Powered surgical instrument and method for identifying tissue type with same

Abstract

The present disclosure relates to electric surgical instruments and methods of identifying tissue types therewith, and provides a surgical instrument comprising: an end effector configured to clamp tissue; an electric motor configured to actuate the end effector; and a controller in communication with the electric motor and configured to determine a stress and a strain of the tissue, identify a tissue type of the tissue based on the determined stress and strain of the tissue, and set an operating parameter of the surgical instrument based on the identified tissue type of the tissue.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit and priority of U.S. Provisional Patent Application No. 63 / 027,060, filed May 19, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to surgical instruments. More specifically, it relates to a handheld electromechanical surgical system for performing surgical procedures, having reusable components. Background Technology

[0004] Linear clamping, cutting, and suturing devices are used in surgery to remove cancerous or abnormal tissue from the gastrointestinal tract. Surgical sutures are used to remove and repair abdominal and chest tissue. The sutures simultaneously seal and transversely cut the tissue using staples and a scalpel. This seal ensures that bleeding is stopped, the lumen / internal contents are contained, and healing is promoted.

[0005] Conventional linear clamping, cutting, and suturing instruments comprise a pistol-grip-type structure with an elongated shaft and an end effector with a pair of clamping components located at the distal end of the shaft to clamp, cut, and suture tissue. Actuation of the clamping components is typically achieved by actuating a trigger coupled to a handle in response to movement or pivoting of one of the two clamping components (e.g., the anvil portion) relative to the elongated shaft while the other clamping element remains stationary. The stationary clamping component includes a staple cartridge and a mechanism for abutting against the anvil portion to eject staples through the clamped tissue for suturing. The end effector may be integrally formed with the shaft or detachable, allowing for interchangeability of various clamping and suturing components.

[0006] Many surgical instrument manufacturers have also developed proprietary electric drive systems for operating and / or manipulating end effectors. These electric drive systems may include a reusable electric handle assembly and a disposable end effector removably attached to the electric handle assembly. Summary of the Invention

[0007] According to one aspect of this disclosure, a surgical instrument is provided. The surgical instrument includes: an end effector having a pair of jaws configured to clamp and suture tissue; an electric motor configured to actuate the end effector; and a controller communicating with the electric motor. The controller is configured to determine the stress and strain of the clamped tissue, identify the tissue type of the clamped tissue based on the determined stress and strain, and set operating parameters of the surgical instrument based on the identified tissue type.

[0008] In various aspects, the controller can be configured to direct a motor to move a pair of jaw components from a first state to a second state, wherein the pair of jaw components compress tissue. The strain of the tissue can be determined as the pair of jaw components move from the first state to the second state.

[0009] In various aspects, the controller can be configured to direct a motor to maintain a pair of jaw components in a second state for a predetermined time period. The controller can also be configured to monitor stress on the tissue throughout the predetermined time period to determine stress relaxation of the tissue.

[0010] In various aspects, the controller can be configured to determine multiple biomechanical parameters based on the determined stress and strain of the clamped tissue and the stress relaxation of the clamped tissue. The controller can be configured to input the determined multiple biomechanical parameters into a classification algorithm stored in memory, thereby identifying the tissue type.

[0011] In various respects, the controller can be configured to determine the stress on the tissue based on a measurement of the clamping force applied to the tissue by the pair of jaws as the pair of jaws moves from a first state toward a second state.

[0012] In various aspects, the controller can be configured to determine the strain of the tissue based on measurements of changes in the tissue's thickness as a pair of jaw components move from a first state toward a second state.

[0013] In various aspects, the controller may be configured to direct a motor to maintain a pair of jaw components in a second state for a predetermined time period, monitor the stress on the tissue throughout the predetermined time period to determine the stress relaxation of the tissue, and identify the tissue type of the clamped tissue based on the determined stress relaxation of the clamped tissue and the stress and strain of the clamped tissue.

[0014] In various aspects, the surgical instrument may further include sensors associated with one or more of a pair of jaw components. The sensors may be configured to measure the physical properties of the clamped tissue. The controller may be configured to determine the stress and / or strain of the clamped tissue based on the measured physical properties.

