Control system for ultrasonic handpiece

Abstract

A control system for an ultrasonic handpiece is provided. The control system includes: a perfusion pressure sensor configured to measure a pressure of a perfusion fluid; an ultrasonic power source configured to provide power to the ultrasonic transducer; and a controller. The controller is configured to: receive a selection of an ultrasonic power modality; generating a control signal based on the selected ultrasonic power modality; providing the control signal to the ultrasonic power source; determining a perfusion flow rate according to the measured perfusion pressure provided by the perfusion pressure sensor; calculating a thermal index value based on the perfusion flow and the selected ultrasound power modality; and adjust the control signal based on the thermal index value in response to the thermal index value reaching a threshold. The ultrasonic power mode is one of a two-dimensional power mode and a three-dimensional power mode.

Description

Cross-reference to related applications

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 588,951 (filed on October 9, 2023), the contents of which are incorporated herein by reference in their entirety. Background Technology

[0002] A typical ultrasound surgical apparatus / system for ophthalmic surgery includes an ultrasound-driven handpiece, an attached hollow working end, an infusion sleeve, and an electronic control console. The handpiece assembly is attached to the control console via cables and a flexible tube. The control console modulates the power level transmitted from the handpiece to the attached working end via cables, and the flexible tube is used to supply infusion fluid through the infusion subsystem and to aspirate fluid and other particles, such as emulsified tissue, from the eye through the aspiration subsystem. Summary of the Invention

[0003] In some embodiments, a control system for an ultrasonic handheld device is provided. The control system includes: an infusion pressure sensor configured to measure the pressure of an infusion fluid; an ultrasonic power source configured to provide power to an ultrasonic transducer; and a controller coupled to the infusion pressure sensor and the ultrasonic power source. The controller is configured to: receive selection of an ultrasonic power mode; generate a control signal based on the selected ultrasonic power mode; provide the control signal to the ultrasonic power source; determine an infusion flow rate based on the measured infusion pressure provided by the infusion pressure sensor; calculate a thermal index value based on the infusion flow rate and the selected ultrasonic power mode; and adjust the control signal based on the thermal index value in response to the thermal index value reaching a threshold value. The ultrasonic power mode is one of a two-dimensional power mode and a three-dimensional power mode.

[0004] In some embodiments, the two-dimensional power mode is one of the longitudinal power mode and the torsional power mode, and the three-dimensional power mode is a combination of the longitudinal power mode and the torsional power mode.

[0005] In some embodiments, the control system further includes a temperature sensor configured to measure the temperature of the perfusion fluid, and the calculation of the thermal index value is also based on the measured temperature.

[0006] The following description and accompanying drawings illustrate certain illustrative features of one or more embodiments. Attached Figure Description

[0007] The accompanying drawings depict certain aspects of one or more of the disclosed embodiments and should therefore not be construed as limiting the scope of this disclosure.

[0008] Figure 1A Examples of ultrasonic emulsification systems according to certain embodiments are shown.

[0009] Figure 1B Demonstrates certain embodiments Figure 1A An example of a subsystem of an ultrasonic emulsification system.

[0010] Figure 1C According to certain embodiments Figure 1A ultrasonic emulsification system and Figure 1B Block diagram and 3D view of the handheld component of the subsystem.

[0011] Figure 2A According to certain embodiments Figure 1A A block diagram of an embodiment of the control system of an ultrasonic emulsification system.

[0012] Figure 2B According to certain embodiments Figure 1A A block diagram of another embodiment of the control system of the ultrasonic emulsification system.

[0013] Figures 3A to 3B It is a description of the composition according to certain embodiments. Figures 2A to 2B A graph illustrating exemplary operation of thermal management performed by the control system.

[0014] Figure 4 A flowchart illustrating a technique for controlling the power supplied to an ultrasonic handheld device according to certain embodiments is shown.

[0015] To facilitate understanding, the same reference numerals are used where possible to refer to common elements in the figures. It is contemplated that elements and features of one embodiment can be advantageously combined in other embodiments without further description. Detailed Implementation

[0016] In some examples of the aforementioned ultrasonic surgical apparatus / systems, the operating portion of the ultrasonically driven handpiece is a centrally positioned hollow resonant rod or amplitude transformer directly attached to one or more ultrasonic transducers (such as a set of piezoelectric crystals) forming a piezoelectric element assembly. The crystals supply the ultrasonic vibrations required to drive both the amplitude transformer and the attached working tip during ultrasonic emulsification, and the crystals are controlled by a console. The crystal / amplifier assembly is suspended within the hollow body or housing of the handpiece. The handpiece body terminates at its distal end with a reduced-diameter portion or a nose cone. The nose cone is externally threaded to receive an infusion sleeve. Similarly, the amplitude transformer bore at its distal end is internally threaded to receive the external thread of the working tip. The infusion sleeve also has an internally threaded bore that is screwed onto the external thread of the nose cone. The working tip is adjusted such that it protrudes a predetermined amount only through the open end of the infusion sleeve.

