Patent Description:
Some surgical procedures may require a clinician to access a surgical site via the abdominal cavity of a patient. To gain such access, an opening is first formed through the abdominal wall tissue overlying the abdominal cavity. In some surgical procedures (referred to as "laparoscopic" or "endoscopic" surgeries), a relatively small opening is made through the abdominal wall tissue, and the surgical site is then accessed with elongate instruments inserted through an access device generally referred to as a "trocar" positioned within the opening. Traditional trocars generally include a cannula assembly and an obturator that is removably received within a working channel of the cannula assembly. In use, the obturator is mated with the cannula assembly, and the combined structure (i.e., the trocar) is directed by a clinician downwardly through the abdominal wall of the patient such that the distal ends of the obturator and the cannula assembly extend into the abdominal cavity. The clinician then withdraws the obturator from the cannula assembly so that surgical instruments may be directed downwardly through the working channel of the cannula assembly to access the surgical site.

Merely exemplary versions of trocars, components thereof, and other varieties of surgical access devices are disclosed in <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>.

While various kinds of surgical instruments, including surgical access devices and end effectors, and other associated components have been made and used, it is believed that no one prior to the inventor(s) has made or used the invention described in the appended claims.

<CIT> discloses a surgical cannula for providing insufflation gases to a surgical cavity of a patient, allowing insertion of medical instruments into the surgical cavity through the cannula, and venting gases from the surgical cavity to the outside environment can include venting features including filters to more safely reduce the amount of undesirable materials such as smoke from reaching the outside environment.

<CIT> discloses another surgical cannula for providing insufflation gases to a surgical cavity of a patient.

The present invention is defined in the independent claim. Optional features are recited in the dependent claims.

The drawings are not intended to be limiting in any way, and it is contemplated that the invention may be carried out in a variety of other ways, including those not necessarily depicted in the drawings.

The drawings and descriptions should be regarded as illustrative in nature and not restrictive.

For clarity of disclosure, the terms "proximal" and "distal" are defined herein relative to a surgeon, or other operator, grasping a surgical device. The term "proximal" refers to the position of an element arranged closer to the surgeon, and the term "distal" refers to the position of an element arranged further away from the surgeon. Moreover, to the extent that spatial terms such as "top," "bottom," "upper," "lower," "vertical," "horizontal," or the like are used herein with reference to the drawings, it will be appreciated that such terms are used for exemplary description purposes only and are not intended to be limiting or absolute. In that regard, it will be understood that surgical instruments such as those disclosed herein may be used in a variety of orientations and positions not limited to those shown and described herein.

Furthermore, the terms "about," "approximately," and the like as used herein in connection with any numerical values or ranges of values are intended to encompass the exact value(s) referenced as well as a suitable tolerance that enables the referenced feature or combination of features to function for the intended purpose(s) described herein.

<FIG> depict exemplary surgical access devices in the form of a single-use first trocar (<NUM>) and a reusable second trocar (<NUM>), each configured to provide surgical site access in a laparoscopic surgical procedure. Each trocar (<NUM>, <NUM>) includes a cannula assembly (<NUM>, <NUM>) having a working channel (<NUM>, <NUM>), and an obturator (<NUM>, <NUM>) configured to be removably inserted coaxially into the working channel (<NUM>, <NUM>) so that the assembled trocar (<NUM>, <NUM>) may be directed distally through the abdominal wall of a patient and into the abdominal cavity, for example as described below in connection with <FIG>.

As shown in <FIG>, cannula assembly (<NUM>) of single-use trocar (<NUM>) includes a cannula (<NUM>) and a seal housing (<NUM>). Cannula (<NUM>) and seal housing (<NUM>) cooperate to define working channel (<NUM>), which extends longitudinally along a central axis (A) of trocar (<NUM>). In particular, working channel (<NUM>) is defined by a lumen of cannula (<NUM>) in communication with a hollow interior of seal housing (<NUM>). Cannula assembly (<NUM>) is configured to receive elongate surgical instruments distally through working channel (<NUM>) to provide access to surgical sites within the abdominal cavity of a patient. As described in greater detail below, seal housing (<NUM>) houses a pair of seal structures defining a seal assembly configured to maintain insufflation of the patient's abdominal cavity while permitting passage of surgical instruments and tissue fragments along working channel (<NUM>).

Cannula (<NUM>) of the present version may include a bell-shaped hub (not shown) at a proximal end thereof, and an elongate cylindrical tube (<NUM>) extending distally from the hub and terminating at an angled cannula tip (<NUM>). An outer surface of cannula tube (<NUM>) includes a plurality of tissue gripping features in the form of annular ribs (<NUM>) arranged axially along a medial portion of cannula tube (<NUM>). Ribs (<NUM>) are configured to grip the layers of abdominal wall tissue through which cannula (<NUM>) is inserted, and thereby assist in stabilizing cannula (<NUM>) in axial and radial directions while cannula (<NUM>) is positioned within the opening formed in the abdominal wall of a patient.

More specifically, tissue gripping ribs (<NUM>) of the present example are formed as annular scallops in the sidewall of cannula tube (<NUM>) such that each rib (<NUM>) tapers radially inwardly in a distal direction from a radially outermost edge of the rib (<NUM>). The radially outermost edges of ribs (<NUM>) are thus generally flush with the non-ribbed proximal and distal portions of cannula tube (<NUM>). The resulting configuration of ribs (<NUM>) promotes advancement of cannula tube (<NUM>) through tissue layers in a distal direction and resists retraction of cannula tube (<NUM>) through the tissue layers in a reverse, proximal direction. Advantageously, this configuration protects against unintended withdrawal of cannula tube (<NUM>) from the abdominal wall of patient during a surgical procedure. It will be appreciated, however, that cannula tube (<NUM>) may be provided with various other types of tissue gripping features in other versions of trocar (<NUM>). For instance, cannula tube (<NUM>) may include a tissue gripping feature in the form of one or more helical ribs that extend around at least a medial portion of cannula tube (<NUM>), and which may be scalloped similar to ribs (<NUM>).