[0015] In various aspects, the operating parameters of surgical instruments may include staple size, staple firing speed, the rate at which a pair of jaws releases tissue, the rate at which a pair of jaws clamps tissue, staple firing force, and / or clamping force of a pair of jaws.

[0016] According to another aspect, a method for operating a surgical instrument is provided. The method includes: moving a pair of jaw components of an end effector from a first state to a second state, wherein tissue is clamped between the pair of jaw components; determining the stress and strain of the clamped tissue as the pair of jaw components move from the first state to the second state; identifying the tissue type of the clamped tissue based on the determined stress and strain of the clamped tissue; and setting operating parameters of the surgical instrument based on the identified tissue type of the clamped tissue.

[0017] In various aspects, the method may further include: maintaining a pair of jaw components in a second state for a predetermined time period; and monitoring the stress on the tissue throughout the predetermined time period to determine stress relaxation of the tissue.

[0018] In various aspects, the method may further include: determining multiple biomechanical parameters based on determined stress and strain of the clamped tissue and stress relaxation of the clamped tissue; and inputting the determined multiple biomechanical parameters into a classification algorithm stored in memory, thereby identifying the tissue type.

[0019] In various aspects, determining the stress on the tissue may include measuring the clamping force applied to the tissue by the pair of jaws as the jaws move from a first state to a second state.

[0020] In various aspects, determining the strain of an organization may involve measuring the change in the organization's thickness as a pair of jaw components move from a first state toward a second state.

[0021] According to another aspect, a surgical instrument is provided, comprising an end effector having a pair of jaw members configured to clamp and suture tissue, a motor configured to actuate the end effector, and a controller in communication with the motor. The controller is configured to: direct the motor to move the pair of jaw members from a first state to a second state, wherein the pair of jaw members compress tissue; determine the stress and strain of the clamped tissue as the pair of jaw members move from the first state to the second state; direct the motor to maintain the pair of jaw members in the second state for a predetermined time period; monitor the stress on the tissue throughout the predetermined time period to determine stress relaxation of the tissue; and identify the tissue type of the clamped tissue based on the determined stress and strain of the clamped tissue and the determined stress relaxation of the tissue.

[0022] In various aspects, the controller can be configured to set the operating parameters of the surgical instruments based on the identified tissue type of the clamped tissue. The operating parameters of the surgical instruments may include staple size, staple firing rate, the rate at which the pair of jaws releases the tissue, the rate at which the pair of jaws clamps the tissue, staple firing force, and / or the clamping force of the pair of jaws. Attached Figure Description

[0023] The objects and features of the surgical systems disclosed herein will become apparent to those skilled in the art when the description of various embodiments of the surgical systems is read with reference to the accompanying drawings.

[0024] Figure 1 This is a perspective view of a surgical instrument comprising an electric handle assembly, an adapter assembly, and an end effector, according to one aspect of this disclosure;

[0025] Figure 2 yes Figure 1 Front perspective view of the handle assembly with the parts separated;

[0026] Figure 3 Is with Figure 2 A front perspective view of the power supply unit separated from the inner rear housing of the handle assembly;

[0027] Figure 4 It was cut along the cross-section line "4-4". Figure 2 A cross-sectional view of the handle assembly;

[0028] Figure 5 Based on this disclosure Figure 1 A schematic diagram of a handheld surgical instrument; and

[0029] Figure 6 It is for use Figure 1 A flowchart of a method for identifying tissue types using surgical instruments. Detailed Implementation

[0030] The surgical instruments disclosed in this invention are described in detail with reference to the accompanying drawings, in which similar reference numerals denote the same or corresponding elements in each of the several views. As used herein, the term "distal" refers to the portion of the surgical instrument or its components that is further away from the user, while the term "proximal" refers to the portion of the surgical instrument or its components that is closer to the user.

[0031] Surgical suture height depends on the biomechanics of the transverse tissue. The stapler jaws seal the tissue through compression, inducing internal pressure greater than that of blood vessels and their contents. Compression is then maintained by shaped staples after the jaws are removed. The biomechanics of the target tissue determines the suture output, such as suture pressure, tissue damage, hemostasis, and oxygenation. Therefore, specific techniques incorporating stapler size, firing speed, and clamp relaxation time should be used for suturing different organs. The electric stapler disclosed herein has the ability to measure the biomechanics of the tissue after clamping but before firing the staples. This information can be used to classify the tissue for optimized firing and to provide information on tissue health. Classification algorithms can be used to test the compression and relaxation distribution of lung, stomach, colon, or other suitable tissue types.