[0017] When used to perform phacoemulsification, the working tip and the end of the infusion sleeve are inserted into a small incision of predetermined width in the cornea, sclera, or other location in the eye tissue to access the anterior chamber of the eye. A lens-driven ultrasonic amplifier causes the working tip to vibrate ultrasonically along its longitudinal axis within the infusion sleeve, thereby emulsifying the selected tissue in situ upon contact. A hollow hole in the working tip communicates with a hole on the amplifier, which in turn communicates with an aspiration line from the handpiece to the control console. A depressurization or vacuum source in the control console passes through the open end of the working tip, the hole in the working tip, the amplifier hole, and the aspiration line to aspirate or aspirate the emulsified tissue from the eye and into a collection device. Aspiration of the emulsified tissue is aided by injecting an irrigation fluid (such as a saline irrigation solution) into the surgical site through a small annular gap between the inner surface of the infusion sleeve and the outer surface of the working tip.

[0018] Unwanted heating can occur at the surgical site when too much power is applied to the handpiece at too low an infusion flow rate. Friction between the infusion sleeve and the tip is a primary source of heat. Heat is generated when the tip rubs against the sleeve. Because different power modes involve different shapes and / or movements of the tip, the increase in heat at the surgical site can vary due to the different thermal behaviors of each power mode. In these cases, thermal management techniques may not take into account these different thermal behaviors.

[0019] Accordingly, certain embodiments described herein provide systems for preventing overheating of the surgical site by controlling the amount of power supplied to the handpiece based on the handpiece's power mode. These systems take into account the power mode of the handpiece when determining the thermal index value at the end of the handpiece and automatically reduce the amount of power supplied to the handpiece in response to the thermal index value reaching a threshold that could cause burns. By automatically reducing the supplied power when the threshold is reached, the system reduces the likelihood of burns at the surgical site.

[0020] refer to Figures 1A to 1C The ultrasonic emulsification system, its subsystems, and examples of its handheld components are described in further detail.

[0021] Figure 1A Examples of an ultrasonic emulsification system 100 according to certain embodiments are shown. The ultrasonic emulsification system 100 can be used to perform ophthalmic surgery on the eye 110. Figure 1AAs shown, the phacoemulsification system 100 includes multiple components in a fluid path through the eye 110 (e.g., during cataract surgery). In some embodiments, these components include an infusion fluid source 102, an infusion pressure sensor 104, an infusion valve 106, an infusion line 108, a handheld device 112, a suction line 114, a suction pressure sensor 116, a vent valve 118, a pump 120, a reservoir 122, and a discharge bag 124. The infusion line 108 can provide an infusion fluid to the eye 110, such as a balanced salt solution (BSS), an alkaline saline solution containing a drug, a perfluorocarbon liquid, a viscoelastic substance, or other similar fluid, and the suction line 114 can remove fluid and / or other particles from the eye 110, such as emulsified lens particles.

[0022] As the infusion fluid leaves the infusion fluid source 102, it travels through the infusion line 108 and enters the eye 110 via the handpiece 112. An infusion pressure sensor 104 can be configured to measure the pressure of the infusion fluid in the infusion line 108. The measured pressure of the infusion fluid may be referred to herein as “measured infusion pressure” or “infusion pressure measurement.” An infusion valve 106 may also be optionally configured to control the infusion on / off. The infusion pressure sensor 104 is implemented using any of a variety of commercially available fluid pressure sensors and can be located anywhere in the infusion fluid path between the infusion fluid source 102 and the eye 110.

[0023] The handheld component 112 can be placed in the eye 110 during ophthalmic surgery (such as phacoemulsification). The handheld component 112 has a working end (such as...). Figure 1C (As seen in the image), the working tip can be ultrasonically vibrated within the eye 110 to break up diseased lenses, etc. A sleeve positioned around the working tip provides perfusion fluid from the perfusion line 108. The perfusion fluid passes through the space between the outer side of the working tip and the inner side of the sleeve. Fluid and / or lens particles are aspirated through the working tip. In this way, the internal passage of the working tip can be fluidly connected to the aspiration line 114. A pump 120 draws the aspirated fluid from the eye 110. Aspiration pressure sensor 116 measures the pressure in the aspiration line 114. An optional vent valve 118 can be used to ventilate the vacuum generated by the pump 120. The aspirated fluid passes through a reservoir 122 and enters a discharge bag 124.

