In the
standby mode, a user interface (UI), such as the UI 300 shown in
FIG. 3, is displayed to the user on display 115. To exit standby
mode, a start control 305 is displayed on the user interface 300
after a probe 165 is connected to the generator. The start control
305 is activated by depressing soft key 220. When activated, the
start control 305 causes the generator 100 to exit the standby mode
and enter an appropriate operating mode as described below.
[0076] FIG. 4 shows an exemplary procedure 400 employed using the
electrosurgical generator 100 discussed above with respect to FIGS.
1 and 2. After the operator powers up the generator 100 and the
generator 100 boots (step 402), the operator connects a probe 165
to the generator 100 (step 405) and depresses soft key 220 to
activate the start control 305. The generator 100 recognizes the
probe (step 410) and selects a desired mode based on the recognized
probe (step 415). For example, if the recognized probe is a
SPINECATH.RTM., SPINECATH.RTM. AUTOTEMP.RTM. mode is entered, if
the recognized probe is a Decompression Catheter, Decompression
AUTOTEMP.RTM. mode is entered, and if the recognized probe is a
Denervation Probe, the stimulate mode is entered.
[0077] The generator includes a processor (not shown) running
software that recognizes which type of probe 165 is being connected
to the generator by reading a sensor in the handle of the probe
165. The processor can be, for example, a microprocessor. The
processor is capable of responding to and executing instructions in
a defined manner. The software can include a program, a piece of
code, an instruction, a device, or a combination of these for
independently or collectively instructing the processor to interact
and operate as described. The software can be embodied permanently
or temporarily in various types of machines, components, physical
or virtual equipment, storage media, or propagated signals capable
of providing instructions to the processor. The processor typically
has an associated memory (not shown), such as an internal or
external memory, for storing data and programs. In one
implementation, the processor can access programs externally stored
in and/or performed by one or more device(s) external to the
processor. The processor can include a single processor or multiple
processors.
[0078] The generator also includes a probe recognition circuit (not
shown) that is configured to recognize a probe that is connected to
the generator. In one implementation, the probe recognition circuit
can recognize a probe by recognizing a resistance value of the
probe. Different probes may have different resistance values or
ranges of resistance values. In one implementation, the probe
recognition circuit measures a voltage that corresponds to a
resistance value. The probe recognition circuit can convert the
measured analog voltage into a digital value. In one
implementation, the probe recognition circuit includes a feature to
identify the probe based upon the digital value. In another
implementation, the probe recognition circuit supplies the digital
value to the processor and the processor identifies the probe.
[0079] When the probe 165 is connected to the generator 100, the
generator 100 automatically switches to the appropriate mode,
resets a timer, and sets default values for the selected mode (step
420). Switching to the appropriate mode can include selecting a
maximum allowed power output based on the recognized probe. The
maximum allowed power for the recognized probe typically is less
than the maximum power output of the generator. In one
implementation, the processor controls the switching of the mode,
the resetting of the time, and the setting of default values for
the selected mode based on the recognized probe. The display 115 is
updated to reflect the mode entered and the default values set
(step 425). In one implementation, the processor supplies the mode
entered and the default values to the display. The operator can
change the default settings from the preset values using the soft
keys and/or arrow keys (step 430). In one implementation, the soft
keys and/or arrow keys are connected to provide an input to the
processor to change the default settings. The display is updated
(step 435) to reflect the values set by the operator. In one
implementation, the processor supplies the values set by the
operator to the display. The operator then performs the desired
surgical procedure (step 440). During the surgical procedure, the
operator may change the mode, if allowed (step 445). For example,
when in stimulation mode, the operator can change between a motor
stimulation mode and a sensory stimulation mode, and can change
from a stimulation mode to RF lesion mode or pulsed RF mode. If the
mode is changed, then steps 420-440 are repeated as described above
for the new mode.
[0080] SPINECATH.RTM. AUTOTEMP.RTM. Mode
[0081] Referring to FIG. 5, when the recognized probe is a
SPINECATH.RTM., the generator enters SPINECATH.RTM. AUTOTEMP.RTM.
mode and user interface (UI) 500 is presented to the operator on
display 115. User interface 500 indicates the generator mode as the
SPINECATH.RTM. mode 505. Several parameters for the SPINECATH.RTM.
mode are displayed to the operator. For example, the measured probe
impedance 510, elapsed procedure time 515, actual probe temperature
525, set temperature 530, and set temperature profile 535 are
displayed.
[0082] The actual probe temperature 525 is measured by a
temperature sensing device, such as a thermocouple in the probe.
The set temperature 530 is a target temperature that the generator
100 attempts to achieve and hold. The set temperature 530 can be
entered manually by the operator or adjusted automatically by the
generator 100. For example, the set temperature 530 can be changed
manually using arrow keys 230 or can be adjusted automatically by
the generator 100 while executing a set profile 535. Typically, a
manual entry of set temperature 530 overrides an automatic
adjustment of set temperature 530. The set profile 535 is a peak
temperature that is to be achieved by the generator 100 for a
predetermined duration of time. The generator 100 increases the
temperature in a controlled manner until the peak temperature is
achieved, and dwells at the peak temperature for a predetermined
dwell time. Multiple profiles can be stored, and a particular
profile selected manually by the operator or automatically by the
generator. The set profile can be changed manually using arrow keys
235, or set automatically by the generator using a default setting
or based upon other criteria. The operator also has a control 520
to reset the timer and set temperature using soft key 205.