Seal housing (<NUM>) of cannula assembly (<NUM>) includes a proximal housing portion (<NUM>) and a distal housing portion (<NUM>) to which proximal housing portion (<NUM>) is removably attached. Proximal housing portion (<NUM>) includes a proximal head (<NUM>) and a distal base (<NUM>) secured together. Distal housing portion (<NUM>) includes a distal shroud (<NUM>) that encircles the proximal hub (not shown) of cannula (<NUM>), a cap plate (<NUM>) secured to a proximal end of distal shroud (<NUM>), and a latch ring (<NUM>) rotatably disposed therebetween and having a radially outwardly projecting tab (<NUM>). Latch ring (<NUM>) is selectively rotatable via tab (<NUM>) about the central axis (A) of trocar (<NUM>) between a locked position and an unlocked position. In the locked position, latch ring (<NUM>) locks proximal housing portion (<NUM>) to distal housing portion (<NUM>). In the unlocked position, latch ring (<NUM>) permits separation of proximal housing portion (<NUM>) from distal housing portion (<NUM>), for example to directly access a distal seal structure (not shown) housed within distal housing portion (<NUM>). In some versions, distal shroud (<NUM>) may be formed integrally with the proximal end of cannula tube (<NUM>) such that distal shroud (<NUM>) is a component of cannula (<NUM>).

Though not shown, proximal housing portion (<NUM>) houses a proximal (or "outer") seal structure, and distal housing portion (<NUM>) houses a distal (or "inner") seal structure, both arranged along the central axis (A) of trocar (<NUM>). The proximal and distal seal structures cooperate to define a seal assembly that maintains insufflation of the patient's abdominal cavity during a surgical procedure while permitting passage of surgical instruments and tissue fragments along working channel (<NUM>). For instance, the proximal seal structure may include an annular seal member configured to sealingly engage the shaft of a laparoscopic surgical instrument directed through working channel (<NUM>). The distal seal structure may include a duckbill seal member configured to maintain working channel (<NUM>) in a sealed stated in the absence of a surgical instrument shaft.

Cannula assembly (<NUM>) further includes an insufflation port (<NUM>) operatively coupled with the proximal end of cannula (<NUM>) and having an adjustable valve in the form of a stopcock (<NUM>). Insufflation port (<NUM>) is configured to direct insufflation fluid, such as carbon dioxide, from a fluid source (not shown) distally through working channel (<NUM>) and into the patient's abdominal cavity to thereby expand (or "insufflate") the cavity with the fluid. This expansion of the abdominal cavity creates additional space for performing a laparoscopic surgical procedure with improved ease.

As shown in <FIG> and <FIG>, obturator (<NUM>) of trocar (<NUM>) includes a proximal head (<NUM>), an elongate cylindrical shaft (<NUM>) extending distally from head (<NUM>), and a tapered distal tip (<NUM>). Obturator shaft (<NUM>) is configured to be received within working channel (<NUM>) of cannula assembly (<NUM>) such that obturator tip (<NUM>) extends through and distally of cannula tip (<NUM>). Obturator head (<NUM>) includes a domed upper body (<NUM>), a base plate (<NUM>), and an actuatable latch member (<NUM>), which includes a pair of latch arms (<NUM>) and a corresponding pair of latch buttons (<NUM>). Latch arms (<NUM>) are configured to be captured within respective slots (not shown) formed in a top surface of seal housing head (<NUM>) to couple obturator (<NUM>) with cannula assembly (<NUM>). Latch buttons (<NUM>) are actuatable to release latch arms (<NUM>) from the slots and thereby permit separation of obturator (<NUM>) from cannula assembly (<NUM>). Obturator (<NUM>) further includes a central passage (<NUM>) that extends longitudinally through obturator head (<NUM>) and obturator shaft (<NUM>), and is configured to receive an endoscope (not shown) therein to provide visualization during insertion of trocar (<NUM>) through the abdominal wall of a patient. A clamp lever (<NUM>) of obturator head (<NUM>) is pivotable to selectively fix the endoscope within central passage (<NUM>). Central passage (<NUM>) and clamp lever (<NUM>) are merely optional features and may be omitted from obturator (<NUM>) in other versions.

Cannula assembly (<NUM>) and obturator (<NUM>) may be constructed to be disposed of after a single use with a patient. In other versions, one or more components of trocar (<NUM>) may be suitably constructed to withstand sterilization and multiple reuses, for example as described in greater detail below in connection with trocar (<NUM>) of <FIG>.

<FIG> illustrate an exemplary method of accessing an abdominal cavity (<NUM>) of a patient through the patient's abdominal wall (<NUM>) with trocar (<NUM>) described above. It will be appreciated that abdominal wall (<NUM>) includes outward superficial layers and inward deep layers. Superficial layers generally include an outer layer of skin (<NUM>) and an inner layer of fat (<NUM>); whereas the deeper layers include alternating layers of muscle (<NUM>) and fascia (<NUM>), which are fibrous and flexible with relatively higher tensile strength than the superficial layers.

As shown in <FIG>, with obturator (<NUM>) received within cannula assembly (<NUM>) and connected to seal housing (<NUM>), a clinician manipulates trocar (<NUM>) via obturator head (<NUM>) and seal housing (<NUM>) to urge obturator tip (<NUM>) against skin (<NUM>) and inward toward abdominal cavity (<NUM>) while rotating trocar (<NUM>) back and forth. Continued inward urging of trocar (<NUM>) further directs obturator tip (<NUM>) and cannula tip (<NUM>) distally through the layers of fat (<NUM>) and fascia (<NUM>) and into cavity (<NUM>), as shown in <FIG>. As discussed above, this step may be facilitated with visualization provided by an endoscope (not shown) mounted within obturator (<NUM>). Once cannula (<NUM>) has reached a desired depth of insertion into cavity (<NUM>), the clinician releases obturator head (<NUM>) from seal housing (<NUM>) via depression of latch buttons (<NUM>), and then withdraws obturator (<NUM>) from proximally from cannula assembly (<NUM>), as shown in <FIG>. This renders working channel (<NUM>) of cannula assembly (<NUM>) free to receive surgical instruments distally therethrough for performing the laparoscopic surgical procedure. As described above, tissue engagement ribs (<NUM>) provided on cannula tube (<NUM>) grip the layers of tissue (<NUM>, <NUM>, <NUM>) of abdominal wall (<NUM>), thus providing cannula assembly (<NUM>) with at least a minimum degree of stability relative to abdominal wall (<NUM>). Upon completion of the laparoscopic surgical procedure, the clinician grasps seal housing (<NUM>) and withdraws cannula assembly (<NUM>) proximally from abdominal wall (<NUM>), as shown in <FIG>.