[0024] Figure 1B An ultrasonic emulsification system 100 according to certain embodiments is shown. Figure 1A Example of subsystem 101. Subsystem 101 includes an infusion fluid source 102, an infusion pressure sensor 104, and a handheld device 112, as shown in the reference. Figure 1BAs described. Although subsystem 101 is shown as including some of the components of ultrasonic emulsification system 100, the subsystem may include more or fewer components of ultrasonic emulsification system 100.

[0025] exist Figure 1B In this embodiment, temperature sensor 126 and power source 128 are coupled to handheld device 112. Temperature sensor 126 may be configured to measure the temperature of the infusion fluid supplied by handheld device 112. The measured temperature of the infusion fluid may be referred to herein as a “temperature measurement.” Power source 128 may be an ultrasonic power source or other similar power source configured to provide ultrasonic power to handheld device 112 to actuate its ultrasonic emulsification tip.

[0026] Although temperature sensor 126 is shown separate from infusion pressure sensor 104, temperature sensor 126 and infusion pressure sensor 104 can be implemented as a single sensor configured to perform the functions of both temperature sensor 126 and infusion pressure sensor 104. As an example, the sensor configured to perform the functions of both temperature sensor 126 and infusion pressure sensor 104 can be implemented in the handpiece 112, on the infusion line 108, or at another location within the ultrasonic emulsification system 100.

[0027] Figure 1C This is a block diagram of a controller 160 according to certain embodiments and an ultrasonic emulsification system 100 ( Figure 1A ) and subsystem 101 ( Figure 1B A perspective view of the handheld device 112. The controller 160 can be configured to control the handheld device 112. The handheld device 112 can be an ultrasonic handheld device, which can be used, for example, to perform phacoemulsification. The handheld device 112 is shown with its housing removed, allowing the components of the handheld device 112 to be seen.

[0028] Handheld component 112 includes an ultrasonic amplitude transformer 130, for example, made of titanium alloy. The amplitude transformer 130 has a plurality of helical slits 132. At least one ultrasonic transducer (such as a piezoelectric element or crystal) forms an ultrasonic transducer assembly (such as a piezoelectric element assembly 134). The piezoelectric element or crystal may be annular and may be held against the amplitude transformer 130 by a clamping nut 136. Some handheld components may include a plurality of piezoelectric element assemblies 134, each physically separated from each other along the longitudinal axis of the handheld component 112, and each piezoelectric element assembly may form a separate assembly / package. Each piezoelectric element assembly 134 may be individually electrically coupled to a controller 160.

[0029] A suction shaft or tube 138 extends along the length of the handpiece 112 through the amplitude rod 130, the piezoelectric element assembly 134, the nut 136, and a plug 140 at the proximal end of the handpiece 112. The suction tube 138 allows material to be drawn through the hollow working end 142 attached to the amplitude rod 130, through the handpiece 112, and out of the handpiece. Although the hollow working end 142 is shown as a straight end, other end configurations (such as a bent end) may also be used. The plug 140 seals the housing of the handpiece 112 to be impermeable to fluids, thereby allowing autoclaving of the handpiece 112 without adversely affecting the piezoelectric element assembly 134. An additional groove 144 may be provided on the amplitude rod 130 for sealing an O-ring gasket.

[0030] Figure 1C The location of the longitudinal and torsional nodes of the handpiece 112 is indicated. The longitudinal and torsional nodes are the locations where the corresponding node velocities are zero. The torsional node 146 is preferably located at the proximal longitudinal node 148, such that the torsional node 146 coincides with the longitudinal node 148 and is located on the stopper 140. The handpiece 112 also includes a distal longitudinal node 150, which is located at the diameter reduction portion 152 of the amplitude rod 130.

[0031] The controller 160 is typically located away from the handheld device 112 and may be part of an electronic control unit. The controller 160 is coupled to the handheld device 112 via a cable or connector 168 at the piezoelectric element assembly 134, or may be coupled via other communication devices. The electronic control unit is further coupled to the handheld device 112 via a flexible tube to provide infusion and aspiration.

[0032] The controller 160 includes a processor 162, a memory 164, and a controller circuitry 166. The processor 162 can be any type of general-purpose processor, or it can be a processor specifically designed for the handheld device 112, such as an application-specific integrated circuit (“ASIC”). The processor 162 can be the same processor that operates the entire handheld device 112, or it can be a separate processor.

[0033] Memory 164 can be any type of storage device or non-transitory computer-readable medium, such as random access memory (“RAM”) or read-only memory (“ROM”). Memory 164 stores instructions executed by processor 162, including instructions for simultaneously (i.e., concurrently) providing multiple oscillation modes via piezoelectric element assembly 134, as well as instructions for providing other functions disclosed herein. In addition to the functions of processor 162, controller circuitry 166 also provides the function of simultaneously providing multiple oscillation modes via piezoelectric element assembly 134. In example embodiments, the functions disclosed herein may be provided by processor 162 and memory 164 (i.e., software-based), by controller circuitry 166 (i.e., hardware-based), or by a combination thereof.

