Patent Application
20240423702
The present disclosure relates generally to systems and methods for treating a patient's skin (e.g., dermis and hypodermis), adipose layers and other target tissue with radiofrequency (RF) energy.
For individuals who seek to surgically modify the contours of their body, liposuction is a common procedure, normally practiced by plastic surgeons. In 2019, plastic surgeons performed 1.4 million liposuction procedures worldwide, second only to breast augmentations. The procedure was first done using suction and a hollow cannula in 1975 and underwent a paradigm shift in 1987 with the introduction of large volumes of very dilute aesthesia (tumescence) prior to the suction step to aid in vasoconstriction to reduce blood loss and post operation bruising.
The procedure is physically demanding for the surgeon, requiring multiple full arm and shoulder reciprocating motions of the cannula fanning out from one of several incision points. Depending on the patient's tissue structure and history of prior surgeries in the area of treatment, this area can be fibrous and resist the liposuction probe from advancing in the tissue. Procedures can take hours and practitioner fatigue is common.
Over the years, advances have taken place to assist the physician in faster, less physically demanding liposuction. Power assisted liposuction (PAL) is commonly used to address this. PAL uses a motorized reciprocating (˜40 strokes per second) tube inside the cannula that helps break up the fat near the suction port. While this improves the rate of tissue removal versus standard liposuction, the present disclosure improves upon and addresses some of the challenges regarding the state-of-the-art liposuction procedures and devices.
Ultrasound assisted liposuction (UAL) may be used to disrupt fat. The UAL procedure is followed by a separate procedure, specifically, by standard suction-assisted liposuction (SAL) procedure, which adds to the procedure time. In some embodiments, UAL is advantageously practiced with simultaneous suction as disclosed herein. Laser-assisted liposuction (LAL) may be implemented in some embodiments similar to UAL using only laser to disrupt fat and adding a second step of SAL.
The instant disclosure relates in part to the use of radio-frequency assisted liposuction (RFAL) that may be configured to assist in the speed or case of fat removal in a single system. The RFAL disclosure improves on multi system procedures like, for example, the UAL and SAL combination procedure and the LAL and SAL combination procedure, because the disclosed RFAL procedure can be accomplished with a single system.
In part, the disclosure relates to a RFAL system that includes a housing; one or more probe connectors; a first pump disposed in the housing; a radio-frequency (RF) generator disposed in the housing; the RF generator configured to output treatment energy signals at one or more modes or two or more modes; a power supply disposed in the housing, the power supply in electrical communication with the first pump and the RF generator; and a control system disposed in the housing, the control system in electrical communication with the RF generator and/or the first pump, wherein the control system adjusts the operation of the RF generator in response to one or more user inputs, wherein the control system is configured to operate the RF generator in one or more modes.
In some embodiments, the one or more modes is a pulsed RF energy mode otherwise referred to as a pulsed RF power mode. In some embodiments, the one or more modes is a continuous RF power mode. And in still other embodiments, the systems utilizes continuous RF power mode for some aspects of treatment and pulsed RF energy mode for other aspects of treatment. In some embodiments, the first pump is a suction pump (e.g., a vacuum pump) configured to create suction in a probe connected to the one or more probe connectors, wherein an opening of the probe is in fluid communication with the suction pump (e.g., the vacuum pump). In some embodiments, a first pump is an infiltration pump (e.g., a peristaltic pump) configured to deliver one or more fluids to a probe, wherein an opening of the probe is in fluid communication with the peristaltic pump. Optionally, a second pump may be a second peristaltic pump configured to deliver one or more fluids to a probe when an opening of the probe is in fluid communication with the peristaltic pump. In various embodiments, the system may further include a user input device in electrical communication with the control system, wherein the user input device receives one or more user inputs and delivers one or more control signals in response thereto to the control system. In some embodiments, the user input device comprises one or more foot pedal switches. In some embodiments, the device comprises a first probe. In some embodiments, the first probe may be selected from the group of a liposuction probe, a RF tissue treatment handpiece, a monopolar RF delivery probe, a bipolar RF delivery probe, a cannula-based probe, a suction assisted liposuction probe, a RF-assisted liposuction probe and an RF-based suction-assisted bubble generation liposuction probe. In some embodiments, the first probe is a cannula-based probe comprising a substantially cylindrical housing, the housing defining three or more ports.
In some embodiments, the three or more ports in the probe include a first port, a second port, and a third port, wherein the first port is an opening at a first end of the substantially cylindrical housing, wherein the second port is an opening at a second end of the substantially cylindrical housing, wherein the third port is an opening defined by a sidewall of the substantially cylindrical housing. In some embodiments, the first probe is a radio frequency assisted liposuction (RFAL). In various embodiments, the system may further include a first probe, wherein the first probe is an RFAL probe, the RFAL probe comprising one or more sensors.
In some embodiments, at least one of the ports is a thermally insulated tissue surface (skin) port. In various embodiments, the system may further include a ring structure, the ring structure disposed along the length of the cylindrical housing. In some embodiments, the RF generator is configured to output one or more modes and/or frequencies configured to cause a portion of a probe or a probe tip to generate bubbles in response thereto. In various embodiments, one or more of the sensors is a sound or acoustic wave detection sensor. In some embodiments, the system may further include a display, the display in electrical communication with the control system, the display configured to output a graphical user interface, wherein the graphical user interface shows one or more of the following: infiltrate rate, liposuction RF level, liposuction RF pulsing characteristics, treatment temperature, heating RF temperature, heating RF level, heating RF pulse characteristics, vacuum level, wherein one or more of the following change during a treatment session.
Many embodiments of the disclosure are designed to streamline the systems and methods and avoid reliance on multiple different probes and associated technologies and support systems. Floor space and wall service is at a premium in medical practices that endeavor to offer several procedures requiring different medical device platforms. Various embodiments of the disclosure are configured to improve workflow, usability, and use of floor space and wall services (e.g., to lessen demand for electrical wall service) through the design of a given system, the associated disposables, and the treatment methods and as otherwise disclosed herein.
In part, in one aspect, the disclosure relates to a cosmetic tissue treatment probe. The probe may include a cannula having a length. The cannula includes a conductive material, an inner surface, an outer surface, a cannula wall disposed between the inner surface and the outer surface, a proximal end, a distal end, a tip, and one or more apertures defined by the cannula wall. The cannula wall has a cannula wall thickness and a cannula length. In some embodiments, at least a portion of the tip is defined by the distal end, the proximal end attachable to a handle. The conductive material is configured for electrical communication with an RF generator, the conductive material configured to generate a heat effect in response to a RF signal received from the RF generator, wherein the heat effect is generated relative to a medium or tissue in fluid communication with the one or more apertures.
In various embodiments, the RF signal has one or more probe parameters, the one or more probe parameters selected to adjust or achieve the heat effect or a heat effect parameter. In some embodiments, the one or more probe parameters of the RF signal that are selected include at least two of pulsed RF, continuous wave RF, peak power of the RF signal, average power of RF signal, a repetition rate of RF signal, on-time of the RF signal and a RF frequency. In some embodiments, the heat effect parameter is selected from one or more of the following: volume of heating, duration of heating, gradient of heating, amount of heat localization, heating efficiency for localized change of state or steam formation, heating efficiency for localized tissue effects, RF efficiency for localized change of state or plasma formation, and heating efficiency for localized change of state or plasma formation.
In various embodiments, a heating efficiency for localized tissue effects includes one or more of more of localized tissue coagulation, localized tissue ablation or vaporization, localized mechanical disruption, localized thermo-mechanical tissue disruption, localized pressure disruption, or localized shockwave tissue disruption. In some embodiments, the one or more probe parameters are peak power, average power, an energy per pulse and a repetition rate, wherein the pulsed RF signal has a peak power having a range of about 200 W to about 3 kW, an average power having a range of about 5 W to about 100 W, an energy per pulse range of about 1 J to about 5 J per pulse and a repetition rate range of about 5 Hz to about 100 Hz. In various embodiments, the one or more probe parameters are peak power, average power, an energy per pulse, wherein the pulsed RF energy signal has a peak power having a range of about 200 W to about 3 kW, an average power having a range of 0.1 W to 10 W, an energy per pulse range of 1 J to 5 J per pulse and a repetition rate of about 0.5 Hz to about 10 Hz. In some embodiments, the one or more probe parameters are peak power, average power, an energy per pulse, wherein the pulsed RF signal has a peak power having a range of 200 W to 3 KW, an average power having a range of about 1 W to about 60 W, an energy per pulse range of 0.5 J to 3 J per pulse and a repetition rate of about 1 Hz to about 60 Hz.
In some embodiments, the one or more apertures are holes or channels that span the cannula wall thickness. In some embodiments, the one or more apertures are slots defined by the inner surface and the exterior surface of the cannula, wherein each slot defines a channel disposed through the cannula wall. In various embodiments, the one or more apertures includes a first aperture having a first perimeter and a second aperture having a second perimeter, wherein a shape of the first perimeter is substantially the same as a shape of the second perimeter, wherein the cannula has a longitudinal axis, wherein a first point within the first perimeter and a second point within the second perimeter are colinear along a line segment substantially perpendicular to the longitudinal axis.
In some embodiments, the probe may further include a second set of two apertures disposed through the cannula wall thickness of two cannula walls that face one another along the length of the cannula and are placed at a location ninety degrees off set from the other set of two apertures such that about the perimeter of the cannula there are four apertures each having centers that are approximately equidistant from the center of the next aperture about the perimeter of the cannula.
In some embodiments, the probe may further include an insulative layer disposed on at least a portion of a surface or edge of the cannula. In various embodiments, the cannula further includes a port for communication with a first pump or a second pump, wherein the first pump is a suction pump, the suction pump configured suction pump for removal of unwanted tissue through the cannula. In some embodiments, the second pump is an infiltration pump for delivery of tumescent fluid through the cannula.
In some embodiments, the application of the RF signal is selected based on one or more parameters of the RF signal to promote heat generation regions in an aqueous medium surrounding the cannula. In various embodiments, the probe may further include a control system, the control system in electrical communication with one or more electrical contacts of the probe, wherein the control system is programmed to terminate delivery of an RF signal during treatment when a measured reactance value is received or generated by the control system that is indicative of plasma formation. In some embodiments, application of the pulsed RF energy signal initiates, promotes or causes formation of one or more heat bubbles in an aqueous medium surrounding the cannula and in fluid communication with the one or more apertures.
In various embodiments, the one or more apertures includes two apertures each disposed through the cannula wall thickness and adjacent to one another along the length of the cannula. In some embodiments, the one or more apertures includes three apertures each disposed through the cannula wall thickness and placed at a location about 120 degrees off set from the two adjacent apertures such that about the perimeter of the cannula there are three apertures each having centers that are approximately equidistant from the center of the next aperture about the perimeter of the cannula. In some embodiments, the cannula tip is dome-shaped.
In some embodiments, at least one of the one or more apertures is an end hole defined by the dome-shaped tip. In various embodiments, the insulative layer is disposed on the exterior surface of the cannula but leaves conductive material of the cannula wall thickness and/or the exterior surface exposed at the one or more apertures. In some embodiments, the insulative layer is disposed on the surface of the cannula but leaves conductive material exposed about the one or more apertures on the exterior surface of the cannula. In some embodiments, the insulative layer is wrapped about the exterior surface of the cannula. In various embodiments, the insulative layer is heat shrunk about the exterior surface of the cannula. In some embodiments, the insulative layer is a coating disposed about the exterior surface of the cannula.
In part, in another aspect, the disclosure relates to a cosmetic tissue treatment system. The system includes a housing; a first pump disposed in the housing; a RF generator disposed in the housing; the RF generator configured to output treatment energy signals; a power supply disposed in the housing, the power supply in electrical communication with the first pump and the RF generator; a control system disposed in the housing, the control system in electrical communication with the RF generator and/or the first pump, the control system is configured to operate the RF generator in one or more of a pulsed RF energy mode and a continuous RF power mode; one or more probe connectors; and a tissue treatment probe having a length. The probe may be connected to one or more probe connectors, the probe includes a cannula includes a conductive material, the cannula having a wall thickness, the cannula includes a cannula wall, an inner surface, an outer surface, a proximal end, a length, a distal end, and a tip disposed is in a region of the distal end, the proximal end attachable to a handle, one or more apertures defined by the cannula wall, wherein application of an RF energy signal to an electrical contact of the probe generates a heat effect, wherein the heat effect is generated relative to a medium or tissue in fluid communication with the one or more apertures.