[0032] like Figure 1 As described herein, the surgical instrument 2 according to this disclosure is shown as a powered handheld electromechanical instrument comprising a powered handle assembly 100 configured to selectively attach to a plurality of different end effectors or disposable loading units (“SULUs”), such as end effector 400. Specifically, the handle assembly 100 is configured to selectively connect to an adapter 200, and the adapter 200 is in turn configured to selectively connect to the end effector 400. In various respects, the end effector 400 may be operated by a robotic system rather than the powered handle assembly 100.

[0033] Although linear surgical loading units suitable for performing endoscopic gastrointestinal anastomosis (EGIA) procedures are in Figure 1 While shown as an end effector 400, it is anticipated that the principles of this disclosure can also be applied to surgical loading units (e.g., circular staplers), transverse suture loading units, curved loading units, multipurpose loading units (“MULU”), grippers, electrosurgical sealing forceps, rotary tissue ablation devices, and the like configured to perform end-to-end anastomosis (EEA) procedures.

[0034] refer to Figure 1 and 2 The handle assembly 100 includes a power supply unit 101. Figure 2 The adapter 200 includes an external housing 10 configured to selectively receive and enclose the power supply assembly 101. The external housing 10 includes a distal half 10a and a proximal half 10b. The proximal half 10b is pivotally connected to the distal half 10a by a hinge 16 positioned along the upper edges of the distal half 10a and the proximal half 10b, such that the distal half 10a and the proximal half 10b are divided along a plane traversing the longitudinal axis defined by the adapter 200. When the distal half 10a and the proximal half 10b are engaged, they together define a housing cavity 10c for receiving the power supply assembly 101.

[0035] refer to Figure 2 Each of the distal half 10a and the proximal half 10b includes a corresponding upper shell portion 12a, 12b and a corresponding lower shell portion 14a, 14b. The lower shell portion 14a includes a closure tab 18a configured to engage the closure tab 18b of the lower shell portion 14b to selectively fasten the distal half 10a and the proximal half 10b to each other and to maintain the shell housing 10 in a closed configuration.

[0036] The distal half 10a of the housing 10 also includes a connection portion 20 configured to connect to a corresponding drive coupling assembly 210 of the adapter 200. Specifically, the connection portion 20 includes a recess 21 configured to receive a portion of the drive coupling assembly 210 of the adapter 200 when the adapter 200 engages with the handle assembly 100. The connection portion 20 of the distal half 10a also defines three openings 22a, 22b, 22c and an elongated slot 24 formed in the distally facing surface of the connection portion 20.

[0037] The distal half 10a of the housing 10 also includes a plurality of buttons, such as trigger control buttons 30. In various respects, the trigger control buttons 30 may be a dual-axis control lever configured to be actuated in the left, right, up, and down directions. The trigger control buttons 30 may also be pressable. The distal half 10a of the housing 10 may also support a plurality of other buttons, such as a pair of control buttons on the right and a pair of control buttons on the left.

[0038] The housing 10 includes a sterile barrier plate 60 removably supported in the distal half 10a. The sterile barrier plate 60 interconnects the power supply 101 with the adapter 200. Specifically, the sterile barrier plate 60 is positioned behind the connection portion 20 of the distal half 10a and within the shell cavity 10c of the housing 10. The plate 60 includes three coupling shafts 64a, 64b, 64c rotatably supported therein. Each coupling shaft 64a, 64b, 64c extends through a corresponding aperture 22a, 22b, 22c of the connection portion 20 of the distal half 10a of the housing 10.

[0039] The plate 60 further includes an electrically pass-through connector 66 supported thereon. When the sterile barrier plate 60 is positioned within the shell cavity 10c of the shell housing 10, the pass-through connector 66 extends through an aperture 24 in the connection portion 20 of the distal half 10a. The coupling shafts 64a, 64b, 64c and the pass-through connector 66 electrically and mechanically interconnect corresponding features of the adapter 200 with the power supply group 101.

