Powered surgical instruments and methods of identifying tissue types therewith

Abstract

To provide powered surgical instruments and methods of identifying tissue types therewith.SOLUTION: A surgical instrument includes an end effector configured to clamp tissue, a motor configured to actuate the end effector, and a controller in communication with the motor and configured to determine a stress and strain of the tissue, identify a tissue type of the tissue based on the determined stress and strain of the tissue, and set an operational parameter of the surgical instrument based on the identified tissue type of the tissue.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 027,060, filed May 19, 2020, the entire contents of which are incorporated herein by reference.

[0002] Field The present technology relates to surgical instruments and, more particularly, to handheld electromechanical surgical systems for performing surgical procedures having reusable components. [Background technology]

[0003] Linear clamping, cutting, and stapling devices are used in surgical procedures to remove cancerous or abnormal tissue from the digestive tract. Surgical staplers are used to cut and repair abdominal and thoracic tissue. The stapler uses staples and a knife to simultaneously seal and cut tissue. In doing so, the seal ensures that bleeding is prevented, the lumen / internal contents are contained, and healing is promoted.

[0004] Conventional linear clamping, cutting, and stapling instruments include a pistol-grip structure with an elongated shaft and an end effector with a pair of gripping members disposed at the distal end of the shaft for clamping, cutting, and stapling tissue. Actuation of the gripping members is typically achieved by actuating a trigger coupled to the handle, in response to which one of the two gripping members, such as an anvil portion, moves or pivots relative to the elongated shaft while the other gripping element remains fixed. The fixed gripping member includes a staple cartridge and a mechanism for firing staples through the clamped tissue and against the anvil portion, thereby stapling the tissue. The end effector can be integrally formed with the shaft or can be detachable to allow for interchangeability of various gripping and stapling members.

[0005] Many surgical instrument manufacturers have also developed proprietary powered drive systems to operate and / or manipulate end effectors. The powered drive systems can include a powered handle assembly, which can be reusable, and a disposable end effector that is removably connected to the powered handle assembly. Summary of the Invention [Means for solving the problem]

[0006] According to one aspect of the present disclosure, a surgical instrument is provided that includes an end effector having 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, the controller configured to determine stress and strain in the clamped tissue, identify a tissue type of the clamped tissue based on the determined stress and strain in the clamped tissue, and set operating parameters of the surgical instrument based on the identified tissue type of the clamped tissue.

[0007] In some embodiments, the controller can be configured to direct the motor to move the pair of jaw members from a first state toward a second state in which the pair of jaw members compress the tissue, and the strain on the tissue can be determined as the pair of jaw members move from the first state toward the second state.

[0008] In some embodiments, the controller can be configured to direct the motor to maintain the pair of jaw members in the second state for a predetermined period of time. The controller can be configured to monitor the stress on the tissue over the predetermined period of time to determine stress relaxation of the tissue.

[0009] In some embodiments, the controller may be 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. The controller may be configured to input the determined plurality of biomechanical parameters into a classification algorithm stored in the memory, whereby the controller identifies the tissue type.

[0010] In some embodiments, 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 jaw members as the pair of jaw members moves from the first state toward the second state.

[0011] In some embodiments, the controller may be configured to determine the strain of the tissue based on a measurement of the change in tissue thickness as the pair of jaw members moves from the first state toward the second state.

[0012] In some embodiments, the controller directs the motor to maintain the pair of jaw members in the second state for a predetermined period of time, and monitors the stress on the tissue over the predetermined period of time to determine stress relaxation of the tissue; and identifying a 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.

[0013] In some embodiments, the surgical instrument may further include a sensor associated with at least one or more of the pair of jaw members. The sensor may be configured to measure a physical property of the clamped tissue. The controller may be configured to determine a stress and / or strain on the clamped tissue based on the measured physical property.

[0014] In some embodiments, the operating parameters of the surgical instrument may include staple size, staple firing rate, rate at which the pair of jaw members unclamps the tissue, rate at which the pair of jaw members clamp the tissue, staple firing force, and / or clamping force of the pair of jaw members.

