Trocar assembly with obturator

Abstract: A trocar (10) adapted to extend across the body wall into a body cavity, forming a seal around an instrument inserted through the trocar, comprises a cannula (12) having a first axis extending between proximal (16) and distal (14) ends. A valve housing (23) attached to the proximal end of the cannula forms a working channel with the cannula and includes a rigid housing portion (25) and a flexible housing portion (27). First and second septum valves are formed in an end wall of the flexible housing portion and form separate valve sets with associated zero closure valves disposed within the valve housing. The valve sets (52-56) are sized and configured accommodating different ranges of instrument diameters. The first and second septum valves are offset from the axis of the cannula in normal positions but are movable to positions more aligned with the axis of the cannula, due to elastomeric characteristics of the flexible housing.

Description: BACKGROUND OF THE INVENTION Field of the Invention This invention relates generally to surgical access devices, such as trocars, which are adapted to provide access across a body wall and into a body conduit or cavity. Discussion of the Prior Art Trocars of the past have typically included a cannula and a valve housing which together define an access or working channel for various surgical instruments. The cannula has been formed in the configuration of an elongate rigid cylinder which has been inserted, with the help of an obturator, into a body cavity, such as the abdominal cavity to provide access across a body wall, such as the abdominal wall. Such a device is disclosed in DE 43 12 147 Al, corresponding to the preamble of claim 1, where the complete trocar assembly is made of flexible materials to permit curved tools to be passed therethrough. In a typical abdominal laparoscopic surgery, the abdomen is insufflated to pressurize and thereby enlarge the cavity within which a surgical procedure is to be performed. Various instruments used in the procedure have been inserted, previously one at a time, through the working channel of the trocar to perform the surgery. In order to maintain the insufflation pressure when the instrument is inserted through the trocar, a valve has been provided in the housing to form a seal around the instrument. These instrument valves have typically been provided in the form of septum valves. When the instrument is removed, a zero closure valve has typically been provided to seal the trocar in order to maintain the insufflation pressure. A septum valve similar to that disclosed and claimed by applicant in copending application Serial No. 08/051,609 filed April 23, 1993 and entitled Seal Assembly for Access Device, now published as US-A-5 443 452, is typical of the instrument valves. A typical zero closure valve might be in the form of a double duck bill valve such as that disclosed in the same application. Instruments vary in size and diameter. While the zero closure valves of the past can accommodate a relatively wide range of diameters, the septum valves are generally capable of stretching only a nominal amount to accommodate larger diameters. Accordingly, these valve sets are generally limited as to the size of instrument which they can accommodate. Attempts have been made to increase the range of septum valves by providing levers which prestretch the valve in order to reduce some of the friction forces. These universal septum valves, such as those disclosed and claimed by applicant in U.S. Patent Number 5,209,737, are relatively complex in structure but nevertheless are able to accommodate a wide range of instruments. In trocars of the past, the septum valves and zero closure valves have been formed as a valve set. This set has typically been configured along a common axis which extends through the opening of the septum valve, the zero closure valve, and the cannula. In the past, only a single valve set was provided in the trocar. This necessitated that instruments used with the trocar be inserted only one at a time. Thus a first instrument would be inserted through the septum valve and the zero closure valve to gain access to the abdominal cavity. With the instrument in place, the septum valve would maintain the insufflation pressure. Once the first instrument was removed, this insufflation pressure was maintained by the zero closure valve. Only upon removal of the first instrument could a second instrument be inserted through the same septum valve and the same zero closure valve. When an instrument was required that had a diameter outside the range of a particular valve set, the entire trocar had to be replaced with one which could accommodate a different range of diameters. In some cases alternative septum valves were provided each of which functioned with the same zero closure valve but accommodated a different range of instrument diameters. Even where the trocars of the past provided for alternative valve sets, only a single instrument could be inserted at a time. According to the present invention as claimed in claim 1 there is provided a trocar assembly including: a cannula having an axis extending between a proximal end and a distal end of the cannula; a rigid housing portion having a distal end and a proximal end, the distal end of the rigid housing portion having a fixed