In some instances, it may be desirable to configure a trocar such that one or more components thereof may be sterilized and reused for multiple surgical procedures, while one or more other components may be easily and economically disposed of and replaced after each procedure. <FIG> show another exemplary trocar (<NUM>) that is configured in such a manner, and which is similar in structure and function to trocar (<NUM>) described above except as otherwise described below.

Similar to trocar (<NUM>), trocar (<NUM>) includes a cannula assembly (<NUM>) having a working channel (<NUM>) and an obturator (<NUM>) configured to be inserted into cannula assembly (<NUM>) coaxially along working channel (<NUM>). Cannula assembly (<NUM>) includes a cannula (<NUM>) having a bell-shaped hub (<NUM>) at a proximal end thereof, and an elongate cylindrical tube (<NUM>) extending distally from hub (<NUM>) and terminating at an angled cannula tip (<NUM>). An outer surface of cannula tube (<NUM>) includes a plurality of tissue gripping features in the form of annular ribs (<NUM>) arranged axially along a medial portion of cannula tube (<NUM>) and which are similar to ribs (<NUM>) described above.

Cannula assembly (<NUM>) further includes a seal assembly (<NUM>). Unlike the seal assembly defined by seal housing (<NUM>) of trocar (<NUM>), seal assembly (<NUM>) is constructed as a modular, replaceable unit configured to releasably mate with proximal hub (<NUM>) of cannula (<NUM>). As shown best in <FIG>, seal assembly (<NUM>) of the present example generally includes an upper frame member (<NUM>), a middle frame member (<NUM>), and a lower frame member (<NUM>) secured relative to one another in a coaxial arrangement. Though not shown, a proximal (or "outer") seal structure is supported within upper frame member (<NUM>), and a distal (or "inner") seal structure is supported within lower frame member (<NUM>). Such seal structures may be similar in structure and function to the proximal and distal seal structures of trocar (<NUM>) described above. Seal assembly (<NUM>) further includes an insufflation port (<NUM>) having an adjustable valve in the form of a stopcock (<NUM>).

A lower portion of seal assembly (<NUM>) distal to insufflation port (<NUM>) is configured to seat within proximal hub (<NUM>) of cannula (<NUM>) such than an annular seal member (<NUM>) disposed circumferentially about the lower portion sealingly engages an inner surface of cannula hub (<NUM>). In this manner, an interior of seal assembly (<NUM>) fluidly communicates with a lumen of cannula (<NUM>) to define a working channel (<NUM>) of cannula assembly (<NUM>) through which insufflation fluid, surgical instruments, and tissue fragments may be directed in the manners generally described above in connection with trocar (<NUM>). Seal assembly (<NUM>) may be further configured in accordance with one or more teachings of <CIT>; and/or <CIT>.

As shown best in <FIG>, obturator (<NUM>) of trocar (<NUM>) includes a proximal head (<NUM>), an elongate cylindrical shaft (<NUM>) extending distally from head (<NUM>), and a tapered tip (<NUM>) at a distal end of shaft (<NUM>). Obturator head (<NUM>) includes a domed upper body (<NUM>), a base plate (<NUM>), and an actuatable latch member (<NUM>), which includes a pair of downwardly extending latch arms (<NUM>) and a corresponding pair of latch buttons (<NUM>). Latch arms (<NUM>) are configured to be captured within respective slots (<NUM>) formed in a top surface of upper frame member (<NUM>) of seal assembly (<NUM>) to couple obturator (<NUM>) with cannula assembly (<NUM>). Latch buttons (<NUM>) are actuatable to release latch arms (<NUM>) from slots (<NUM>) and thereby permit separation of obturator (<NUM>) from cannula assembly (<NUM>).

Cannula (<NUM>) and obturator (<NUM>) of the present example are suitably constructed of a robust material, such as surgical steel, such that they may be sterilized and reused for multiple surgical procedures. In contrast, as described above, seal assembly (<NUM>) is constructed as a disposable unit, intended to be separated from cannula (<NUM>) and replaced after each procedure. For instance, seal assembly (<NUM>) may be constructed of various polymeric materials, including plastics and rubbers, such that seal assembly (<NUM>) may be easily manufactured and sold at a price point that renders seal assembly (<NUM>) suitable for disposal after a single use, similar to trocar (<NUM>) described above.

Some laparoscopic surgical procedures include use of electrosurgery instruments to apply radio frequency (RF) energy to tissue to thereby cut and seal the tissue, electrocautery instruments to apply thermal energy to tissue to thereby cauterize the tissue, ultrasonic instruments to apply ultrasonic energy to tissue to thereby seal and/or cut the tissue, or other instruments that apply energy to tissue. Use of such instruments may generate smoke within the abdominal cavity (<NUM>) of the patient. Unless properly evacuated from the abdominal cavity (<NUM>), such smoke may collect and eventually obscure the surgeon's ability to visualize the surgical site via one or more endoscopes (not shown) positioned within the abdominal cavity (<NUM>).

During such procedures in which a surgical instrument having a shaft of a relatively larger diameter is positioned within the working channel (<NUM>, <NUM>) of cannula assembly (<NUM>, <NUM>), smoke within the abdominal cavity (<NUM>) may be at least partially obstructed by the instrument shaft from passing proximally through the cannula lumen and outwardly through insufflation port (<NUM>, <NUM>). This results in the undesirable vision obscurity condition discussed above. Accordingly, it may be desirable to provide cannula (<NUM>, <NUM>) with a feature that facilitates smoke evacuation from the abdominal cavity (<NUM>) when an instrument shaft of relatively larger diameter is positioned within the cannula lumen. It may also be desirable for such a feature to facilitate maintenance of an insufflated state of abdominal cavity (<NUM>) while such an instrument shaft of relatively larger diameter is positioned with the cannula lumen.

