Flapper Valve for an Insufflation Cannula Assembly

1. Field of the Invention

The present invention relates to an insufflation cannula assembly adapted to receive a trocar, endoscope or other surgical instrument and for use in conjunction with insufflatory surgical techniques. More particularly the invention relates to a valve used in the assembly for maintaining insufflation pressure in a body cavity.

2. Description of the Prior Art

Insufflatory surgery involves filling a body cavity with a pressurized gas to maintain the cavity under a certain predetermined pressure. One way of performing the surgery is by first puncturing the skin in a desired body cavity region with a needle. The needle includes a stylet which introduces an insufflation gas into the body cavity to inflate it.

A trocar is then used to puncture the body cavity. The trocar is inserted through a cannula or sheath, which cannula partially enters the body cavity through the incision made by the trocar. The trocar can then be removed from the cannula, and an elongated endoscope may be inserted through the cannula to view the anatomical cavity.

Various types of cannula or trocar assemblies are provided with valves for maintaining a certain gas pressure in the cavity when the trocar or other surgical instrument is removed from the cannula.

For example, U.S. Pat. No. 4,654,030, which issued to Frederic Moll et al., and copending U.S. application Ser. No. 920,509, filed Oct. 17, 1986, disclose a trocar assembly having a cannula and employing a flapper valve to close off the cannula passage after the trocar or other instrument has been withdrawn.

As shown in FIG. 7 of the Moll et al. patent, the flapper valve includes a U-shaped flapper 82 and a grommet 77 formed with a central opening 78 through which the trocar may be inserted or withdrawn. The flapper carries a circular pad 87, and is spring-biased so that the pad engages grommet 77 and forms a seal with the grommet.

Although the flapper valve disclosed in the Moll et al. patent functions satisfactorily in most applications to maintain pressure in the body cavity, the potential for improvement nevertheless exists.

First, the circular pad is rigidly mounted on the flapper so that it cannot move with respect to the flapper. If the pad and grommet are slightly out of alignment when the valve closes, the pad may not seat properly on the grommet, and insufflating gas may leak from the body cavity through the valve.

Second, the circular pad is made of a deformable material such as Tygon (TM), and is formed by a molding process. Irregularities in the pad's grommet-engaging surface due to shrinkage of the pad material during its formation may provide leakage paths through the valve. Also, the pad bears with considerable spring pressure on the side of the trocar when the trocar is inserted into the cannula through the valve. A depression may form in the pad's surface which may cause further leakage when the valve closes.

Third, the circular pad is relatively flat or has a slight curvature. It engages protruding lips 88 formed on the grommet, which lips surround the grommet opening 78. With this structure, the flapper valve disclosed in the Moll et al. patent provides minimal contact area between the pad and the grommet, and any slight irregularity in one or the other may cause the valve to leak.

In addition to the Moll development, other improvements in such valves have been developed. For example, in copending commonly assigned Application No. 07/140,025, filed Dec. 31, 1987, improvements in such valves are disclosed which include, inter alia, the provision of a self-seating valve plug.

In all of these aforementioned developments however, there still remains room for improvement. For example, one difficulty which has existed with all such developments relates to the accumulation of body fluids, usually blood, on the proximal surface of the valve member when the trocar is removed and passed by the valve members. Such accumulation of fluid, while not affecting the functioning capability of the valve, nevertheless has a tendency to be transferred to other instruments inserted into the cannula after the trocar is removed. In particular, when an endoscope is inserted into the cannula to view the inner region of the body cavity, the lens of the endoscope engages and actually opens the valve. This engagement causes the lens to become smeared with the blood, thus inhibiting the surgeon's view through the endoscope. The present invention relates to a flapper valve for such instruments which preferably includes self-seating and sealing improvements while avoiding the aforementioned disadvantages when used in conjunction with sensitive instruments such as endoscopes.