relationship with the cannula; an elastomeric housing portion coupled to the proximal end of the rigid housing portion, the elastomeric housing portion being axially compressible; the rigid housing portion and the elastomeric housing portion forming a valve housing and defining with the cannula a working channel of the trocar; an obturator sized and configured for removable insertion through the working channel via the valve housing; a shaft included in the obturator and having an axis extending from a proximal end to a distal tip, the shaft being sized and configured for removable insertion into the cannula to an operative position wherein the distal tip of the shaft extends beyond the distal end of the cannula; a handle of the obturator attached in a fixed relationship to the proximal end of the shaft, characterised in that the obturator comprises means located part way along the shaft of the obturator between the proximal end of the shaft and the distal end of the shaft for engaging at least one of the cannula and the rigid housing portion in order to prevent insertion of the obturator into the cannula beyond the operative position of the obturator, the means being arranged for insertion with the shaft of the obturator through the elastomeric housing portion and being larger than the inside diameter of the cannula. Preferred embodiments are claimed in the dependent claims. The deficiencies of the prior art have been overcome with the present invention which may provide for the insertion of two or more instruments into the same trocar at the same time. This trocar which may provide for a seal assembly having multiple valve sets in a single valve housing, is significantly simplified so that manufacturing costs are greatly reduced. Each of the valve sets in the preferred embodiment accommodates a different range of instrument sizes so that only a single trocar and seal assembly is required in order to accommodate all possible instrument sizes. Thus, a single simplified trocar can accommodate not only a full range of instrument sizes, but can even accommodate multiple instruments simultaneously. Not only is the single trocar less expensive to manufacture, but the number of assemblies and trocars required for a given surgical operation is also reduced. This will be greatly appreciated in a cost sensitive marketplace where as many as one million laparoscopic surgeries are performed annually in the United States, each requiring as many as four to six trocars per surgery. Each of the valve sets is provided with characteristics for forming an instrument seal as well as a zero closure seal. These characteristics can be provided for the smallest range of instruments, by a single septum valve which additionally has zero closure characteristics. For larger valve sets, a septum valve is combined with a zero closure valve in each of the sets. In an embodiment wherein the cannula has a first axis, the septum valve a second axis, and the zero closure valve a third axis, at least one of the second and third axes is offset from the first axis. It may also be desirable to offset the second axis of the second septum valve from the third axis of the zero closure valve in order to accommodate more valve sets in the single valve housing. In these embodiments, the zero closure valves can be formed in any manner associated with the prior art, but the double duck bill valve configuration is preferred. The trocar can be adapted to extend across a body wall into a body cavity, and to form a seal around an instrument inserted through the trocar into the body cavity. The trocar comprises a cannula forming an elongate passage and a valve housing disposed at a proximal end of the trocar. A valve assembly is disposed relative to the housing and includes a first valve set forming a first working channel with the passage of the cannula and a second valve set forming a second working channel with the passage of the cannula. The first valve set includes a first septum valve and a first zero closure valve each disposed along the first working channel. The second valve set includes a second septum valve and second zero closure valve each disposed along the second working channel. The trocar further comprises means for further supporting at least one of the first septum valve and the second septum valve relative to the housing in a "floating" relationship with the cannula. Preferably, transverse movement of the end cap is limited by a projection which extends from either the valve housing or the end cap to provide an interference fit between the projection and the other of the valve housing and end cap. A rigid partition may be provided within the valve housing and extends along the axial length of the valve sets. This rigid partition is movable with the end cap and the valve assembly to inhibit contact between the sidewalls of the housing and the axial walls of the valves which would otherwise undesirably deform the valves and permit leakage of the insufflation gas. These and other features and advantages of the invention will become more apparent with the description of preferred embodiments and reference to the associated drawings. DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a preferred embodiment of the trocar of the present invention; Fig. 2 is an axial cross-section view taken along lines 2-2 of Fig. 1, and illustrating a