In some embodiments, the RF energy signal has one or more probe parameters, the one or more probe parameters selected to adjust or achieve the heat effect or a heat effect parameter. In some embodiments, the RF energy signal is a pulsed RF signal, wherein parameters of the pulsed RF signal results in heat confinement in an aqueous medium surrounding the cannula. In various embodiments, application of the pulsed RF energy signal causes formation of one or more heat bubbles in an aqueous medium surrounding the cannula. In some embodiments, the one or more probe parameters of the RF energy signal that are selected include at least one of pulsed RF, continuous wave RF, peak power of the RF energy signal, average power of RF energy signal, a repetition rate of RF signal, on-time of the RF signal and a RF frequency.
In some embodiments, the heat effect parameter is selected from one or more of the following: volume of heating, duration of heating, gradient of heating, amount of heat localization, heating efficiency for localized change of state or steam formation, heating efficiency for localized tissue effects, and RF efficiency for localized change of state or plasma formation, and heating efficiency for localized change of state or plasma formation. In various embodiments, a heating efficiency for localized tissue effects include one or more of more of localized tissue coagulation, localized tissue ablation or vaporization, localized mechanical disruption, localized thermo-mechanical tissue disruption, localized pressure disruption, or localized shockwave tissue disruption.
In some embodiments, the control system is configured to measure impedance on a real-time basis relative to a localized treatment region; and automatically adjust applied voltage of RF energy signal, using a control system, in response to a change in an impedance value measured with regard to the localized treatment region, wherein the applied voltage of the RF energy signal is adjusted in response to the change in impedance value such that the RF energy signal is delivered with a maximum peak power level. In some embodiments, the control system is configured to compensate for impedance variability during a cosmetic treatment by setting a pulse duration limit, and discontinuing treatment when the pulse duration limit is met. In various embodiments, the control system is programmed to terminate delivery of an RF energy signal during treatment when a measured reactance value is received or generated by the control system that is indicative of plasma formation.
In some embodiments, the control system is programmed to measure reactance, allowing plasma formation for a time period when a reactance value is measured that is indicative of plasma formation and terminating delivery of an RF energy signal upon the expiration of the time period. In some embodiments, a portion of the probe generates bubbles in response to delivery of RF energy to tissue or an aqueous medium in contact with one or more apertures of the cannula; wherein the control system provides audible or tactile feedback indicative of reaching a target per pulse energy delivery suitable for performing a cosmetic procedure. In various embodiments, the one or more probe parameters are peak power, average power, an energy per pulse and a repetition rate, wherein the pulsed RF signal has a peak power having a range of 200 W to 3 kW, an average power having a range of about 5 W to about 100 W, an energy per pulse range of about 1 J to about 5 J per pulse and a repetition rate range of about 5 Hz to about 100 Hz.
In some embodiments, the one or more probe parameters are peak power, average power, an energy per pulse, wherein the pulsed RF energy signal has a peak power having a range of about 200 W to about 3 kW, an average power having a range of about 0.1 W to about 10 W, an energy per pulse range of about 1 J to about 5 J per pulse and a repetition rate of about 0.5 Hz to about 10 Hz.
In some embodiments, the one or more probe parameters are peak power, average power, an energy per pulse, wherein the pulsed RF signal has a peak power having a range of about 200 W to about 3 KW, an average power having a range of about 1 W to about 60 W, an energy per pulse range of about 0.5 J to about 3 J per pulse and a repetition rate of about 1 Hz to about 60 Hz.
In various embodiments, application of the pulsed RF energy signal causes heat confinement in an aqueous medium surrounding the cannula. In some embodiments, the cannula further includes a port for communication with the first pump. In some embodiments, the first pump is an infiltration pump for delivery of tumescent fluid through the cannula. In various embodiments, the first pump is a suction pump for removal of unwanted tissue through the cannula. In some embodiments, application of at least one of the pulsed RF energy signal or the continuous RF power signal creates heat generation regions in an aqueous medium surrounding the cannula.
In part, in another aspect, the disclosure relates to a tissue disruptor. The tissue disruptor includes a hollow cylindrical structure having a wall thickness and sized to compliment a shape and one or more dimensions of one of the outer diameter or the inner diameter of a cannula employed to suction tissue; at least one disruptor aperture disposed through the wall thickness, the disruptor aperture sized to compliment dimensions of a cannula aperture disposed through a cannula wall thickness in a cannula employed to suction tissue and the disruptor aperture is positioned to align with a cannula aperture; and a resistor is disposed about an edge of the disruptor aperture, the resistor positioned to generate heat sufficient to thermally confine heating of an aqueous media surrounding the resistor.
In some embodiments, tissue disruptor further includes at least one gap in the continuity of the resistor disposed about the edge of the disruptor aperture. In various embodiments, the resistor is a thin film resistor heater. In some embodiments, the thin film resistor heater includes one or more materials, wherein the one or more materials includes at least one of Platinum, Tungsten, Nickel, Iron, Chromium, Nickel-chromium alloys, Iron-chromium alloys, or combinations of these. In some embodiments, the resistor selected to deliver between about 0.1 Joules and about 5 Joules of heating energy per aperture during electrical on-time that ranges between about 1 ms and about 10 ms.
In various embodiments, at least two ends of the resistor are capable of connection to a power supply. In some embodiments, the hollow cylindrical structure compliments the outer diameter of a cannula employed to suction tissue such that when the hollow cylindrical structure is assembled with a cannula the disruptor aperture aligns with a cannula aperture to form a single opening through both the cannula wall thickness and the disruptor wall thickness. In some embodiments, the resistor can generate heat sufficient to clear unwanted tissue from a cannula aperture in a cannula employed to remove unwanted adipose tissue.
In various embodiments, the resistor is configured to deliver RF energy configured to generate steam bubbles in a material in fluid communication with a cannula aperture in a cannula employed to remove unwanted adipose tissue, wherein a RF energy signal received by the resistor has one or more probe parameters, the one or more probe parameters selected to adjust or achieve the heat effect or a heat effect parameter. In some embodiments, the resistor delivers short electrical pulses near a cannula aperture in response to the probe parameters selected. In some embodiments, the resistor is electrically insulated from a cannula includes a conductive material. In various embodiments, the disruptor has a bore or cavity sized to slidably receive the cannula.
In part, in another aspect, the disclosure relates to a tissue disruptor and cannula assembly. The assembly includes a cannula employed to suction tissue, at least one cannula aperture defined by a cannula wall, the cannula wall having a cannula wall thickness; a disruptor includes a hollow cylindrical structure includes a disruptor wall having a disruptor wall thickness and inner dimensions sized to compliment the outer shape and dimensions of the cannula; at least one disruptor aperture defined by the disruptor wall, the disruptor aperture is sized to compliment all or a portion of the cannula aperture dimensions, the disruptor aperture having an edge defined by the disruptor wall; and a resistor disposed about the edge of the disruptor aperture, the resistor configured to generate heat sufficient to thermally heat a volume of an aqueous media surrounding the resistor. In various embodiments, the hollow cylindrical structure of the disruptor is sized and arranged to align the disruptor aperture and the cannula aperture, wherein the disruptor aperture aligned with the cannular aperture define a channel through both the cannula wall and the disruptor wall.
In many embodiments, the assembly further includes providing instructions to insert the cannula into the hollow cylindrical structure of the disruptor and to align the disruptor aperture with the cannula aperture. In some embodiments, the assembly further includes at least one gap in the continuity of the resistor disposed about the edge of the disruptor aperture. In various embodiments, the resistor is selected to deliver between about 0.1 Joules and about 5 Joules of heating energy per disruptor aperture during electrical on-time that ranges between about 1 ms and about 10 ms.
In some embodiments, at least two ends of the resistor are capable of connection to a power supply. In many embodiments, the resistor is selected to generate heat sufficient to clear unwanted tissue from a cannula aperture in a cannula employed to remove unwanted adipose tissue. In various embodiments, the resistor is selected to deliver heat sufficient to generate steam bubbles near a cannula aperture in a cannula employed to remove unwanted adipose tissue. In some embodiments, the resistor is selected to deliver short electrical pulses near a cannula aperture in a cannula employed to remove unwanted adipose tissue. In various embodiments, the resistor is electrically insulated from a cannula.
In part, in one aspect, the disclosure relates to a cosmetic tissue treatment method. The method includes providing a tissue treatment probe includes a cannula includes a conductive material, the cannula having a cannula wall thickness, and having a proximal end, a length, and a distal end, a tip is in the region of the distal end, the proximal end is coupled to a handle, one or more apertures are disposed through the wall thickness; inserting the distal end of the probe into a region of tissue targeted for cosmetic treatment; and applying an RF energy signal to the cannula to generate a heat effect on a medium or tissue in fluid communication or adjacent the one or more apertures, wherein the RF energy signal that is applied has one or probe more parameters, the one or more probe parameters selected to adjust or achieve the heat effect or a heat effect parameter.
In many embodiments, the one or more probe parameters of the RF energy signal that are selected include at least one of pulsed RF, continuous wave RF, peak power of the RF energy signal, average power of RF energy signal, a repetition rate of RF signal, on-time of the RF signal and a RF frequency.
In some embodiments, the heat effect parameter is selected from one or more of the following: volume of heating, duration of heating, gradient of heating, amount of heat localization, heating efficiency for localized change of state or steam formation, heating efficiency for localized tissue effects, and RF efficiency for localized change of state or plasma formation, and heating efficiency for localized change of state or plasma formation.
In various embodiments, a heating efficiency for localized tissue effects include one or more of more of localized tissue coagulation, localized tissue ablation or vaporization, localized mechanical disruption, localized thermo-mechanical tissue disruption, localized pressure disruption, or localized shockwave tissue disruption. In many embodiments, the cannula is connected to a first pump. In some embodiments, the first pump is an infiltration pump for delivery of tumescent fluid through the cannula to adipose tissue targeted for cosmetic treatment, wherein the medium is an aqueous medium, the aqueous medium includes tumescence and unwanted adipose tissue.
In various embodiments, the method further includes a first pump, wherein the first pump is a suction pump for removal of at least a portion of an aqueous medium comprising tumescence and unwanted adipose tissue from the region of tissue targeted for cosmetic treatment through the cannula. In some embodiments, the tissue is at least one of dermal tissue, septa, and fibrous tissue.
In many embodiments, the application of the pulsed RF energy signal causes heat confinement in the aqueous medium surrounding the cannula to cause rapid vaporization of a portion of the aqueous medium present in the region of the aperture thereby forming one or more bubbles. In various embodiments, forming the bubbles is followed by collapse of one or more of the formed bubbles thereby contributing to breakdown of the adipose tissue in the aqueous medium.
In some embodiments, the cannula is connected to a first pump and the first pump is a suction pump for removal of at least a portion of the aqueous medium from the region of tissue targeted for cosmetic treatment through the cannula. In many embodiments, the pulsed RF energy signal applies pulsed RF energy that ranges from about 1 Joule per pulse to about 5 Joules per pulse and delivered at a pulse frequency that ranges from about 5 Hz to about 100 Hz. In various embodiments, the cannula is connected to a first pump and the first pump is a suction pump for removal of at least a portion of the aqueous medium from the region of tissue targeted for cosmetic treatment through the cannula, wherein the bubbles disrupt all or a portion of any blockage in the one or more apertures thereby reducing or avoiding interruption of aqueous medium removal through the cannula.
In some embodiments, the pulsed RF energy signal applies pulsed RF energy that ranges from about 1 Joule per pulse to about 5 Joules per pulse and delivered at a pulse frequency that ranges from about 0.5 Hz to about 10 Hz. In many embodiments, the method further includes measuring impedance on a real-time basis relative to a localized treatment region; and automatically adjust applied voltage of RF energy signal, using a control system, in response to a change in an impedance value measured with regard to the localized treatment region, wherein the applied voltage of the RF energy signal is adjusted in response to the change in impedance value such that the RF energy signal is delivered with a maximum peak power level.
In various embodiments, the method further includes compensating for impedance variability during a cosmetic treatment by setting a pulse duration limit, and discontinuing treatment when the pulse duration limit is met. In some embodiments, the method further includes measuring reactance and terminating the delivery of an RF energy signal during treatment when a reactance value is measured that is indicative of plasma formation. In various embodiments, the method further includes measuring reactance, allowing plasma formation for a time period when a reactance value is measured that is indicative of plasma formation and terminating the delivery of an RF energy signal upon the expiration of the time period.
In many embodiments, the method further includes initiating, promoting or causing formation of one or more heat bubbles in an aqueous medium surrounding the cannula and in fluid communication with the one or more apertures in response to application of the RF energy signal. In some embodiments, the method further includes generating bubbles in response to delivery of RF energy to tissue or an aqueous medium in contact with one or more apertures of the cannula; providing audible or tactile feedback indicative of reaching a target per pulse energy delivery suitable for performing a cosmetic procedure. In various embodiments, the RF energy signal is pulsed.