[0040] During use, the shell housing 10 is opened (i.e., the distal half 10a is separated from the proximal half 10b around the hinge 16), the power assembly 101 is inserted into the shell cavity 10c of the shell housing 10, and the distal half 10a is pivoted about the hinge 16 into a closed configuration. In the closed configuration, the closing tab 18a of the lower shell portion 14a of the distal half 10a engages the closing tab 18b of the lower shell portion 14b of the proximal half 10b. After surgery, the shell housing 10 is opened, and the power assembly 101 is removed from the shell cavity 10c of the shell housing 10. The shell housing 10 can be discarded, and the power assembly 101 can then be sterilized and cleaned.

[0041] refer to Figure 2 and 3 The power supply assembly 101 includes an internal handle housing 110 having a lower housing portion 104 and an upper housing portion 108 extending from and / or supported on the lower housing portion 104. The internal handle housing 110 also includes a distal half 110a and a proximal half 110b, which define an internal housing cavity 110c for receiving a power supply core assembly 106. The power supply core assembly 106 is configured to control various operations of the surgical instrument 2.

[0042] refer to Figure 3 The distal half 110a of the inner handle housing 110 supports the distal trigger control interface 130, which is connected to the trigger control button 30 of the outer housing 10. Figure 2 The internal handle housing 110 is operably engaged such that when the power supply unit 101 is housed within the housing 10, actuation of the trigger control button 30 applies force to the trigger control interface 130. The distal half 110a of the internal handle housing 110 also supports various other control interfaces operably engaged with other buttons on the housing 10.

[0043] refer to Figure 3 and 4 The power supply core assembly 106 includes a battery circuit 140, a motor controller circuit 143, a main controller circuit 145, a main controller 147, and a rechargeable battery 144 configured to supply power to any one of the electrical components of the surgical instrument 2.

[0044] The power supply core assembly 106 further includes a display screen 146 supported on the main controller circuitry 145. The display screen 146 is visible through a light-transmitting or transparent window 110d located in the proximal half 110b of the internal handle housing 110.

[0045] The power supply core assembly 106 further includes a first motor 152, which is electrically connected to the controller circuit 143 and the battery 144. Figure 4 ), second motor 154 ( Figure 3 ) and the third motor 156 ( Figure 4 Motors 152, 154, and 156 are positioned between motor controller circuit 143 and main controller circuit 145. Each motor 152, 154, and 156 is controlled by a corresponding motor controller (not shown) located on motor controller circuit 143 and connected to main controller 147. Main controller 147 is also connected to memory 141. Figure 5 The memory is also housed on the motor controller circuit 143. The main controller 147 communicates with the motor controller via an FPGA, which provides control logic signals (e.g., coasting, braking, and any other suitable control signals). The motor controller uses fixed-frequency pulse width modulation (PWM) to output corresponding excitation signals to its respective motors 152, 154, and 156.

[0046] The power supply core assembly 106 also includes an electrical socket 149. The electrical socket 149 is electrically connected to the main controller board 145 via a second ribbon cable (not shown). The electrical socket 149 defines a plurality of electrical slots for receiving power from the board 60 of the housing 10. Figure 2 The corresponding electrical contacts extend from the through connector 66.

[0047] Each motor 152, 154, 156 includes a corresponding motor shaft (not shown) extending therefrom. Each motor shaft may have a recess defined therein, the recess having a trilobed transverse cross-sectional profile for receiving the proximal end of a corresponding connecting shaft 64a, 64b, 64c of the plate 60 of the housing 10.

[0048] The rotation of the motor shafts by the corresponding motors 152, 154, and 156 actuates the shafts and / or gear assemblies of the adapter 200 to perform various operations of the surgical instrument 2. Specifically, the motors 152, 154, and 156 of the power supply core assembly 106 are configured to actuate the shafts and / or gear assemblies of the adapter 200 to selectively actuate the components of the end effector 400, causing the end effector 400 to rotate about a longitudinal axis, to pivot about a pivot axis perpendicular to the longitudinal axis defined by the adapter 200, and to close and perform the suturing function of the jaw components 402a and 402b of the end effector 400.

[0049] refer to Figure 5A schematic diagram of power supply unit 101 is shown. For simplicity, only one of motors 152, 154, and 156 is shown, namely motor 152. Motor 152 is connected to battery 144. In all respects, motor 152 can be connected to any suitable power source configured to provide power to motor 152, such as an AC / DC transformer.