Typically, the reset control 520 may be activated only after a
pause in the delivery of RF energy. When reset, the timer
re-zeroes, the set temperature 530 returns to the default value,
and the set profile 535 remains unchanged.
[0083] An exemplary set of profiles is shown below in Table 1. The
profiles include information about a peak temperature, the time
required to achieve the peak temperature, the dwell time at the
peak temperature, and the total treatment time. By manipulating
arrow keys 235, the operator can change the set profile, and the
profile set by the operator will perform according to the values
shown in Table 1. In the SPINECATH.RTM. auto-temperature mode, the
set profile 535 typically defaults to the profile "P90", which
corresponds to a peak temperature of 90 degrees C. Other
implementations are possible, and the values in Table I are meant
to be exemplary.
[0084] The generator 100 automatically ramps up the actual probe
temperature in a controlled manner up to the peak temperature shown
in Table 1 for the set profile 535, and then dwells for the given
dwell time at the peak temperature according to the profile. The
set temperature 530 is the temperature at which the controlled ramp
up is started. The set temperature 530 is initialized to a default
value and is incremented by the generator in a controlled manner
until the set temperature equals the peak temperature. As the
generator automatically increments the set temperature, the
displayed value of set temperature 530 in display 115 also is
incremented.
[0085] For example, the parameters may include a default
temperature profile "P90," a default value of the set temperature
of 65 degrees C., and a measured probe temperature below 65 degrees
C. In this case, the generator initially increases the temperature
up to a value of 65 degrees C. by, for example, applying full power
until the set temperature of 65 degrees C. is achieved. Full power
can be a maximum allowed power for a given probe, or may be the
maximum power that can be supplied by the generator. Once delivery
of RF power has begun the elapsed procedure time clock 515 begins
counting up. When a probe temperature of 65 degrees C. is reached,
the generator follows a ramped profile which is usually defined by
a temperature increment per unit time, e.g., 1 degree C. every 30
seconds. The temperature ramp typically is discontinuous because
the temperature increment (e.g., 1 degree C.) often is achieved
more rapidly than the increment of unit time allotted until the
temperature increment (e.g., more rapidly than 30 seconds). In
other words, the generator affects the 1 degree C. temperature
increase much more quickly than 30 seconds, and the remainder of
the 30 second period before the next increase is spent at the newly
achieved temperature. A ramped profile that increments the
temperature 1 degree C. every 30 seconds takes 12.5 minutes to
reach the peak temperature 90 degrees C. Once the peak temperature
of 90 degrees C. is reached, that temperature is maintained for the
dwell time of 4.0 minutes, as shown in Table 1. The entire profile
takes 16.5 minutes of total treatment time--12.5 minutes to achieve
the peak temperature and 4 minutes duration at the peak
temperature. Energy delivery automatically stops upon completion of
the profile. Once the procedure is complete, another procedure
typically cannot be started without first removing the probe 165
and inserting a new probe. The energy delivery is started, and can
be stopped if desired, by pressing the RF output on/off control 135
or the foot switch (not shown).
[0086] The profiles are chosen to balance patient comfort against
overall treatment time, and typically are derived experimentally.
If the probe temperature is raised rapidly, the overall treatment
time is decreased. However, it may be more likely to cause patient
discomfort.
[0087] Because the tolerance of individuals will vary, the
temperature may be raised more rapidly or more slowly than the
exemplary profiles described herein.
[0088] In another implementation, the maximum power allowed for the
particular probe is applied until the measured temperature is equal
to or within a specified value, such as, for example, 1 degree C.,
of the target temperature. When the difference between the target
temperature and the measured temperature is equal to or less than
the specified value, a control routine, such as a
proportional-integral ("PI") routine,
proportional-integral-derivative ("PID") routine, or other suitable
routine, is used to control to the target temperature by adjusting
the output voltage of the generator. However, when the difference
between the target temperature and the measured temperature is
greater than the specified value, no control routine is used.
Instead, the maximum power allowed for the particular probe is
applied while the difference between the target temperature and the
measured temperature is greater than the specified value. Thus, the
specified value acts as a transition point between a mode of
applying the maximum power output allowed for the particular probe
and a mode of controlling the temperature by using a control
routine. The control routine can control, for example, the power
output or the voltage output of the generator.
[0089] SPINECATH.RTM. AUTOTEMP.RTM. Profiles TABLE-US-00001 TABLE 1
Peak Selected Temperature Time to Peak Dwell Time Total Treatment
Profile .degree. C. (min.) (min.) Time (min.) P80 80 7.5 6.0 13.5
P81 81 8.0 5.7 13.7 P82 82 8.5 5.5 14.0 P83 83 9.0 5.5 14.5 P84 84
9.5 5.2 14.7 P85 85 10.0 5.0 15.0 P86 86 10.5 4.7 15.2 P87 87 11.0
4.5 15.5 P88 88 11.5 4.5 16.0 P89 89 12.0 4.2 16.2 *P90 90 12.5 4.0
16.5 P91 91 13.0 4.0 17.0 P92 92 13.5 4.0 17.5 P93 93 14.0 4.0 18.0
P94 94 14.5 4.0 18.5 P95 95 15.0 4.0 19.0 *Default setting
[0090] The operator can change the selected profile using the arrow
key 235 before the procedure begins or while the procedure is in
progress. If the selected profile is changed, the generator
automatically changes the peak temperature and the initial set
temperature to the default value. For example, if the selected
profile is changed before the procedure begins, the default set
temperature is used and the temperature profile behaves similarly
to the example above for profile P90, except that the actual values
used in the profile will differ according to the selected profile.