[0034] Control of the ultrasonic power and ultrasonic motion modes of a handheld device (such as handheld device 112) can be implemented through various methods. One method involves a control loop that servo-drives the frequency of a drive voltage using the impedance of a piezoelectric drive transducer as feedback. In this method, the impedance feedback of the piezoelectric transducer is calculated as the ratio of the root mean square (“RMS”) value of the transducer drive voltage to the RMS value of the drive current.

[0035] In some embodiments, controller 160 may be implemented as part of a control system for managing the power supplied to handheld device 112, such as controller 230 described below. Reference Figures 2A to 2B An example of the control system is described in further detail.

[0036] Figure 2A The ultrasonic emulsification system 100 according to certain embodiments ( Figure 1A A block diagram of one embodiment of the control system 200. The control system 200 includes a controller 230 connected to a power source 228 (e.g., an ultrasonic power source), an infusion pressure sensor 204, and a temperature sensor 226, as shown in the reference. Figures 1A to 1C As described. In this manner, controller 230 is connected to infusion pressure sensor 204, temperature sensor 226, and power source 228. Although not shown, controller 230 can be connected to handheld device 112 ( Figures 1A to 1C The handheld device can be, for example, an ultrasonic emulsification handheld device.

[0037] In some embodiments, controller 230 receives infusion pressure information from infusion pressure sensor 204, infusion fluid temperature information from temperature sensor 226, and ultrasonic power mode information from power source 228. Controller 230 also interfaces with and controls the operation of power source 228, thereby controlling the power supplied to handheld device 112. Figures 1A to 1CIn other words, controller 230 is configured to generate control signals provided to power source 228 to control the ultrasonic power mode.

[0038] The ultrasonic power mode can be selected from two-dimensional (2D) power modes (such as longitudinal power mode, torsional power mode, etc.) and three-dimensional (3D) power modes (such as combinations of longitudinal and torsional power modes, etc.). When the handheld component 112 is operated using the longitudinal power mode, the end of the handheld component 112 can move longitudinally (e.g., vertically up and down). When the handheld component 112 is operated using the torsional power mode, the end of the handheld component 112 can move rotationally (e.g., clockwise and counterclockwise). When the handheld component 112 is operated using the 3D power mode, the end of the handheld component 112 can move both vertically and rotationally (e.g., vertically up / down and clockwise / counterclockwise). Due to the different thermal behaviors caused by the different shapes and / or movements of the end of the handheld component 112, each power mode may increase the thermal index value in different ways.

[0039] Unwanted heating may occur at the incision site when too much power is applied to the handpiece 112 at too low an infusion flow rate. Heating can occur when the flow rate decreases (e.g., when blockage occurs) because the infusion fluid carries away heat. Typically, the amount of heat generated is a function of the amount of power applied to the handpiece 112 and the infusion flow rate. Friction between the infusion sleeve and the ultrasonic emulsification tip is the primary source of heat. Heat is generated when the tip rubs against the sleeve. The amount of power applied to the handpiece 112 is linearly related to the tip travel or the distance the tip travels. The greater the power applied, the more the tip travels (and the more friction there is between the tip and the sleeve).

[0040] In some embodiments, the thermal index value is provided in degrees Celsius (°C). The perfusion flow rate is provided in cubic centimeters per minute (cc / min) based on a double-exponential Green's (impulse response) function with six pre-optimized coefficients. ) and the ultrasound power modes provided as a percentage (%) that can be extracted from the surgical console. It is estimated based on the heat index value. In other words, the heat index value ( The following is given by Equation 1: (Equation 1) Where, Indicates the first thermal rise coefficient; Indicates the second thermal rise coefficient; Indicates the first air attenuation coefficient; This represents the second air attenuation coefficient; Indicates the first flow rate attenuation coefficient; The second flow rate attenuation coefficient is represented by F; the flow rate determined based on the measured infusion pressure is represented by P; and the ultrasonic power provided is represented by P. and Represents the dummy integral variable; and This indicates the temperature of the infusion fluid, which can be determined by a temperature sensor (e.g., temperature sensor 126). Figure 1B ) or 226 ( Figure 2A ))supply.

[0041] In other words, the thermal rise coefficient controls the change in thermal index value due to the change in the provided ultrasonic power mode, the air attenuation coefficient controls the thermal index response to environmental conditions, and the flow attenuation coefficient controls the thermal index response to changes in perfusion flow rate. The 2D longitudinal power mode and the 2D torsional power mode can linearly increase the thermal index value, while the 3D power mode can non-linearly increase the thermal index value.