It will be appreciated that the exemplary gas flow channel features described below in connection with <FIG> may be applied to disposable single-use cannulas and sterilizable multi-use cannulas alike, such as cannulas (<NUM>, <NUM>) described above.

<FIG> show an exemplary cannula (<NUM>) configured to facilitate evacuation of smoke from abdominal cavity (<NUM>), as well as facilitate maintenance insufflation of abdominal cavity (<NUM>), even when a surgical instrument having a shaft of maximum permissible diameter is directed distally through cannula (<NUM>). Cannula (<NUM>) is similar to cannula (<NUM>) described above except as otherwise described below.

Cannula (<NUM>) includes a bell-shaped hub (<NUM>) at a proximal end, and an elongate cylindrical tube (<NUM>) extending distally from hub (<NUM>) and terminating at an angled distal tip (<NUM>). An outer surface of cannula tube (<NUM>) includes a plurality of tissue gripping features in the form of annular ribs (<NUM>) that are similar in structure and function to ribs (<NUM>, <NUM>) described above. Cannula tube (<NUM>) includes a cylindrical inner surface (<NUM>) that defines a lumen (<NUM>) extending longitudinally along a central axis (C) through cannula (<NUM>). Cannula lumen (<NUM>) is configured to cooperate with a seal assembly (not shown), which may be similar to seal assembly (<NUM>) described above, to define a working channel of a corresponding trocar cannula assembly, such that cannula lumen (<NUM>) is configured to receive and guide a surgical instrument shaft distally therethrough and into the abdominal cavity (<NUM>) of a patient in which cannula tube (<NUM>) is positioned.

Unlike cannulas (<NUM>, <NUM>) described above, cannula (<NUM>) of the present example includes a pair of gas flow channels (<NUM>) formed in cylindrical inner surface (<NUM>). As described in greater detail below in connection with <FIG> and <FIG>, gas flow channels (<NUM>) are configured to facilitate proximally-directed smoke evacuation from abdominal cavity (<NUM>), or alternatively distally-directed maintenance insufflation of abdominal cavity (<NUM>), during a surgical procedure while a surgical instrument shaft is disposed within cannula lumen (<NUM>). Gas flow channels (<NUM>) extend longitudinally between a proximal end of cannula lumen (<NUM>) that opens to an interior of cannula hub (<NUM>), and a distal end of cannula lumen (<NUM>) that opens through distal tip (<NUM>). In the present version, channels (<NUM>) are provided in a pair and are arranged at diametrically opposed positions, though it will be appreciated that channels (<NUM>) may be provided in various other quantities and arrangements in other versions, for example as described in greater detail below.

In the example shown, channels (<NUM>) each have a generally uniform transverse cross-sectional shape and size along their respective lengths. More particularly, and as best shown in <FIG>, channels (<NUM>) of the present example each have a rounded, generally semi-circular transverse cross-sectional shape of uniform size along their respective lengths. It will be appreciated that channels (<NUM>) may be provided with various other uniform or non-uniform cross-sectional shapes and sizes in other versions, for example as described in greater detail below. In some examples, proximal ends of channels (<NUM>) may smoothly transition to a proximal face of cannula tube (<NUM>), such as via one or more radiuses or chamfers, to prevent interfering with distal insertion of surgical instrument shafts into lumen (<NUM>) (e.g., snagging). Channels (<NUM>) may be formed in inner surface (<NUM>) in any suitable manner, including via subtractive processes such as machining or broaching, stamping, or 3D printing.

As shown, channels (<NUM>) are each formed in inner surface (<NUM>) such that each channel (<NUM>) extends radially outwardly from inner surface (<NUM>) relative to central axis (C) into tube (<NUM>) and is in fluid communication with lumen (<NUM>), at least in the absence of any surgical instrument shaft in lumen (<NUM>). As a result, lumen (<NUM>) and channels (<NUM>) may collectively define a single continuous bore extending longitudinally between proximal and distal ends of cannula tube (<NUM>). Thus, channels (<NUM>) may be configured to at least partially define one or more gas flow path(s) through such a bore, irrespective of whether lumen (<NUM>) is occupied by a surgical instrument shaft and irrespective of a cross dimension of such a shaft. Such a gas flow path may be considered "persistent" since the path is maintained even when lumen (<NUM>) is fully occupied by a surgical instrument shaft.

In this regard, and as shown in <FIG>, lumen (<NUM>) forms a first diameter (D1) and channels (<NUM>) collectively form a second effective diameter (D2) that extends through central axis (C) and is greater than first diameter (D1). First diameter (D1) of lumen (<NUM>) is sized to accommodate surgical instruments having shafts of various cross dimensions restricted to an upper limit or maximum permissible third diameter (D3) substantially equal to or slightly less than first diameter (D1) so that such shafts may be slidable within lumen (<NUM>) with a suitable degree of tolerance, including an exemplary surgical instrument (<NUM>) having a shaft (<NUM>) with such a maximum permissible third diameter (D3). Thus, shaft (<NUM>) may substantially occupy lumen (<NUM>) when surgical instrument (<NUM>) is positioned within the working channel of the corresponding trocar cannula assembly, and may consequently substantially obstruct flow of gas (e.g., smoke and/or insufflation gas) through lumen (<NUM>) in either a proximal or distal direction. Channels (<NUM>) may be configured to permit flow of such gas therethrough in either the proximal or distal direction while at least partially circumventing or bypassing lumen (<NUM>).

For example, in cases where third diameter (D3) of instrument shaft (<NUM>) is appreciably less than first diameter (D1) of lumen (<NUM>) such that shaft (<NUM>) only partially obstructs flow of gas through lumen (<NUM>), channels (<NUM>) and the unoccupied portion(s) of lumen (<NUM>) may collectively define a single, enlarged gas flow path extending longitudinally between proximal and distal ends of cannula tube (<NUM>) for improving flow of gas relative to a gas flow path defined by the unoccupied portion(s) of lumen (<NUM>) alone. In cases where third diameter (D3) of shaft (<NUM>) is substantially equal to first diameter (D1) of lumen (<NUM>) such that shaft (<NUM>) fully obstructs flow of gas through lumen (<NUM>), channels (<NUM>) may define discrete gas flow paths each extending longitudinally along an outer surface of shaft (<NUM>) between proximal and distal ends of cannula tube (<NUM>) for permitting flow of gas despite complete blockage of lumen (<NUM>).