In part, in another aspect, the disclosure relates to a cosmetic tissue treatment method. The method includes providing a tissue treatment probe includes a cannula includes a conductive material, the cannula includes a cannula wall, a proximal end, a length, a distal end, and a probe tip, one or more apertures are defined by the cannula wall, wherein the cannula is connected to a suction pump; inserting the probe tip into a region of tissue targeted for adipose tissue removal and/or tissue heating; delivering tumescent fluid to the region of tissue targeted for adipose tissue removal, thereby forming an aqueous medium of tumescence and unwanted adipose tissue; and applying pulsed RF energy to the cannula to generate one or more heat effects on an aqueous medium or tissue adjacent the one or more apertures, wherein the one or more heat effects is at least one of: heat confinement, plasma formation, bubble formation, and localized heating.
In many embodiments, the pulsed RF energy signal applies pulsed RF energy that ranges from about 1 Joule per pulse to about 5 Joules per pulse and delivered at a pulse frequency that ranges from about 5 Hz to about 100 Hz thereby forming one or more bubbles followed by bubble collapse thereby contributing to breakdown of the adipose tissue in the aqueous medium prior to removal thereof through the cannula by application of suction using the suction pump.
In some embodiments, the pulsed RF energy signal applies pulsed RF energy that ranges from about 1 Joule per pulse to about 5 Joules per pulse and delivered at a pulse frequency that ranges from about 0.5 Hz to about 10 Hz thereby forming one or more bubbles, wherein the bubbles disrupt all or a portion of any blockage in the one or more apertures thereby reducing or avoiding interruption of aqueous medium removal through the cannula by application of suction using the suction pump. In various embodiments, the pulsed RF energy signal applies pulsed RF energy that ranges from about 0.5 Joule per pulse to about 3 Joules per pulse delivered at a pulse frequency that ranges from about 1 Hz to about 60 Hz, wherein the heat confined aqueous medium transfers heat to surrounding tissue includes one or more of dermal tissue, septa tissue, and fibrous tissue.
In some embodiments, the method further comprises an infiltration pump, wherein the cannula is connected to the infiltration pump and wherein the infiltration pump delivers tumescent fluid through the cannula to the region of tissue targeted for adipose tissue removal. In various embodiments, the one or more heat effects is heat confinement.
In many embodiments, the heat confinement is promoted in the aqueous medium surrounding the cannula, wherein the heat confined aqueous medium transfers heat to surrounding tissue comprising one or more of dermal tissue, septa tissue, and fibrous tissue. In some embodiments, the heat confinement is promoted in the aqueous medium surrounding the cannula and configured to initiate rapid vaporization of a portion of the aqueous medium present in the region of the aperture thereby forming one or more bubbles followed by bubble collapse thereby contributing to breakdown of the adipose tissue in the aqueous medium prior to removal thereof through the cannula by application of suction using the suction pump.
In various embodiments, the heat confinement is promoted in the aqueous medium surrounding the cannula and configured to initiate rapid vaporization of a portion of the aqueous medium present in the region of the aperture thereby forming one or more bubbles wherein the bubbles disrupt all or a portion of any blockage in the one or more apertures thereby reducing or avoiding interruption of aqueous medium removal through the cannula by application of suction using the suction pump. In some embodiments, the method further includes reducing clogging of material flowing through one or more apertures of the probe by selectively insulating the probe from an RF energy signal received by the probe and directing RF energy from the conductive material to the material.
Although, the disclosure relates to different aspects and embodiments, it is understood that the different aspects and embodiments disclosed herein can be integrated, combined, or used together as a combination system, or in part, as separate components, devices, and systems, as appropriate. Thus, each embodiment disclosed herein can be incorporated in each of the aspects to varying degrees as appropriate for a given implementation. Further, the various systems, probes, applicators, needle arrays, controllers, components and parts of the foregoing can be used with any suitable tissue surface, cosmetic applications, and medical applications and other methods and conjunction with other devices and systems without limitation.
These and other features of the applicant's teachings are set forth herein.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fec.
Unless specified otherwise, the accompanying drawings illustrate aspects of the innovations described herein. Referring to the drawings, wherein like numerals refer to like parts throughout the several views and this specification, several embodiments of presently disclosed principles are illustrated by way of example, and not by way of limitation. The drawings are not intended to be to scale.
Multiple separate systems are required to accomplish the multiple steps required in the procedure. More specifically, about three separate systems are required to accomplish the procedure according to the state-of-the-art. The prior art plastic surgery suite 10 depicted in
In part, the disclosure relates to various design enhancements and other advantageous systems, subsystem, and component embodiments. For example, as shown in
The system 100 disclosed herein and shown in
In various embodiments, the probe includes a housing that defines various fluid transporting cavities, bores, volumes as well as apparatus, channels, holes, and slots. The probe includes a cannula that has a cannula wall in various embodiments. The probe may include one or more electrically conductive assemblies, regions, sections or other conductive surfaces or structures as disclosed and depicted herein. Various insulator and insulative materials may also be used in the probe such that only some conductive regions of the probe are in electrical communication with an RF source such as an RF generator. A given probe may also include various signal lines and cables or other conductive pathways and circuit elements to receive RF signals and generate a heat effect or otherwise heat a tissue and/or an aqueous medium or slurry of tissue. The heating performed by the probe is confined in various embodiments such that one or more parameters are selected such that the degree of heating of tissue and/or aqueous medium is limited to support targeted liposuction or other cosmetic treatments without heating other tissue such as muscle, veins, arteries, muscle, and other non-target tissues.
The RF probe 500 can traverse the tissue area being treated more smoothly than state of the art approaches to liposuction thereby lessening and/or avoiding arm fatigue associated with the procedure. The RF probe 500 provides an improved opportunity to control the application of energy as initially laid down in the tissue thereby enabling the practitioner who uses care to achieve the desired level of unwanted adipose tissue removal from a targeted area with precision thereby reducing the time required to complete the procedure as desired.
In some embodiments, faster fat removal is achieved by the disclosed system because the disclosed system can actively avoid clogging in the cannula caused by the removal of fat tissue, thereby avoiding downtime associated with clog removal remediation. Clogs and the required breaks in treatment to remove clogs from treatment probes occur routinely in state-of-the-art liposuction methods. In current practice, clogs are removed from liposuction probes in various way, including, by the practitioner stopping the liposuction procedure and then brushing the interior of the probe to remove the clog and/or by pulling off the suction and reversing the suction being applied to dislodge the clog. In part, the disclosure relates to a method of reducing clogging of a liposuction probe during various cosmetic procedures. The method of reducing clogging may include applying RF energy to a conductive region of the cannula of the probe such that the fat or other tissue that would otherwise clog a given aperture of the probe is reduced in size, volume, density, texture, consistency and other parameters as disclosed herein such that the individual broken down tissue elements pass through the aperture or are cause to release from the aperture before, during, or after the application of RF and a resultant heating effect such as localized or confined heating.
The RF probe 500 described herein can provide tissue tightening simultaneous with the fat removal step (e.g., during liposuction). The tissue tightening is via soft tissue coagulation and tightens relatively deep tissue (e.g., at a depth of a fiber septa network in a specific treatment region, which will vary based on the volume of unwanted adipose tissue content in a region to be treated) during the liposuction. Subsequent to aspiration of the unwanted fat via suction the RF probe 500 may provide tightening to tissue that is more superficial, e.g., at a depth of the tissue immediately below the dermis in a specific treatment region, which sometimes presents a challenge because the goal is to treat immediately below the dermis to even out the tissue appearance after treatment. The relatively deep tissue is at a depth that is deeper than the superficial tissue being treated according to the disclosure.
The system disclosed here includes a complete plastic surgery platform suitable for an operating room or surgical suite and such a platform combines the specific requirements of the RF generator 150 and its probes 500. Further, in addition to the RF generator 150, the platform may further support liposuction procedures by having an integrated suction aspiration vacuum pump 148 (or suction pump) and/or infiltration tumescence pump 142 in addition to the RF generator 150. The platform can further support PAL procedures; practitioners are commonly comfortable and capable doing PAL procedures and may utilize PAL alternatively or in addition to the RFAL procedure.
The patient procedure capability goals of this new RF platform may also include full surgical capabilities, non-invasive aesthetic capabilities and minimally invasive capabilities.
The proposed treatment system may include one or more housings. In some embodiments, a RF generator 150 (optionally, for example, a one frequency RF generator or a two frequency RF generator), a peristaltic pump 142 and a suction pump 148 (e.g., a vacuum pump) may be part of the system and disposed in one or more housings. A peristaltic or infiltration pump 142 allows for infiltration, specifically, the administration of tumescence 147 to minimally invasive procedures and the suction pump 148 (e.g., vacuum pump) is required for tissue harvesting, specifically, aspiration, (a) tissue harvesting/tissue removal without RF or (b) tissue harvesting/tissue removal in concert with RF assisted liposuction.
The RF generator 150 can be employed with one or more frequencies (e.g., two frequencies) and the multiple temporal modes that can be used to deliver different invasive tissue effects which will be explained in greater detail. This same RF generator 150 can be used for standard electrosurgical cutting and coagulation via electrosurgery probe(s) 152 as well as driving monopolar and bipolar RF into skin for temperature-controlled tissue heating (e.g., surface tissue heating) via tissue heating RF handpieces 157 such as are sold under the tradename TempSure Envi (available from Cynosure, LLC in Westford, Massachusetts), for example. Such electrosurgical cutting and coagulation and surface tissue heating functions are disclosed in International Publication No. WO2019/157076A1 having International Application No. PCT/US2019/016883 entitled Methods and Apparatus for Controlled RF Treatment and RF Generator System and/or are commercially available under the tradename Tempsure® (available from Cynosure, LLC in Westford, Massachusetts).
Table 1 describes additional detail about the procedures achieved by using the pedal footswitch shown in
All of the procedures disclosed in Table 1 labeled (1) to (6) and including RFAL can be controlled with/using a single footswitch 134 or another controller. A layout of a given user controller, such as a footswitch 134 (e.g., a 3 pedal footswitch 134 having pedals 561, 562, 563 as depicted in
The disclosed system shown in
In various embodiments, the systems and methods support monopolar and bipolar application of the RF via the liposuction probe shown and described in
An explanation of the different polarity modes can be shown in
The monopolar probe construction of
A range of optional monopolar probe designs is described in concert with
Probe 2 depicted in
Probe 4 depicted in
For some probe designs, RF is used to heat tissue with a surgical probe via a minimally invasive approach to achieve tissue tightening via soft tissue coagulation. By increasing the electrode area, one lowers the current density and subsequently achieves a gentler heating of tissue rather than vaporizing tissue which occurs at where there is a relatively high current density, for example, where the available electrode area is limited, for example, on the edge of a scalpel.
For a probe of about 3 mm in diameter and a coated tip 10 mm long, and ignoring apertures for the time being, there is approximately 60 mm2 of area to conduct current to the surrounding tissue. Taking an average current of 1 A for example, 1 A will be distributed over 60 mm2=0.017 A/mm2. This is considered a low current density compared to the edge of a scalpel blade where that same 1 A may be applied to an area 0.5 mm thick and 5 mm long=0.4 A/mm2. The low current density will heat tissue without necessarily getting to phase changes such as that achieved at high current densities where one or more of steam bubbles, vaporization, plasma, and carbonization of tissue may occur.
Alternatively, the heating could be achieved through temporal manipulation of the power to achieve different tissue effects. For example, whereas high energy, short pulses (high power) might be optimized for tissue disruption and well suited for liposuction, the same frequency of RF could be temporally adjusted to deliver lower energy pulses at longer pulses (low power) and be optimized for localized heating and coagulation near the probe tip.
An invasive probe may be manufactured that operates with relatively lower current density heating properties (or only such properties) and because such an invasive probe does not require a suction lumen, the diameter of the probe can be quite small (sub-millimeter is possible). A smaller probe diameter is generally attractive to plastic surgeons performing minimally invasive cosmetic procedures or other invasive procedures. The RF frequency is not necessarily specific to this design-almost any frequency will work if the only goal is heating without vaporization, thus providing a relatively low current density. While the probe may feature an insulative layer or coating, the insulative layer or coating is not a requirement; in fact, in some embodiments, the absence of coating, e.g., using uncoated stainless steel, may also be employed for the heating mode.