[0042] In this way, the controller 230 can be configured to calculate the thermal index value based on the perfusion flow rate, the temperature of the perfusion fluid, and the ultrasonic power mode. The perfusion flow rate can be determined based on the perfusion pressure. For example, since the cross-sectional area of ​​the perfusion path is known, the perfusion flow rate through the perfusion line can be determined based on the perfusion pressure measurement received from the perfusion pressure sensor. The temperature of the perfusion fluid can be determined based on the temperature of the perfusion fluid received from the temperature sensor. The ultrasonic power mode can be selected by the user (e.g., a surgeon).

[0043] The calculated thermal index value provides an estimate of the actual temperature experienced at the incision site where burns are most likely to occur. Because the temperature sensor determines the temperature of the infusion fluid, an absolute thermal index value can be calculated instead of a relative thermal index value.

[0044] Although the calculated thermal index value is described as being based on perfusion flow rate, perfusion fluid temperature, and ultrasonic power mode, it can also be determined without the temperature of the perfusion fluid. In other words, the control system may not include a temperature sensor, and the thermal index value can be calculated based on perfusion flow rate and ultrasonic power mode. Therefore, the calculated thermal index value ( It can be a function of the power (P) applied to the handpiece and the infusion flow rate (F); in other words, = f(P, F).

[0045] Since the calculated heat index value provides an estimate of the actual temperature, a threshold (such as a threshold heat index value) can be used to control the ultrasonic power supplied to the handheld device. For example, in response to the calculated heat index value reaching a threshold (e.g., when the calculated heat index value reaches a threshold), the ultrasonic power is reduced to decrease the likelihood of heating. The threshold can be based on a sensitivity level representing the friction between the infusion sleeve and the ultrasonic emulsification tip of the ultrasonic handheld device. The sensitivity level can be input, set, adjusted, etc., by the user. Furthermore, in some embodiments, the heat index (… ) and the temperature rise of the incision above the ambient temperature ( ( ) are compared to evaluate the overall accuracy of the power control process.

[0046] like Figure 2A As seen, controller 230 can receive infusion pressure measurements from infusion pressure sensor 204 (which are used to determine infusion flow rate) and the temperature of the infusion fluid from temperature sensor 226. Since controller 230 controls power source 228, controller 230 also has the capability to apply power to handheld device 112. Figures 1A to 1C The controller 230 uses these three values ​​(in combination with the coefficient of friction) to calculate the estimated actual temperature at the cut site. In this way, the controller 230 continuously or periodically calculates the thermal index value. = f(P, F, Tp). The calculated thermal index value is continuously or periodically compared with a threshold. In response to the calculated thermal index value reaching the threshold, the power of the handheld device is reduced. In some embodiments, the controller 230 may be configured to adjust the thermal index value based on the temperature of the infusion fluid over time, and to calculate the change in the thermal index value as the temperature of the infusion fluid changes continuously.

[0047] In some embodiments, the calculated thermal index value is used as input to control, adjust, etc., the amount of power supplied to the handheld device. In this way, when the calculated thermal index value reaches a threshold, the actual power applied to the handheld device follows the reciprocal of the calculated thermal index value. In other words, the power level indicated by the control signal provided to the power source follows the reciprocal of the segment of the calculated thermal index value that reaches the threshold thermal index value. This will be referred to... Figures 3A to 3B Let me describe it in more detail.

[0048] As described, the threshold can be input, set, adjusted, etc., by the user, or it can be preset. A range of thresholds can be selected, each of which provides a level of protection against unwanted corneal burns. For example, the highest threshold in the range can be set to a value that minimizes the difference between the corneal burn temperature and the threshold (e.g., 1°F). A lower threshold can be set such that the difference between the corneal burn temperature and the threshold is much larger (around 10°F).

[0049] Regardless of the selected threshold, the ultrasonic power supplied to the handheld device can be adjusted in response to the calculated thermal index value reaching the threshold (i.e., when the calculated thermal index value is equal to or greater than the threshold). When the calculated thermal index value is less than the threshold, the ultrasonic power supplied to the handheld device is not adjusted, and the ultrasonic power is controlled by the selected ultrasonic power mode. (Reference) Figure 2B This process is performed by the control system in further detail.

[0050] Figure 2B The ultrasonic emulsification system 100 according to certain embodiments ( Figure 1A A block diagram of another embodiment of the control system 202. Figure 2B The control system 202 shown illustrates the process in operation more clearly.