[0050] Battery 144 and motor 152 are connected to motor controller circuit 143, which controls the operation of motor 152, including the flow of electrical energy from battery 144 to motor 152. Motor controller circuit 143 includes multiple sensors 408a, 408b, ... 408n configured to measure the operating states of motor 152 and battery 144. Sensors 408a-n may include voltage sensors, current sensors, temperature sensors, telemetry sensors, optical sensors, and combinations thereof. Sensors 408a-408n can measure the voltage, current, and other electrical properties of the electrical energy supplied by battery 144. Sensors 408a-408n can also measure the angular velocity (e.g., rotational speed) (revolutions per minute (RPM)), torque, temperature, current draw, and other operating properties of motor 152. The angular velocity can be determined by measuring the rotation of motor 152 or a drive shaft (not shown) connected to and rotatable by motor 152.

[0051] The position of various axially movable drive shafts can also be determined by using various linear sensors mounted in or near the shaft, or by extrapolating the position from RPM measurements. Optical or magnetic encoders, linear variable differential transformers (LVDTs), or other methods are expected to be used to determine the linear position of the drive shaft.

[0052] In some respects, torque can be calculated based on the regulated current draw of motor 152 at a constant RPM. In others, motor controller circuit 143 and / or controller 147 can measure time and process the values ​​described above that vary over time, including, for example, integration and / or differentiation, to determine the rate of change of the measured values.

[0053] The motor controller circuit 143 is also coupled to a controller 147, which includes multiple inputs and outputs for interfacing with the motor controller circuit 143. Specifically, the controller 147 receives measured sensor signals from the motor controller circuit 143 regarding the operating state of the motor 152 and the battery 144, and then outputs control signals to the motor controller circuit 143 to control the operation of the motor 152 based on sensor readings and specific algorithm instructions. The controller 147 is also configured to accept multiple user inputs from a user interface (e.g., a switch, button, touchscreen, etc. coupled to the controller 147).

[0054] The controller 147 is coupled to the memory 141 or any other suitable computer-readable non-transitory medium for storing software instructions (e.g., algorithms) for identifying tissue type based on biomechanical parameters of the tissue measured by the surgical instrument 2.

[0055] This disclosure provides an apparatus and method for evaluating the stress and strain distribution of tissue gripped by an end effector 400 and the stress relaxation of the gripped tissue, wherein a controller 147 of a surgical instrument 2 identifies the tissue type of the gripped tissue, such as lung, stomach, and colon, based on the determined stress and strain distribution and stress relaxation distribution. The measured stress is the compressive normal stress experienced by the tissue, and the measured strain is the compressive normal strain experienced by the tissue.

[0056] To measure the stress-strain distribution and stress relaxation of tissue, the surgical instrument 2 may be equipped with multiple sensors. For example, the jaw components 402a, 402b of the end effector 400 ( Figure 1 The device may include a gap measuring sensor 404 configured to determine a gap defined between jaw components 402a, 402b, which is directly related to the thickness of the tissue. The gap measuring sensor 404 may be a potentiometer. In some aspects, the motor 152 may have an associated encoder (not explicitly shown) configured to determine the jaw angle and thus the tissue thickness. Other methods for determining tissue thickness (e.g., strain) are also contemplated, such as linear sensors mentioned above housed in or near the drive shaft of the surgical instrument 2.

[0057] To determine the stress experienced by the tissue when the jaw components 402a, 402b clamp around the tissue, the surgical instrument 2 may include a strain gauge 157 associated with the main drive shaft 159. Figure 5 Strain gauge 157 is configured to determine the mechanical load on drive shaft 159, which is directly related to the load or stress applied to the tissue. In other aspects, force measurement sensors (not explicitly shown) may be disposed on the tissue contact surfaces of jaw components 402a, 402b. Known algorithms can be used to convert the force measured by each force measurement sensor into a value of tension applied to the tissue. Other methods for determining stress on the tissue are also contemplated. For example, the current drawn by motor 152 can be used to detect the biomechanical properties of the tissue (e.g., stress experienced by the tissue in response to jaw clamping), as the current drawn by motor 152 and the angular velocity of the motor change in response to the mechanical load encountered by motor 152. Therefore, analysis of the amount of change in current draw and angular velocity (e.g., rate of change) allows for the determination of the load or stress applied to the tissue.