If the selected profile is changed while the procedure is in
progress and the selected profile corresponds to a higher peak
temperature, the generator 100 continues to increase the set
temperature according to the temperature ramp (e.g., 1 degree C.
every 30 seconds) until reaching the new peak temperature in order
to keep a smooth profile that increases temperature quickly with
minimal patient discomfort. The dwell timer begins counting once
the newly selected peak temperature is reached. If, on the other
hand, the selected profile corresponds to a lower peak temperature
and the new peak temperature is below the current set temperature,
the set temperature value is decreased to the new peak temperature
by stopping or reducing the RF energy to the probe and waiting for
the actual temperature to decrease to the new peak temperature. The
dwell timer begins counting when the new, lower, peak temperature
is reached. If the selected profile corresponds to a lower peak
temperature and the new peak temperature is above the current set
temperature, the generator continues to increase the set
temperature according to the ramp (e.g., 1 degree C. every 30
seconds) until reaching the new, lower, peak temperature. The dwell
timer begins counting when the new peak temperature is reached. If
the profile is changed to a new profile after the peak temperature
has been reached for the current profile, the peak temperature,
dwell timer, and other parameters are reset to the values
corresponding to the new profile and the new profile is reached as
described above.
[0091] The operator can change the set temperature 530 using the
arrow keys 230 while the procedure is in progress, typically to
manually expedite the temperature ramp by rapidly achieving the
initial set temperature. For example, if a P90 profile is selected,
the operator can change the set temperature to 80 degrees C. and
the generator 100 rapidly achieves the 80 degrees C. setting, e.g.,
by applying full power until the set temperature is achieved,
before starting the temperature ramp of, e.g., 1 degree C. every 30
seconds from the 80 degree C. initial set temperature to the 90
degrees C. peak temperature. The set temperature is adjustable by 1
degree C. for each time a key 230a, 230b is depressed. When the set
temperature is manually changed, the generator 100 tracks the new
temperature. Once the manual setting is complete and the new set
temperature is achieved, the generator automatically increases the
set temperature 1 degree C. every 30 seconds until reaching the
peak temperature for the selected profile.
[0092] To pause delivery of RF power, the operator presses the RF
output on/off control 135. The generator stops the timer and
continues to monitor and display the device parameters. To continue
with the automatic temperature profile, the operator presses the RF
output on/off control 135, causing the generator to restart RF
delivery with the timer counting from where it left off. The
procedure can be reset using soft key 205, as discussed above.
Typically, the reset control 520 may be activated only after a
pause in the delivery of RF energy. When reset, the timer
re-zeroes, the set temperature 530 returns to the default value,
and the set profile 535 remains unchanged. After resetting the
procedure, RF delivery is continued by pressing the RF output
on/off control 135.
[0093] FIG. 11 shows an exemplary procedure 1100 for automatic
temperature control, which may be used, for example, in the
automatic temperature control of the SPINECATH.RTM. AUTOTEMP.RTM.
mode described above or the Decompression AUTOTEMP.RTM. mode
described below. First, a target temperature is received (step
1105). Next, a first set temperature is calculated (step 1110). The
first set temperature may be calculated by subtracting a
predetermined value, e.g. ten degrees, from the default value of
set temperature. The default set temperature is usually 65 degrees
C. Therefore, the first set temperature typically is 55 degrees C.
(i.e., a value that is ten degrees less than the default set
temperature of 65 degrees C.).
[0094] Next, the generator 100 commands a first output power level
(step 1115). The first output power level typically is full power.
The generator receives a measured temperature (step 1120). If the
generator determines that the measured temperature is less than the
first set temperature (step 1125), then the generator waits a first
predetermined period, e.g., 400 ms, (step 1130) and repeats steps
1120, 1125 and 1130 until the measured temperature is equal to (or
has exceeded) the first set temperature (e.g., 55 degrees C.).
[0095] Once the generator determines that the measured temperature
is equal to (or has exceeded) the first set temperature (step
1125), e.g., 55 degrees C., the generator commands a second power
output level (step 1135). The second power level usually is a power
level that will cause a temperature increase according to a desired
temperature ramp profile, e.g., 1 degree C. every 30 seconds. The
second power output level typically is less than the first power
output level of step 1115. Thus, the temperature increases more
slowly and in a controlled manner according to a temperature ramp
profile at this point onward in the procedure 1100.
[0096] Next, the generator 100 calculates an updated set
temperature (step 1140). The updated set temperature is calculated,
e.g., by adding a pre-selected amount (e.g., one degree) to the
first set temperature. The generator receives a measured
temperature 1145. If the generator determines that the measured
temperature is less than the updated set temperature (step 1150),
the generator waits a second predetermined period of time, e.g.,
400 ms (step 1155) and repeats steps 1145, 1150, and 1155 until the
measured temperature is equal to the updated set temperature.
[0097] Once the generator determines that the measured temperature
is equal to or greater than the updated set temperature, a
determination is made as to whether the updated set temperature is
equal to the target temperature (step 1160). If the updated set
temperature is not equal to the target temperature, a new updated
set temperature is calculated (step 1165). Typically, the new
updated set temperature is calculated as described above with
respect to the updated set temperature in step 1140. The new
updated set temperature is used in steps 1145-1160. In another
implementation, the set temperature is not updated and is equal to
the target temperature.