preferred embodiment of a valve housing and associated valve assembly; Fig. 3 is a top plan view taken along lines 3-3 of Fig. 2; Fig. 4 is a radial cross-section view taken along lines 4-4 of Fig. 2; Fig. 5 is an axial cross-section view similar to Fig. 2 and illustrating an additional embodiment of a valve housing; Fig. 6 is a cross-section view similar to Fig. 2 and illustrating a small sized instrument and a medium sized instrument simultaneously operatively disposed through first and second valve sets of the trocar; Fig. 7 is a radial cross-section view similar to Fig. 6 and illustrating a large instrument in the form of an obturator operatively disposed in the trocar; Fig. 8 is a side view partially in section of the trocar illustrating a flapper valve having zero closure characteristics; Fig. 9 is a top plan view taken along lines 9-9 of Fig. 8; Fig. 10 is a perspective view illustrating an instrument inserted into a trocar not according to the invention; Fig. 11 is an exploded axial cross-section view of the trocar embodiment of Fig. 10 illustrating components including (from top to bottom) an end cap, a valve assembly, a partition structure, a valve housing, and a cannula; Fig. 12 is an axial cross-section assembled view of the trocar illustrated in Fig. 11; Fig. 13 is an axial cross-section view of the partition structure illustrated in Fig. 11; Fig. 14 is a top plan view of the partition structure of Fig. 11; Fig. 15 is an enlarged side elevation view of the partition structure of Fig. 11. DESCRIPTION OF PREFERRED EMBODIMENTS A multiport trocar is illustrated in Figure 1 and designated generally by the reference numeral 10. The trocar 10 is representative of any access device including a cannula 12 which is in the form of a hollow elongate cylinder having a distal end 14 and a proximal end 16. It is this cannula 12 which is sized and configured to extend across a body wall, such as an abdominal wall 15, into a body conduit or cavity, such as a blood vessel or an abdominal cavity 17. The cannula 12 is preferably rigid, or semi-rigid and in preferred embodiments is formed of plastics or surgically compatible metals such as stainless steel. A passage 18 formed by the walls of the cannula 12 extends along a central axis 21. A valve housing 23 also forms a significant part of the trocar 10. In the illustrated embodiment, the valve housing 23 includes a rigid housing portion 25 and an elastomeric housing portion 27 which together define a housing cavity 30. The rigid housing portion 25 is preferably formed of plastic and disposed at the proximal end 16 in a fixed relationship with the cannula 12. In the illustrated embodiment, a pair of finger tabs 32 are formed as an integral part of the rigid housing portion 25 and provide means for engaging the trocar 10 and manipulating the cannula 12 into a preferred operative position. A collar 34 is disposed distally of the tabs 32 where it is sized and configured to receive the proximal end 16 of the cannula 12, as best illustrated in Figure 2. The elastomeric housing portion 27 is preferably formed of natural rubber and includes a cylindrical side wall 36 and an end wall 38 which are integral in a preferred embodiment. The side wall 36 is preferably centered on the axis 21 of the cannula 12 while the end wall 38 is transverse, for example perpendicular, to the axis 21. In a preferred embodiment, the side wall 36 of the elastomeric housing portion 27 is joined to and forms a seal with the rigid housing portion 25 at a circumferential joint 40. The cavity 30 formed by the valve housing 23 is in fluid communication with the passage 18 of the cannula 12. Together this cavity 30 and passage 18 form a working channel 41 of the trocar 10. In the illustrated embodiment, this channel 41 extends from regions exterior of the trocar 10, through the end wall 38, into the housing cavity 30, and through the passage 18 and the distal end 14 of the cannula 12. Thus the trocar 10 functions as an access device so that instruments can be inserted through the seal housing 23 and the cannula 12 into the abdominal cavity 17. In a typical laparoscopic surgery, the trocar 10 is disposed with the cannula 12 extending across the abdominal wall 15 and into the abdominal cavity 17. In order to increase the working space at the surgical site, the abdominal cavity 17 is typically pressurized or insufflated. In the trocar 10 illustrated in Figure 3, this insufflation of the abdominal cavity 17 is implemented by use of an insufflation tube 45 which is in fluid communication with the housing cavity 30 as well as the passage 18 of the cannula 12. After the abdominal cavity 17 is appropriately insufflated, various instruments, such as catheters, guide wires, graspers, staplers, can be inserted through the working channel 41 of the trocar 10 to perform various functions within the abdominal cavity 17. It is important in such an operation, that the insufflation pressure be maintained both when the instruments are disposed within the working channel 41 of the trocar 10, as well as when the instruments are removed from the working channel 41. Such is the function of a valve assembly 46 which is typically disposed within the housing cavity 30 or formed as part of the valve housing 23. The valve assembly 46 of the present invention is sized and configured to accommodate a surgical instrument