[0058] Further details regarding a method for measuring stress and strain of clamped tissue can be found in U.S. Patent No. 8,002,795, the entire contents of which are incorporated herein by reference.

[0059] By collecting stress and strain data during tissue clamping, as well as stress relaxation data, certain biomechanical parameters of the tissue can be determined by curve fitting the collected data using selected mathematical equations (mentioned below). The determined biomechanical parameters then serve as input to a custom classification algorithm that identifies tissue types, such as those referenced from... Figure 6 Further detailed description.

[0060] refer to Figure 6 Initially, with the tissue positioned between the jaw components 402a and 402b, in step 600, the controller 147 signals the motor controller circuit 143 to operate the motor 152 based on, for example, desired user input, to control the motors 152, 154, and 156 to close the end effector 400 around the tissue (without firing). The controller 147 provides the desired command to the motor controller circuit 143, which then outputs a corresponding excitation signal to the motor 152 to execute the command received from the controller 147.

[0061] The jaw components 402a, 402b of the end effector 400 move from a first state to a second state. In the first state, the jaw components 402a, 402b grip (without compression) tissue. In the second state, the jaw components 402a, 402b compress the tissue by a threshold amount (e.g., stopping blood flow). The jaw components 402a, 402b can close at a constant speed of 0.31 in / s, 0.1 in / s, or 0.01 in / s. Other closing speeds are also anticipated. The jaw components 402a, 402b may be equipped with perfusion sensors that communicate with the controller 147 when perfusion through the gripped tissue stops to determine when to stop closing the jaw components 402a, 402b. In other respects, controller 147 may be configured to direct motor 152 to close jaw components 402a, 402b until the jaw gap is reduced to a preset percentage of the initial jaw gap (e.g., when gripping tissue without compression). For example, controller 147 may be configured to stop closing jaw components 402a, 402b when they are closed to between approximately 10% and 40% of the initial jaw gap.

[0062] As the jaw components 402a and 402b move from the first state to the second state, in step 602, stress and strain measurements of the clamped tissue are performed at preset time intervals (e.g., every 0.25 seconds, 0.5 seconds, or 1 second), and these stress and strain measurements are stored in memory 141. Determining the stress on the tissue includes: measuring the clamping force applied to the tissue by the pair of jaw components 402a and 402b (e.g., using strain gauge 157) as the pair of jaw components 402a and 402b move from the first state to the second state; and dividing the measured clamping force by the known surface area of ​​the tissue contact surfaces of the jaw components 402a and 402b. Determining the strain of the tissue includes measuring the change in tissue thickness using, for example, a gap measuring sensor 404 or a motor encoder, as the pair of jaw components 402a and 402b move from the first state to the second state.

[0063] In step 604, controller 147 is configured to maintain jaw components 402a, 402b in a second state for a preset time period to apply a constant strain to the tissue for the preset time period. While the constant strain is applied to the tissue, the stress on the tissue is measured at preset time intervals, and the measurements are stored in memory 141. The stress measurements provide a stress relaxation distribution within the tissue. At this stage, the clinician can manually actuate the surgical instrument 2 to open the jaw components 402a, 402b, thereby releasing the tissue. In other aspects, controller 147 may be configured to automatically open the jaw components 402a, 402b to release the tissue.

[0064] In various aspects, controller 147 may generate and display stress-strain and / or stress relaxation plots based on the received measurement data. The plots may be a collection of measured data points. In other aspects, the plots may not be visualized or illustrated by controller 147 (e.g., output on a display device) and may be simply stored in memory 141 for use by controller 147.

[0065] In step 606, controller 147 identifies the tissue type of the clamped tissue based on determined stress and strain data and stress relaxation data of the clamped tissue. Identifying the tissue type involves determining multiple biomechanical parameters based on the determined stress and strain data and stress relaxation data of the tissue. Biomechanical parameters are determined by curve fitting the measured stress and strain data to the following equations (I) through (III). Specifically, the biomechanical parameters include α and β from exponential equation (I), α, β, and γ from exponential equation (II), and α and β from the inverse equation (III), each of which is stored in memory 141 and accessible by controller 147. In other aspects, the biomechanical parameters in stress relaxation equation (IV) can also be determined by curve fitting the measured stress relaxation data to equation (IV).