More particularly, and as shown in <FIG>, channels (<NUM>) may define first and second gas flow paths indicated by first and second arrows (A1, A2), respectively, each extending longitudinally along an outer surface of shaft (<NUM>) between proximal and distal ends of cannula tube (<NUM>). When cannula (<NUM>) is coupled to seal assembly (<NUM>) to form a cannula assembly (<NUM>), the first and second gas flow paths may converge together into a third gas flow path indicated by third arrows (A3) and collectively defined by an annular chamber and connecting passageways provided in and between cannula hub (<NUM>) and seal assembly (<NUM>). As shown, third gas flow path may pass outwardly through insufflation port (<NUM>) of seal assembly (<NUM>). In this regard, third gas flow path may be partially defined by a bore of a luer lock fitting (not shown) configured to couple with insufflation port (<NUM>) and in fluid communication with an insufflation fluid source and/or vacuum source. In one example, hub (<NUM>) may include notches (<NUM>) radially aligned with channels (<NUM>) for assisting in providing fluid communication between each of the first and second gas flow paths with the third gas flow path.

Each of the first, second, and third gas flow paths described above may be bidirectional to permit gas to be proximally-directed from the first and second flow paths to the third gas flow path and evacuated via insufflation port (<NUM>); and alternatively to permit gas to be introduced via insufflation port (<NUM>) and distally directed from the third flow path to the first and second flow paths. Thus, while cannula lumen (<NUM>) is occupied by surgical instrument shaft (<NUM>), undesirable fluids such as smoke may be directed proximally along the first, second, and third gas flow paths for evacuation from abdominal cavity (<NUM>), or an insufflation fluid such as carbon dioxide may be directed distally along the first, second, and third flow paths to provide maintenance insufflation of abdominal cavity (<NUM>). It will be appreciated that the proximal evacuation of smoke from abdominal cavity (<NUM>) and the distal supply of inflation gas to abdominal cavity (<NUM>) described above may be mutually exclusive actions, such that during procedure gas flow channels (<NUM>) may direct only one of smoke or insufflation gas therethrough at any selected point in time.

In this manner, gas flow channels (<NUM>) may allow third diameter (D3) of surgical instrument shaft (<NUM>) to be maximized relative to first diameter (D1) of cannula lumen (<NUM>) while maintaining at least one open gas flow path through the bore of cannula tube (<NUM>) for evacuation and/or insufflation. In other words, channels (<NUM>) may provide at least one gas flow path through the bore of cannula tube (<NUM>) without interfering with the size restrictions imposed on surgical instrument shaft (<NUM>) by first diameter (D1) of lumen (<NUM>). Thus, inner surface (<NUM>) of cannula tube (<NUM>) may remain configured to radially contact and constrain shaft (<NUM>) having maximum permissible third diameter (D3) at various contact points between channels (<NUM>) to thereby assist in centering shaft (<NUM>) relative to central axis (C) while the persistent first and second gas flow paths are maintained in an open state by channels (<NUM>).

In one example, gas flow channels (<NUM>) may be sized relative to the bores and/or passageways that define the third gas flow path such that the first and second gas flow paths are relatively unconstricted compared to third gas flow path and/or compared to other upstream/downstream flow paths in fluid communication therewith. For example, a bore of a luer lock fitting coupled with insufflation port (<NUM>) may define a greater fluid constriction than channels (<NUM>), even when lumen (<NUM>) is occupied by surgical shaft (<NUM>). Thus, fluids directed along the first, second, and third gas flow paths either proximally or distally may experience greater fluid constriction while traversing the third gas flow path and/or such other upstream/downstream flow paths than while traversing either of the first or second gas flow paths. In this manner, gasses may travel predictably and consistently between insufflation port (<NUM>) and the bore of cannula tube (<NUM>), including lumen (<NUM>) and gas flow channels (<NUM>), irrespective of whether lumen (<NUM>) is occupied by a surgical instrument shaft and irrespective of a cross dimension of such a shaft.

During operation, cannula (<NUM>) may be positioned at a desired depth of insertion in the patient's abdominal cavity (<NUM>) as described above with respect to <FIG> to permit performance of a laparoscopic surgical procedure. The procedure may include distally inserting shaft (<NUM>) of surgical instrument (<NUM>) into cannula lumen (<NUM>) such that lumen (<NUM>) is at least partially occupied by shaft (<NUM>). In one example, the procedure may also include applying radio frequency (RF) energy and/or thermal energy to tissue via instrument (<NUM>), and evacuating smoke generated within abdominal cavity (<NUM>) by such energy application proximally through the bore of cannula tube (<NUM>) along the first, second, and third gas flow paths and outwardly through insufflation port (<NUM>). In another example, the procedure may include introducing insufflation fluid, such as carbon dioxide, via insufflation port (<NUM>) and directing such insufflation fluid distally through the third gas flow path and through the bore of cannula tube (<NUM>) along first and second gas flow paths into abdominal cavity (<NUM>) to facilitate maintenance of an insufflated state of abdominal cavity (<NUM>).

In some instances, it may be desirable to provide a cannula with gas flow channels provided in an inner cylindrical surface thereof in quantities and arrangements that differ from those of cannula (<NUM>) described above. Each of the exemplary cannulas (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) described below in connection to <FIG> is configured to facilitate evacuation of smoke from abdominal cavity (<NUM>), as well as facilitate maintenance insufflation of abdominal cavity (<NUM>), even when a surgical instrument having a shaft of maximum permissible diameter is directed distally therethrough; and each is similar to cannula (<NUM>) described above except as otherwise described below.