having substantially any diameter regardless of the size limitations of a single valve. Such instruments are represented by a catheter 48, a retractor 49 and a obturator 50 best illustrated in Figures 6 and 7. In the following discussion, the catheter 48, retractor 49 and obturator 50 are sometimes referred to respectively as the small, medium and large instruments 48, 49, 50, and collectively as the instruments 48, 49 and 50. As noted, these instruments 48-50 will vary widely in diameter. For example, the small size instrument 48 might include a guidewire or catheter up to two millimeters in diameter. The medium size instrument 49 might include graspers or retractors between two and five millimeters in diameter. The large size instrument 50 might include an obturator or laparoscope having diameters as small as five millimeters and as large as eleven or twelve millimeters. This entire range of diameters, for example from zero to eleven or twelve millimeters, can be accommodated with the single multiport trocar 10 of the present invention. In this concept, the valve assembly 46 includes at least two and preferably three or four valve sets each adapted to receive a different range of instrument sizes, and collectively to accommodate the entire range of instrument sizes. In the illustrated embodiment the valve assembly 46 includes a small valve set 52, a medium valve set 54 and a large valve set 56. These valve sets 52, 54 and 56 form, with the passage 18 of the cannula 12, three respective working channels 41a, 41b, and 41c. Each of the valve sets 52-56 must have characteristics for forming a seal around the associated instrument 48-50 when it is operably disposed in the working channel 41, as well as characteristics for forming a seal across the working channel 41 when the associated instrument 48-50 is removed. For the small valve set 52, both of these characteristics can be provided by a single septum valve 58 which has an opening 59 small enough to close upon itself in the absence of the instrument 48, but large enough to accommodate instruments of up to about two millimeters in diameter. The large valve set 56 is representative of the other valve sets in the valve assembly 46. This large valve set 56 includes a large septum valve 61 as well as a large zero closure valve 63. These valves 61 and 63 can be of the type disclosed in applicant's copending application Serial No. 08/051,609 filed on April 23, 1993 and entitled Seal Assembly for Access Device. In order to accommodate a large instrument, such as the obturator 50, the large septum valve 61 is provided with a hole 65 which in its natural state has a diameter, such as about five millimeters. Forcing the instrument 50 with a diameter larger than about five millimeters through this hole 65 causes the valve 61 to expand so that it forms a tight seal with the outer surface of the instrument 50. However, when the instrument 50 is removed, the septum valve returns to its natural state leaving the hole 65 in an open state. Under these circumstances, the zero closure valve 63 is of particular importance as it fully closes in the absence of the instrument 50. This insures that the working channel 41c through the large valve set 56 is fully closed when the instrument 50 is removed. The medium valve set 54 is similar to the large valve set 56 in its function, however, it is generally smaller in size. Thus the medium valve set 54 includes a medium septum valve 67 and a medium zero closure valve 70. As was the case with the large septum valve 61, the medium septum valve 67 has a hole 71 which is sufficiently large to accommodate medium size instruments between about two millimeters and five millimeters, for example. This medium septum valve 67 does not fully close as did the small septum valve 58, so the zero closure valve 70 is required to seal the working channel 41b through the medium valve set 54 when the instrument 49 is removed. In order to accommodated the multiple valve sets 52-56 within a single valve housing 23, the lateral orientation of the respective septum valves 58, 67 and 61 in the end wall 38 can be of particular importance. With reference to Figure 3, it will be noted that the three septum valves 58, 67 and 61 are each centered on an associated longitudinal axis 72, 74 and 76. Similarly, the zero closure valves 70 and 63 are centered on respective longitudinal axes 78 and 81. Each of the axes 72-76, associated with the respective septum valves 58, 67 and 61, is separated or off set from the axis 21 of the trocar 10 by a different distance. In the illustrated embodiment the axis 76 associated with the large septum 61 is disposed closest to the axis 21. This orientation is preferred since a larger instrument, such as the obturator 50, requires a more vertical orientation with the trocar 10 due to the fact that its diameter more closely approaches that of the cannula 12. Thus, by locating the axis 76 relatively close to the axis 21, the septum valve 61 is required to move only a small distance in order to achieve the more vertical orientation required by the large instrument 50. As illustrated in Figure 6, the medium sized instruments, such as the retractor 49, can pass through the cannula 12 at an angle so that the medium size instrument 49 does not require as vertical an orientation as the large instrument 50. Thus the medium septum valve 