The desired RF platform of the disclosure herein features a minimally invasive probe that can address both tissue tightening and tissue removal (e.g., adipose tissue) and be combined into one single probe, thus providing two functions in a single probe. There are various methods of optimizing liposuction and various methods of achieving tissue heating. The disclosed system 100 shown in
Use of the system disclosed in
Use of the system 100 disclosed in
In continuous RF power mode, referring still to
Preferably, the dielectric material or coating on the body of the probe (e.g., the tip 520 and/or the shaft 525) has dielectric properties that are insulative for both the fat removal frequency (e.g., 500 kHz) and the heating frequency (e.g., 200 kHz-10 MHz, or 350 kHz-7 MHz, and 500 kHz-4 MHZ). The dielectric properties are selected or chosen such that if active RF is applied to the stainless-steel cannula during the fat removal phase, there is little to no current leakage through the body (e.g., the tip 520 and/or the shaft 525) of the probe due to the properties of the dielectric material that is employed. Instead, the RF is concentrated about the perimeter of the one or more apertures 530 that are employed as suction ports during fat removal procedures. In various embodiments, probe shaft may also refer to probe cannula and vice versa.
Referring now to
Referring now to
In some embodiments, this rapid heating results in vaporization and heat and bubble formation to disrupt the tissue as suction is applied, thus expected to augment the liposuction process. The rapid heating can lead to vaporization of fluids and even plasma—this immediately breaks down tissue adjacent to the aperture. The RF-assist is intended to speed up a tedious operation and lyse immediately adjacent tissue into small pieces (e.g., decompose) or into liquid. Referring still to
Referring still to
After heating the reticular dermis, in Step 3 the probe was then operated with the other footswitch 561 to channel the volume and attempt to remove fat from the treatment area. However, RF assisted liposuction in continuous mode was found to cause thermally unconfined heating with variable heat generation that is dependent upon the local tissue impedance of the adipose tissue. The result can be a clog of the cannula that terminates the ability for tissue to flow through the cannula for aspiration. Unlike cannula clogs that occur in PAL or other forms of liposuction, the clogs that occur during continuous mode RF can be extremely difficult or impossible to resolve due to charring of tissue on the cannula. As a result, it was determined that the aspiration portion of Step 3 should not be completed with continuous mode RF. Thus, with continuous mode RF step 3 should be skipped. Instead, with Steps 1 and 2 of
The RF probe 500 described herein can provide tissue tightening simultaneous with the fat removal step (e.g., during liposuction). The tissue tightening is via soft tissue coagulation and tightens relatively deep tissue (e.g., at a depth of a fiber septa network in a specific treatment region, which will vary based on the volume of unwanted adipose tissue content in a region to be treated) during the liposuction. Subsequent to aspiration of the unwanted fat via suction the RF probe may provide tightening to tissue that is more superficial, e.g., at a depth of the tissue immediately below the dermis in a specific treatment region, which sometimes presents a challenge because the goal is to treat immediately below the dermis to even out the tissue appearance after treatment. The relatively deep tissue is at a depth that is deeper than the superficial tissue being treated according to the disclosure.
The Steps 1 and 2 shown and described in
Referring now to
Referring now to
A more detailed schematic diagram explanation of
Referring again to
A treatment benefit of the finessing RF pulses is to enable the flow of suction, or aspiration, of unwanted adipose tissue flowing through the cannula of the probe by decreasing the incidence of clogging of the treatment cannula of the probe 500. In this way, interruption of unwanted adipose tissue removal is lessened and/or avoided due to the finessing RF pulses that avoid clogging by generating disruption in the vicinity of the one or more apertures 530 present on the cannula of the probe 500.
Generally, a relatively smaller diameter suction cannula would leave a smaller injury on the surface of the patient skin at the entrance point. Smaller skin injury is preferable in cosmetic liposuction procedures. The desire to use a smaller diameter cannula must be balanced with the observation that generally non-power-assisted treatment cannulas having a diameter of less than about 4 mm are associated with cannula clogging with fibrous tissue that can significantly decrease the rate of aspiration of unwanted adipose tissue being removed from the treatment region, [Young, V. Leroy, and Harold J. Brandon. “The physics of suction-assisted lipoplasty.” Aesthetic Surgery Journal 24, no. 3 (2004): 206-210.].
The finessing RF pulses deliver thermally confined heating of the tumescent aqueous media intermixed with adipose and/or fibrous tissue that is near the probe apertures 530 energized with pulsed RF power and generate steam bubbles. The expanding steam bubbles in the intermixed aqueous and adipose media will lead to generation and propagation of disruptive energy originating from the steam bubbles. The expanding steam bubbles in the intermixed aqueous and adipose media or the intermixed aqueous and fibrous media can generate and/or propagate pressure waves and/or shock waves originating from the steam bubbles. At least a part of the fibrous tissue that may be in the process of clogging the cannula of the treatment probe 500 is likely to near the probe 500 aperture(s) 530 energized with pulsed RF energy. The combined effects of steam bubble formation, expansion, contraction, and a pushing force, possibly pressure waves and/or possibly shock waves will lead to disruption of the fibrous tissue and likely prevent and/or decrease the incidence of clogging in the cannula of the probe 500. For example, the finessing RF pulses are delivered in an energy control mode, having an energy range of from about 0.5 to 3 about J/pulse, with high peak power, larger than about 1 kW, delivered for short RF on-times, for example, on-times ranging between about 1 ms and about 10 ms as determined in real-time by the energy control system.
Referring still to
Depending on the suction pressure differential and cannula geometry together with the local treated tissue properties, the finessing energized RF pulses must be delivered at a sufficiently high repetition rate to disrupt fibrous tissue clogging while keeping the repetition rate sufficiently low to avoid unwanted tissue heating. For example, the repetition rate of the RF pulses during the finessing stage can be set between 0.5 and 5 Hz, or more preferably 0.5 to 2 Hz.
Another example of the application of thermally confined RF pulses aimed at preventing or decreasing clogging is in liposuction cannulas used to remove the bulk of the unwanted adipose tissue. The thermally confined RF pulsing can be implemented in addition to or instead of the cannula venting and tip and port(s) geometry designs that have been used to increase aspiration rates and to decrease the incidence of clogging [Young 2004]. The treatment benefit of finessing RF pulses is that the sporadic intentional disruption of all or a portion of a blockage in the one or more apertures disposed in a cannula employed for liposuction by a pushing force originating from steam bubbles keeps the flow of suction and/or aspiration of unwanted adipose tissue.
For example, in an exemplary pulsed RF power liposuction step (e.g.,
Employment of finessing RF pulses to decrease the incidence of clogging of the treatment cannula can be extended beyond RF assisted liposuction to traditional or state of the art methods of liposuction. For example, referring to
In some embodiments a tissue disruptor 580 may be used to retrofit an existing liposuction system and can be slidably disposed or received by or with respect to a legacy cosmetic probe. In some embodiments, the tissue disruptor may include a hollow cylindrical structure having a wall thickness and sized to compliment a shape and one or more dimensions of one of the outer diameter or the inner diameter of a cannula employed to suction tissue; at least one disruptor aperture disposed through the wall thickness, the disruptor aperture sized to compliment dimensions of a cannula aperture disposed through a cannula wall thickness in a cannula employed to suction tissue and the disruptor aperture is positioned to align with a cannula aperture; a resistor is disposed about an edge of the disruptor aperture, the resistor positioned to generate heat sufficient to thermally confine heating of an aqueous media surrounding the resistor.
Alternatively, the finessing element or disruptor 580 is a thin film resistor that is electrically insulated from a cannula made of electrically conducting material, for example stainless steel. The thin film resistor 584 can be shaped as an incomplete circle having a gap 586 at or near the edge of the suction port or aperture 582 of the disruptor 580. For example, disruptor 580 includes a resistor region 584 shown as a black incomplete circle in
Optionally, referring still to
In some embodiments, the tissue disruptor may include a tissue disruptor and cannula assembly, comprising: a cannula employed to suction tissue, at least one cannula aperture defined by a cannula wall, the cannula wall having a cannula wall thickness; a disruptor comprising a hollow cylindrical structure comprising a disruptor wall having a disruptor wall thickness and inner dimensions sized to compliment the outer shape and dimensions of the cannula; at least one disruptor aperture defined by the disruptor wall, the disruptor aperture is sized to compliment all or a portion of the cannula aperture dimensions, the disruptor aperture having an edge defined by the disruptor wall; a resistor disposed about the edge of the disruptor aperture, the resistor configured to generate sufficient heat sufficient to thermally heat a volume of an aqueous media surrounding the resistor, wherein the hollow cylindrical structure of the disruptor is sized and arranged to align the disruptor aperture and the cannula aperture, wherein the disruptor aperture aligned with the cannular aperture define a channel through both the cannula wall and the disruptor wall.
Referring still to
In one embodiment, referring to
The probe 500 cannula has an inner diameter measuring in the range of from about 2.7 to about 2.9 mm, which is comparable to a 4 mm outer diameter liposuction cannula used in standard PAL applications. Referring now to Step 1 of
Next, Step 2 of
Next, Step 3 of
The cannula of the probe 500, for example, the cannula shown in
Where the cannula of the probe 500 has the four apertures 530 (e.g., a first set of through holes in cross configuration with a second set of through holes) as is shown in
Where the cannula 525 has four apertures and has a rounded distal end as shown in
Probes suitable for use with RFAL and/or tightening may be disposable, reusable, partially disposable, or partially reusable. In one embodiment, a timer (e.g., a chip) is employed to prevent reuse based, for example, on a time period of probe use that ranges from about 1 hour to about 12 hours, from about 2 hours to about 10 hours, and from about 4 hours to about 6 hours. In one embodiment, the cable is reusable that attaches the probe handle to the system console (e.g., the RF system console). In another embodiment, both the cable and the handle are reusable. The probe cannula may be disposable and can be inserted into the handle end, twisted, and locked in place for use. Alternatively, the probe cannula can be cleaned and reused one or more times between uses. In one embodiment, the temperature is sensed such that RF delivery is controlled based upon temperature resistance whereby impedance is sensed to determine temperature. Voltage can be adjusted based on impedance or RF delivery may be adjusted based on impedance. The system can read the overall resistance. The position of the return electrode relative to the site of entry into the patient. The resistance may also be informed by (a) the thickness of the patient (b) the body composition (e.g., connective tissue and visceral fat) and (c) the fluid being administered. The voltage may be adjusted based upon the detected impedance. The length of each pulse can be managed such that the time between each pulse and/or the peak power of each pulse can be adjusted based upon what impedance is detected.
Referring again to
Referring now to
Referring to
The probe 500 depicted in
In another embodiment, referring to
Referring now to
Referring still to
Some of the factors that go into a successful design of a liposuction probe are known and some need to be determined experimentally. For example, too much stainless-steel tube flexing removes control and too large a diameter limits the surgical viability. Smaller diameter probes can be used in shorter lengths to improve stiffness and control. Small diameter probes are desirable because they limit the entry incision size and enable treatment of smaller areas, but the internal lumen of the probe is selected to be large enough to allow lysed fat to suck freely through the lumen without clogging. The method of applying RF, continuously or pulsed, and aperture arrangement, the amount of power and current density about the probe's apertures all contribute to the propensity of a certain probe to clog. Maximizing the internal diameter will improve suction force and reduce the incidence of clogging. The location of the apertures along the axis of the probe can also be related to clogging incidence; apertures more distal are subject to less suction force and clog more frequently.
Referring now to
As described, the probe 500 coatings 550 may enhance the performance and behavior of the probe. Proper selection of biocompatible coatings may support toggling the probe between two different frequencies to achieve two different tissue effects by depositing the current in two different areas of the probe whether lysing fat or adipose tissue or heating reticular dermal tissue to achieve tightening via soft tissue coagulation (see, e.g.,
Referring now to
Simple plastic insulation such an added layer of heat shrink may contribute to insulation of the probe 500 lumen. Such an insulation may be composed of an aerated plastic in a woven layer to introduce more air to help with thermal insulation. However, dimensional restrictions on the OD of probe tip 520 may limit the thickness of the insulation layer. A tube-in-tube probe lumen design that utilizes two stainless steel tubes with a thin air gap therebetween can provide the air gap providing insulation. The tube-in-tube approach with air gap therebetween can be employed to maximize thermal insulation with a small added thickness. A further improvement on the tube-in-tube design may also include evacuating the air therebetween, for example, by having a vacuum applied to the air gap instead. The vacuum approach may be effective and may reduce the required amount of thermal insulation but is relatively costly.
Referring now to
In some embodiments, referring now to
For a probe construction which only uses FEP coating throughout the length of the probe and does not use the combination of FEP and PVDF, the collar 555 may not be required.