<FIG> shows a second exemplary cannula (<NUM>) which includes an elongate cylindrical tube (<NUM>) including a cylindrical inner surface (<NUM>) that defines a lumen (<NUM>) extending longitudinally along a central axis (C) through cannula (<NUM>). Cannula (<NUM>) also includes a plurality of gas flow channels (<NUM>) formed in cylindrical inner surface (<NUM>). In the present version, four channels (<NUM>) are arranged with uniform circumferential spacing about central axis (C). Channels (<NUM>) of the present example each have a rounded, generally semi-circular transverse cross-sectional shape. In this regard, the center points of the circular profiles defined by each channel (<NUM>) are positioned substantially on the circular profile defined by inner surface (<NUM>). In other words, the center points of the circular profiles defined by each channel (<NUM>) are positioned at a same radial distance from central axis (C) as the circular profile defined by inner surface (<NUM>).

<FIG> shows a third exemplary cannula (<NUM>) which includes an elongate cylindrical tube (<NUM>) including a cylindrical inner surface (<NUM>) that defines a lumen (<NUM>) extending longitudinally along a central axis (C) through cannula (<NUM>). Cannula (<NUM>) also includes a single gas flow channel (<NUM>) formed in cylindrical inner surface (<NUM>). Channel (<NUM>) of the present example has a rounded, generally C-shaped transverse cross-sectional shape. In this regard, the center point of the circular profile defined by channel (<NUM>) is positioned radially outwardly from the circular profile defined by inner surface (<NUM>) relative to central axis (C).

<FIG> shows a fourth exemplary cannula (<NUM>) which includes an elongate cylindrical tube (<NUM>) including a cylindrical inner surface (<NUM>) that defines a lumen (<NUM>) extending longitudinally along a central axis (C) through cannula (<NUM>). Cannula (<NUM>) also includes a plurality of gas flow channels (<NUM>) formed in cylindrical inner surface (<NUM>). In the present version, four channels (<NUM>) are arranged with uniform circumferential spacing about central axis (C). Channels (<NUM>) of the present example each have a sharp, generally L-shaped transverse cross-sectional shape. In this regard, each channel (<NUM>) includes an inside corner (<NUM>). As a result, channels (<NUM>) collectively have a generally square-shaped transverse cross-section.

<FIG> shows a fifth exemplary cannula (<NUM>) which includes an elongate cylindrical tube (<NUM>) including a cylindrical inner surface (<NUM>) that defines a lumen (<NUM>) extending longitudinally along a central axis (C) through cannula (<NUM>). Cannula (<NUM>) also includes a plurality of gas flow channels (<NUM>) formed in cylindrical inner surface (<NUM>). In the present version, six channels (<NUM>) are arranged with uniform circumferential spacing about central axis (C). Channels (<NUM>) of the present example each have a sharp, generally obtusely bent L-shaped transverse cross-sectional shape. In this regard, each channel (<NUM>) includes an inside corner (<NUM>). As a result, channels (<NUM>) collectively have a generally hexagon-shaped transverse cross-section.

<FIG> shows a sixth exemplary cannula (<NUM>) which includes an elongate cylindrical tube (<NUM>) including a cylindrical inner surface (<NUM>) that defines a lumen (<NUM>) extending longitudinally along a central axis (C) through cannula (<NUM>). Cannula (<NUM>) also includes a single gas flow channel (<NUM>) formed in cylindrical inner surface (<NUM>). Channel (<NUM>) of the present example has a sharp, generally obtusely bent L-shaped transverse cross-sectional shape. In this regard, channel (<NUM>) intersects with inner surface (<NUM>) generally tangentially and includes an inside corner (<NUM>). As a result, channel (<NUM>) and lumen (<NUM>) collectively have a generally teardrop-shaped transverse cross-section.

<FIG> shows a seventh exemplary cannula (<NUM>) which includes an elongate cylindrical tube (<NUM>) including a cylindrical inner surface (<NUM>) that defines a lumen (<NUM>) extending longitudinally along a central axis (C) through cannula (<NUM>). Cannula (<NUM>) also includes a single gas flow channel (<NUM>) formed in cylindrical inner surface (<NUM>). Channel (<NUM>) of the present example has a generally rectangular keyway-shaped transverse cross-sectional shape. In this regard, channel (<NUM>) includes a pair of inside corners (<NUM>).

<FIG> shows an eighth exemplary cannula (<NUM>) which includes an elongate cylindrical tube (<NUM>) including a cylindrical inner surface (<NUM>) that defines a lumen (<NUM>) extending longitudinally along a central axis (C) through cannula (<NUM>). Cannula (<NUM>) also includes a plurality of gas flow channels (<NUM>) formed in cylindrical inner surface (<NUM>). In the present version, channels (<NUM>) are provided in a pair and are arranged at diametrically opposed positions. Channels (<NUM>) of the present example each have a generally rectangular keyway-shaped transverse cross-sectional shape. In this regard, channels (<NUM>) each include a pair of inside corners (<NUM>).

<FIG> shows a ninth exemplary cannula (<NUM>) which includes an elongate cylindrical tube (<NUM>) including a cylindrical inner surface (<NUM>) that defines a lumen (<NUM>) extending longitudinally along a central axis (C) through cannula (<NUM>). Cannula (<NUM>) also includes a single gas flow channel (<NUM>) formed in cylindrical inner surface (<NUM>). Channel (<NUM>) of the present example has a generally circumferentially extending slot-shaped transverse cross-sectional shape. In this regard, channel (<NUM>) includes a pair of inside corners (<NUM>).

In some instances, it may be desirable to configure a trocar cannula such that it is resistant to unwanted tipping, or tilting, relative to the abdominal wall (<NUM>) of a patient when the corresponding cannula assembly is temporarily released by the surgeon, such that the cannula assembly remains axially aligned with the surgical site throughout a procedure. Each of the exemplary cannulas (<NUM>, <NUM>) described below in connection with <FIG> is similar to cannula (<NUM>) described above except as otherwise described below. For example, each of the exemplary cannulas (<NUM>, <NUM>) described below includes gas flow channels that are constructed so as to position the center of mass, and thus center of gravity, of cannula (<NUM>, <NUM>) further distally along cannula tube (<NUM>, <NUM>) compared to cannulas (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) described above. Advantageously, this distal relocation of the center of gravity effectively reduces the "tipping" torque that it exerts about the portion of cannula (<NUM>, <NUM>) positioned within abdominal wall (<NUM>), which acts as a pivot point, thereby reducing unwanted tipping of cannula (<NUM>, <NUM>) when released by the surgeon.