[0015] According to another aspect, a method for operating a surgical instrument is provided that includes moving a pair of jaw members of an end effector from a first state to a second state in which tissue is clamped between the pair of jaw members, determining stress and strain on the clamped tissue as the pair of jaw members moves from the first state to the second state, identifying a tissue type of the clamped tissue based on the determined stress and strain on the clamped tissue, and setting operating parameters of the surgical instrument based on the identified tissue type of the clamped tissue.

[0016] In some embodiments, the method may further include maintaining the pair of jaw members in the second state for a predetermined period of time and monitoring the stress on the tissue over the predetermined period of time to determine stress relaxation of the tissue.

[0017] In some embodiments, the method may further include determining 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 inputting the determined plurality of biomechanical parameters into a classification algorithm stored in memory, thereby identifying the tissue type.

[0018] In some embodiments, determining the stress on the tissue may include measuring 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.

[0019] In some embodiments, determining the strain in the tissue may include measuring a change in thickness of the tissue as the pair of jaw members moves from the first condition toward the second condition.

[0020] According to yet another aspect, a surgical instrument is provided that includes an end effector having 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. The controller is configured to: direct the motor to move the pair of jaw members from a first state toward a second state in which the pair of jaw members compress the tissue; determine stress and strain on the clamped tissue as the pair of jaw members move from the first state toward the second state; direct the motor to maintain the pair of jaw members in the second state for a predetermined period of time; monitor the stress on the tissue over 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.