Preferably, the handle 510 is lightweight. Because RFAL treatment offers an case of pushing through tissue, the handle and probe have a comfortable feel or an attractive feel. In one embodiment, referring to
Referring now to
An example of a graphical user interface (GUI) 700 disposed on a console of a treatment system, such the system of
The clinical goals of the System of
The construction of the probe tip is configured to support easy passage of the probe tip through tissue. A plastic tip will not have the electrical properties or thermal mass required to (1) heat up tissue via RF and/or (2) serve as a heated leading edge to case passage through tissue. Thus, in some embodiments, the probe tip is constructed of stainless steel. Alternatively, the probe tip may be made from another biocompatible metal material. In order for the probe tip to be able to perform heating and/or liposuction treatment, the metal material may be coated with one or more insulative materials. Coatings suitable for application to the exterior of the probe tip are polytetrafluoroethylene (PTFE) or fluorinated ethylene propylene (FEP), which are sold under the trade name Teflon. These have a much higher operating temperature before melting as compared to PVDF. FEP is more easily formable than PTFE and has advantages in forming the coating over the end of the probe in embodiments when it the probe end has a domed shape. The electrical properties of PTFE and/or FEP do not favor the dramatic difference in dielectric properties that differentiate 500 kHz and 4 MHz like PVDF, but both PTFE and/or FEP can work to the clinical endpoint(s) envisioned and described herein.
The PTFE may be used for the 500 kHz liposuction—as well or better than PVDF. Since PTFE is more commonly manufactured, lead times and costs associated with PTFE are reduced relative to PVDF. While PTFE may work for tissue heating at 4 MHZ, it does not exploit the ability of the coating to leak through at the higher frequency as is present when PVDF is employed, but rather, the current at 4 MHz will be concentrated about the apertures of the cannula similar to the concentration during liposuction. PTFE does have a higher melting temperature than the PVDF probe tip with either PTFE or PVDF was previously discussed herein, however, the inside of the cannula wall may in some embodiments also benefit from a lubricious coating such as PTFE (e.g., Teflon) to aid the flow of the lysed fat aspirate as it flows down the tube to be removed from the subject's body.
In one embodiment, all or a portion of the interior of the cannula is electrically insulated. Insulating the interior of the cannula in addition to having an insulated exterior would provide a very limited conductive region. For example, the exposed edge of the cannula wall comprising conductive material is the only portion of cannula that acts as a conduit of conduction of RF energy. In this way, the energy density near the edge of the aperture is highly concentrated. Further, insulating in addition to the exterior, the interior of the cannula could offer benefits including, for example, maintaining a more consistent impedance during usage. Where insulation is present on both the exterior and interior of the cannula the effective load impedance would increase relative to a cannula that has insulation only on the exterior and as a result control would need to be adjusted accordingly. Finally, the inside of the cannula wall may in some embodiments also benefit from a lubricious coating such as PTFE (e.g., Teflon) to aid the flow of the lysed fat aspirate as it flows down the tube to be removed from the subject's body.
In one manifestation, FEP can be used to electrically and thermally insulate the cannula length but leaving a portion of the probe tip uninsulated. A second complete FEP layer will double the insulating along the cannula and cover the tip. In this way, the FEP thickness will be half (or any ratio of the two layers thicknesses) at the tip and promote more current leakage on the coated area of the tip and act more like the PVDF, frequency dependent design solution.
In some embodiments, two probes may be used to implement one or more of the methods and tissue treatments disclosed herein, referring to
Since the RF probe shown in
Referring now to
In some embodiments when using a pulsed RF energy mode, an acoustic popping sound that is emitted may be used to determine if something useful is happening to tissue being targeted for treatment. The method of determining this threshold is to begin at a low setting and increase the number of Joules until a reliable audible or tactile signal is achieved. To be conservative, a user may increase the energy 10-20% above this threshold and continue to monitor popping noises and tissue vibration with the non-dominant hand.
The probe and handle assembly disclosed herein may be disposable after a single use. Alternatively, they may be separable parts where portions are reusable and other portions are disposable.
Referring now to
In another embodiment (not shown), at least a portion of the probe cannula is also reusable and autoclavable with the remainder of the reusable handle and thermocouple portions of the assembly, but such an embodiment features interchangeable disposable tips that perform the varied functions of heating and liposuction. Such a disposable tip may be PTFE or FEP coated and screwed onto the probe tip. After use the disposable coated tip is removed and disposed so that the probe cannula, handle and thermocouple may be easily cleaned and autoclaved before use with the next patient. A new disposable coated tip is employed with the next patient. In one embodiment, there are two separate disposable removable tips one shown in
Detecting cannula clogs is an important part of any liposuction procedure. Normally, clogs happen when movement of fluid and fat within the transparent tubing becomes dormant. When the apertures are exposed to ambient pressure within the room by removing the probe from the body, the pressure differential might remove the clog and the hissing vacuum will become audible. In cases of larger clogs, the cannula may have to be flushed with saline, sucked out or pushed out to remove the clog and continue.
With the addition of continuous RF power, clogs are more important because if a clog occurs and the RF is being applied, that tissue may be further congealed or solidified into the tip of the cannula and become an irreversible adherent piece of tissue that may be difficult or impossible to fully remove/clean. When the clogs occur, it would be ideal to sense the change in flow within the cannula and/or tubing, but practically this is not possible. The flow between the body and the canister is the place to measure, but this is a messy conduit and difficult to get a good, reliable signal. Perhaps with an external ultrasound or optical flow meter such a measurement would be possible, but still difficult and expensive. The clean flow after the canister to the console is buffered by the volume of the canister and one loses the signal fidelity making it harder to detect changes in flow. For example, the vacuum pressure that is applied to the cannula is maintained by the large volume of the canister, so small changes in flow on the other side (direct to liposuction probe) are not easily detectable.
In one embodiment, impedance changes in the probes are measured to detect clogs during liposuction. For example, at the onset of the procedure, with recently tumesced tissue and a fresh probe, the measured impedance is expected to be at its lowest. As the procedure advances, the measured impedance will go up slightly and so the power will drop. Significant impedance changes and consequent power drops are likely the result of and are indicative of a clogged probe.
Typical power versus time and impedance versus time curves are shown in the following
Variations in both power and impedance are visible and are to be expected as impedance conditions at the probe tip are continuously changing as the tip moves through the anatomy and as aspirated material moves through the tip. Intermittent spikes in impedance can be observed which may be explained by aspirated tissue becoming stuck intermittently (reversible clog) in an aperture or inside the tube. When this happens, fluid flow is reduced, and the local temperature will rise more rapidly. This may lead to the desiccation (drying) of the stuck tissue and/or the formation of vapor bubbles which may both account for the observed intermittent rise in impedance. When the tissue becomes unstuck, fluid flow is restored, and the impedance returns to the baseline value.
Where a clog remains in place, the rise in impedance and reduction in power persists. This behavior measured and shown in
Similarly, a sustained period of time with an impedance level above a predefined level or the “baseline” level may trigger an alert to the user that a clog is suspected. Any algorithm for generating user alerts around clogging should not be triggered by the expected intermittent rises in impedance which are caused by intermittent clogging events such algorithms should be sensitive to clogs that are difficult to clear, lasting clogs, and/or irreversible clogs.
A challenge of the cosmetic tissue treatment systems, devices, and methods disclosed herein is that tissue impedance is variable throughout a subject's body. Moreover, the subject's tissue impedance varies within a given treatment region targeted for treatment with the disclosed devices, systems, and methods. Because tissue impedance variability is unavoidable, uncontrolled, and to be expected, methods of managing varied tissue impedance have been built into the disclosed devices, systems and methods. For example, system voltage may be adjusted in response to the impedance measured in a treatment region during the course of a single treatment. In one embodiment, the applied voltage is automatically adjusted in real time based on locally instantaneously detected impedance measurement.
Detection of the presence of high tissue impedance could be employed to signal to the system or to the practitioner that there is a presence of fibrous tissue such as scar tissue or cellulate, for example. If the system detects the presence of high impedance together with a drop in suction, then this might signal to the system or the practitioner the presence of a clog in the system.
In a pulsed RF energy system plasma detection can be based upon power. If power drops rapidly with a great rate of change plasma may be present. In pulsed RF energy system plasma detection can be based upon impedance, for example, where impedance measured greater than 1000 Ohms and/or if impedance increases rapidly with a great rate of change. In pulsed RF energy system plasma detection can be based upon reactance, where reactance measured is less than about −200 Ohms and/or if reactance rate of change drops rapidly with a great rate of change.
Measuring reactance can offer a reliable indication about the presence of a plasma enabling plasma detection. Reactance results due to the formation of an electric field and formation of an electric field is indicative of formation of plasma. When plasma formation is indicated, power delivery may be cut off or stopped to terminate plasma formation. Avoiding the presence of plasma formation or the risk of plasma formation can be aided by creating a control to cut off power when the reactance hits the cut off measurement of −200 Ohms whereby the system cuts off when about −200 Ohms is detected. In another embodiment, plasma formation or the risk of plasma formation can be aided by creating a control to cut off power when the reactance hits the cut off measurement of −100 Ohms whereby the system cuts off when −100 Ohms is detected. In one embodiment, a reactance cut off is employed to determine that plasma risk is present and that there is a risk of damage to a given device if it is used below the reactance cut off.
In some embodiments, plasma is avoided such that a desirable pulse has no drop in power and no spike in impedance during the pulse. Referring again to
In some embodiments of pulsed RF energy applications, the presence of plasma may be desirable. For example, in some embodiments, where the presence of plasma is desired one can determine the presence of plasma based upon a rapid drop in power, for example, with a great rate of change of power. The presence of plasma may be detected where impedance measured is greater than 1000 Ohms and/or where impedance increases rapidly with a great rate of change of impedance. In pulsed RF energy system plasma detection can be based upon reactance. The presence of plasma may also be detected where the reactance measured is less than −100 Ohms, or less than −200 Ohms, and/or if reactance rate of change drops rapidly with a great rate of change. In those embodiments where the presence of plasma may be desirable, this method of detection could allow for a degree of control over the duration of plasma exposure. For example, once plasma is detected, a time delay could be introduced such that the pulse would terminate after 1 ms, or after 2 ms, or after 3 ms. In this way, a degree of control over the time duration of the plasma could be realized.
In order to detect plasma one may monitor changes in impedance, changes in reactance, and/or changes in power. Further, plasma may be detected by monitoring one or more, or two or more of changes in impedance, changes in reactance, and changes in power. Bubble formation may be detected by monitoring one or more, or two or more of changes in impedance, changes in reactance, and changes in power. More specifically, bubble formation may be detected by monitoring one or more, or two or more rates of changes in impedance, rates of changes in reactance, and rates of changes in power. The behavior of these parameters provides an electrical signature related to the successful formation of bubbles. These electrical signatures can be employed to detect bubble formation as a closed loop to have the system react automatically in a way that keeps us in a “sweet spot” for bubble formation, i.e. the system would automatically adjust parameters to achieve and maintain bubble formation under changing anatomical conditions as identified by the electrical signature of the device.
For some embodiments, there may be advantages to using a pulsing RF energy delivery-based system instead of continuous wave RF delivery. In addition, in some embodiments a combination of pulsing RF and continuous wave RF delivery may be provided according to different delivery modes, tissue regions, and treatment types.
Step c shows bubble (B) formation resulting from rapid vaporization of one or more of water, fat tissue and/or tumescence present in the region of the aperture A. The formation and collapse of the bubble B contributes to the breakdown of fat and the fragments thereof (F) are aspirated into the aperture of the cannula as shown in Step d. In Step d, the five inwardly directed arrows show the movement of lysed fat fragments into the aperture in response to the collapse of the bubble and the ongoing suction. Step d shows that the expansion and collapse of the bubble in Step c causes a localized disruption that disrupts, breaks apart, or breaks down fat tissue, which is then sucked into the aperture A 530 and thereby removed via suction from the treatment region. In some embodiments, steps a, b, c, and d of
In most embodiments, a given cannula defines multiple apertures along its length. This process is repeated at a repetition rate from about 1 to about 1000 Hz, preferably at 20 Hz and the multi-aperture cannula is reciprocated through the tissue at a rate of 1-10 cm/sec many times to remove adipose tissue evenly and effectively. In some embodiments, a given probe or treatment device, such as a cannula-based device, may include one or more detectors. In some embodiments, a given probe or treatment device or liposuction system may include a temperature sensor and an acoustic/sound sensor. The various sensors may be disposed on or in a given treatment device or otherwise be positioned relative to a given treatment area. Various other sensors may be used such as motion sensors, accelerometers, pressure sensors, sound sensors, force sensors and others.