A flapper valve for an insufflation cannula assembly is disclosed, the cannula assembly including a cannula defining a cannula passage and a housing mounted on one end of the cannula and having an opening formed therein, the flapper valve being mounted in the housing of the assembly. The flapper valve comprises a valve seat situated at the housing opening, the valve seat having an opening formed therein and being in communication with the cannula passage and being adapted to allow a surgical instrument to pass therethrough and into the cannula passage. A valve plug is adapted to engage the valve seat at the opening thereof and to form therewith a substantially gas tight seal, the proximal side of the valve plug being engageable by a surgical instrument passing through the valve seat and into the cannula passage when the valve plug is seated in engagement with the valve seat. The valve plug is configured on the proximal side to prevent collection of body fluids or the like in a manner which would transfer the body fluid to the distal face of the instrument when the instrument engages the valve plug. Biasing means is provided for biasing the valve plug into engagement with the valve seat, and means is provided for mounting the valve plug in the housing and for pivoting the plug into and out of engagement with the valve seat. The valve plug is preferably movable on the plug mounting means so as to be self-aligning with the valve seat opening when the plug and the seat are in engagement.

The present invention provides a valve for an insufflation cannula assembly which minimizes fluid leakage through the cannula. In particular, a flapper valve is disclosed whose sealing members automatically align with each other when the valve closes to provide an enhanced gas tight seal. The sealing members of the flapper valve contact each other over a greater surface area.

Also, an insufflation cannula assembly is disclosed for use with a trocar, endoscope or other surgical instrument, which cannula assembly provides negligible or no gas leakage. The present invention provides a flapper valve which is an improvement over the flapper valve disclosed in Moll et al. U.S. Pat. No. 4,654,030.

In one form of the present invention, a cannula assembly for use in conjunction with insufflatory surgical techniques includes a cannula having opposite open ends, a housing mounted on one end of the cannula and having an opening formed in the housing, and a flapper valve mounted in the housing to seal the cannula passage when a surgical instrument, such as a trocar, endoscope or the like, is withdrawn from the cannula.

The flapper valve basically includes a valve seat situated at the housing opening, a valve plug which engages the valve seat and forms a substantially fluidtight seal with the seat, and a support plate and spring mechanism for mounting the valve plug in the housing and for pivoting the plug into and out of engagement with the valve seat. The valve plug includes an annular rim over the proximal face which surrounds a reservoir for collecting blood or other body fluids such that insertion of an endoscope or other instrument into the cannula causes the lens to engage the rim. Thus smearing the lens with blood from the valve plug is thereby avoided.

The valve seat has an opening formed through its thickness, which opening is in communication with the cannula passage. The valve seat is positioned in the housing such that its opening is co-axial with the cannula so that a surgical instrument, such as a trocar or endoscope, may be inserted through the valve seat opening and into the cannula passage.

The valve plug is preferably mounted loosely but securely on the support plate so that it can move radially on a surface of the support plate and align itself with the opening formed in the valve seat when the two engage each other. The surface of the valve plug which engages the valve seat has a frusto-conical shape so that the surface is partially received by the valve seat opening when the valve closes.

The support plate is basically a U-shaped member which extends from the radial side of an upstanding post mounted in the housing. A helical spring mounted co-axially on the post engages the housing and the support plate and biases the valve plug into engagement with the valve seat when the valve plate is biased into a position immediately adjacent the valve seat and parallel thereto, i.e. perpendicular to the longitudinal axis of the cannula. In the preferred embodiment, the support plate is configured and dimensioned to engage the valve seat, particularly in the peripheral portion surrounding the opening. Simultaneously therewith, the plug engages the portion of the valve seat which defines the opening. A trocar or other surgical instrument inserted through the valve seat opening will cause the valve plug to pivot away from the valve seat and out of the trocar's axial path of travel between the valve seat opening and the cannula passage, i.e. toward a direction parallel to the longitudinal axis of the cannula.

In a preferred embodiment, an insufflation cannula assembly is disclosed which comprises a cannula having opposite end portions, a housing mounted on one end of the cannula, the housing having an opening formed therein. A flapper valve is mounted in the housing, the flapper valve including a valve seat disposed at the housing opening and having an opening formed therein to allow a surgical instrument to pass therethrough and into the cannula. The valve seat is formed of a resilient material and has an annular portion of reduced thickness defining the opening. The annular portion is of greater flexibility than adjacent portions thereof due to the reduced thickness. A valve plug is adapted to engage the valve seat at the opening thereof and to form a seal with the valve seat. Means is provided for mounting the valve plug and for pivoting the valve plug into and out of engagement with the valve seat. The valve plug is movable on the plug mounting means so as to provide the valve plug with self-seating capability to allow the valve plug to automatically align itself with the valve seat opening when the plug and the valve seat are in engagement. The valve seat includes a circular ridge at the proximal side and defines a recessed reservoir in the valve plug dimensioned and configured for collecting blood or other body fluids, whereby the self-seating capability of the valve plug combines with the resilient annular flexible portion of the valve seat to provide a substantially gas tight seal and insertion of an endoscope or other instrument into the valve opening and the cannula causes the endoscope to engage the circular ridge at the proximal side of the valve plug.