[0098] Steps 1145-1160 are repeated until the updated set
temperature is equal to the target temperature. Then, the target
temperature is maintained (step 1175). Typically, the target
temperature is maintained for the pre-selected dwell time according
to temperature profile selected for the given procedure.
[0099] In another implementation, a control routine such as, for
example, a PI or a PID routine can be used to adjust the output
voltage to control to the measured temperature to achieve the set
temperature.
[0100] FIG. 12 shows an exemplary procedure 1200 for automatic
temperature control which may be used, for example, in automatic
temperature control of the SPINECATH.RTM. AUTOTEMP.RTM. mode
described above or the Decompression AUTOTEMP.RTM. mode described
below. A target temperature is received (step 1205). Next, a first
output level is delivered (step 1210). The first output level can
be chosen based upon a recognized probe that is connected to the
generator 100. Next, a temperature measurement is received (step
1215). The probe is able to measure a temperature, or the
temperature measurement may be received from a different
source.
[0101] A test is made to determine whether the measured temperature
is within a specified value of the target temperature (step 1220).
The specified value may be stored by the generator, retrieved by
the generator, or calculated by the generator. In one example, the
specified value may be 1 degree C. The specified value can vary,
for example, depending upon the identity of the probe that is
connected to the generator 100. If the measured temperature is not
within the specified value (e.g., 1 degree C.) of the target
temperature, the first power output level continues to be delivered
until the measured temperature is within the specified value of the
target temperature.
[0102] If the measured temperature is within the specified value of
the target temperature, then a control algorithm is used to control
power delivery by the generator (step 1225). The control algorithm
calculates a second power level and controls the generator power
delivery so as to make the measured temperature equal to the target
temperature. The control algorithm can be a PID algorithm, a PI
algorithm, or other suitable control algorithm. The control
algorithm can control, for example, the output power or the output
voltage of the generator 100.
[0103] In implementations using a PID
(proportional-integral-derivative) control algorithm, the
coefficient of the derivative term can be set to zero so that the
control algorithm uses only the proportional and integral terms. In
other implementations, the coefficient of the derivative term is
non-zero and the control algorithm uses the derivative,
proportional, and integral terms.
[0104] Also, the control values of the PID control algorithm can be
pre-loaded with a starting value for the second output power level.
Pre-loading a starting value for the second output power level
allows for a smooth transition between the first output level and
the second output level. Thereafter, the second output level
typically is calculated by the control algorithm. Using a
pre-loaded value for the second output level helps to ensure a more
continuous transfer between the first and the second output levels.
The starting value for the second output power can be derived, for
example, by measuring the steady state output of the generator once
the measured temperature is equal to the target temperature. The
steady-state output can be measured for each type of probe that
will be connected to the generator, and thereafter used as a base
point for the pre-loaded value.
[0105] If the starting value for the second output level is too
low, the measured temperature will drop some during transition
between the first output level and the second output level, leading
to an increased time required to achieve the target temperature. A
low starting value also may lead to oscillations about the target
temperature. Also, if the starting value is too high at the point
of transition, the measured temperature can exceed the target
temperature for a period of time until the control algorithm can
reduce the output of the generator.
[0106] Each device used with the generator can have its own preload
value for the second output level. In one example, the preloaded
value is not adjusted for changes in target temperature. In another
example, the preloaded value is calculated so to improve the
algorithm performance. The pre-loaded value can differ depending
upon the identity of the probe connected to the generator 100. The
pre-loaded value can be stored in a computer readable format, or
can be calculated based upon the target temperature.
[0107] Finally, the control algorithm is used to maintain the
target temperature (step 1230).
[0108] FIG. 13 shows an exemplary procedure 1300 for automatic
temperature control which may be used, for example, in automatic
temperature control of the SPINECATH.RTM. AUTOTEMP.RTM. mode
described above or the Decompression AUTOTEMP.RTM. mode described
below. In the example of FIG. 13, the RF output of the generator
100 is controlled by a digital to analog converter (DAC). In one
implementation, the output value of the DAC ranges from 0 to 4095.
Other output values of the DAC may be used.
[0109] A target temperature (TARGET_TEMP) is received (step 1305).
Next, a maximum DAC setting (MAX_DAC) is received (step 1310). The
MAX_DAC value is chosen for the particular probe being used, and
the probe is installed in the electrosurgical generator 100. A
check is made to determine whether RF output is activated for the
generator 100 (step 1315). If the RF output is activated, then a
RAMP_FLAG is set to TRUE (step 1320).
[0110] A check is made to determine: (1) if the RAMP_FLAG is set to
TRUE and; (2) if the difference between the target temperature
(TARGET_TEMP) and the actual temperature (ACTUAL_TEMP) is greater
than 1 degree C. (step 1325). If both are true, then the maximum
DAC setting (MAX_DAC) is delivered (step 1330). A check is made to
determine if the power output is less than the maximum power output
allowed for the particular probe connected to the electrosurgical
generator (step 1335). The probe connected to the generator 100 may
be identified, for example, in a manner similar to that discussed
above with respect to the probe recognition step (step 410) of FIG.