The disclosed pulsed RF energy delivery for liposuction may be used to initiate tissue changes in fatty tissue by introducing bubbles (e.g., steam bubbles) into the fatty tissue. Generating steam bubbles via pulsed RF energy requires a minimum threshold amount of energy density compared to methods that introduce RF energy via continuous wave energy density to heat fatty tissue. At a high level, with regard to the various steps and stages shown in
The liposuction cannula provides pulsed RF energy delivery that generates bubbles in fatty tissue. Bubble expansion, collapse and associated pressure or shock waves break the cell membranes of some of the fat cells and this appears to make it easier for the disrupted fatty tissue to be extracted via the liposuction cannula. In contrast to continuous wave RF energy delivery, the generation of bubbles via pulsed RF energy delivery requires less energy per unit volume of tissue delivery and unlike the continuous wave approach does not require the whole volume of extracted fatty tissue to have been heated.
Benefits of pulsed RF energy delivery include that the generation of steam bubbles in fatty tissue appears to enable a higher volume of fat to be removed via cannula (e.g., more efficient removal of fat) than via a continuous wave (“CW”) approach that requires all of the fatty tissue being removed to be heated. As a result, there is potential for a shorter treatment time via pulsed RF than via CW RF power delivery for liposuction. Further, where pulsed RF is employed to generate steam bubbles, less energy density is applied to fatty tissue to achieve a given result, and so it is expected that unwanted heat related side effects can be lessened and/or avoided.
In some embodiments, bubbles may be generated via pulsed RF. Without being held to a particular theory or mechanism, in some embodiments, heat confinement in the area near the electrode where the bubbles are formed may initiate, cause, or support bubble generation.
For pulsed RF treatment, sufficient RF power is needed for energy delivery. As such, a pulsed RF device is more complex to build versus a CW RF power device, because of the required increase in peak RF power delivery during pulsed on-time. Specifically, for a CW RF treatment a device delivering between 50 watts and about 300 watts may be sufficient, whereas, for pulsed RF a device delivering between about 1000 watts and about 3000 watts, or about 1600 watts pulsed for from about 3 to about 60 milliseconds, from about 5 to about 30 milliseconds, from about 10 to about 50 milliseconds, from about 3 to about 20 milliseconds, or from about 20 to about 30 milliseconds may be employed.
In one embodiment, the practitioner may be presented with a GUI screen with energy delivered per pulse setting and the pulse may have variable energy from between about 1 and about 20 Joules, from about 2 to about 15 Joules, and from about 5 to about 10 Joules. The pulsed RF treatment approach may provide feedback to the practitioner regarding successful bubble formation due to pulsed RF the feedback being in the form of an audible sound of a bubble and/or a tactile feeling of a bubble felt from palpating the exterior skin of a patient or from a sound level detected by a piezoelectric transducer present on either the cannula or on the exterior surface of the skin of the subject. In some embodiments, the initiation of the sound of the bubble provides clinical set point information to the practitioner who after starting at relatively low energy delivery per pulse raises the energy delivery level until the bubble feedback is received.
More specifically, bubble formation may be detected by monitoring one or more, or two or more rates of changes in impedance, rates of changes in reactance, and rates of changes in power (as disclosed in
In some embodiments, upon detection of bubble feedback, (e.g., energy per pulse that achieves the desired bubble formation) the practitioner can begin the treatment regime in a given region of the subject's body with the desired/appropriate energy delivery per pulse. In some embodiments, the sounds associated with a bubble forming or popping or otherwise associated with a change in sound with fat fragmentation or another sound of interest may be detected with a sound detector. In various embodiments, the sounds detected by the sound detector may be converted into a visual alert or used to generate other visual reports, automatic control signals, or other events of interest and correlated system actions. Spatial uniform energy density deposition via pulsed RF energy over the volume of the treatment area helps to avoid undesirable outcomes like uneven treatment for many embodiments.
In some embodiments, pulsing RF delivery may be suitable for generating steam bubbles in aqueous media, materials and tissue. A schematic showing the method of action of pulsed RF power applied to liposuction probe apertures is shown in
Delivery of RF energy in aqueous media generally leads to heating of the media in the vicinity of the RF electrode(s). When RF power is sufficiently high, the heating of the aqueous media may lead to generation of steam bubbles and plasma. The process can be utilized for various applications in aesthetic medicine. The following considerations highlight important parameters of the process under a few simplifying assumptions.
Laser energy assisted lipolysis is a well-established technique. Laser assisted lipolysis is practiced both with repeatedly pulsed devices as well as with Continuous Wave (“CW”) devices (usually based on diode lasers). At sufficiently high pulsed peak power the pulsed laser devices can generate steam bubbles in the adipose tissue while delivering moderate average power, for example 5W to 50W. Existing RF assisted lipolysis devices available on the market deliver RF power at levels that heat the adipose tissue without any consideration for delivering sufficiently high peak power to create steam bubbles in the adipose tissue. The use of the wet infiltration technique in the adipose tissue utilizing infiltration with a solution containing 2% lidocaine with vasoconstrictor in warm saline solution is a commonly used local anesthesia technique that may be used with laser assisted lipolysis [See Badin, Ana, et al. “Laser lipolysis: flaccidity under control.” Aesthetic plastic surgery 26:335-339, (2002)].
The commonly used anesthesia by infiltration of the adipose tissue with a saline solution can provide a medium suitable to an approach disclosed herein however where an RF assisted lipolysis technique in which the RF power is repeatedly pulsed, but unexpectedly, leads to generation of steam bubbles in the aqueous media composed of the adipose tissue with saline solution, referred to as the intermixed media. The proposed technique employing formation of steam bubbles in the aqueous media will lead to generation and propagation of pressure waves and possibly shock waves originating from the steam bubbles. The pressure wave's propagation through intermixed media is affected by the value of each medium's acoustic absorption and impedance. The acoustic absorption is directly related to protein content, and acoustic absorption is substantially larger in fatty tissue vs water like saline solution [See Shankar, Hariharan, at al. “Potential adverse ultrasound-related biological effects: a critical review.” The Journal of the American Society of Anesthesiologists 115.5:1109-1124, (2011)]. Steam bubble formation, bubble expansion and pressure wave propagation in the adipose tissue is expected to lead to selective thermo-mechanical damage to fat cells and surrounding fatty, fibrous or other tissues while limiting the damage to vascular structures in the treated anatomical site.
The bulk dielectric properties of fatty tissue are documented over extended frequency range [See Gabriel, Sami, R. W. Lau, and Camelia Gabriel. “The dielectric properties of biological tissues: III. Parametric models for the dielectric spectrum of tissues.” Physics in medicine & biology 41.11:2271, (1996)]. On a microscopic scale fatty tissue is inhomogeneous with pockets of fat cells surrounded by fibrous tissue and blood vessels leading to spatially varying electrical impedance. The infiltration of the adipose tissue with a saline solution typically leads to inhomogeneous saline intermixing and increases the spatial variation of the electrical impedance.
Operator controlled movement of a RF delivery cannula with one or more annular electrodes through the fatty tissue will lead to varying electrical impedance in the electrical circuit delivering the RF power.
A typical generator of RF power controls the amplitude or the RMS value of the delivered voltage (V). It is less common to have RF generator that controls the amplitude or the RMS value of the delivered current (I). In adipose tissue with spatially variable impedance (R), the typical voltage control RF generator will deliver spatially variable power per unit volume P=V2/R (or for the current control generator, the spatially variable power per unit volume is P=I2R). The delivery of spatially variable power may lead to inconsistent levels of adipose tissue damage and inconsistent clinical effects.
One possible way to compensate for the spatially variable impedance of the infiltrated adipose tissue is to use a RF generator with real-time voltage or current control that adjust the voltage or current level so that it delivers substantially uniform spatially distributed power per unit volume for a range of tissue impedance values. The design of such uniform power per unit volume real-time voltage or current control RF generator is more difficult and would result in a more complicated, more expensive device.
An alternative approach is proposed where the goal is to deliver substantially uniform spatially distributed energy per unit volume of adipose tissue, Q, by delivering the variable power per unit volume P over variable periods of on-time t. The control system of the example voltage control device varies in real time the RF pulsed on-time t so that delivered energy density per unit volume Q=(V2/R)τ is substantially uniform for a range of impedance values between 50 and 500052. The control system may deliver preset energy density per unit volume Q by delivering lower power per unit volume for longer on-times, τ, in regions with high impedance, R; and by delivering higher power per unit volume for shorter on-times, τ, in regions with low impedance, R. For example,
In some embodiments, the control system sets the output control parameter, for example the rms voltage V, to be approximately the same for each pulse during the treatment. In other embodiments, for each pulse during the treatment the control system delivers a lower voltage impedance-diagnostic short pre-pulse. Then the control system calculates the local impedance for the RF delivery site and sets the output voltage so that it optimized the RF power delivery during the treatment pulse for the measured local impedance. For example,
In some embodiments, the practical range for the pre-pulse time interval is the speed of motion of the RF treatment cannula held in the operator's hand and the size of the annular RF electrodes. An example estimate can be based on the approximately 5 m/s hand speed reported in [See Elgendi, Mohamed, et al. “Arm movement speed assessment via a Kinect camera: a preliminary study in healthy subjects.” Biomedical engineering online 13.1:1-14, (2014)] and a 1 to 4 mm estimate for the annular electrode diameter. Then the estimated range of values for the pre-pulse time interval is between 0.2 and 0.8 ms. In further embodiments, the control system varies the output control parameter based on real-time impedance measurement while the treatment pulse is delivered.
In another example for a voltage control system, at the beginning of each on-time interval the voltage is set at a value that will deliver a safe amount of power per unit volume P=V2/R. Then the real time control system monitors the local tissue impedance and increases the control voltage, V, when it detects higher impedance R, on a time scale much shorter than the individual pulse on-time, so that the desired energy density per pulse Q=(V2/R)τ can be delivered in the desired pulse on-time, for example 1 ms to 10 ms. In a further example, in some device implementations where the available range of control voltages is limited and the delivered energy density per unit volume, Qv, cannot exceed the threshold energy density for bubble formation, Qth, at the higher voltage setting, the power delivery can be terminated in order to limit the localized tissue heating without steam bubble formation, for example after about 3 ms to about 10 ms.
The generation of vapor cavities, or bubbles, near the RF electrodes in aqueous media and ionization of the vapor cavities is demonstrated to occur sequentially in time in [Palanker 2008]. The sequential nature of the process allows for separate analysis of the process of bubble formation.
A simplified model for bubble generation in aqueous media is outlined in [See Gerstman, Bernard S., et al. “Laser induced bubble formation in the retina.” Lasers in Surgery and Medicine 18.1:10-21, (1996)]. The simplified model assumes a spherical volume in aqueous media where energy is delivered in a small volume embedded in a larger volume of aqueous media without energy deposition. The model considers pulsed energy delivery with sufficiently short pulses for heat confinement and derives the constraint that bubble formation is a threshold limited process. In the adiabatic approximation, the threshold limited process for bubble formation is characterized by a threshold energy density per unit volume, Qth. Delivery of energy density below the threshold, Qth, would lead to a temperature rise in the region where energy is delivered with no steam bubble formation. Delivery of energy density, Q, above the threshold, Qth, would lead to formation of a steam bubble with volume proportional to the amount of excess energy density above the threshold, Q−Qth.
In a threshold limited process, like bubble formation, the energy utilization efficiency favors operation high above threshold. For delivered energy densities below the threshold, Qth, the energy utilization efficiency is zero—there is no generated bubble. For delivered energy densities above the threshold, Qth, the energy utilization efficiency can be defined as
Qv is the energy density that accumulates at the end of the pulse in the volume of water that may be converted into a steam bubble and Qin is the total delivered input energy density. Operation at short pulse durations that provide sufficient thermal confinement allows for the most efficient energy delivery, Qv≈Qin.
In some embodiments, operation at longer pulse durations that do not provide thermal confinement may decrease the fraction of input energy density, γ, that may accumulate at the end of the pulse in the volume of water that may be converted into a steam bubble, Qv=γQin. In the limit of very long pulses, approaching continuous operation, the fraction of input energy density, γ, may be the lowest. A low fraction of accumulated input energy density, γ, may lead to low energy utilization efficiency for fixed input energy density. Referring now to
The dependence of the energy utilization efficiency, η, as a function of the normalized input energy is plotted on
The determination of the exact geometrical shape of the volume of superheated water that may be converted into a steam bubble is not part of the present simplified analysis. In a simplified example, for an annular shaped RF electrode exposed to the aqueous media, the volume of water that may be converted into steam can be expected to have a toroidal like, or doughnut like, shape. The annular shaped RF electrode is expected to be in contact with the external surface of the toroid and possibly the toroid external surface may extend beyond the edge of the electrode. Limiting the area of the electrode in contact with the aqueous media may lead to a higher current density and more efficient generation of steam bubbles.