67 need not move as close to the axis 21 of the cannula 12 for operative disposition of the instrument 49. For this reason, the axis 74 of the medium septum valve 67 can be offset from the axis 21 of the cannula 12 a distance greater than that separating the axis 76 of the large septum valve 61 from the axis 21 of the cannula 12. With respect to the small septum 58, its axis 72 can be located at an even greater distance from the axis 21. Not only do small instruments, such as guidewires and the catheter 48, require very little vertical orientation, but they are often flexible so that no movement of the septum 58 is required for operative disposition of these small instruments. For the reasons just discussed, it is important that the septum valves 61 and 67 be located so that they can move from their natural position, in the absence of the instruments 49, 50 to a more centered position, in the presence of the instruments 49, 50. This movement must occur without substantial deformation of the septum valve 67 and 61 so that the valve portions forming the respective holes 71 and 65 can form a suitable seal with the outer surface of the instruments 49, 50. In a preferred embodiment, this movement without deformation is accommodated by two characteristics of the trocar 10. First, the end wall 38 is formed of an elastomeric material thereby permitting the septum valves 58, 67 and 61 to move laterally within the end wall 38. Perhaps more importantly, the side wall 36 of the housing portion 27 is also formed of an elastomeric material and is easily deflected laterally. This movement of the side wall 36 carries the entire end wall 38 to a desired position without deformation of the associated septum valve 58, 67 and 61. Thus the septum valves 58, 67 and 61 have a floating relationship with the cannula 12 which permits them to move laterally while still maintaining their properties for forming a seal with the outer surface of the associated instrument 48-50. This lateral deflection of the side wall 36 is illustrated in both Figures 6 and 7 for the respective instruments 49 and 50. In the foregoing embodiment, the septum valves 58, 67 and 61 are formed in the end wall 38 of the elastomeric housing portion 27. It will be apparent, however, that these valve 58, 67 and 61 can be formed generally in any wall which is transverse to the axis 21 of the cannula 12. The resulting valve wall can be included within the housing cavity 30 or can form part of the valve housing 23. Nevertheless, it is generally preferred that the septum valves 58, 67, and 61 be formed in the proximal-most wall, such as the end wall 38, of the valve housing 23. The location of the zero closure valve 70 and 63 can also be critical in a particular embodiment. It is not required that the axes 78 and 81 associated with the zero closure valves 70 and 63 respectively, be aligned with the axes 74 and 76 of the associated septum valves 67 and 61. This alignment of valves within a valve set, which is characteristic of the prior art, is not required by the present invention. Rather the location of the zero closure valves 70 and 63 is generally dependent on two different considerations. First, the zero closure valve 70 must be positioned such that the instrument 49 passing through the associated septum valve 67 also passes through zero closure valve 70. Similarly, the zero closure valve 63 must be positioned so that the instrument 50, passing through the associated septum valve 61 also passes through the zero closure valve 63. As can be seen from Figure 3, this requirement is not particularly stringent so that the septum valves 67 and 61 can be located relatively close to the central axis 21 while the associated zero closure valve 70 and 63 are located relatively far from the central axis 21. The second consideration for location of the zero closure valves 70 and 63, is based on their proximity to each other. It is important that when the medium instrument 49 is positioned within the medium valve set 54, that it not interfere with the ability of the large zero closure valve 63 seal the working channel 41c. This generally requires that the medium zero closure valve 70 be separated from the large zero closure valve 63 a distance sufficient to prevent deformation of the large zero closure valve 63. In the illustrated embodiment, this interference with a non-associated zero closure valve 63 is of perhaps greatest concern with respect to the medium valve set 54. In this valve set 54, the medium instrument 49 will typically have a more angled disposition within the housing cavity 30 than the large instrument 50. Furthermore, the large zero closure valve 63 will typically extend further into the housing cavity 30, as illustrated in Figure 2, making it more susceptible to interference from the medium instrument 49. The double duck bill valve configuration illustrated for the zero closure valves 63 and 70 is particularly beneficial in avoiding this interference. Each of these zero closure valves 70 and 63 includes respectively, a cylindrical side wall 82 and 83, and a closure structure defined by walls 85 and 87. These walls 85, 87 define lateral recesses 89, 92 as they converge to lines 94, 96, respectively, which form the cross seal associated with this type of zero closure valve. These lines 94 and 96 are best illustrated in Figure 4. The configuration of