4. After the probe is identified, a maximum power output
corresponding to that probe may be retrieved from a storage
location or dynamically computed. If the TARGET_TEMP and
ACTUAL_TEMP difference is more than 1 degree C., then the maximum
DAC setting (MAX_DAC) is increased by a value, such as 5 (step
1340). On the other hand, if the power is not less than the maximum
allowed power for the particular probe connected to the generator,
then a test is made to determine whether the power is more than the
maximum allowed power for the device (step 1345). If the power is
more than the maximum power allowed for the device, then the
maximum DAC setting (MAX_DAC) is decreased by a value such as 5
(step 1350). If on the other hand, the power is not more than the
maximum power allowed by the device, then a test is again made to
determine whether the power is less than the maximum allowed power
(step 1335).
[0111] Referring again to step 1325, if the difference between the
TARGET_TEMP and the ACTUAL_TEMP is not greater than 1 degree C.,
then the RAMP_FLAG is set to FALSE (step 1355). Next, the output of
the generator 100 is set to the initial DAC control level defined
for the specific probe connected to the generator 100 (step 1360).
Next, the DAC output is set to a calculated value (step 1365). The
calculated value may be, for example, a value equal to Ki*ERROR
Integral +Kp*ERROR, where the ERROR is the difference between
TARGET_TEMP and ACTUAL_TEMP, and where Ki and Kp are defined for
the specific probe connected to the electrosurgical generator.
[0112] Next, a test is made to determine whether the set value of
the DAC output exceeds the MAX_DAC (step 1370). If the set value of
DAC output exceeds the MAX_DAC, then the output is limited to the
MAX_DAC (step 1375). On the other hand, if the set value of the DAC
output does not exceed the MAX_DAC, then a test is made to
determine whether the set value of the DAC output is less than 0
(step 1380). If the set value of the DAC output is less than 0,
then the output is limited to 0 (step 1385). If, on the other hand,
the set value of the DAC output is not less than 0, then a test is
made to determine whether the set value of the DAC output equals
the MAX_DAC (step 1390). If the set value of the DAC output equals
the MAX_DAC, then the ERROR value, which is the difference between
the TARGET_TEMP and the ACTUAL_TEMP is not integrated in the
computation of the DAC output described above with respect to step
1365 (step 1295).
[0113] Decompression AUTOTEMP.RTM. Mode
[0114] Referring to FIG. 6, when the recognized probe is a
Decompression catheter, the generator enters Decompression
AUTOTEMP.RTM. mode and user interface (UI) 600 is presented to the
operator on display 115. User interface 600 indicates the generator
mode as the Decompression mode 605. Several parameters for the
Decompression mode are displayed to the operator. For example,
measured probe impedance 610, elapsed procedure time 615, actual
probe temperature 625, set temperature 630, and set profile 635. A
reset control 620 is activated by soft key 205. The set temperature
630 can be changed by manipulation of arrow keys 230 and the set
profile 635 can be changed through manipulation of arrow keys 235.
An example of possible Decompression AUTOTEMP.RTM. profiles is
illustrated in Table 2. Table 2 shows the selected profile, the
peak temperature, the time to achieve the peak temperature, dwell
time, and the total treatment time. The decompression
auto-temperature mode default profile is shown as profile "P90." In
a similar manner to that discussed above with respect to FIG. 5,
the generator 100 automatically increases the temperature in a
controlled manner from the initial set temperature to the peak
temperature, and then dwells at the peak temperature. Energy
delivery stops automatically at the completion of the profile.
TABLE-US-00002 TABLE 2 Peak Selected Temperature Time to Peak Dwell
Time Total Treatment Profile .degree. C. (min.) (min.) Time (min.)
P80 80 3.0 6.0 9.0 P81 81 3.3 6.0 9.3 P82 82 3.6 6.0 9.6 P83 83 3.9
6.0 9.9 P84 84 4.2 6.0 10.2 P85 85 4.5 6.0 10.5 P86 86 4.8 6.0 10.8
P87 87 5.1 6.0 11.1 P88 88 5.4 6.0 11.4 P89 89 5.7 6.0 11.7 *P90 90
6.0 6.0 12.0 P91 91 6.3 6.0 12.3 P92 92 6.6 6.0 12.6 P93 93 6.9 6.0
12.9 P94 94 7.2 6.0 13.2 P95 95 7.5 6.0 13.5
[0115] The set temperature 630 default typically is 50 degrees C.
for the start of the automatic temperature ramp for the
decompression automatic temperature mode. The set profile default
of P90 corresponds to a peak temperature of 90 degrees C. as shown
by Table 2. To begin delivery of the RF power, the operator presses
RF output on/off control 135 and the elapsed procedure time clock
615 begins counting up. Once the delivery of the RF power has begun
and the initial set temperature of 50 degrees C. is achieved, the
temperature is increased at a rate corresponding to a desired
temperature ramp, e.g., 1 degree C. every 6 seconds, from 50
degrees to a value of 80 degrees C. Above 80 degree C., and until
reaching the peak temperature of 90 degrees C. for the selected P90
profile, the temperature is increase at a different desired
temperature ramp, e.g., a rate of 1 degree C. every 18 seconds.
Thus, the temperature ramp changes slope at a certain point so as
to increase the temperature more slowly as the actual temperature
approaches the peak temperature value. This change in temperature
ramps will reduce the possibility of overshooting the peak
temperature and enhances patient comfort. Upon reaching the peak
temperature, the generator holds the peak temperature for a dwell
time of a predetermined duration as shown in Table 2.
[0116] The values for the temperature profiles in the Decompression
AUTOTEMP.RTM. mode typically differ from the values for the
temperature profiles in the SPINECATH.RTM. AUTOTEMP.RTM. mode due
to differences in the probes used for each mode. As with the
SPINECATH.RTM. AUTOTEMP.RTM. profiles, the Decompression
AUTOTEMP.RTM. profiles are derived experimentally and balance speed
of achieving the peak temperature against patient comfort.