Preferred embodiments of the invention are described hereinbelow with reference to the drawings wherein:

FIG. 1 is a perspective view of the cannula assembly of the present invention with a trocar assembly mounted thereon;

FIG. 2 is a cross-sectional view of the cannula assembly and trocar assembly shown in FIG. 1, taken along lines 2--2 of FIG. 1;

FIG. 3 is an exploded view with parts separated for illustration purposes, of the cannula assembly of the present invention;

FIG. 3A is a perspective view of a valve plug from the proximal side, constructed according to the present invention, illustrating a feature pertaining to the provision of an annular rim and body fluid reservoir;

FIG. 3B is a perspective view from the distal side, of an alternative embodiment of the valve plug constructed according to the invention;

FIG. 4 is a perspective view of the cannula assembly shown in FIG. 3 with the housing partially cutaway;

FIG. 5 is a rear perspective view of a portion of the cannula assembly showing the novel valve plug;

FIG. 6 is a partial cross-sectional view of the flapper valve used in the cannula assembly of the present invention illustrating the novel valve plug feature;

FIG. 7 is a top view of the cannula assembly with its housing partially broken away to illustrate the flapper valve and the valve plug according to the invention; and

FIG. 8 is an enlarged, detailed view, partially in cross-section, of a portion of the flapper valve of the present invention.

Referring initially to FIGS. 1 and 2 of the drawings, it will be seen that a cannula assembly 2 used in connection with insufflatory surgical techniques basically includes a cannula 4 and a housing 6 mounted on one end of the cannula 4. The cannula 4 is formed as an elongated sleeve having opposite proximal and distal open ends, and thus defines a cannula passage 8 in its interior. The cannula 4 may be formed from a stainless steel or other rigid material.

The housing 6 of the cannula assembly is rigidly secured to the proximal end of the cannula 4. It has an open interior for mounting other components of the cannula assembly, and has a rear opening 10 defined by a circular flange 12 extending inwardly of the housing, which opening 10 is situated co-axially with the cannula 4. 0-ring 13 is mounted on the cannula as shown in FIG. 3, to prevent leakage between the cannula and the housing. Additionally, the housing 6 includes a stopcock port 14 into which the nozzle of stopcock 16 is inserted as shown in FIG. 4. The port 14 is provided for passing additional insufflating gas into the body cavity.

The cannula assembly 2, together with cannula 4 and housing 6, is adapted to receive a surgical instrument through the opening 10 in the housing. An example of such an instrument is the trocar assembly 20 shown in FIGS. 1 and 2 of the drawings, the trocar assembly being mounted on the rear side of housing 6. Another example of such instruments is an endoscope which is utilized to view internal portions of the body cavity.

The trocar assembly 20 basically includes a hand grip portion or head 22, an obturator 24 mounted on the head 22 of the trocar assembly and extending outwardly from the head, and an obturator shield 26 which houses the obturator 24. The obturator 24 is formed with a piercing tip 28 for puncturing the body cavity. A spring 30 in the head 22 of the trocar assembly biases the shield 26 axially away from the head so that it covers the obturator tip 28.

The trocar assembly 20 is mounted on the cannula assembly 2 so that its obturator 24 and shield 26 are slidably received in the cannula passage 8 with the obturator shield extending beyond the distal end of the cannula 4.

In operation, the distal end of the cannula/trocar assembly is placed against the skin at the body cavity region, and pressure is exerted on the assembly against the skin. This pressure causes the obturator shield 26 to be pushed rearwardly against the force of the spring 30 to a retracted position, thereby exposing the piercing tip 28 of the obturator. The tip enters the skin and underlying tissue with continued pressure. Once the tip has penetrated the tissue and has entered the cavity, the force against the distal end of the shield 26 ceases and the shield is automatically moved axially forward to its extended position covering the tip 28 through the action of the spring 30.

