US20120211542A1 - Controlled tissue compression systems and methods - Google Patents

Abstract

A surgical instrument is provided including an end effector configured to clamp, staple or cut tissue tissue, a motor configured to drive the end effector and a control system. The control system is configured to receive information about at least one tissue property and select a tissue management mode based on the at least one tissue property. The control system controls the motor based on the selected tissue management mode.

Description

CROSS REFERENCE TO RELATED APPLICATION
• The present application claims the benefit of and priority to U.S. Provisional Application Ser. No. 61/445,700, filed on Feb. 23, 2011, the entire contents of which are incorporated herein by reference.
BACKGROUND
• 1. Technical Field
• The present disclosure relates generally to medical devices. More specifically, the present disclosure relates generally to systems and methods for controlled tissue compression.
• 2. Background of the Related Art
• Some surgical procedures require the compression, e.g., clamping, of a patient's tissue. Such procedures may include, e.g., anastomosing, stapling, and resecting of tissue. For example, where cancerous tissue is identified in a patient's gastrointestinal tract, the cancerous tissue may need to be surgically removed. Where, for example, the cancerous tissue is located on the colon and is accessible by surgical instrumentation, the surgeon may make an incision in the patient's abdomen to allow access to the bowel. The surgeon may then use a linear cutting and stapling device, such as that described in U.S. patent application Ser. No. 12/235,362, filed Sep. 22, 2008 (U.S. Patent Publication No. 2009/0101692), which is expressly incorporated herein in its entirety by reference thereto, to cut and staple the colon tissue on opposite sides of the cancerous portion to be removed. In this procedure, the colon is externally clamped (e.g., between opposed jaws) to compress the tissue. While the tissue is compressed, a cutter and a stapler are activated to make a linear cut and apply typically two linear rows of staples in the areas adjacent the cut. The stapling thus closes both open ends of the portion of the bowel to be removed, as well as providing a temporary closure of the two cut ends of the bowel. This closure limits exposure of the surrounding tissue to the interior of the bowel, thus limiting the risk of infection. After the cutting and stapling procedure, the cancerous portion of tissue may be removed from the patient's body.
• After the resection of the cancerous tissue, the surgeon may employ an anastomosing and stapling device, e.g., a circular stapler/cutter, such as that described in U.S. patent application Ser. No. 10/785,682, filed Feb. 24, 2004 (U.S. Pat. No. 7,342,983), which is expressly incorporated herein in its entirety by reference thereto. During this procedure a head portion is positioned within the colon adjacent one of the cut ends and a base or shaft portion is positioned within the colon adjacent the other cut end. The head portion and the base portion may be coupled via a shaft and/or cable that extends out of one cut end and into the other. Via this coupling, the surgeon is able to actuate the anastomosing and stapling device to draw the head portion and the base portion together. After the two cut ends of the colon contact each other, the actuation continues such that the two portions of the colon are clamped together at an annular area of contact. While clamped, the anastomosing and stapling device may be further actuated to apply an annular ring of staples into the compressed tissue. The device may also cut excess tissue disposed within the colon. The head portion and the base portion are then moved apart and the anastomosing and stapling device removed from the patient.
• To achieve effective stapling in the above procedures, the tissue must be compressed to the extent that there is an adequately small tissue gap, e.g., one millimeter, between the faces of the tool. If the clamping structures of the instrument are exposed to excessive force, maintaining a uniform target tissue gap across the length of tissue to be stapled may be difficult or even impossible.
• Moreover, when performing the compression, a constant closing rate (e.g., the closing rate between jaws of a linear stapler or between the head and base portion of a circular stapler/cutter) may exert a high level of pressure on the clamped tissue. This high level of pressure may result in excess tissue trauma. It is thus desirable to limit this trauma, e.g., by effectively controlling the pressure applied to the tissue.
• Further, it is desirable to determine how the tissue to be clamped is responding to compression and process this information to determine clamping pressure. U.S. patent application Ser. No. 09/510,927, filed Feb. 22, 2000 (now U.S. Pat. No. 6,716,233), which is expressly incorporated herein in its entirety by reference hereto, describes apparatus and methods of using a tissue sensor to control operation of a surgical stapler.
SUMMARY
• In an embodiment of the present disclosure, a surgical device is provided. The surgical device includes an end effector configured to clamp, staple or cut tissue, a motor configured to drive the end effector and a control system. The control system receives information about at least one tissue property and selects a tissue management mode based on the at least one tissue property. The control system controls the motor based on the selected tissue management mode.
• The surgical device may also include an indicator that provides a clinician with a status of a tissue gap range of the end effector and a sensor array configured to detect at least one tissue property. The sensor array may detect at least one tissue property by measuring the current draw on the motor or the dwell effect at the end effector. The sensor array may also assess tissue properties by taking measurements such as pulse oximetry, tissue oxygen saturation or tissue impedance. The dwell effect occurs as the jaws remain at a static pressure for a period and fluids escape from the tissue cells, allowing the tissue to relax.
• The tissue management modes that can be selected by the surgical device include a constant torque profile, a modulated torque profile, a maximum torque profile or a manual override mode. The control system applies a constant signal to the motor in the constant torque profile or a periodic signal to the motor in the modulated torque profile. In the maximum torque profile, the powered surgical instrument fires at a speed that is faster than the speed of firing in the constant torque profile, the modulated torque profile or the manual override mode. In the manual override mode, the user manually controls the motor. Typically, pressure during tissue clamping will be a function of the motor torque.