[0066] (I)σ=β(e α∈ -1)

[0067] (II)

[0068] (III)

[0069] (IV) in

[0070] After the controller 147 determines the biomechanical parameters using equations (I) to (III) or equations (I) to (IV), the controller 147 inputs the determined biomechanical parameters into a classification algorithm stored in memory 141 to identify the tissue type. Other parameters, such as tissue bioimpedance, tissue geometry, and / or tissue loading, are expected to be used in the prediction algorithm. The classification algorithm may be a support vector machine algorithm or a collection of bagged trees or any other suitable classification algorithm. Memory 141 is expected to store known biomechanical parameters for various tissue types, such as colon, lung, stomach, etc. In various aspects, the controller 147 may be configured to compare the determined stress and strain data of the tissue with known stress and strain data of discrete tissue types to determine the tissue type. The controller may be further configured to compare the determined stress relaxation data of the tissue with known stress relaxation data of discrete tissue types to determine the tissue type.

[0071] In step 608, the controller 147 sets the operating parameters of the surgical instrument 2 based on the identified tissue type. The parameters set by the controller 147 may include the staple firing speed of the end effector 400, the staple firing force of the end effector 400, the clamping speed of the end effector 400, the release speed of the end effector 400, the clamping force of the end effector 400, and the staple size. Other operating parameters may be stored in the memory 141 of the surgical instrument 2, such as tissue thickness indication or blade retraction speed. The operating parameters selected by the controller 147 are those known to be most suitable for the specific tissue being operated on.

[0072] This disclosure provides multiple surgical loading units, each configured for use with a specific type of tissue (e.g., liver, lung, heart, gastrointestinal tract, etc.) and / or during a specific type of surgical procedure (e.g., hepatectomy, gastrointestinal anastomosis, lesion resection). Thus, each loading unit has a discrete set of operating parameters unique to the type of tissue on which the selected surgical loading unit is to be used and / or the type of surgical procedure to be performed by the surgical loading unit. For example, if the tissue identified using the method of this disclosure is liver tissue, then a surgical loading unit with operating parameters for liver resection is selected. Because liver tissue is highly vascularized and thick, the surgical loading unit for liver resection can be pre-programmed with instructions that, when executed, result in a rapid and constant staple firing rate regardless of the sensed tissue thickness. If another type of tissue is identified, then a loading unit equipped with appropriate operating parameters, rather than the surgical loading unit for liver resection, will be selected. In various aspects, the controller 147 can provide instructions to clinicians via audio or visual cues, indicating that the surgical loading unit may not be suitable for the selected tissue and recommending an appropriate surgical loading unit.

[0073] It should be understood that the various aspects disclosed herein can be combined in combinations different from those specifically presented in the specification and drawings. It should also be understood that, depending on the instance, certain actions or events of any of the processes or methods described herein may be performed in different sequences, added, combined, or omitted entirely (e.g., all described actions or events may not be necessary for performing these techniques). Furthermore, for clarity, although some aspects of this disclosure are described as being performed by a single module or unit, it should be understood that the techniques of this disclosure can be performed by combinations of units or modules associated with, for example, a medical device.

[0074] In one or more instances, the described techniques may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, functionality may be stored on a computer-readable medium in the form of one or more instructions or code and may be executed by a hardware-based processing unit. The computer-readable medium may include non-transitory computer-readable media, which corresponds to tangible media such as data storage media (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that is accessible by a computer).

[0075] The instructions can be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Therefore, the term "processor" as used herein can refer to any of the foregoing structures or any other physical structure suitable for implementing the described techniques. Furthermore, the techniques can be fully implemented in one or more circuit or logic elements.