[0117] The operator can change the set profile before or during
power delivery by pressing arrow keys 235. As described above with
respect to the SPINECATH.RTM. automatic temperature mode of FIG. 5,
when the set profile is increased during the procedure, the
generator 100 increases the set temperature according to a
temperature ramp (e.g., 1 degree C. every 18 seconds) until
reaching the new peak temperature. The dwell timer begins counting
when the new peak temperature is reached. When the set profile is
decreased and the new peak temperature is below the current set
temperature, the set temperature value is changed to the new peak
temperature and the new peak temperature is achieved as described
above. The dwell timer begins counting when the new peak
temperature is reached. When the set profile is decreased and the
current set temperature is below the peak temperature, the
generator 100 continues to increase the temperature according to
the profile (e.g., 1 degree C. every 18 seconds) until reaching the
new peak temperature. The dwell timer begins counting when the new
peak temperature is reached. When the set profile is changed after
the peak temperature for the current profile has been reached, the
peak temperature, dwell duration timer, and other parameters are
reset to the values corresponding to the new profile and the new
peak temperature is achieved as described above.
[0118] The set temperature 630 can be manually changed during the
auto-temperature routine using arrow keys 230. The set temperature
is adjustable by 1 degree C. for each time the key is pressed. The
temperature range typically ranges from 50 degrees C. to the peak
temperature of the selected profile. The set temperature 630 can be
used, for example, to manually expedite the temperature ramp. When
the initial set temperature is manually changed, the generator
tracks the new set temperature and will rapidly achieve the new set
temperature by, for example, applying full power until the new set
temperature is reached. Once the manual setting is complete and the
generator has achieved the new set temperature, the generator
automatically increments the set temperature according to a desired
temperature ramp (e.g., 1 degree C. every 6 seconds if the new set
temperature is from 50-80 degrees C. and 1 degree C. every 18 from
a set temperature of 80 degrees C. onward) until reaching the peak
temperature for the selected profile.
[0119] The automatic temperature routine can be paused by
depressing the RF output on/off control 135, and can be resumed by
pressing RF output on/off control 135 again. Upon the continuation
of the procedure, the RF power delivery commences and the timer
begins counting from where it left off. The procedure can be reset
by activating the reset control 620, which is activated by soft key
205. This reset action resets the timer to zero and set temperature
to the default value, and leaves the profile selection unchanged.
RF power delivery can be continued by pressing the RF output on/off
control 135.
Sensory Stimulation Mode
[0120] Referring to FIG. 7, when the recognized probe is a
denervation probe, the generator enters sensory stimulation mode
and user interface (UI) 700 is presented to the operator on display
115. User interface 700 indicates the generator mode as the Sensory
Stimulation mode 705. The sensory stimulation mode is one of two
stimulations modes, sensory stimulation and motor stimulation, and
each has its own default parameters. The sensory stimulation mode
stimulates sensory nerves to cause a pain sensation in the patient,
and the motor stimulation mode stimulates motor nerves that cause
muscle movement in the patient. The stimulation modes are used to
confirm proper placement of a probe in a denervation or other pain
management procedure.
[0121] Upon connection of a denervation probe, the generator 100
defaults to the sensory stimulate mode as shown in UI 700. In
sensory stimulation, the frequency typically defaults to 50 hertz
and the pulse width defaults to 1 millisecond. The stimulation
output voltage typically defaults to zero volts and is displayed as
"off." Once the stimulate mode is activated, the output voltage
typically starts at zero volts and may be incremented by operator
action.
[0122] UI 700 shows the sensory stimulation mode 705, which
includes parameters such as measured probe impedance 710,
stimulation volts 730, frequency 735, pulse width 740, and controls
the switching between other modes including the motor stimulation
mode 715, pulsed RF mode 720, and RF lesion mode 725. The mode may
be switched between the sensory stimulation and the motor
stimulation modes by activation of soft key 205. The motor
stimulation mode is shown and described with respect to FIG. 8. The
mode may be changed between the sensory stimulation mode and the
pulsed RF mode by activating soft key 215. The pulsed RF mode is
shown and described with respect to FIG. 10. The mode may be
changed between the sensory stimulation mode and the RF lesion by
activating soft key 220. The RF lesion mode is shown and described
with respect to FIG. 9. When switching between modes, a user
modified parameter may be retained.
[0123] After placing the probe in the patient, the rotary encoder
knob 150 is pressed once to turn the voltage on. The stimulation
volts display 730 will change from "off" to zero volts. The rotary
encoder knob 150 is then turned clockwise to increase the stimulate
voltage from zero volts up to a maximum of 1 volt. The width of the
stimulate pulses 740 may be changed using the arrow keys 235. The
pulse width may be adjusted to 0.1, 0.5, 1, 2, or 3 milliseconds.
In another implementation, the pulse width is not adjustable. The
frequency of the pulses is typically 50 hertz for the stimulation
mode 735 and is not adjustable. The voltage may be turned off by
depressing the rotary encoder knob 150. Thus, the rotary encoder
knob 150 acts as a "radio knob" with complete on/off and voltage
increase and decrease control. Sequentially pressing the rotary
encoder knob 150 toggles voltage between off and active. The active
voltage is typically restarted at zero volts when switching between
off and active states. When active, the voltage may be incremented
up from zero volts by operator action. The voltage range for the
sensory stimulation mode typically is 0-1 volt, and the pulse width
range typically is 0.1, 0.5, 1, 2, and 3 milliseconds. In another
implementation, the pulse width is not adjustable.