<FIG> show a cannula (<NUM>) in accordance with the present invention which includes a bell-shaped hub (<NUM>) at a proximal end, and an elongate cylindrical tube (<NUM>) extending distally from hub (<NUM>) and terminating at an angled distal tip (<NUM>). An outer surface of cannula tube (<NUM>) includes a plurality of tissue gripping features in the form of annular ribs (<NUM>) that are similar in structure and function to ribs (<NUM>, <NUM>) described above. Cannula tube (<NUM>) includes a cylindrical inner surface (<NUM>) that defines a lumen (<NUM>) extending longitudinally along a central axis (C) through cannula (<NUM>).

Cannula (<NUM>) also includes a plurality of gas flow channels (<NUM>) formed in cylindrical inner surface (<NUM>). Gas flow channels (<NUM>) are configured to facilitate proximally-directed smoke evacuation from abdominal cavity (<NUM>), or alternatively distally-directed maintenance insufflation of abdominal cavity (<NUM>), during a surgical procedure while a surgical instrument shaft is disposed within cannula lumen (<NUM>) in manners similar to those described above in connection with <FIG>. Gas flow channels (<NUM>) extend longitudinally between a proximal end of cannula lumen (<NUM>) that opens to an interior of cannula hub (<NUM>), and a distal end of cannula lumen (<NUM>) that opens through distal tip (<NUM>). In the present version, four channels (<NUM>) are arranged with uniform circumferential spacing about central axis (C), though it will be appreciated that channels (<NUM>) may be provided in various other quantities and arrangements in other versions, for example as described in greater detail below.

In the embodiment shown, channels (<NUM>) each have a generally non-uniform transverse cross-sectional shape and/or size along their respective lengths. More particularly, channels (<NUM>) of the present embodiment each have a generally circumferentially extending slot-shaped transverse cross-sectional shape of non-uniform size along their respective lengths. In this regard, and as best shown in <FIG>, channels (<NUM>) each include a proximal end having a first circumferential width (W1) and a distal end having a second circumferential width (W2) less than the first width (W1). In the present embodiment, each channel (<NUM>) tapers circumferentially inwardly in a distal direction from a circumferentially widest portion of channel (<NUM>) at the proximal end thereof to a circumferentially narrowest portion of channel (<NUM>) at the distal end thereof. In other words, a width of each channel (<NUM>) tapers distally and uniformly from the proximal end of channel (<NUM>) to the distal end of channel (<NUM>). It will be appreciated that channels (<NUM>) may be provided with various other non-uniform cross-sectional shapes and/or sizes in other versions which result in an increased sizing (e.g., widening) of channels (<NUM>) at proximal ends thereof relative to distal ends thereof, for example as described in greater detail below.

Such increased sizing of each channel (<NUM>) at the proximal end thereof relative to the distal end thereof may allow cannula tube (<NUM>) to include a relatively reduced amount of material at or near the proximal end thereof and a relatively increased amount of material at or near the distal end thereof. As a result, the weight distribution of cannula (<NUM>) may be shifted distally such that the center of mass, and thus center of gravity, of cannula (<NUM>) may be located further distally along cannula tube (<NUM>) compared to cannulas (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) described above. In this manner, channels (<NUM>) may be configured to effectively reduce the "tipping" torque exerted by cannula (<NUM>) about the portion of cannula (<NUM>) positioned within abdominal wall (<NUM>), and to thereby reduce unwanted tipping of cannula (<NUM>) when released by the surgeon.

During operation, cannula (<NUM>) may be positioned at a desired depth of insertion in the patient's abdominal cavity (<NUM>) as described above with respect to <FIG> to permit performance of a laparoscopic surgical procedure. The procedure may include distally inserting shaft (<NUM>) of surgical instrument (<NUM>) into lumen (<NUM>) such that lumen (<NUM>) is at least partially occupied by shaft (<NUM>). In one example, the procedure may also include evacuating smoke generated within abdominal cavity (<NUM>) by radio frequency (RF) energy and/or thermal energy application to tissue as described above with respect to <FIG>. In another example, the procedure may include introducing insufflation fluid, such as carbon dioxide, into abdominal cavity (<NUM>) to facilitate maintenance of an insufflated state of abdominal cavity (<NUM>) as described above with respect to <FIG>. In any case, the relatively distal center of gravity of cannula (<NUM>) may be positioned at or near the abdominal wall (<NUM>) of the patient (e.g., the effective pivot point of cannula <NUM>) and thereby resist unwanted tipping to allow the corresponding cannula assembly to remain axially aligned with the surgical site throughout performance of the laparoscopic surgical procedure, even in instances when the surgeon may at least temporarily release the cannula assembly.

<FIG> show another cannula (<NUM>) in accordance with the present invention which includes a bell-shaped hub (<NUM>) at a proximal end, and an elongate cylindrical tube (<NUM>) extending distally from hub (<NUM>) and terminating at an angled distal tip (<NUM>). An outer surface of cannula tube (<NUM>) includes a plurality of tissue gripping features in the form of annular ribs (<NUM>) that are similar in structure and function to ribs (<NUM>, <NUM>) described above. Cannula tube (<NUM>) includes a cylindrical inner surface (<NUM>) that defines a lumen (<NUM>) extending longitudinally along a central axis (C) through cannula (<NUM>).

Cannula (<NUM>) also includes a plurality of gas flow channels (<NUM>) formed in cylindrical inner surface (<NUM>). Gas flow channels (<NUM>) are configured to facilitate proximally-directed smoke evacuation from abdominal cavity (<NUM>), or alternatively distally-directed maintenance insufflation of abdominal cavity (<NUM>), during a surgical procedure while a surgical instrument shaft is disposed within cannula lumen (<NUM>) in manners similar to those described above in connection with <FIG>, and are further configured to effectively reduce the "tipping" torque exerted by cannula (<NUM>) about the portion of cannula (<NUM>) positioned within abdominal wall (<NUM>) in a manner similar to that described above in connection with <FIG>. Gas flow channels (<NUM>) extend longitudinally between a proximal end of cannula lumen (<NUM>) that opens to an interior of cannula hub (<NUM>), and a distal end of cannula lumen (<NUM>) that opens through distal tip (<NUM>). In the present version, four channels (<NUM>) are arranged with uniform circumferential spacing about central axis (C), though it will be appreciated that channels (<NUM>) may be provided in various other quantities and arrangements in other versions, for example as described in greater detail below.