[0021] In some embodiments, the controller can be configured to set operating parameters of the surgical instrument based on the identified tissue type of the clamped tissue. The operating parameters of the surgical instrument can include staple size, staple firing rate, speed at which the tissue is unclamped by the pair of jaw members, speed at which the tissue is clamped by the pair of jaw members, staple firing force, and / or clamping force of the pair of jaw members. The present invention provides, for example: (Item 1) 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; in communication with the motor; and determining stress and strain in the clamped tissue; identifying a 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. (Item 2) 10. The surgical instrument of claim 9, wherein the controller is configured to instruct the motor to move the pair of jaw members from a first state toward a second state in which the pair of jaw members compress the tissue, and the strain on the tissue is determined as the pair of jaw members move from the first state toward the second state. (Item 3) The controller: directing the motor to maintain the pair of jaw members in the second state for a predetermined period of time; and monitoring the stress on the tissue over the predetermined period of time to determine stress relaxation of the tissue. (Item 4) The controller: determining a plurality of biomechanical parameters based on the determined stress and strain of the clamped tissue and the stress relaxation of the clamped tissue; 10. The surgical instrument of claim 1, wherein the controller is configured to input the determined plurality of biomechanical parameters into a classification algorithm stored in a memory, thereby identifying the tissue type. (Item 5) 10. 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 moves from the first condition toward the second condition. (Item 6) 10. The surgical instrument of claim 1, wherein the controller is configured to determine the strain in the tissue based on a measurement of a change in thickness of the tissue as the pair of jaw members moves from the first condition toward the second condition. (Item 7) The controller: directing the motor to move the pair of jaw members from a first position toward a second position in which the pair of jaw members compress the tissue; directing the motor to maintain the pair of jaw members in the second state for a predetermined period of time; monitoring the stress on the tissue over the predetermined period of time to determine stress relaxation of the tissue; and identifying 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. (Item 8) 10. 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. (Item 9) 10. The surgical instrument of claim 1, wherein the operating parameters of the surgical instrument include at least one of a staple size, a staple firing rate, a rate at which the tissue is unclamped by the pair of jaw members, a rate at which the tissue is clamped by the pair of jaw members, a staple firing force, or a clamping force of the pair of jaw members. (Item 10) 1. A method for operating a surgical instrument, the method comprising: moving a pair of jaw members of an end effector from a first condition to a second condition in which tissue is clamped between the pair of jaw members; determining stress and strain on the clamped tissue as the pair of jaw members move from the first condition to the second condition; identifying a 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. (Item 11) maintaining the pair of jaw members in the second condition for a predetermined period of time; 10. The method of claim 1, further comprising monitoring the stress on the tissue over the predetermined period of time to determine stress relaxation of the tissue. (Item 12) determining a plurality of biomechanical parameters based on the determined stress and strain of the clamped tissue and the stress relaxation of the clamped tissue; 2. The method of claim 1, further comprising inputting the determined plurality of biomechanical parameters into a classification algorithm stored in a memory, thereby identifying the tissue type. (Item 13) 10. The method of claim 1, wherein determining the stress on the tissue includes measuring a clamping force applied to the tissue by the pair of jaw members as the jaw members move from the first condition toward the second condition. (Item 14) 10. The method of claim 9, wherein determining the strain on the tissue includes measuring a change in thickness of the tissue as the pair of jaw members moves from the first condition toward the second condition. (Item 15) 10. The method of claim 1, wherein the operating parameters of the surgical instrument include at least one of a staple size, a staple firing rate, a rate at which the pair of jaw members unclamp the tissue, a rate at which the pair of jaw members clamp the tissue, a staple firing force, or a clamping force. (Item 16) 1. A surgical instrument comprising: an end effector including a pair of jaw members configured to clamp and staple tissue; and a motor configured to actuate the end effector; in communication with the motor; and directing the motor to move the pair of jaw members from a first position toward a second position in which the pair of jaw members compress the tissue; determining stress and strain on the clamped tissue as the pair of jaw members move from the first condition toward the second condition; directing the motor to maintain the pair of jaw members in the second state for a predetermined period of time; monitoring the stress on the tissue over the predetermined period of time to determine stress relaxation of the tissue; and identifying 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. (Item 17) The controller: determining a plurality of biomechanical parameters based on the determined stress and strain of the clamped tissue and the stress relaxation of the clamped tissue; 10. The surgical instrument of claim 1, wherein the controller is configured to input the determined plurality of biomechanical parameters into a classification algorithm stored in a memory, thereby identifying the tissue type. (Item 18) 10. 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 moves from the first condition toward the second condition. (Item 19) 10. The surgical instrument of claim 1, wherein the controller is configured to determine the strain in the tissue based on a measurement of a change in thickness of the tissue as the pair of jaw members moves from the first condition toward the second condition. (Item 20) 10. The surgical instrument of claim 1, wherein the controller is configured to set operating parameters of the surgical instrument based on the identified tissue type of the clamped tissue, and the operating parameters of the surgical instrument include at least one of a staple size, a staple firing rate, a speed at which the tissue is unclamped by the pair of jaw members, a speed at which the tissue is clamped by the pair of jaw members, a staple firing force, or a clamping force of the pair of jaw members. (Summary) The surgical instrument includes an end effector configured to clamp tissue, a motor configured to actuate the end effector, and a controller in communication with the motor and configured to determine stress and strain on the tissue, identify a tissue type of the tissue based on the determined stress and strain on the tissue, and set operating parameters of the surgical instrument based on the identified tissue type of the tissue. [Brief explanation of the drawings]

[0022] Objects and features of the surgical system of the present disclosure will become apparent to those skilled in the art upon reading and understanding the description of the various embodiments herein in conjunction with the accompanying drawings. [Figure 1] FIG. 1 is a perspective view of a surgical instrument including a powered handle assembly, an adapter assembly, and an end effector according to one aspect of the present disclosure; [Figure 2]FIG. 2 is a front perspective view, with parts separated, of the handle assembly of FIG. 1; [Figure 3] FIG. 3 is a perspective view of the front of the power pack separated from the inner rear housing of the handle assembly of FIG. 2. [Figure 4] 4 is a cross-sectional view of the handle assembly of FIG. 2 taken along section line "4-4." [Figure 5] 2 is a schematic diagram of the handheld surgical instrument of FIG. 1 in accordance with the present disclosure; [Figure 6] 2 is a flowchart of a method for identifying tissue using the surgical instrument of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0023] Several aspects of the presently disclosed surgical instruments will be described in detail with reference to the drawings, in which like reference numerals indicate identical or corresponding elements in each of the several views. As used herein, the term "distal" refers to that portion of, or component of, the surgical instrument that is farther from the user, while the term "proximal" refers to that portion of, or component of, the surgical instrument that is closer to the user.