the walls 85, 87 and the associated recesses 89, 92 and lines 94, 96 are described in greater detail in applicant's copending application Serial No. 08/051,609. In general, this configuration of the zero closure valves 70 and 63 facilitates a structure wherein one of the valves, such as the valve 70, can be provided with a side wall, such as the side wall 82, which is shorter than the side wall, for example the side 83, associated with the other zero closure valve, such as the valve 70. Then, a recess or indentation 98, can be formed in the other side wall, such as the side wall 83. It will be apparent that this solution will be equally appropriate with a longer side wall 82 in the medium zero closure valve 70, and an appropriate indentation, such as the indentation 98, in that side wall 82. Another way of accommodating the close proximity of the zero closure valves 70 and 63 is to orient the associated seal lines 94 and 96 so that neither is disposed along a line interconnecting the axes 78 and 81 of the respective valve 70 and 63. Since these seal lines 94 and 96 extend to the greatest diameter of the associated walls 85 and 87 they are most susceptible to interference by an instrument 78, 80 extending through the opposite valve set 54, 56. By orienting these lines 94 and 96, as illustrated in Figure 4, the natural recesses 89 and 92 formed between lines 94, 96 are automatically faced toward the opposing axis 78, 81. As one contemplates an appropriate length for either of the side walls 83, 85, it must be appreciated that additional length will ultimately demand a longer valve housing 23. For comparison, it will be noted that in the embodiment of Figure 2, the zero closure valve 63 extends beyond the joint 40 between the rigid housing portion 25 and the elastomeric housing portion 27. In an embodiment wherein the length of the seal housing 23 is to be minimized, it may be desirable to shorten the side walls 85 associated with the zero closure valve 63. This could produce an embodiment wherein neither of the zero closure valves 63 or 70 extends beyond the joint 40 between the housing portions 25 and 27. When an instrument, such as the instruments 49 and 50, is removed from the trocar 10, it is desirable that the elastomeric housing portion 27 return to its natural state wherein its side wall 36 is coaxial with the central axis 21. This return to the natural state is facilitated in a preferred embodiment wherein the housing portion 27 is provided with a plurality of ribs 101 which extend radially and longitudinally of the side wall 36 within the housing cavity 30. In a preferred embodiment, the entire elastomeric housing portion 27 (including the ribs 101) and the entire valve assembly 46 (including the septum valves 58, 67, 61 and the zero closure valves 70, 63) are formed as an integral structure from an elastomeric material such as latex. The lateral flexibility desired for the elastomeric housing portion 27 also produces an axial flexibility which may not be desired when the trocar 10 is used with obturators of the prior art. As illustrated in Figure 7, the obturator 50 of the present invention is typical of those of the past in that it includes a handle 102 and a shaft 103 having a sharp distal tip 104. This obturator 50 is designed for axial insertion through the valve housing 23 and into the cannula 12 as illustrated by the dotted line position in Figure 7. Further axial movement into the cannula 12 brings the obturator 50 to an operative position where the sharp distal tip 104 of the obturator 50 extends beyond the distal end 14 of the cannula 12. This operative position is shown by the solid line position of the obturator 50 in Figure 7. Once the obturator 50 is disposed in its operative position within the cannula 12, further axial pressure on the handle 102 is intended to force the sharp distal tip 104 through the abdominal wall 15 to position the distal end 14 of the cannula 12 within the abdominal cavity 14. With obturators of the past, this axial pressure was directed through the handle and applied against the proximal end of the valve housing. In the present invention, however, this additional pressure on the proximal end of the housing 23 would only seek to compress the elastomeric housing portion 27. This would not only make it difficult to insure the operative disposition of the sharp tip 96 beyond the cannula 12, but also could damage the elastomeric housing portion 27. In a preferred embodiment, illustrated in Figure 7, the obturator 50 is provided with an enlargement or projection 105 which is fixed to the outer surface of the shaft 95. In the illustrated embodiment, the projection 105 takes the form of an annular flange which extends radially outwardly from the outer surface of the shaft 95. When the obturator 50 is inserted from its dotted line position in Figure 7 to its solid line operative position, this projection 105 moves through the housing cavity 30 into engagement with the proximal end 16 of the cannula 12 which functions as a stop for the projection 105. Since the projection 105 is larger than the inside diameter of the cannula 12 in this embodiment, further axial movement of the obturator 50 is prevented. In this operative position of the obturator 50, the distal tip 104 of the shaft 103 extends beyond the distal end 14 of the cannula 12, but the handle 102 does not