In the embodiment shown, channels (<NUM>) each have a generally non-uniform transverse cross-sectional shape and/or size along their respective lengths. More particularly, channels (<NUM>) of the present embodiment each have a generally circumferentially extending slot-shaped transverse cross-sectional shape of non-uniform size along their respective lengths. In this regard, and as best shown in <FIG> and <FIG>, channels (<NUM>) each include a proximal channel portion (1220p) having a third uniform circumferential width (W3) along a length thereof and a distal channel portion (1220d) having a fourth uniform circumferential width (W4) along a length thereof and less than the third width (W3). In the present embodiment, each channel (<NUM>) further includes a medial channel portion (<NUM>) defining a stepped transition between proximal channel portion (1220p) and distal channel portion (1220d) such that each channel (<NUM>) steps circumferentially inwardly in a distal direction from a circumferentially widest portion of channel (<NUM>) at the proximal end thereof to a circumferentially narrowest portion of channel (<NUM>) at the distal end thereof.

While the illustrated medial channel portions (<NUM>) each define a stepped transition between the respective proximal channel portion (1220p) and distal channel portion (1220d), it will be appreciated that some or all of medial channel portions (<NUM>) may alternatively define a tapered transition between the respective proximal channel portion (1220p) and distal channel portion (1220d). In the present version, a single medial channel portion (<NUM>) is provided for each channel (<NUM>), though it will be appreciated that multiple medial channel portions (<NUM>) may be provided in other versions to define a multi-stage stepped and/or tapered transition between proximal portion (1220p) and distal channel portion (1220d).

Similar to cannula (<NUM>), the increased sizing of each channel (<NUM>) at the proximal end thereof relative to the distal end thereof may allow cannula tube (<NUM>) to include a relatively reduced amount of material at or near the proximal end thereof and a relatively increased amount of material at or near the distal end thereof. As a result, the weight distribution of cannula (<NUM>) may be shifted distally such that the center of mass, and thus center of gravity, of cannula (<NUM>) may be located further distally along cannula tube (<NUM>) compared to cannulas (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) described above. In this manner, channels (<NUM>) may be configured to effectively reduce the "tipping" torque exerted by cannula (<NUM>) about the portion of cannula (<NUM>) positioned within abdominal wall (<NUM>), and to thereby reduce unwanted tipping of cannula (<NUM>) when released by the surgeon.

Furthermore, any one or more of the teachings herein may be combined with any one or more of the teachings disclosed in <CIT>, entitled "Pinch-To-Release Cannula Depth Limiter," filed on even date herewith; <CIT>, entitled "Multi-Diameter Cannula Depth Limiter," filed on even date herewith; <CIT>, entitled "Pinch-To-Clamp Cannula Depth Limiter," filed on even date herewith; <CIT>, entitled "Universal Size Multi-Walled Elastomer Cannula Depth Limiter," filed on even date herewith; <CIT>, entitled "Threaded Cannula Depth Limiter," filed on even date herewith; <CIT>, entitled "Tilting Tang Cannula Depth Limiter," filed on even date herewith; <CIT>, entitled "Two Piece Separable Obturator," filed on even date herewith; <CIT>, entitled "Latchless Obturator with Interference Fit Feature," filed on even date herewith; <CIT>, entitled "Balancing Feature for Reusable Trocar," filed on even date herewith; and/or <CIT>, entitled "Stabilizer for Surgical Shafts or Cannulas," filed on even date herewith.

Similarly, those of ordinary skill in the art will recognize that various teachings herein may be readily combined with various teachings of any of the following: <CIT>; <CIT>; <CIT>; <CIT>; and/or <CIT>.

Claim 1:
A surgical access device comprising:
(a) a proximal end portion (<NUM>, <NUM>) configured to support a seal assembly having an insufflation port (<NUM>);
(b) a cannula tube (<NUM>, <NUM>) extending distally from the proximal end portion and having an inner surface that defines a lumen (<NUM>, <NUM>) extending longitudinally through the cannula tube, wherein the cannula tube is configured to be inserted distally through a body cavity wall of a patient, wherein the lumen (<NUM>, <NUM>) is configured to guide a surgical instrument shaft distally through the cannula tube (<NUM>, <NUM>) for accessing a body cavity of the patient; and
(c) at least one channel formed in the inner surface (<NUM>, <NUM>) of the cannula tube, wherein the at least one channel extends longitudinally between a proximal end of the lumen (<NUM>, <NUM>) and a distal end of the lumen (<NUM>, <NUM>), wherein the at least one channel (<NUM>, <NUM>) is configured to direct a gas therethrough at least one of to or from the insufflation port (<NUM>) of the seal assembly while a surgical instrument shaft is disposed within the lumen (<NUM>, <NUM>), wherein a proximal end of the at least one channel (<NUM>, <NUM>) has a greater width than a distal end of the at least one channel (<NUM>, <NUM>), characterised in that either:
(i) a width of the at least one channel (<NUM>) tapers uniformly from a proximal end of the at least one channel (<NUM>) to a distal end of the at least one channel (<NUM>), or
(ii) the at least one channel (<NUM>) includes a proximal channel portion (1220p) and a distal channel portion (1220d), wherein the proximal channel portion (1220p) has a first uniform width along a length thereof, wherein the distal channel portion (1220d) has a second uniform width along a length thereof, wherein the first uniform width is greater than the second uniform width, wherein the at least one channel further includes a medial channel portion (<NUM>) between the proximal channel portion (1220p) and the distal channel portion (1220d), wherein the medial channel portion (<NUM>) defines a stepped transition between the proximal channel portion (1220p) and the distal channel portion (1220d).