Motor Stimulation Mode
[0124] Referring to FIG. 8, if the operator enters motor
stimulation mode from sensory stimulation mode, user interface (UI)
800 is presented to the operator on display 115. User interface 800
indicates the generator mode as the Motor Stimulation mode 805.
[0125] The UI 800 includes parameters such as stimulation volts
825, frequency 830, and pulse width 840. Indications are also
provided to switch to a different mode including the stimulation
sensory mode 810, the pulsed RF mode 815, and RF lesion mode 820.
These controls are activated by using soft key 205 to switch to the
sensory mode 810, soft key 215 to switch to the pulsed RF mode 815,
and soft key 220 to switch to the RF lesion mode 820.
[0126] After the probe is placed in the patient, the rotary encoder
knob 150 is pressed once to activate the voltage output. The output
voltage defaults to 0 volts at a default pulse width value therapy
profile. The rotary encoder knob 150 then is turned clockwise to
increase the motor stimulate voltage from zero volts up to a
maximum value, which typically is 10 volts. The width of the
stimulate pulses may be changed using the arrow keys 235. The pulse
width may be adjusted to 0.1, 0.5, 1, 2, or 3 milliseconds. In
another implementation, the pulse width is not adjustable. The
frequency of the pulse is fixed at 2 hertz for the motor stimulate
mode. The voltage may be turned off at any time by depressing the
rotary encoder knob 150. Sequentially depressing the rotary encoder
knob 150 toggles the voltage between active and off. The active
voltage is restarted at 0 volts, and may be incremented by the
operator. The voltage range for the motor stimulation mode
typically is 0-10 volts, the pulse width typically is adjustable
but frequency typically is not, and the pulse width range typically
is 0.1, 0.5, 1, 2, and 3 milliseconds.
[0127] RF Lesion Mode
[0128] Referring to FIG. 9, if the operator enters RF Lesion Mode
from the sensory or motor stimulation mode, user interface (UI) 900
is presented to the operator on display 115. User interface 900
indicates the generator mode as the RF Lesion mode 905. The RF
Lesion mode is used to destroy tissue in a denervation procedure
once the probe has been properly placed. In this mode, the
generator automatically controls the power to reach and maintain a
selected temperature for a selected time.
[0129] The UI 900 includes parameters such as measured probe
impedance 910, elapsed procedure time 915, actual probe temperature
935, set temperature 940, and set time 945. Controls are also
provided to reset the mode 920, and to switch to other modes
including the sensory stimulation mode 925 and the motor
stimulation mode 930. The reset control is activated by soft key
205, switching to the sensory mode is done using soft key 215, and
switching to the motor stimulation mode is done using soft key
220.
[0130] The actual probe temperature reads room temperature if the
probe is in free air and body temperature if the probe is inside
the patient. The measured probe impedance 910 reads between 0 and
999 ohms when the denervation probe is placed in the patient. The
set temperature 940 default is 80 degrees C. for the RF lesion
mode. The set temperature may be selected in a range from
approximately 50 degrees C. to 90 degrees C. using arrow key 230.
The default set time value for the RF lesion mode is 90 seconds.
The timer may be set to 30, 60, 90, or 120 seconds using arrow key
235.
[0131] To begin delivery of the RF power to the probe, the operator
presses the RF output on/off control 135. The elapsed procedure
time display starts counting up when the RF power delivery begins.
RF power delivery ceases when the elapsed procedure time reaches
the set time. The RF lesion mode is exited by pressing one of the
soft keys 120 across the bottom of the display that correspond to
sensory stimulation mode 925 and the motor stimulation mode 930, to
switch to the respective mode.
[0132] When the set temperature 940 is increased by the operator,
the generator increases the actual temperature until reaching the
new set temperature. When the set temperature 940 is decreased by
the operator, the generator decrease the actual temperature by
decreasing or stopping the RF power delivery until the actual
temperature reaches the set temperature. The set time 945 may be
changed by the operator to change the RF deliver time. Typically,
RF power delivery is paused by pressing the RF output on/off
control 135 prior to changing the set time 945. If the probe 165 is
repositioned during the pause, typically the operator returns to
the stimulate mode to confirm that the probe is positioned
correctly prior to recommencing the denervation procedure. Upon
leaving the stimulate mode and returning to the RF lesion or pulsed
RF mode, the timer resets to zero. While paused, the timer may be
reset by pressing the reset soft key 205 to operate control 920.
This reset action will reset the elapsed procedure time and leave
the set temperature selection unchanged, RF power delivery may then
be continued by pressing the RF output on/off control 135.
[0133] For the RF lesion mode, the set time typically is adjusted
for 30, 60, 90, and 120 seconds. The default time is usually 90
seconds. The RF lesion mode set temperature range normally is 50
degrees C. to 90 degrees C.
Pulsed RF Mode
[0134] Referring to FIG. 10, if the operator enters Pulsed RF Mode
from sensory or motor stimulation mode, user interface (UI) 1000 is
presented to the operator on display 115. User interface 1000
indicates the generator mode as the Pulsed RF mode 1005. The Pulsed
RF mode is used to denature nervous tissue by exposing it to
voltage.