A more detailed description of the trocar assembly described herein, and its operation, is provided in Moll et al. U.S. Pat. No. 4,654,030, which is incorporated herein by reference.

As is provided in the device disclosed in the above-identified Moll et al. patent, the cannula assembly 2 of the present invention includes a flapper valve which opens to allow a surgical instrument, such as the trocar assembly 20, to be inserted through the cannula 4, and closes when the surgical instrument has been withdrawn, in order to maintain gas pressure in the body cavity which has been inflated with an insufflation gas. The flapper valve of the present invention as shown in FIG. 3 basically includes three components: a valve seat 32, a valve plug 34 which engages the valve seat 32, and a mechanism 36 for mounting the valve plug 34 and for pivoting the plug into and out of engagement with the valve seat 32.

As shown in FIGS. 3 through 8 of the drawings, the valve seat 32 is mounted in the circular flange 12 at the rear opening 10 formed in the housing 6 of the cannula assembly. The seat 32 basically includes a forward portion 38 and a rearward portion 40 which are interconnected and which define a recess 42 between them, which recess 42 receives the circular flange 12 of the housing. The rearward portion 40 is preferably circular, and is received in a recess 44 formed in the circular flange 12.

The forward portion 38 is substantially rectangular, and has a greater transverse width than the diameter of the circular rearward portion 40 so that it extends substantially to the opposite lateral sides 46 of the housing 6. The forward and rearward portions 38, 40 contact the sides of the flange over an area sufficient to prevent leakage.

The valve seat 32 includes an opening 48 formed centrally through its thickness. The valve seat 32 is situated in the housing 6 so that its opening 48 is co-axial with the cannula 4 and is in communication with the cannula passage 8 through the interior of the housing; this will allow a surgical instrument, such as the trocar assembly 20 shown in FIGS. 1 and 2, or an endoscope, for example, to pass through the valve seat opening 48 and into the cannula passage 8 from the rear side of the cannula assembly housing 6.

A portion of the valve seat 32 surrounding the opening is reduced in thickness. This portion is defined by a circular recess 50 formed in the rearward portion 40 of the valve seat, and a recessed groove 52 formed in the surface of the forward 38 of the valve seat and concentrically surrounding the opening 48.

The valve seat 32 is formed from a rubber or other elastic material. As will be seen, because of the elasticity of the material from which it is formed and the reduced thickness of the area surrounding the opening 48, the valve seat 32 will deform to accommodate the valve plug 34 and thereby conform to the shape of the valve plug 34 when the two engage each other, with substantial areas of the two being in contact so as to form a substantially gas tight seal. Also, the reduced thickness portion at 50 and 52 surrounding the valve seat opening 48 allows the valve seat 32 to expand and closely engage the obturator shield 26 of the trocar assembly 20 or other surgical instrument inserted in the cannula assembly, and to prevent fluid from escaping from the body cavity.

As mentioned previously, the flapper valve also includes a mechanism 36 for mounting the valve plug 34 and for pivoting the valve plug into and out of engagement with the valve seat 32. As shown in FIG. 3 of the drawings, such a mechanism includes a support plate 54 which is preferably U-shaped. The support plate 54 extends outwardly from a radial side of an upstanding post 56 mounted in the housing of the cannula assembly.

A tensioned helical spring 58 is co-axially mounted on the post 56, and includes two ends 60, 62. One end 60 bears against a side 46 of the cannula housing 6, and the other end 62 bears against the rear side 63 of the support plate below a tab 64 extending outwardly from the rear side, which tab 64 keeps the spring end in place. The spring 58 biases the support plate 54 such that the valve plug 34 mounted on the plate will engage the valve seat 32 to effect a gas tight seal when the support plate 54 is biased to the position shown in FIG. 6, i.e. parallel to and immediately adjacent the support plate 54.

When a trocar or other surgical instrument (i.e., an endoscope) is inserted through the valve seat opening 48 into the housing 6 of the cannula assembly, it will engage the valve plug 34 and cause the support plate 54 to pivot against the force of the spring 58 towards the side 46 of the housing so that the valve plug 34 is out of engagement with the valve seat 32 as shown in FIG. 7. In this position, the orientation of the support plate is near a direction generally parallel to the longitudinal axis of the cannula. This opens the valve and allows the surgical instrument to be inserted through the interior of the cannula assembly housing 6 and into the cannula 4. When the trocar or endoscope is withdrawn, the support plate 54 is spring biased to pivot so that the valve plug 34 will automatically engage the valve seat 32, thereby closing the valve.