• In another embodiment of the present disclosure, a method for applying a staple by a powered surgical instrument is provided. The method includes the steps of providing a surgical instrument having an end effector that is powered by a motor, inputting a tissue type and/or disease type to determine an initial clamping or tissue management mode, clamping tissue using the end effector driven by the motor, detecting at least one tissue property of the clamped tissue, determining if a desired tissue gap range is achieved by the end effecter, if necessary, selecting an additional clamp mode to iteratively adjust clamping to achieve the desired tissue gap, and firing the powered surgical instrument to apply staples to the clamped tissue once the desired tissue gap has been achieved.
• The method may also include the step of providing an indication of a status of a tissue gap range. The tissue property may be detected by measuring the current draw on the motor or measuring a dwell effect at the end effector.
• Selecting the clamping or tissue management mode may be based on the tissue property of the clamped tissue detected or be performed by a clinician. The tissue management modes that can be selected by the surgical device include a constant torque profile, modulated torque profile or maximum torque profile. A manual override mode may allow the user to select a tissue management mode.
BRIEF DESCRIPTION OF THE DRAWINGS
• The above and other aspects, features, and advantages of the present disclosure will become more apparent in light of the following detailed description when taken in conjunction with the accompanying drawings in which:
• FIG. 1 is a perspective view of a powered surgical instrument according to an embodiment of the present disclosure;
• FIG. 2 is a system block diagram of the powered surgical instrument according to an embodiment of the present disclosure;
• FIG. 3 is a flow chart depicting operation of the powered surgical instrument according to an embodiment of the present disclosure; and
• FIG. 4 is a flow chart depicting an indicator system according to an embodiment of the present disclosure.
DETAILED DESCRIPTION
• Particular embodiments of the present disclosure are described hereinbelow with reference to the accompanying drawings; however, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure and may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure.
• Like reference numerals may refer to similar or identical elements throughout the description of the figures. As shown in the drawings and described throughout the following description, as is traditional when referring to relative positioning on a surgical instrument, the term “proximal” refers to the end of the apparatus which is closer to the user and the term “distal” refers to the end of the apparatus which is farther away from the user. The term “clinician” refers to any medical professional (i.e., doctor, surgeon, nurse, or the like) performing a medical procedure involving the use of embodiments described herein.
• A powered surgical instrument, e.g., a surgical stapler, in accordance with the present disclosure is referred to in the figures asreference numeral100. Poweredsurgical instrument100 is merely an example of a surgical instrument that utilizes the embodiments of the present disclosure described herein and therefore, is not intended to limit the present disclosure to this one particular embodiment of a surgical instrument.
• Referring initially toFIG. 1, poweredsurgical instrument100 includes a housing or handle110, anendoscopic portion140 defining a longitudinal axis A-A extending therethrough, and anend effector160, defining a longitudinal axis B-B (illustrated substantially aligned with axis A-A inFIG. 1) extending therethrough.Endoscopic portion140 extends distally fromhousing110, and clamping mechanism orend effector160 is disposed adjacent adistal portion142 ofendoscopic portion140.End effector160 is used to clamp, staple and/or cut tissue disposed therebetween.
• Poweredsurgical instrument100 may include a control system designated generally as200 inFIG. 2. Control system200 may be integrated inhousing110 of poweredsurgical instrument100 or some of the components may be provide in a stand-alone unit. Control system200 includes aprocessor202, aninput device204, adisplay206, amemory208, anindicator210, amotor212 and asensor array214.
• Processor202 may be an integrated circuit or may include analog and/or logic circuitry that may be used to: execute instructions according to inputs provided by theinput device204 orsensor array214; execute instructions according to a program provided inmemory208; and/orcontrol motor212 thereby controlling theend effector160 to clamp, staple and/or cut tissue therebetween.
• Input device204 may include a keyboard, a touchscreen input device, switches and/or buttons to control operation of the poweredsurgical instrument100.Input device204 may be used to: select between tissue management modes; controlend effector160; apply a staple or clamp; and input tissue properties such as tissue type and/or disease.
• Display206 may include a liquid crystal display, a light emitting diode display or the like.Display206 may output a status of the powered surgical instrument, the measured tissue properties, the number of staples/clips applied, etc.
• Control system200 may also include anindicator210 that may include at least one light emitting diode (LED) to indicate whether a tissue gap range, between the jaws ofend effector160, has been met.Indicator210 may include a single multi-color LED or separate LEDs for red, yellow and green. The red LED may indicate a malfunction, a yellow LED may indicate that a tissue gap range has not been met and a green LED may indicate that the tissue gap range has been met. Additionally, an LED may be pulsed to indicate additional information. For instance, a pulsing yellow LED can indicate that an additional clamping cycle is being performed.
• Sensor array214 determines tissue properties by detecting the current draw onmotor212 or a dwell effect atend effector160. The detected tissue properties are used to determine a clamping or tissue management mode, a tissue gap range, firing parameters, a speed of the motor, a modulation/pulse of the motor, deployment of the staples, etc. The tissue properties are used as an input to the iterative adjustment of the clamping pressure and duration for a tissue management mode.
• Memory208 may be a volatile type memory (e.g., RAM) and/or non-volatile type memory (e.g., flash media, disk media, etc.) that stores programs or sets of instructions for the operation of the poweredsurgical instrument100.