[0024] Surgical stapling relies heavily on the biomechanics of the tissue being incised. The stapler jaws seal the tissue through compression, inducing an internal pressure greater than the pressure of the blood vessel and its internal contents. The compression is then maintained by the formed staple after the jaws are removed. The biomechanics of the target tissue determine the stapling effects, including staple tract pressure, tissue damage, hemostasis, and pulmonary hemostasis. This requires that various organs be stapled using unique techniques, including stapler size, firing speed, and clamp relaxation time. The disclosed power stapler has the ability to measure the biomechanics of the tissue once it is clamped, but before the staples are fired. This information can be used to classify the tissue to optimize firing and provide information about the health of the tissue. Classification algorithms can be used to test the compression and relaxation profiles of lung, stomach, colon, or other suitable tissue types.

[0025] As shown in FIG. 1 , a surgical instrument 2 according to the present disclosure is shown as a powered handheld electromechanical instrument and includes 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. In particular, handle assembly 100 is configured to selectively connect with adapter 200, which in turn is configured to selectively connect with end effector 400. In some aspects, end effector 400 can be operated by a robotic system rather than powered handle assembly 100.

[0026] Although FIG. 1 illustrates end effector 400 as a linear surgical loading unit suitable for performing an endoscopic gastrointestinal anastomosis (EGIA) procedure, it is believed that the principles of the present disclosure may be equally applicable to surgical loading units (e.g., circular staplers) configured to perform end-to-end anastomosis (EEA) procedures, transverse stapling loading units, curved loading units, multipurpose loading units ("MULUs"), graspers, electrosurgical sealing forceps, rotary tissue morcellation devices, and the like.

[0027] 1 and 2, the handle assembly 100 includes a power pack 101 (FIG. 2) and an outer shell housing 10 configured to selectively receive and seal the power pack 101. The outer shell housing 10 includes a distal half section 10a and a proximal half section 10b. The proximal half section 10b is pivotally connected to the distal half section 10a by a hinge 16 disposed along the upper edges of the distal and proximal half sections 10a, 10b, such that the distal and proximal half sections 10a, 10b are separated by a plane transverse to the longitudinal axis defined by the adapter 200. When coupled, the distal and proximal half sections 10a, 10b define a shell cavity 10c for receiving the power pack 101.

[0028] 2, each of the distal and proximal half sections 10a, 10b includes a respective upper shell portion 12a, 12b and a respective lower shell portion 14a, 14b. The lower shell portion 14a includes a closure tab 18a configured to engage a closure tab 18b on the lower shell portion 14b to selectively secure the distal and proximal half sections 10a, 10b to one another and maintain the shell housing 10 in a closed configuration.

[0029] Distal half-section 10a of shell housing 10 also includes a connecting portion 20 configured to couple to a corresponding drive coupling assembly 210 of adapter 200. Specifically, connecting portion 20 includes a recess 21 configured to receive a portion of drive coupling assembly 210 of adapter 200 when adapter 200 is mated to handle assembly 100. Connecting portion 20 of distal half-section 10a also defines three apertures 22a, 22b, 22c and an elongated slot 24 formed in their distally-facing surfaces.

[0030] The distal half section 10a of the shell housing 10 also includes a plurality of buttons, such as toggle control buttons 30. In some embodiments, the toggle control buttons 30 can be two-axis control sticks configured to actuate in left-right and up-down directions. The toggle control buttons 30 can also be depressible. The distal half section 10a of the shell housing 10 can also support a plurality of other buttons, such as a pair of control buttons on the right side and a pair of control buttons on the left side.

[0031] The shell housing 10 includes a sterile barrier plate 60 removably supported within the distal half section 10a. The sterile barrier plate 60 interconnects the power pack 101 and the adapter 200. Specifically, the sterile barrier plate 60 is disposed behind the connecting portion 20 of the distal half section 10a and within the shell cavity 10c of the shell housing 10. The plate 60 includes three connecting shafts 64a, 64b, and 64c rotatably supported therein. Each connecting shaft 64a, 64b, and 64c extends through a respective aperture 22a, 22b, and 22c of the connecting portion 20 of the distal half section 10a of the shell housing 10.