Referring now to FIG. 3A, a major feature of the present invention is illustrated. This Figure is a perspective view of the valve plug 34 of the present invention. Valve plug 34 is shown separated from the support plate 54 for convenience of illustration. In FIG. 3A the valve plug 34 is configured to include at the proximal face, a recessed reservoir 35 whose outer boundary is defined by annular rim 36 as shown. The recessed reservoir is provided to collect any body fluids, i.e. blood, etc., which would normally tend to accumulate on the proximal side of the plug when trocar 16 is removed from the cannula after the body cavity has been pierced. Passage of the trocar by the flapper valve would naturally cause the valve plug to be somewhat covered with the fluid.

The collection of such fluid within the reservoir 35 of the present valve structure thus avoids accumulation of fluid on a proximal outer surface of the valve plug 34. Moreover, the presence of the rim 36 on the proximal side of the valve plug 34 thus presents a clean rim at all times to any instrument inserted into the cannula, rather than a surface covered with blood. Hence, when the trocar is removed and the surgeon inserts another instrument such as an endoscope 31 (see FIG. 3A) having a clear lens 33 at the distal end, the engagement of the lens 33 with the rim 36 of the plug 34 avoids transfer of the body fluid to the face of the endoscope as would otherwise occur with prior art instruments. Thus the presence of the reservoir 35 and rim 36 tend to prevent the accumulation of blood or other body fluids on the proximal side of the plug where the lens 33 engages the plug 34. The absence of such fluid collection makes it possible to insert the endoscope without the aforementioned adverse affects.

Turning once again to FIG. 4 in conjunction with FIGS. 1 and 7, a lever 66 is provided on the outside of the housing 6. The lever 66 is mounted to the upstanding post 56 and pivots with the post when the support plate 54 is pivoted. In addition to providing visual indication of the position of the support plate 54, lever 66 is provided for the surgeon to manipulate so that the valve can be manually opened to desufflate the body cavity. To ensure fluid tightness, an 0-ring 68 is mounted on the post between the spring 58 and the lever 66.

The support plate 54 also has an opening 70 extending entirely therethrough as shown, that is, between its rear and front sides 63, 65. As will be seen, the opening 70 is provided for mounting the valve plug 34 to the support plate.

As can be seen in FIGS. 3A and 8, the valve plug 34 of the flapper valve basically includes a recessed reservoir 35 having a front face 72 (shown in phantom lines) surrounded by rim 36, and a rear face 74 opposite the front face. The outer portion 76 of the front face is formed with a conical shape, and more preferably, a frusto-conical shape. The conically-shaped portion 76 of the valve plug is preferably sloped inwardly on its sides at an angle "A" of about 30.degree..

As shown in FIGS. 3 and 3A, the recessed face 72 of the reservoir 35 of valve plug 34 is surrounded by a conical or frusto-conical face 76. A flange 78 which surrounds the conically-shaped portion 76 and extends radially outward as shown acts to ensure that the tip of shield 26 of the trocar assembly, or lens 33 of endoscope 31, or other surgical instrument which may be inserted, is guided into the cannula 4 and does not momentarily get hung up at the joint formed by valve plug 34 and support plate 54 as the support plate 54 and plug 34 pivot inwardly.

As mentioned previously, the valve plug 34 is mounted on the support plate 54 and pivots with the support plate into and out of engagement with the valve seat 32. One of the important features of the flapper valve of the present invention which distinguishes it from the valve employed in the trocar disclosed in U.S. Pat. No. 4,654,030 (Moll et al.) and others, is that the valve plug 34 is loosely but securely mounted on the support plate 54 so that it can move radially to a certain extent on the front face of the support plate. The ability of the plug 34 to move with respect to the support plate 54 and the particular shape of the valve plug (i.e., conical or frusto-conical) provide the valve plug with a self-seating capability which allows it to automatically align itself with the valve seat 32 when the two engage. This capability is further enhanced by the provision of recess 35 and annular rim 36 which is engaged by the surgical instruments.