Examples of annular shaped RF electrodes or apertures 530 are shown in
Multiple annular shaped electrodes may be formed in various patterns on the RF conducting material. All other surfaces of the RF conducting material that may come into contact with the aqueous media, except the annular electrode surface(s) labeled as E, should be modified to decrease their RF conductivity into the aqueous media for example by coating, plating, anodizing or any other suitable process leading to a substantial decrease in RF conductivity. Here substantial decrease in RF conductivity is defined as conductivity decrease by a factor larger than 2×, or more preferably larger than 5×, or most preferably larger than 10×.
In the present analysis the convoluted toroidal like shape of the volume of water that may be converted into a steam bubble may be approximated with a cylinder with variable diameter and length that matches the circumference of the annular shaped RF electrode. The diameter of the cylinder can be chosen so that its volume matches approximately the superheated water volume in the vicinity of the annular shaped electrode. In the approximate model the cylinders are considered to be heated by a source depositing uniform energy density in their volume.
The calculated accumulated energy fractions at the end of the pulse, γ, at the center of a uniformly heated cylindrical volumes of water with a range of diameters embedded in unheated water volume are plotted on
The calculated accumulated energy fractions at the end of the pulse, γ on
The finite amount of RF power that can be delivered over the time intervals corresponding to heat confinement in the range of considered diameters of heated region sets a practical limit for the circumferential length of the annular electrode(s). The deposited input energy density can be calculated as
where Ein is the delivered RF electrical energy and the denominator accounts for the considered cylindrical volume of heated water. In designs where multiple annular electrodes or apertures are desired, L is the total circumferential length of the annular electrode aperture(s). The value for the energy density threshold for steam bubble formation can be calculated for water as Qth=1.42 J/mm3, following the method outlined in [Gerstman 1996]. Instead of the deposited input energy density, Qin, it is more convenient to consider the normalized input energy density, Qin/Qth, used also in the energy utilization efficiency calculation.
Following earlier discussion for the energy utilization efficiency, only values of the normalized input energy density above 1 may lead to generation of steam bubbles. Depending on the actual level of heat confinement and corresponding accumulated energy fraction at the end of the pulse, the normalized input energy density, Qin/Qth, that is expected to lead to steam bubble formation should be larger than about 2, or more preferably larger than about 5, or most preferably larger than 10, as plotted on
In designs where electrically parallel multiple annular electrodes in isotonic saline like aqueous media are desirable, steam bubble formation at a subset of one or more electrodes facilitates more efficient bubble formation for the remaining electrodes due to the higher impedance of steam vs isotonic saline.
During the on-time of the pulsed energy delivery, the subset of one or more electrodes with early steam bubble(s) formation may receive decreased energy flow after the bubble formation while the remaining electrodes may receive increased energy flow that may increase the rate of steam bubble formation. In some embodiments, steam bubble formation in devices with electrically parallel multiple annular electrodes is a cooperative process-once steam bubble formation starts it is expected to lead to bubble formation at all annular electrodes, provided sufficient RF energy is delivered in a sufficiently short on-time. In some embodiments, preferred on-time ranges between about 0.1 ms-about 100 ms, or from about 0.5 ms-about 20 ms, or from about 0.5 ms-about 15 ms, or from about 0.5 ms-about 10 ms, or from about 0.5-about 7.5 ms.
In another example for real time control of the energy in each pulse, the detection of steam bubble formation with a piezo electric transducer can be used for termination of the power delivery in the pulse shortly after the steam bubble detection leading to delivering of real time adjustable energy per pulse. Such real time control mode of operation minimizes the pulse energy in each pulse while delivering consistent bubble formation in most pulses when the delivered peak power is sufficient for bubble formation. The minimized pulse energy in each pulse will lead to minimized average power delivered in the treated region while maintaining the treatment mode of operation based on steam bubble formation. The minimized average power delivered in the treated region will lead to improved treatment safety.
An additional feedback mechanism can be envisioned where steam bubble formation in the infiltrated adipose tissue is detected in real time and for every pulse RF power delivery is terminated at deposited energy levels about 10% or about 20% above the detected threshold for steam bubble formation. For example, steam bubble formation can be detected with a microphone or a piezo transducer connected to the delivery cannula or to the patient skin. A feedback mechanism for pulse energy control based on the formation of steam bubbles may allow treatment of adipose tissue with minimal spatially averaged energy delivery in a tissue region and improved treatment safety. In delivery devices where energy delivery continues after steam bubble formation, the delivered additional energy density might lead to ionization and plasma formation in one or more of the steam bubbles associated with the annular RF electrodes.
Adipose tissue infiltrated with a saline like solution typically has spatially varying RF electrical impedance. The delivery of substantially uniform spatially distributed energy per unit volume in the tissue with varying RF electrical impedance is facilitated by delivering the uncontrollable variable power per unit volume P over real-time controlled variable periods of on-time τ. The control system delivers preset energy density per unit volume Q=Pτ by delivering lower power per unit volume for longer on-times, τ, in regions with high impedance; and by delivering higher power per unit volume for shorter on-times, τ, in regions with low impedance.
Pulsed energy delivery of RF power in adipose tissue infiltrated with saline like solution may lead to generation of vapor cavities, or steam bubbles, for a range of deposited energy densities and on-times. Generation of vapor cavities, or steam bubbles, in aqueous media is a threshold limited process. The efficiency of generation of steam bubbles near RF energy delivery devices with multiple annular RF electrodes, each having one or more apertures, in fatty tissue infiltrated with saline like solution can be improved by delivering, through the one or more apertures, short-pulsed bursts of high peak power density that provide sufficient heat confinement and energy per unit length. Varying in real time, pulse to pulse, the on-time of the RF high peak power density bursts allows the delivery of consistent energy density per unit volume at every pulse when the RF impedance of the surrounding medium varies.
Decreasing the annular electrode size exposed to the isotonic saline like media may improve the efficiency of bubble formation by increasing the current density near the exposed electrode and decreasing the size and volume of the heated water to be converted into steam. The disclosed annular electrode may also be referred to as the perimeter of the aperture in the electrode and can have any geometric shape not limited to a shape featuring an ellipse. In a cannula like device with one or more annular electrode areas, electrical insulation on the external and internal surface of the cannula walls may be beneficial for limiting the energy deposition only to the vicinity of the annular electrode areas. When the pulsed mode of operation reliably generates steam bubbles near the annual electrode(s) in the aqueous media that is evacuated through the cannula, a high-volume density of steam bubbles may increase sufficiently the impedance of the evacuated aqueous media so that the energy loss through the uninsulated internal cannula may become less significant.
For some RF or other energy delivery embodiments, pulsed operation is employed in contrast to continuous operation. The two modes of operation differ by varying the temporal component and in the pulsed application the peak power. A minimum energy per unit time may be selected to affect the tissue, either thermally or through mechanical disruption via the bubble formation or both, and this is represented as power. There also exists an upper limit on the same application of that power. If the objective is to confine the heat to a small volume, as is the case with forming bubbles high peak powers may be used. For example, high peak powers can be used for a limited amount of time in a pulsed fashion, thus limiting the average power applied to the tissue. The RF generator may be designed to be operated at high powers for short sequential pulses and low duty cycles, but also use safe average powers.
Laser assisted lipolysis is practiced both with repetitively pulsed lasers as well as with CW devices (usually based on diode lasers). Early clinical and histology observations with repetitively pulsed lasers showed some skin tightening associated with superficial, subdermal deposition of laser energy using 1064 and/or 1320 nm repetitively pulsed lasers. Sec, Dibernardo, Barry et all. “Evaluation of tissue thermal effects from 1064/1320-nm laser-assisted lipolysis and its clinical implications.” Journal of Cosmetic and Laser Therapy 11, no. 2:62-69, (2009).
Subsequent introduction of the 1440 nm repetitively pulsed, side firing laser device demonstrated neck contouring and skin tightening in the neck area. See, FAAD, Deborah S. Sarnoff MD. “Evaluation of the safety and efficacy of a novel 1440 nm Nd: YAG laser for neck contouring and skin tightening without liposuction.” Journal of Drugs in Dermatology 12, no. 12: 1382-1388, (2013), and DiBernardo, Gabriella A., and Barry E. DiBernardo. “Prediction of treatment outcomes for neck rejuvenation utilizing a unique classification system of treatment approach using a 1440-nm side-firing laser.” Aesthetic Surgery Journal 38, no. suppl_2: S43-S51, (2018).
The increased absorption of 1440 nm in the dermis and in fatty tissue facilitates localized dermal tissue heating when the energy is delivered sub-dermally with a side-firing fiber delivering about 50% of the energy towards the dermis.
Existing RF assisted lipolysis devices deliver RF power at levels that heat the adipose tissue and may lead to skin tightening. Sec, Paul, M and Mulholland R S “A new approach for adipose tissue treatment and body contouring using radiofrequency-assisted liposuction.” Aesthetic plastic surgery 33:687-694, (2009). It is possible that clinical optimization of CW RF power level and temperature setting at the cannula thermistor will lead to some level of skin tightening, possibly approaching the effect of the 1064 and/or 1320 nm lasers. The 1064 and/or 1320 nm lasers deliver the optical energy coaxially with the fiber axis predominantly in the sub-dermal adipose layer. Direct laser energy delivery in the dermis is minimal, most dermal heating is by heat diffusion from the heated adipose layer. For the repetitively pulsed 1064 and/or 1320 nm lasers even though the energy delivery by the individual laser pulse is thermally confined in the adipose layer, the observed dermal temperature rise is the result of the combined effect of multiple pulses with the associated thermal diffusion during the pulse and the inter-pulse time intervals, resulting in unconfined heating of the treated dermal tissue volume. At 1440 nm the main chromophore in the lower dermis is water. The water absorption coefficient is 29.4 cm−1 at 1444 nm. The 1444 nm laser delivery fiber combines coaxial and side firing capabilities and can deliver about 50% of the pulse energy directed towards the dermis where the repetitively pulsed energy delivered in pulse widths of approximately 380 us is thermally confined.
Ex-vivo tests on excised human tissue from abdominoplasties as well in-vivo cases have led to various observations regarding the operation and performance of the devices disclosed herein. A summary of some of these observations is outlined as follows:
A pulsed RF device can be envisioned with pulse delivery parameters optimized for thermally confined energy delivery with the goal to approach or exceed the performance of the 1444 nm repetitively pulsed laser. The l/e penetration depth of the 1444 nm laser is approximately 1/29.4 cm−1≈340 μm. An RF delivery cannula may be envisioned where the high volumetric energy density deposition volume surrounding the cannula surface will be thinner than 340 μm due to the very fast decrease of RF current density surrounding the outer surface of the cannula. In one embodiment, the high volumetric energy density deposition volume surrounding the cannula surface with range from about 1 μm to about 340 μm, from about 5 μm to about 100 μm, from about 10 μm to about 50 μm.
A probe having a cylindrically shaped RF delivery cannula positioned near the dermis/fat junction would contact the dermis/fat junction over a narrow stripe or strip on its external cylindrical surface. The rest of its external cylindrical surface will be in contact with adipose tissue infiltrated with saline like tumescent solution. The narrow stripe or strip of the cannula in contact with the dermis is expected to offer lower RF impedance vs the adipose tissue due to the lower dermis impedance. Pulsed RF energy deposition in the dermal stripe can result in thermally confined localized heating and possibly coagulation of all or a portion of the dermal layer in contact with stripe of the cannula in contact with the dermal tissue. When the practitioner moves the cannula to be in contact with another region of the dermis/fat junction and then still another region of the dermis/fat junction, multiple coagulated stripes on the dermis/fat junction can be created over multiple RF pulses delivered under pulsed energy control accommodating variable impedance. Optimization of the width, length and thickness of the coagulated stripes on the dermis/fat junction can be used to optimize the skin tightening effect of the pulsed RF treatment. It is expected that a stripe generated by a given cannula will be approximately the size and/or shape of the portion of cannula in contact with the tissue that it contacts. Due to the higher adipose tissue impedance, a lower volumetric density of RF pulsed energy will be delivered by each pulse in the surrounding tumesced adipose tissue. As a result, from the unconfined heating over multiple on- and off-time cycles little to no localized thermal damage is expected in the adipose tissue while its temperature is rising and providing generalized heating to the overlying dermis. Another advantage of the pulsed RF energy control mode of operation is that it provides consistent average power delivery and generalized heating energy dosing in the tissues near the dermal/fat junction with variable RF impedance. In this way, during liposuction the dermal tissue at the dermal/fat junction may be exposed to heat treatment.