[0032] Plate 60 further includes an electrical feed-through connector 66 supported thereon that extends through aperture 24 in connecting portion 20 of distal half section 10a when sterile barrier plate 60 is disposed within shell cavity 10c of shell housing 10. Coupling shafts 64a, 64b, 64c and feed-through connector 66 electrically and mechanically interconnect corresponding features of adapter 200 and power pack 101, respectively.

[0033] During use, the shell housing 10 is opened (i.e., the distal half section 10a is separated from the proximal half section 10b about the hinge 16), the power pack 101 is inserted into the shell cavity 10c of the shell housing 10, and the distal half section 10a is pivoted about the hinge 16 to a closed configuration. In the closed configuration, the closure tab 18a on the lower shell portion 14a of the distal half section 10a engages with the closure tab 18b on the lower shell portion 14b of the proximal half section 10b. After the surgical procedure, the shell housing 10 is opened and the power pack 101 is removed from the shell cavity 10c of the shell housing 10. The shell housing 10 can be discarded, and the power pack 101 can then be disinfected and cleaned.

[0034] 2 and 3, the power pack 101 includes an inner 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 inner handle housing 110 also includes a distal half section 110a and a proximal half section 110b, which define an inner housing cavity 110c for receiving the power pack core assembly 106. The power pack core assembly 106 is configured to control various operations of the surgical instrument 2.

[0035] 3, the distal half section 110a of the inner handle housing 110 supports a distal toggle control interface 130 that is operably engaged with the toggle control button 30 (FIG. 2) on the shell housing 10 such that, when the power pack 101 is disposed within the shell housing 10, actuation of the toggle control button 30 exerts a force on the toggle control interface 130. The distal half section 110a of the inner handle housing 110 also supports various other control interfaces that operably engage other buttons on the shell housing 10.

[0036] 3 and 4, the power pack 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 power any of the electrical components of the surgical instrument 2.

[0037] The power pack core assembly 106 further includes a display screen 146 supported on the main controller circuit 145. The display screen 146 is viewable through a clear or transparent window 110d disposed in the proximal half-section 110b of the inner handle housing 110.

[0038] The power pack core assembly 106 further includes a first motor 152 ( FIG. 4 ), a second motor 154 ( FIG. 3 ), and a third motor 156 ( FIG. 4 ) electrically connected to the controller circuit 143 and the battery 144, respectively. The motors 152, 154, and 156 are disposed between the motor controller circuit 143 and the main controller circuit 145. Each motor 152, 154, and 156 is controlled by a respective motor controller (not shown) disposed on the motor controller circuit 143 and coupled to the main controller 147. The main controller 147 is also coupled to memory 141 ( FIG. 5 ), which is also disposed on the motor controller circuit 143. The main controller 147 communicates with the motor controllers through an FPGA, which provides control logic signals (e.g., coast, brake, etc., and any other suitable control signals). The motor controllers output corresponding energization signals to each of the motors 152, 154, 156 using fixed frequency pulse width modulation (PWM).

[0039] The electric pack core assembly 106 also includes an electrical receptacle 149. The electrical receptacle 149 is electrically connected to the main controller board 145 via a second ribbon cable (not shown). The electrical receptacle 149 defines a plurality of electrical slots for receiving respective electrical contacts extending from the feed-through connector 66 of the plate 60 (FIG. 2) of the shell housing 10.

[0040] Each motor 152, 154, 156 includes a respective motor shaft (not shown) extending therefrom. Each motor shaft may have a recess defined therein having a trilobal cross-sectional profile for receiving the proximal end of a respective coupling shaft 64 a, 64 b, 64 c of plate 60 of shell housing 10.