• Such programs include a number of tissue management modes that may be used to clamp tissue in order to apply a staple or clip to the tissue grasped byend effector160. The tissue management modes are selected to apply an atraumatic stress or strain to the tissue by varying the compression of the tissue. The tissue management modes include a constant torque profile, a modulated torque profile, a maximum torque profile and a manual override mode. The tissue management modes may be automatically selected based on detected tissue parameters and/or tissue type and disease type inputted by a clinician or the tissue management mode may be selected by a clinician.
• When a constant torque profile is selected, the poweredsurgical instrument100 uses controlled tissue compression to apply constant rate if strain to tissue during the clamp, dwell and firing stages to optimize tissue gap and staple formation by applying a constant signal tomotor212 fromprocessor202. The parameters used to control themotor212 and/orend effector160 in the constant torque profile may be based on a desired speed of firing of thesurgical instrument100 or the type of tissue grasped byend effector160.
• The modulated torque profile applies pulsating or periodic strain energy to tissue by applying a periodic signal tomotor212. More specifically,processor202 applies a pulse width modulated signal (PWM) or any other periodic signal to the motor to achieve an optimized compression profile, i.e., minimum tissue gap (maximum strain) with minimum tissue trauma (minimum stress). The optimized compression profile may vary for different tissue types and/or disease types. The signal fromprocessor202 may be predetermined and stored in a memory. Alternatively, the signal outputted byprocessor202 may be determined by performing a current slope analysis on the current detected from the motor, initial tissue thickness T₀, initial clamped tissue thickness T₁and total strain/energy.
• When the tissue management mode is set for operation in the maximum torque profile, thesurgical instrument100 fires relatively faster than the other modes of operation. While in the maximum torque profile,surgical instrument100 fires relatively faster at the beginning and at the end of the stroke where device stresses are relatively lower. When the tissue management mode is set to operate in the manual override mode, the clinician can manually control the motor ofsurgical instrument100 to achieve the desired tissue gap ofend effector100 and to manually fire thesurgical instrument100.
• Memory208 may also store correlation tables to correlate tissue type and disease type to the requisite tissue gap range and firing parameters that need to be achieved to successfully apply a staple or clip to tissue.
• FIG. 3 depicts a flow chart describing an operation of the control system200 of poweredsurgical instrument100. As shown inFIG. 3, a clinician starts, “powers-up” or “turns on” the poweredsurgical instrument100 instep300. A clinician enters the tissue type and/or disease type instep305 usinginput device204. The clinician then positionsend effector160 onto the desired tissue and an initial clamping (tissue management) mode is determined. Then, instep315,end effector160 clamps the desired tissue and determines tissue properties such as initial thickness, density, initial clamped thickness, etc. instep320.Processor202, then, instep325, determines if the tissue gap range is met for the particular tissue type. If the gap range is met, the control system200 proceeds to step370.
• Instep325, if the gap range is not met, the tissue gap and tissue properties are evaluated byprocessor202 to determine if additional clamping is beneficial. If it is, the gap range and tissue properties are used to determine a new clamping mode instep327. The iterative clamping and evaluation process then returns to step315 and is continued until an optimum gap range is met or it is determined that the tissue is unsuitable for the selected range in which instance the poweredsurgical instrument100 prompts the clinician with a suggestion if a different reload or end effector (loaded with a different sized staple) should be used. If the clinician selects a different reload or end effector, then the poweredsurgical instrument100 is reloaded instep340 and proceeds to step315 to clamp tissue.
• If the clinician does not select a different reload or end effector, the clinician may select a manual override mode instep345. If the user selects the manual override mode, the poweredsurgical instrument100 is placed in the manual override mode instep350.
• Alternatively, the process proceeds to step355 to select a tissue management mode. The tissue management mode may be automatically selected byprocessor202 based on the inputted tissue type, disease type, and/or tissue properties or selected by the clinician. Based on the selection of the tissue management mode, the poweredsurgical instrument100 may enter the constant torque profile ofstep362, modulated torque profile ofstep364 or the maximum torque profile ofstep366. Then the control system200 proceeds to step370 where a determination is made as to whether a staple should be applied. This determination may be made byprocessor202 or by the clinician. If the staple should be applied, then instep375, the control system200 controls the poweredsurgical instrument100 to apply the staple. If the staple is not applied, the control system200 ends the procedure (step380) or restarts to apply a subsequent staple (step300).
• FIG. 4 depicts a flow chart describing an operation of the indicator system of the poweredsurgical instrument100. The poweredsurgical instrument100 is started instep400 and the tissue type and/or disease is entered instep405.Processor202 then uses one of the correlating tables stored inmemory208 to determine the tissue gap range for the red-yellow-green indicator210. The tissue gap range is measured instep415. If an error is determined or the tissue gap range exceeds an upper limit, the process proceeds to step430 and the red indictor is illuminated. If there is no error or the tissue gap range does not exceed an upper limit, the process proceeds to step435. If the tissue gap range is not in the acceptable range but it does not exceed the upper limit, the yellow indicator is illuminated instep440. If the tissue gap range is met, the process proceeds to step445 and the green indicator is illuminated.
• It should be understood that the foregoing description is only illustrative of the present disclosure. Various alternatives and modifications can be devised by those skilled in the art without departing from the disclosure. Accordingly, the present disclosure is intended to embrace all such alternatives, modifications and variances. The embodiments described with reference to the attached drawing figs. are presented only to demonstrate certain examples of the disclosure. Other elements, steps, methods and techniques that are insubstantially different from those described above and/or in the appended claims are also intended to be within the scope of the disclosure.