[0051] The controller 230 calculates the calculated thermal index value based on data received from the injection pressure sensor 204, data received from the temperature sensor 226, and power from the power source 228. Figure 2B In this process, controller 230 can provide proportional-integral (PI) control, proportional-integral-derivative (PID) control, etc. The power applied to the handheld device can be reduced by subtracting the reciprocal of the proportionally scaled calculated thermal index value from the power. In this way, controller 230 controls the output of power source 228 by adjusting the control signal provided to power source 228.

[0052] Therefore, the adjusted control signal indicates that the power output from power source 228 is reduced by an amount inversely proportional to the calculated thermal index value (or by an amount inversely proportional to the thermal index value exceeding a threshold), indicated by xT, where x can be a scalar or a function. In this way, when the calculated thermal index value reaches the threshold, the power supplied to the handheld device is reduced proportionally to the amount exceeding the threshold. When the calculated thermal index value is less than the threshold, normal operation resumes.

[0053] The control process can be performed during ophthalmic surgery. Typically, during surgery, the surgeon manually controls the application of ultrasound power to the handheld device, for example, by using a foot pedal. The control process can override manual power control when the calculated thermal index value reaches a threshold, and can revert to manual power control when the calculated thermal index value falls below the threshold.

[0054] The control procedure advantageously allows surgeons to easily focus on ophthalmic surgery by automatically reducing the ultrasound power supplied to the handpiece upon reaching a threshold, thereby reducing the likelihood of burns at the incision site. Due to this non-invasive control procedure, surgeons can continue the procedure while maintaining thermal safety. Furthermore, the control procedure offers flexibility because it can be adjusted according to different sensitivity levels. Moreover, the control procedure is an additional safety feature that may be beneficial for less experienced surgeons.

[0055] Figures 3A to 3B It describes a control system 200 according to certain embodiments. Figure 2A ) and 202 ( Figure 2B A graph illustrating exemplary operation of thermal management. For clarity, this document will... Figures 3A to 3B Combined descriptions. Figure 3A It is a graph 300 depicting the change of ultrasonic power (y-axis) with time (x-axis) in response to the calculated thermal index value. Figure 3B It describes the thermal index (or temperature index) value calculated during operation of the handheld device (e.g., handheld device 112). ) (y-axis) versus time (x-axis) curve 302.

[0056] In some embodiments, Figure 3A The ultrasonic power quantity shown represents the power level specified by the control signal provided by controller 230 to power source 228. The power level specified by the control signal may be based on ultrasonic power modes. In some embodiments, Figure 3B The calculated thermal index value shown represents the calculated temperature at the end of the handheld component 112, which can be calculated by the controller 230.

[0057] Before operating the handheld device 112, the calculated thermal index value can be equal to the temperature of the injection fluid ( When the calculated heat index value is lower than the threshold ( When performing ultrasound, the surgeon can apply an ultrasound power mode to the handheld device. As an example, the ultrasound power mode can be a 2D power mode or a 3D power mode, and can be adjusted by a foot pedal. As depicted, the surgeon applies 100% power to the handheld device and adjusts it from 0% to 100% by manipulating a foot pedal connected to the controller. Alternatively, when the foot pedal is depressed, power can be applied to the handheld device via power application techniques. For example, the power application techniques can be continuous mode, burst mode, or pulse mode.

[0058] When the calculated heat index reaches a threshold, the control process overrides the surgeon's power control to prevent the calculated heat index from exceeding the threshold further. As the power decreases, the calculated heat index will also tend to decrease. When the calculated heat index is below the threshold, the surgeon reverts to manual power control, in which case the applied power returns to 100%.

[0059] In continuous mode, the degree to which the foot pedal is pressed or the position of the foot pedal determines the amount or level of power applied. The control process reduces the power proportionally to temperature rises exceeding a threshold. In other words, incremental temperature increases exceeding a threshold cause a proportional reduction in the amount of power applied to the handpiece. This power reduction can be smooth, ensuring that power is still smoothly applied to the end of the handpiece.

[0060] In pulse mode, a series of fixed-width power pulses are applied to the handheld device. The surgeon controls the amplitude or power level of the pulses using a foot pedal. In this way, the position of the foot pedal determines the power level of the pulses. The control process can non-linearly reduce the power of any given pulse, allowing the process to act on a single pulse or a series of pulses as needed.

[0061] In some embodiments, an incremental temperature rise exceeding a threshold causes a proportional reduction in the amount of power applied to the handpiece operating in pulse mode. This power reduction can be incremental, such that the incremental reduction in power still results in power being applied to the cutting edge of the handpiece. The control process can operate to reduce the power of the next pulse while maintaining a constant pulse level, such that the control process acts on the next pulse and limits the power level of this next pulse to a constant power level.