[0041] Rotation of the motor shafts by the respective motors 152, 154, 156 actuates shaft and / or gear components of the adapter 200 to perform various operations of the surgical instrument 2. In particular, the motors 152, 154, 156 of the power pack core assembly 106 are configured to actuate the shaft and / or gear components of the adapter 200 to selectively actuate components of the end effector 400 to rotate the end effector 400 about its longitudinal axis, pivot the end effector 400 about a pivot axis that is perpendicular to the longitudinal axis defined by the adapter 200, and perform and terminate stapling functions of the jaw members 402 a, 402 b of the end effector 400.

[0042] 5, a schematic diagram of the electric power pack 101 is shown. For simplicity, only one of the motors 152, 154, 156 is shown, namely, motor 152. Motor 152 is coupled to a battery 144. In some embodiments, motor 152 may be coupled to any suitable power source configured to provide electrical energy to motor 152, such as an AC / DC transformer.

[0043] The battery 144 and the motor 152 are coupled to a motor controller circuit 143 that controls the operation of the motor 152, including the flow of electrical energy from the battery 144 to the motor 152. The motor controller circuit 143 includes a plurality of sensors 408a, 408b, ..., 408n configured to measure the operating conditions of the motor 152 and the battery 144. The sensors 408a-408n may include voltage sensors, current sensors, temperature sensors, telemetry sensors, optical sensors, and combinations thereof. The sensors 408a-408n may measure the voltage, current, and other electrical characteristics of the electrical energy supplied by the battery 144. The sensors 408a-408n may also measure the angular velocity (e.g., rotational speed) of the motor 152 as revolutions per minute (RPM), torque, temperature, current draw, and other operating characteristics. The angular velocity may be determined by measuring the rotation of the motor 152 or a drive shaft (not shown) coupled to and rotatable by the motor 152.

[0044] The position of the various axially movable drive shafts can also be determined by using various linear sensors disposed in or near the shaft, or can be estimated from RPM measurements. It is contemplated that optical or magnetic encoders, linear variable differential transformers (LVDTs), or other methods can be used to determine the linear position of the drive shaft.

[0045] In some embodiments, torque can be calculated based on the regulated current draw of motor 152 at a constant RPM. In further embodiments, motor controller circuitry 143 and / or controller 147 can measure time and process the above-mentioned values ​​as a function of time, including integration and / or differentiation, to determine, for example, the rate of change of the measured values.

[0046] The motor controller circuit 143 is also coupled to a controller 147, which includes a number of inputs and outputs for interfacing with the motor controller circuit 143. In particular, the controller 147 receives measured sensor signals from the motor controller circuit 143 regarding the operating conditions 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 the sensor readings and dedicated algorithm instructions. The controller 147 also receives a number of control signals from a user interface (e.g., switches, buttons, a touchscreen, etc. coupled to the controller 147). It is also configured to accept user input.

[0047] The controller 147 is coupled to a 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.

[0048] The present disclosure provides an apparatus and method for assessing the stress and strain profile of tissue grasped by an end effector 400, as well as the stress relaxation of the grasped tissue, whereby the controller 147 of the surgical instrument 2 identifies the tissue type (e.g., lung, stomach, and colon) of the grasped tissue based on the determined stress and strain profile and the stress relaxation profile. 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.

[0049] To measure the stress-strain profile and stress relaxation of the tissue, the surgical instrument 2 can include multiple sensors. For example, the jaw members 402a, 402b (FIG. 1) of the end effector 400 can include a gap measuring sensor 404 that determines the gap defined between the jaw members 402a, 402b, which directly correlates to tissue thickness. The gap measuring sensor 404 can be a potentiometer. In some embodiments, the motor 152 can have an encoder (not explicitly shown) associated with the motor that is configured to determine the jaw angle and, therefore, the tissue thickness. Other methods of determining the tissue thickness (e.g., strain) of the tissue are contemplated, such as the linear sensor described above disposed in or near the drive shaft of the surgical instrument 2.