Referring now to
Where the cannula 525 of the probe 500 has four apertures 530 (e.g., a first set of through holes in cross configuration with a second set of through holes) as is shown in
In the model shown in
To simplify the models in
The plots of
Comparison of
Referring now to
The plots on
The finite amount of RF power that can be delivered over the time intervals corresponding to heat confinement in the range of considered thicknesses of heat generation region sets a practical limit for the cannula length and diameter. The deposited input energy density can be calculated as
where D and L are the cannula diameter and length, Ein is the delivered RF electrical energy and the denominator accounts for the considered volume of the heat generation region.
The threshold temperature for thermal coagulation in skin exposed to a 10 to 20 ms heating pulse is calculated to be about 70° C. See, Welch, A. J., and Martin J C van Gemert. In Optical-Thermal Response of Laser-Irradiated Tissue, Boston, MA: Springer US, 1995. That temperature corresponds to a temperature rise of about ΔT=35° C. from normal skin temperature. The corresponding threshold value for the deposited energy density that leads to thermal coagulation in 10 to 20 ms heating pulse can be calculated as Qcth=ρcΔT=0.16 J/mm3, where ρ=1.2 g/cm3 is the skin density and c=3.8 J/g° K is the skin heat capacity.
Instead of the deposited input energy density, Qin, it is more convenient to consider the normalized input energy density, Qin/Qcth, values of normalized input energy density above 1 correspond to a necessary condition for forming coagulated stripes on the dermis/fat junction in contact with the RF delivery cannula. The normalized input energy density, Qin/Qcth, for a range of delivered RF energy per unit cannula length, Ein/L, is plotted on
The plot in
Similar estimates can be made for a 1 mm diameter cannula without suction capabilities that can be used for neck tightening in applications similar to the 1440 nm laser. For a 1 mm cannula, the approximate RF pulse powers that will deliver coagulation threshold energies in approximately 10 ms in energy control mode are estimated between 30 W and 70 W.
Referring now to
The annular shaped RF electrode (e.g., the aperture(s) 530 having the shape of a hole or circle) when the aperture(s) 530 are energized via pulsed RF energy the most efficient heat generation occurs in the adjacent aqueous media near the edge of the annular shaped RF electrode also referred to as the aperture 530. This heat generation region has a diameter 545 determined by the gradient of the current density which will vary in accordance with the thickness of the conductive region of the aperture, see, e.g.,
When the practitioner moves the cannula near the dermis/fat junction, multiple coagulated toroidal like volumes 645 on the dermis/fat junction can be created over multiple RF pulses delivered under pulsed energy control accommodating variable impedance. Due to the relatively higher impedance in adipose tissue, a lower volumetric density of RF pulsed energy will be delivered by each pulse through the annular electrodes exposed to tumesced adipose tissue. In addition, there could be some RF power leakage by capacitive coupling through the electrical insulator coated cannula surface. The unconfined heating over multiple on- and off-time cycles is expected to lead to temperature rise in the adipose tissue with minimal to no localized thermal damage. The temperature rise in the adipose tissue will provide generalized heating to the overlying dermis. Another advantage of the pulsed RF energy control mode of operation is that it provides consistent average power delivery and generalized heating energy dosing in the tissues near the dermal/fat junction with variable RF impedance.
In the present analysis the toroidal-like shape of the volume of water that is heated by each annular electrode will be approximated with a cylinder with variable diameter 545 and length that matches the circumference of the annular shaped RF electrode. The diameter of the cylinder can be chosen so that its volume matches approximately the heat generation water volume in the vicinity of the annular shaped electrode. In the approximate model the cylinders are considered to be heated by a source depositing uniform energy density in their volume. The calculated peak normalized temperature rises in the heated toroidal like regions near the annular RF electrodes at the end of the pulse for a range of heat generation region diameters, d, (e.g., the diameters of the toroidal are plotted on
The plots on
The finite amount of RF power that can be delivered over the time intervals corresponding to heat confinement in the range of considered diameters of heat generation region sets a practical limit for the number of annular electrodes on the cannula and their diameter. Assuming heat confinement, the deposited input energy density can be calculated as
where Ein is the delivered RF electrical energy and the denominator accounts for the considered cylindrical volume of heated water. In designs where multiple annular electrodes or apertures are desired, S is the total circumferential length of the annular electrode aperture(s).
In the preceding section the threshold value for the deposited energy density that leads to thermal coagulation by a heating pulse delivered under the conditions for heat confinement was calculated as Qcth=ρcΔT=0.16 J/mm3. The normalized input energy density, Qin/Qcth, for a range of delivered RF energy per unit length of annular electrode(s), Ein/S, is plotted on
The plot in
It is remarkable that the calculated RF pulse energy per pulse of 0.38 to 0.76 J/pulse for localized coagulation with a typical cannula with four annular electrodes is substantially smaller than the calculated energy per pulse of 1 to 2 J/pulse for a typical cannula delivering RF power throughout its surface. The four annular electrodes are expected to deliver more localized tissue coagulation and a substantially slower generalized heating and temperature rise in the skin overlaying the treated region provided the two styles of cannulas are used at the same repetition rate of pulsed energy delivery. One possible way of increasing the rate of generalized heating with the four annular electrodes cannula is to increase the repetition rate of pulsed energy delivery to 40 or 50 Hz. These higher repetition rates might be feasible for desired on-times between 3 and 10 ms with the four annular electrodes cannula.
In one embodiment, a cannula has nine apertures total, specifically, the cannula has three rows containing apertures and each row has three apertures. Each of the set of three apertures in the three rows is separated by 120 degrees from the adjacent aperture in the next row about the circumference of the cannula. In one embodiment, continuous RF power is applied to the cannula with an inner diameter of 2.1 mm and having nine apertures and the cannula was employed to remove tumesced adipose tissue from a patient. The nine apertures pulled in too much tumesced adipose tissue to cause clogging in the cannula. The practitioner attempted to remove the clog by reverse suction and/or manual removal (e.g., via toothbrush or via pick). However, the clog became charred and stuck within the cannula and could not be recovered from such that the cannula could no longer be used for liposuction and needed to be replaced.
The
The leaking of heated aspiration fluid at the treatment site and/or thermal conduction down the external surface of the insulated probe wall can cause unwanted thermal damage to the incision site. In procedures where the heating level of the aspirate and/or probe is relatively high for the area being treated additional measures may be taken to avoid unwanted damage at the incision site. For example, to address and mitigate the risk of unwanted heating at the incision site, a skin port may be employed. The skin port can be a simple plastic insulative bushing that protects the skin incision from friction of probe oscillations and/or thermal events that may cause a burn, effect healing of the incision site, or cause unwanted heating of the incision site. A commercially available skin port can be used to protect the incision site.
Alternatively, one or more skin ports may be employed that are tailored to the RF liposuction probe disclosed herein. For example, in one embodiment, referring to
While commercially available skin ports may penetrate the skin by approximately 1 cm, extensions of the portion that penetrates the skin may offer additional protection. This is significant since the heat buildup of the surrounding tissue may be greater near the fulcrum point of insertion; a deeper skin port could better protect the deeper tissue about the insertion region from unintended heating. A simple solution to this is shown in
Suitable skin ports have a tubular protrusion that enters into the skin and is buried to a depth of greater than 5 mm and less than 50 mm. In embodiments disclosed herein, the protrusion buried to a depth in the body of the subject offers thermal protection to the skin by serving as a barrier between an RF probe that is hot and the surrounding skin. The thermal insulation of the skin port tubular protrusion can be achieved through bulk plastic, aerated plastic, tube-in-tube stainless steel configurations and vacuum sealed stainless-steel cannulas. The thermal insulation can be either on the probe or the introducer described here. A commercially available skin port is shown in, for example,
The introducer design is configured to allow for oscillatory movement of the probe within the tubular introducer as well as freedom to change the angle of approach relative to the skin's surface. Generally, the skin port is anchored to the skin's surface with sutures, staples or may simply be held by the elasticity of the skin. The rings that are shown in
One method of allowing the angular freedom relative to the skin's surface is shown in
Alternatively, the flexible membrane may be fashioned from a harder plastic but made thin and possibly having cutouts to allow more flexibility. An exemplary design is shown in
Referring now to
Systems and methods utilizing energy to cut, remove, and/or treat adipose tissue and other tissue using an integrated system and one or more probes are described herein. In various aspects, the present teachings can provide a cooled (or uncooled) treatment to achieve one or more of body sculpting (lipolysis), skin tightening (laxity improvement), cellulite treatment apparatus, tissue rejuvenation, and treatment of other conditions, by way of non-limiting examples. In some embodiments, RF-based probes may be used that operate in a pulsed mode or a continuous mode. In many embodiments, one or more probes and the system are configured for radio frequency assisted liposuction and/or RF-based probes that generate bubbles that enhance treatment or removal upon the collapse of such bubbles.
It will be appreciated that for clarity, this disclosure explicates various aspects of embodiments of the applicant's teachings, while omitting certain specific details wherever convenient or appropriate to do so. For example, discussion of like or analogous features in alternative embodiments may be somewhat abbreviated. Well-known ideas or concepts may also for brevity not be discussed in any great detail. The skilled person will recognize that some embodiments of the applicant's teachings may not require certain of the specifically described details in every implementation, which are set forth herein only to provide a thorough understanding of the embodiments. Similarly, it will be apparent that the described embodiments may be susceptible to alteration or variation according to common general knowledge without departing from the scope of the disclosure. The following detailed description of embodiments is not to be regarded as limiting the scope of the applicant's teachings in any manner.
The terms “about” and “substantially and “approximately” as used herein, refer to variations in a numerical quantity that can occur, for example, through measuring or handling procedures in the real world; through inadvertent error in these procedures; through differences/faults in the manufacture of electrical elements; through electrical losses; as well as variations that would be recognized by one skilled in the art as being equivalent so long as such variations do not encompass known values practiced by the prior art. Typically, the term “about” means greater or lesser than the value or range of values stated by 1/10 of the stated value, e.g., ±10%. For instance, applying a voltage of about +3V DC to an element can mean a voltage between +2.7V DC and +3.3V DC. Likewise, wherein values are said to be “substantially identical,” the values may differ by up to 5%. Whether or not modified by the term “about” or “substantially” identical, quantitative values recited in the claims include equivalents to the recited values, e.g., variations in the numerical quantity of such values that can occur, but would be recognized to be equivalents by a person skilled in the art.
Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. To aid the Patent Office and any readers of any patent issued on this application in interpreting the claims appended hereto or otherwise presented throughout prosecution of this or any continuing patent application, applicants wish to note that they do not intend any claimed feature to be construed under or otherwise to invoke the provisions of 35 USC 112 (f), unless the phrase “means for” or “step for” is explicitly used in the particular claim.
All of the drawings submitted herewith include one or more ornamental features and views, each of which include solid lines any of which also incorporate and correspond to and provide support for dotted lines and alternatively, each of which include dotted lines any of which also incorporate and correspond to and provide support for solid lines.
The use of the terms “include,” “includes,” “including,” “have,” “has,” or “having” should be generally understood as open-ended and non-limiting unless specifically stated otherwise.
The use of the singular herein includes the plural (and vice versa) unless specifically stated otherwise. Moreover, the singular forms “a,” “an,” and “the” include plural forms unless the context clearly dictates otherwise. In addition, where the use of the term “about” is before a quantitative value, the present teachings also include the specific quantitative value itself, unless specifically stated otherwise.
It should be understood that the order of steps or order for performing certain actions is immaterial so long as the present teachings remain operable. Moreover, two or more steps or actions may be conducted simultaneously.
Where a range or list of values is provided, each intervening value between the upper and lower limits of that range or list of values is individually contemplated and is encompassed within the disclosure as if each value were specifically enumerated herein. In addition, smaller ranges between and including the upper and lower limits of a given range are contemplated and encompassed within the disclosure. The listing of exemplary values or ranges is not a disclaimer of other values or ranges between and including the upper and lower limits of a given range.
It should be appreciated that numerous changes can be made to the disclosed embodiments without departing from the scope of the present teachings. While the foregoing figures and examples refer to specific elements, this is intended to be by way of example and illustration only and not by way of limitation. It should be appreciated by the person skilled in the art that various changes can be made in form and details to the disclosed embodiments without departing from the scope of the teachings encompassed by the appended claims.
This application claims priority to and benefit of U.S. Provisional Patent Application No. 63/523,304, filed on Jun. 26, 2023, the entirety of which is incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 63523304 | Jun 2023 | US |