[0062] In burst mode, a series of pulses are applied to the handpiece. The surgeon controls the off-time between pulses using a foot pedal. In this way, the position of the foot pedal determines the off-time between pulses. The control process reduces power proportionally to temperature rises exceeding a threshold. In other words, incremental temperature increases exceeding a threshold cause a proportional reduction in the amount of power applied to the handpiece. This smooth reduction in power still ensures that power is smoothly applied to the cutting edge of the handpiece. The control process non-linearly reduces the power of any given pulse, allowing the process to act on a single pulse or a series of pulses.

[0063] In some embodiments, an incremental temperature rise exceeding a threshold causes a proportional reduction in the amount of power applied to the handpiece operating in burst mode. This power reduction can be incremental, such that the incremental reduction in power still results in power being applied to the cutting edge of the handpiece. The control process reduces the power of the next pulse while maintaining a constant pulse level, such that the control process acts on the next pulse and limits the power level of this next pulse to a constant power level.

[0064] Several variations of the control process can also be implemented. In one embodiment, the power is reduced proportionally to a scalar factor of temperature increase. In another embodiment, the power is reduced proportionally to a function of temperature increase. In yet another embodiment, a minimum power level can be set, and in this case, the power will not drop below the minimum power level, resulting in a continuous but lower power application to the handpiece. In yet another embodiment, the rate of power reduction can be varied, and in this case, the power reduction is smooth. A smooth reduction in power results in more efficient cutting because the power is continuously applied (i.e., not turned off), which may give the surgeon better feel.

[0065] As can be understood from the foregoing, this disclosure provides a thermal management process for phacoemulsification surgery. This disclosure provides a control system that calculates a thermal index value, compares the calculated thermal index value with a threshold value, and reduces the power supplied to the handpiece when the calculated thermal index value reaches the threshold value. This disclosure is illustrated by example, and various modifications can be made by those skilled in the art.

[0066] Figure 4 A flowchart illustrating a technique for controlling the power supplied to an ultrasonic handheld device according to certain embodiments is shown.

[0067] At box 402, the selection of an ultrasonic power mode is received. The selection of the ultrasonic power mode can be received via user input and transmitted to controller 230. That is, the user can input a selected ultrasonic power mode, which is then transmitted to controller 230 as digital data. Controller 230 then receives the digital data containing the selected ultrasonic power mode. The ultrasonic power mode is one of a two-dimensional power mode or a three-dimensional power mode.

[0068] At block 404, as described above, a control signal is generated based on the selected ultrasonic power mode. The control signal can be generated by controller 230 after the controller has received the selected ultrasonic power mode at block 402.

[0069] At box 406, a control signal is provided to the ultrasonic power source. The control signal can be provided to the power source 228 by the controller 230. For example, the controller 230 can transmit the control signal to the power source 228 as digital data or as an analog signal.

[0070] At box 408, an infusion pressure measurement is received from an infusion pressure sensor. The infusion pressure can be measured by infusion pressure sensor 204 and transmitted to controller 230. Infusion pressure sensor 204 can record the infusion pressure measurement and convert it into digital data, which is then transmitted to controller 230 as measured digital data (or as an analog signal). Controller 230 receives the measured digital data and can then analyze the infusion pressure measurement.

[0071] At box 410, the infusion flow rate is determined based on the infusion pressure measurement. The infusion flow rate can be determined by controller 230 using the infusion pressure measurement received from infusion pressure sensor 204 at box 408.

[0072] At box 412, as described above, the thermal index value is calculated based on the perfusion flow rate and the selected ultrasonic power mode. The thermal index value can be calculated by controller 230. That is, controller 230 can calculate the thermal index value based on the perfusion flow rate determined according to the pressure data measured by perfusion pressure sensor 204 and the selected ultrasonic power mode input by the user.

[0073] At box 414, when the heat index value reaches a threshold, the control signal is adjusted based on the heat index value. Controller 230 can adjust the control signal. That is, controller 230 can compare the calculated heat index value with the threshold, and if the calculated heat index value is greater than or equal to the threshold, controller 230 adjusts the control signal.

[0074] The foregoing description is provided to enable any person skilled in the art to practice the various embodiments described herein. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments. Therefore, the claims are not intended to limit them to the embodiments shown herein, but are given the full scope consistent with the language of the claims.

[0075] It will be readily understood that components, as generally described herein and illustrated in the accompanying drawings, can be arranged and designed in a wide variety of different configurations. Therefore, the more detailed description of the various embodiments below, as illustrated in the drawings, is not intended to limit the scope of this disclosure, but rather represents various embodiments only. While various aspects of the embodiments are presented in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0076] This disclosure may be implemented in other specific forms without departing from the spirit or essential characteristics thereof. The described embodiments are to be considered in all respects as illustrative rather than restrictive. Therefore, the scope of this disclosure is indicated by the appended claims rather than by this specific embodiment. All variations within the equivalent meaning and scope of the claims should be included within their scope.