Claims

1. A surgical instrument comprising: an end effector including a pair of jaw members configured to clamp and staple tissue; a motor configured to actuate the end effector; and a controller in communication with the motor and configured to: determine a stress and a strain of the clamped tissue, and apply a constant strain on the tissue while measuring the stress of the tissue; identify a tissue type of the clamped tissue based on the determined stress and strain of the clamped tissue; and set an operating parameter of the surgical instrument based on the identified tissue type of the clamped tissue, wherein the controller is configured to direct the motor to move the pair of jaw members from a first state toward a second state, wherein the pair of jaw members compress the tissue, the strain of the tissue being determined as the pair of jaw members move from the first state toward the second state, wherein the controller is configured to: direct the motor to maintain the pair of jaw members in the second state for a predetermined time period and apply the constant strain on the tissue for the predetermined time period; and monitor the stress on the tissue at preset time intervals throughout the predetermined time period to determine a stress relaxation of the tissue.

2. The surgical instrument of claim 1, wherein the controller is configured to: determine a plurality of biomechanical parameters based on the determined stress and strain of the clamped tissue and the stress relaxation of the clamped tissue; and input the determined plurality of biomechanical parameters into a classification algorithm stored in a memory, whereby the controller identifies the tissue type.

3. The surgical instrument of claim 1, wherein the controller is configured to determine the stress on the tissue based on a measurement of a clamping force applied to the tissue by the pair of jaw members as the pair of jaw members move from the first state toward the second state.

4. The surgical instrument of claim 3, wherein the controller is configured to determine the strain of the tissue based on a measurement of a change in thickness of the tissue as the pair of jaw members move from the first state toward the second state.

5. The surgical instrument of claim 1, wherein the controller is configured to: direct the motor to move the pair of jaw members from a first state toward a second state, wherein the pair of jaw members compress the tissue; direct the motor to maintain the pair of jaw members in the second state for a predetermined time period; monitor a stress on the tissue throughout the predetermined time period to determine a stress relaxation of the tissue; and identify the tissue type of the clamped tissue based on the determined stress relaxation of the clamped tissue and the stress and strain of the clamped tissue. ​ 6. The surgical instrument of claim 1, further comprising at least one sensor associated with at least one of the pair of jaw members and configured to measure a physical property of the clamped tissue, wherein the controller is configured to determine at least one of the stress or strain of the clamped tissue based on the measured physical property.

7. The surgical instrument of claim 1, wherein the operating parameters of the surgical instrument include at least one of staple size, staple firing speed, rate at which the pair of jaw members releases the tissue, rate at which the pair of jaw members clamps the tissue, staple firing force, or clamping force of the pair of jaw members.

8. A surgical instrument comprising: an end effector including a pair of jaw members configured to clamp and staple tissue; a motor configured to actuate the end effector; and a controller in communication with the motor and configured to: direct the motor to move the pair of jaw members from a first state toward a second state, wherein the pair of jaw members compresses the tissue; determine a stress and a strain of the clamped tissue as the pair of jaw members moves from the first state toward the second state, and apply a constant strain on the tissue while measuring the stress of the tissue; direct the motor to maintain the pair of jaw members in the second state for a predetermined period of time and apply the constant strain on the tissue for the predetermined period of time; monitor the stress on the tissue at preset time intervals throughout the predetermined period of time to determine a stress relaxation of the tissue; and identify a tissue type of the clamped tissue based on the determined stress and strain of the clamped tissue and the determined stress relaxation of the tissue.

9. The surgical instrument of claim 8, wherein the controller is configured to: determine a plurality of biomechanical parameters based on the determined stress and strain of the clamped tissue and the stress relaxation of the clamped tissue; and input the determined plurality of biomechanical parameters into a classification algorithm stored in a memory, whereby the controller identifies the tissue type.

10. The surgical instrument of claim 8, wherein the controller is configured to determine the stress on the tissue based on a measurement of a clamping force applied to the tissue by the pair of jaw members as the pair of jaw members moves from the first state toward the second state.

11. The surgical instrument of claim 10, wherein the controller is configured to determine the strain of the tissue based on a measurement of a change in thickness of the tissue as the pair of jaw members moves from the first state toward the second state. ​ ​ 12. The surgical instrument of claim 8, wherein the controller is configured to set an operating parameter of the surgical instrument based on the identified tissue type of the clamped tissue, the operating parameter of the surgical instrument including at least one of a staple size, a staple firing speed, a rate at which the pair of jaw members releases the tissue, a rate at which the pair of jaw members clamps the tissue, a staple firing force, or a clamping force of the pair of jaw members.

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