A stem portion 80 extends outwardly from the rear face 74 of the valve plug 34. As will be seen, the stem portion 80 is provided for mounting the valve plug 34 to the support plate 54, and for providing the valve plug with a degree of radial movement on the front side of the support plate.

The stem portion 80 includes a free end on which is mounted a retaining head 82. Alternatively, the retaining head 82 may form the free end of the stem portion 80. The retaining head 82 in its preferred form is also frusto-conically shaped with sides that converge in a direction away from the rear side 63 of the support plate, preferably sloping inwardly at an angle "B" of about 20.degree. as shown in FIG. 8.

The valve plug 34 is mounted on the support plate 54 with its conically-shaped front face 72 (and recessed reservoir 35) and its retaining head 82 disposed on opposite front and rear sides 65, 63 of the support plate, respectively, and with its stem portion 80 received within the support plate opening 70.

The retaining head 82 is dimensioned to be oversized, that is, with a diameter that is greater than that of the support plate opening 70, to securely connect the valve plug 34 to the support plate 54. In the preferred embodiment, the stem portion 80 of the valve plug is formed with a diameter that is less than that of the support plate opening 70. Thus, when mounted on the support plate 54, the valve plug 34 is free to move in any radial direction on the front side 65 of the support plate, and is limited in its radial movement by the difference between the diameters of the support plate opening 70 and the stem portion 80.

For example, if the support plate opening 70 is formed with a diameter of 0.127 inches and the valve plug stem portion 80 is formed with a diameter of 0.095 inches, then the valve plug will be able to travel 0.016 inches from the center of the support plate opening in any radial direction.

The valve plug 34 is thus free to "float" on the surface of the support plate 54 in any radial direction, and to align itself with the central opening 48 formed in the valve seat 32. When the valve closes, the engagement of the valve seat 32 with the frusto-conical front face of the valve plug 34 forces the valve plug into proper alignment with the valve seat to effect a gas tight seal.

The rear face 74 of the valve plug 34 is also formed with a recessed central portion 84 concentrically surrounding the stem 80. This recessed central portion 84 is provided basically for two reasons. First, it provides the plug with less surface area on its rear face 73 to contact the front side 65 of the support plate. This reduces the drag or friction between the two and allows free movement of the valve plug 34 on the support plate 54.

Second, if desired, the recessed central portion 84 may serve to receive a silicone grease or other lubricant to lubricate the interface between the valve plug and the support plate, which also minimizes friction between the two.

An alternative embodiment of the plug 34 is shown in FIG. 3B wherein the recessed portion 74B is annular and peripheral and surrounds a central raised portion 84B. This embodiment also provides the same reduced friction and lubrication advantages as specified above in connection with the embodiment of FIG. 3.

If desired, the front face 72 of the valve plug 34 may be formed from a material such as plastic, aluminum, stainless steel or the like. The retaining head 82 may be formed from the same or other material as the front face 72 of the valve plug and joined to the end of stem portion 80 after the stem portion has been mounted in the support plate opening 70, or may be formed from a relatively elastic material and force-fitted through plate opening 70. The retaining head 82, formed of resilient material, can compress and then expand after its insertion through the support plate opening, and thereby return to an intentional interference.

The valve seat 32, being molded of rubber or other elastic material, conforms by stretching and compressing to the shape of the valve plug 34 when the valve plug is wedged in the valve seat opening 48. Thus, the valve seat surrounding the opening 48 can engage the valve plug 34 over substantially all of its entire thickness to form an effective gas tight seal.

The valve seat may be mounted in a circular recess 86 (see FIG. 8) formed in the front side 65 of the support plate 54, the diameter of the circular recess 86 being made sufficiently large so as not to limit the radial movement of the valve plug on the support plate.

The flapper valve of the present invention provides an enhanced gas tight seal by its capability of being self-seating. More significantly, as noted, the recessed reservoir at the proximal side of the plug facilitates collection of blood or other body fluids while the annular rim surrounding the reservoir can be engaged by a sensitive instrument such as an endoscope without smearing the lens. In addition, the frusto-conical shape of the valve plug 34 and its ability to "float" on the support plate 54 allow it to come into proper alignment with the valve seat 32 when the two engage. Furthermore, the configuration and elasticity of the valve seat 32 and the particular shape of the valve plug 34 permit the two to contact each other over a greater surface area, thus ensuring an effective seal.