[0050] To determine the stress experienced by the tissue when the jaw members 402a, 402b clamp around it, the surgical instrument 2 can include a strain gauge 157 ( FIG. 5 ) associated with the main drive shaft 159. The strain gauge 157 is configured to determine the mechanical load on the drive shaft 159, which directly correlates to the load or stress applied to the tissue. In other embodiments, force-measuring sensors (not explicitly shown) can be provided on the tissue in contact with the surfaces of the jaw members 402a, 402b. The force measured by each force-measuring sensor can be converted to a value of tension exerted on the tissue using known algorithms. Other methods of determining stress on the tissue are also contemplated. For example, because the current drawn by the motor 152 and its angular velocity change in response to the mechanical load faced by the motor 152, the current drawn by the motor 152 can be used to detect biomechanical properties of the tissue (e.g., the stress experienced by the tissue in response to the jaws clamping). Thus, analysis of the amount of change (eg, rate of change) of current draw and angular velocity allows the load or stress exerted on the tissue to be determined.

[0051] Further details regarding methods for measuring stress and strain in clamped tissue can be found in US Pat. No. 8,002,795, the entire contents of which are incorporated herein by reference.

[0052] By collecting stress and strain data as the tissue is clamped, as well as stress relaxation data for the tissue, specific biomechanical parameters of the tissue can be determined via curve fitting of the collected data using selected mathematical formulas (described below). The determined biomechanical parameters then serve as input to an application-specific classification algorithm, which identifies the tissue type and is described in further detail with reference to FIG. 6.

[0053] 6, initially, with tissue disposed between jaw members 402a, 402b, controller 147 sends a signal to motor controller circuit 143 to operate motor 152 based on desired user input, e.g., to control motors 152, 154, 156 to close (without firing) end effector 400 around the tissue, in step 600. Controller 147 provides the desired command to motor controller circuit 143, which then outputs a corresponding energization signal to motor 152 to carry out the command received from controller 147.

[0054] The jaw members 402a, 402b of the end effector 400 move from a first state in which the jaw members 402a, 402b grasp (but do not compress) tissue toward a second state in which the jaw members 402a, 402b compress the tissue a threshold amount (e.g., to stop blood flow). The jaw members 402a, 402b may close at a constant speed of 0.31, 0.1, or 0.01 inches per second. Other closing speeds are contemplated. The jaw members 402a, 402b may include an irrigation sensor that communicates with the controller 147 to determine when to stop closing the jaw members 402a, 402b when irrigation through the grasped tissue has stopped. In other aspects, controller 147 can be configured to direct motor 152 to close jaw members 402a, 402b until the jaw gap is reduced by a preset percentage of the starting jaw gap (e.g., when tissue is being grasped without compression). For example, controller 147 can be configured to stop closure of jaw members 402a, 402b when jaw members 402a, 402b are closed to approximately 10%-40% of the starting jaw gap.

[0055] As the jaw members 402a, 402b move from the first state toward the second state, stress and strain measurements of the clamped tissue are obtained at preset time intervals (e.g., every 0.25 seconds, every 0.5 seconds, or every 1 second) and stored in memory 141 in step 602. Determining the stress on the tissue includes measuring (e.g., using strain gauges 157) the clamping force applied to the tissue by the pair of jaw members 402a, 402b as the pair of jaw members 402a, 402b move from the first state toward the second state and dividing the measured clamping force by a known surface area of ​​the tissue in contact with the surfaces of the jaw members 402a, 402b. Determining the strain on the tissue includes measuring the change in tissue thickness, for example, using the gap measurement sensor 404 or a motor encoder, as the pair of jaw members 402a, 402b move from the first state toward the second state.

[0056] In step 604, the controller 147 is configured to maintain the jaw members 402a, 402b in the 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 being applied to the tissue, measurements of the stress on the tissue are taken at preset time intervals and stored in the memory 141. The stress measurements provide a stress relaxation profile of the tissue. At this stage, the clinician can manually actuate the surgical instrument 2 to open the jaw members 402a, 402b and release the tissue. In other aspects, the controller 147 can be configured to automatically cause the jaw members 402a, 402b to open and release the tissue.

[0057] In some embodiments, controller 147 can generate and display stress-strain and / or stress-relaxation plots based on the received measurement data. The plots may be a collection of measurement data points. In further embodiments, the plots may not be visualized or graphed (e.g., output on a display device) by controller 147, but may simply be stored in memory 141 for use by controller 147.