Claims (18)

1. A surgical device comprising:

an end effector configured to clamp, staple or cut tissue;

a motor configured to drive the end effector; and

a control system configured to:

receive information about at least one tissue property;

select a tissue management mode based on the at least one tissue property; and

control the motor based on the selected tissue management mode.

2. The surgical device according toclaim 1, wherein the control system further comprises an indicator that provides a clinician with a status of a tissue gap range of the end effector.

3. The surgical device according toclaim 1, wherein the control system further includes a sensor array configured to detect at least one tissue property.

4. The surgical device according toclaim 3, wherein the sensor array detects a tissue property by measuring a current draw on the motor.

5. The surgical device according toclaim 3, wherein the sensor array detects a tissue property by measuring a dwell effect at the end effector.

6. The surgical device according toclaim 1, wherein the tissue management mode is a constant torque profile, a modulated torque profile, a maximum torque profile or a manual override mode.

7. The surgical device according toclaim 6, wherein the control system applies a constant signal to the motor in the constant torque profile.

8. The surgical device according toclaim 6, wherein the control system applies a periodic signal to the motor in the modulated torque profile.

9. The surgical device according toclaim 6, wherein the powered surgical instrument fires at a speed that is faster than the speed of firing in the constant torque profile, the modulated torque profile or the manual override mode when the powered surgical instrument uses the maximum torque profile.

10. The surgical device according toclaim 6, wherein a user manually controls the motor in the manual override mode.

11. A method of applying staples by a powered surgical instrument, the method comprising the steps of:

providing a surgical instrument having an end effector that is powered by a motor;

inputting tissue type and/or disease type;

clamping tissue using the end effector driven by the motor;

detecting at least one tissue property of the clamped tissue;

determining if a desired tissue gap range is achieved by the end effector;

selecting a tissue management mode to clamp tissue to achieve the desired tissue gap; and

firing the powered surgical instrument in the selected tissue management mode to apply staples to the clamped tissue.

12. The method according toclaim 11 further comprising the step of providing an indication of a status of a tissue gap range.

13. The method according toclaim 11, wherein the step of detecting at least one tissue property further includes measuring a current draw on the motor.

14. The method according toclaim 11, wherein the step of detecting at least one tissue property further includes measuring a dwell effect at the end effector.

15. The method according toclaim 11, wherein the step of selecting the tissue management mode is based on the at least one tissue property of the clamped tissue detected.

16. The method according toclaim 11, wherein the step of selecting the tissue management mode is performed by a clinician.

17. The method according toclaim 11, wherein the tissue management mode is a constant torque profile, modulated torque profile, maximum torque profile or a manual override mode.

18. The method according toclaim 11, further comprising the step of the powered surgical instrument suggesting a different reload when the desired tissue gap range for the end effector is not achieved.

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