[0135] UI 1000 includes parameters such as measured probe impedance
1010, elapsed procedure time 1015, actual probe temperature 1040,
RF volts 1035, frequency 1045, set temperature 1050, and set time
1055. Controls are also provided to reset 1020 the timer, and to
switch to other modes including the sensory stimulation mode 1025
and the motor stimulation mode 1030. In Pulsed RF mode, the
temperature defaults to 42 degrees C., the set time defaults to 2
minutes, the frequency defaults to 2 hertz, and the RF voltage
displays zero.
[0136] In the Pulsed RF mode, the generator delivers pulsed RF
energy to reach and maintain the selected set temperature for the
set time. Typically, the RF pulses are approximately 20 ms in
duration. The amplitude, frequency and/or pulsewidth of the pulses
can be automatically adjusted to maintain the specified set
temperature. In one implementation, the pulse width is not
adjustable. The RF output on/off control 135 is pressed to begin
delivery of RF power. The actual probe temperature reads room
temperature if the probe is in free air or body temperature if the
probe is placed in the patient. The measured probe impedance
typically reads between 80 and 999 ohms when the denervation probe
is placed in the patient. The set temperature typically is selected
from a range of 35 degrees C. to 50 degrees C. using arrow keys
230. The frequency typically may be set to 1, 2, 4, or 8 hertz
using arrow keys 225. The set time may be set to 1, 2, 3, 4, or 5
minutes using arrow keys 235.
[0137] The elapsed procedure time display 1015 starts counting up
when the RF power delivery begins. The RF power delivery ceases
when the elapsed procedure time reaches the set time. The Pulsed RF
mode may be exited by pressing one of the soft keys on the bottom
of the display corresponding to the sensory stimulation mode 1025
and the motor stimulation mode 1030. When the set temperature is
increased in the pulsed RF mode, the rate of increase in
temperature varies depending upon the current frequency setting.
The temperature increases more slowly with a low frequency setting
and more rapidly with a higher frequency setting. The rate of
temperature increase typically is a function of the duty cycle of
the power applied and is directly related to the frequency of
pulses. When the set temperature is decreased the generator
decreases the actual temperature to the set temperature by reducing
or stopping the RF energy output.
[0138] RF power delivery may be paused by pressing the RF output
on/off control 135. When the RF output on/off control 135 is
pressed again, RF power delivery resumes. If the probe is
repositioned during the pause, then the operator typically returns
to the stimulate mode to confirm that the probe is properly placed
prior to recommencing denervation. Upon leaving the stimulate mode
and returning to the RF lesion or pulsed RF mode, the timer resets
to zero. While paused, the timer may be reset 1020 by pressing the
reset soft key 205. This action resets the elapsed procedure time
and leave the set temperature selection unchanged. RF power
delivery may then be continued by pressing the RF output on/off
control 135. The set time may be changed while RF power delivery is
paused using the arrow keys 235.
[0139] For the Pulsed RF mode, the set time is usually adjustable
from 1 to 5 minutes. The default duration normally is 2 minutes.
The Pulsed RF mode set temperature range typically is 35 degree C.
to 50 degree C.
[0140] A number of implementations have been described.
Nevertheless, it will be understood that various modifications may
be made. For example, in the SPINECATH.RTM. AUTOTEMP.RTM. mode and
the Decompression AUTOTEMP.RTM. mode, the initial set temperature
and/or the first set temperature may have a different default value
for each of the different profiles. The initial set temperature
and/or the first set temperature may be a fixed, pre-stored value,
or it may be calculated dynamically. For example, the initial set
temperature may be calculated dynamically by subtracting a
predetermined value from the target temperature or by subtracting a
predetermined value from the default set temperature. Also, the
updated set temperature may be calculated by subtracting a
pre-selected amount, e.g., ten degrees, from the target temperature
or by adding a selected amount, e.g., one degree, to the initial
set temperature or the first set temperature. Furthermore, other
controls may be used. For example, other controls such as a switch
and/or a dial may be used in place of the soft keys and the arrow
keys.
[0141] In procedure 1100, certain steps may be omitted or the order
of steps may be changed. For example, steps 1130 and/or 1155 maybe
omitted. Also, the updated set temperature may be calculated (step
1140) prior to commanding the second power output level (step
1135).
[0142] The generator typically uses an input power source of
100-120 volts AC or 200-240 volts AC, 50 or 60 hertz. The output
power is a maximum of approximately 20 watts into a 90-250 ohm
load. The output power is 0-5 watts when the generator is used with
the SPINECATH.RTM. Intradiscal Catheter, 0-3 watts when the
generator is used with the Decompression Catheter, and 0-20 watts
when the generator is used for denervation with the RF Denervation
Probe. The maximum output voltage is 160 volts RMS. In the
stimulate mode, the maximum output is 10V peak. The generator uses
a sine wave for the RF lesion and pulsed RF modes, and a square
wave for the stimulate modes.
[0143] The embodiments were chosen and described in order to best
explain the principles of the invention and its practical
application to thereby enable others skilled in the art to best
utilize the invention in various embodiments and with various
modifications as are suited to the particular use contemplated.
[0144] As various modifications could be made in the constructions
and methods herein described and illustrated without departing from
the scope of the invention, it is intended that all matter
contained in the foregoing description or shown in the accompanying
drawings shall be interpreted as illustrative rather than limiting.
Thus, the breadth and scope of the present invention should not be
limited by any of the above-described exemplary embodiments, but
should be defined only in accordance with the following claims
appended hereto and their equivalents.
* * * * *