[0077] References to features, advantages, or similar language throughout this specification do not imply that all features and advantages achievable with this disclosure should or actually are present in any single embodiment of this disclosure. Rather, references to features and advantages should be understood as indicating that a particular feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of this disclosure. Therefore, discussions of features and advantages, as well as similar language, throughout this specification may, but do not necessarily, refer to the same embodiment.

[0078] Furthermore, the features, advantages, and characteristics described in this disclosure can be combined in one or more embodiments in any suitable manner. Based on the description herein, those skilled in the art will recognize that this disclosure can be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in some embodiments that may not be present in all embodiments of this disclosure.

[0079] Throughout this specification, references to "an embodiment," "embodiment," or similar language mean that a particular feature, structure, or characteristic described in connection with the indicated embodiment is included in at least one embodiment of this disclosure. Therefore, throughout this specification, the phrases "in an embodiment," "in an embodiment," and similar language may, but do not necessarily, refer to the same embodiment.

Claims

1. A control system for an ultrasonic handheld device, the control system comprising: An infusion pressure sensor configured to measure the pressure of the infusion fluid; An ultrasonic power source, the ultrasonic power source being configured to provide power to an ultrasonic transducer; as well as A controller, connected to the infusion pressure sensor and the ultrasonic power source, is configured to: The receiver selects the ultrasonic power mode. The control signal is generated based on the selected ultrasonic power mode. The control signal is provided to the ultrasonic power source. The infusion flow rate is determined based on the infusion pressure measured by the infusion pressure sensor. The thermal index value is calculated based on the infusion flow rate and the selected ultrasonic power mode, and The control signal is adjusted based on the heat index value in response to the heat index value reaching a threshold. The ultrasonic power mode is one of the two-dimensional power mode and the three-dimensional power mode.

2. The control system of claim 1, further comprising: A temperature sensor, configured to measure the temperature of the perfusion fluid, The calculation of the thermal index value is further based on the measured temperature.

3. The control system as described in claim 2, wherein, The controller is further configured to: The thermal index value is adjusted based on the temperature of the infusion fluid over time; and The change in the thermal index value is calculated as the temperature of the infusion fluid changes continuously.

4. The control system as described in claim 1, wherein, The two-dimensional power mode is one of the longitudinal power mode and the torsional power mode.

5. The control system as described in claim 4, wherein, The three-dimensional power mode is a combination of the longitudinal power mode and the torsional power mode.

6. The control system as described in claim 5, wherein, The calculation of the thermal index value includes nonlinearly increasing the thermal index value when the selected ultrasonic power mode is the three-dimensional power mode.

7. The control system as claimed in claim 1, wherein: The control signal includes a power level; and Adjusting the control signal includes adjusting the power level proportionally to the thermal index value.

8. The control system as described in claim 7, wherein, The adjustment of the power level in proportion to the heat index value includes a reciprocal change following the segment of the heat index value that reaches the threshold.

9. The control system as claimed in claim 7, wherein: The controller is further configured to adjust the power level based on the ultrasonic power mode.

10. The control system as claimed in claim 9, wherein, The controller is further configured to: When the thermal index value reaches the threshold, the manual power control of the ultrasonic power source is activated; and When the thermal index value is less than the threshold, the manual power control of the ultrasonic power source is restored.

11. The control system as claimed in claim 1, wherein, The threshold is based on the sensitivity level representing the friction between the infusion sleeve and the ultrasonic emulsification tip of the ultrasonic handheld device.

12. A method for controlling the power supplied to an ultrasonic handheld device, the method comprising: The receiver selects the ultrasonic power mode; The control signal is generated based on the selected ultrasonic power mode; The control signal is provided to the ultrasonic power source; Receive infusion pressure measurements from the infusion pressure sensor; The infusion flow rate is determined based on the infusion pressure measurement value provided by the infusion pressure sensor; The thermal index value is calculated based on the infusion flow rate and the selected ultrasonic power mode; as well as The control signal is adjusted based on the heat index value in response to the heat index value reaching a threshold. The ultrasonic power mode is one of the two-dimensional power mode and the three-dimensional power mode.

13. The method of claim 12, further comprising: Receive temperature measurements of the infusion fluid from a temperature sensor. The calculation of the thermal index value is further based on the measured temperature.

14. The method of claim 12, wherein, The two-dimensional power mode is one of the longitudinal power mode and the torsional power mode; and The three-dimensional power mode is a combination of the longitudinal power mode and the torsional power mode.

15. The method of claim 12, wherein, The calculation of the thermal index value includes nonlinearly increasing the thermal index value when the selected ultrasonic power mode is the three-dimensional power mode.

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