[0058] In step 606, controller 147 identifies a tissue type of the clamped tissue based on the determined stress and strain data and stress relaxation data of the clamped tissue. Identifying the tissue type includes determining a plurality of biomechanical parameters based on the determined stress and strain data and stress relaxation data of the tissue. The biomechanical parameters are determined by curve fitting the measured stress and strain data using the following equations (I)-(III). In particular, the biomechanical parameters include alpha and beta from exponential equation (I), alpha, beta, and gamma from exponential equation (II), and alpha and beta from inverse equation (III), each of which is stored in memory 141 and accessible by controller 147. In some embodiments, the biomechanical parameters in stress relaxation equation (IV) can also be determined by curve fitting the measured stress relaxation data to equation (IV). (I)

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[0059] Once the controller 147 determines the biomechanical parameters using Equations (I)-(III) or (I)-(IV), the controller 147 inputs the determined biomechanical parameters into a classification algorithm stored in the memory 141, which identifies the tissue type. Other parameters, such as tissue bioimpedance, tissue geometric values, and / or tissue load values, could be used in the prediction algorithm. The classification algorithm could be a support vector machine algorithm, an ensemble of bagged decision trees, or any other suitable classification algorithm. The memory 141 could internally store known biomechanical parameters for various tissue types, such as the colon, lung, stomach, etc. In some embodiments, the controller 147 can be configured to compare the determined stress and strain data of the tissue with known stress and strain data of the individual tissue types to determine the tissue type. The controller can further be configured to compare the determined stress relaxation data of the tissue with known stress relaxation data of the individual tissue types to determine the tissue type.

[0060] In step 608, the controller 147 sets operating parameters for 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 clamp release speed of the end effector 400, the clamping force of the end effector 400, and the staple size. For example, an indication of tissue thickness or other operating parameters, such as the knife retraction speed, may be stored in the memory 141 of the surgical instrument 2. The operating parameters selected by the controller 147 are those known to be best suited for operating on the particular tissue.

[0061] The present disclosure can provide multiple surgical loading units, each configured for use on a particular type of tissue (e.g., liver, lung, cardiac, gastrointestinal, etc.) and / or during a particular type of surgical procedure (e.g., liver resection, gastrointestinal anastomosis, lesion resection). Thus, each loading unit has a distinct set of operating parameters specific to the type of tissue with which the selected surgical loading unit may be used and / or the type of surgical procedure with which the surgical loading unit may be performed. For example, if the tissue identified using the methods of the present disclosure is liver tissue, a surgical loading unit having operating parameters that take liver tissue resection into account is selected. Due to the densely vascularized and thick liver tissue, a surgical loading unit for liver resection can be pre-programmed with instructions that, when executed, can result in a high, consistent staple firing rate regardless of the sensed tissue thickness. If another type of tissue is identified, a loading unit with the appropriate operating parameters would be selected in place of the surgical loading unit used for liver resection. In some embodiments, the controller 147 can indicate to the clinician via an audio cue or via a visual cue that the surgical loading unit may be inappropriate for the selected tissue and provide a recommendation for an appropriate surgical loading unit.

[0062] It should be understood that the various aspects disclosed herein can be combined in different combinations than those specifically presented in the description and accompanying drawings. It should also be understood that certain acts or events of any of the processes or methods described herein may be performed in a different order, or may be added, combined, or omitted entirely (e.g., not all described acts or events may be necessary to practice the techniques), depending on the implementation. Furthermore, while certain aspects of the present disclosure are described for clarity as being performed by a single module or unit, it should be understood that the techniques of the present disclosure may be performed by a combination of units or modules associated with, for example, a medical device.

[0063] In one or more embodiments, the described techniques may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. The computer-readable medium may include a non-transitory computer-readable medium corresponding to a tangible medium, such as a data storage medium (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 can be accessed by a computer).

[0064] The instructions may 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 logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Thus, the term "processor," as used herein, may refer to any of the above structures, or any other physical structure suitable for implementing the described techniques. Also, the techniques may be implemented entirely in one or more circuits or logic elements.

Claims

[Claim 1] The invention described in this specification.

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