axially compress the elastomeric housing portion 27. In general, the projection 105 can be positioned along the shaft 102 at any location where it can engage part of the rigid housing portion 25, such as the collar 34, or the proximal end 16 of the cannula 12. A further example not according to the invention is illustrated in the perspective view of Figure 10. In this embodiment, structures similar to those previously discussed will be designated with the same reference numeral followed by the lower case letter "a". Thus in Figure 10, the trocar 10a includes a cannula 12a, having a distal end 14a and a proximal end 16a, and a valve housing 23a which partially defines a housing cavity 30a. The trocar 10a also includes the insufflation tube 45a and is illustrated in combination with a retractor 49a which is representative of various surgical instruments. Both the cannula 12a and the valve housing 23a are aligned along the axis 21a of the trocar 10a. In the example of Figure 10, the housing cavity 30a is also partially defined by an end cap 121 which is movable transverse to the axis 21a at the proximal end 16a. The end cap 121 includes access ports 123-127 which provide access for small, medium and large diameter instruments, respectively, into a working channel 41a of the trocar 10a. Reference to the exploded view of Figure 11 will show that the trocar 10a also includes a valve assembly 46a and a partition structure 130. Another feature associated with this embodiment is the modularity of construction which provides for a quick disconnect between the cannula 12a and the remainder of the trocar including the valve housing 23 and the valve assembly 46a. This quick disconnect in the illustrated embodiment takes the form of a bayonet connection including tabs 132 and associated slots 134. The concept of modularity offers several advantages to this embodiment of the invention. For example, if a different seal assembly 46a is desired for a particular trocar, that assembly with its housing 23 can be replaced without removing the cannula 12a from its operative site. This same feature permits the replacement of a valve assembly 46a which has been torn or is otherwise inoperative. The quick release separation between the housing 23 and cannula 12a also facilitates rapid and complete desufflation of the abdominal cavity. The cannula 12a of this embodiment extends from the distal end 14a to an enlarged proximal portion 136 having a proximal facing end surface 138. The valve housing 23a has a lower skirt 141 which is sized to receive the proximal portions 136 of the cannula 12a. It is this skirt 141 which defines the slots 134 of the bayonet connection. Extending in the opposite direction from the skirt 141 is a sidewall 143 which extends proximally to an end surface 145. It is the side wall 143 together with the end cap 121 which define the housing cavity 30a. Between the skirt 141 and the sidewall 143, an annular flange 147 extends inwardly providing a proximal facing surface 152 and a distal facing surface 154. An annular projection 156, which extends from the flange 147 toward the skirt 141, will be discussed in greater detail below. The partition structure 130 includes a proximal end wall 161 having a proximal surface 163. Extending downwardly in Figure 11 from the end wall 161, is a partition 165 which has a particular configuration discussed in greater detail below. The partition 165 extends to a bottom surface 167. Extending upwardly from the surface 163 of the end wall 161 are a plurality of buttons 170 which facilitate a snap fit relationship between the partition structure 130 and the end cap 121. The valve assembly 46a is similar to that previously disclosed in its inclusion of multiple valve sets each having a septum valve which is defined in an end wall 172 having a proximal surface 174. Extending downwardly in Figure 11 from the end wall 172 is a sidewall 176 and an inwardly extending shoulder 178 having a distal facing surface 181. A cylindrical annulus 183 extends axially from the shoulder 178 to a distally facing surface 187. This surface 187 is extended radially outwardly by a flange 185. The end cap 121 has a generally planar configuration defined by a wall 190 having a distally facing surface 192. Extending upwardly from the wall 190 are a plurality of cylinders 194 and 196 which aid in aligning the instruments and protecting the septum valve formed in the end wall 172 of the valve assembly 46a. Extending downwardly in Figure 11 from the end wall 190 is an annulus 198 which functions to prevent deformation of the zero closure valve. Also extending downwardly from the end wall 190 are a plurality of male components 197 which register with the female projections 170 in a snap fit relationship. These various components of Figure 11 are also illustrated in the assembled view of Figure 12. Of particular interest in this view are the relationships among the flange 185 of the valve assembly 46a, the flange 147 of the housing 23a, and the surface 138 of the cannula 12a. In this construction, the flange 185 is sandwiched between the surface 138 of the cannula 12a and the surface 154 of the flange 147. It is this combination which automatically forms a seal between the valve assembly 46a, the housing 23a and the cannula 12a. The seal is enhanced by the projection 156 on the flange 147 which increases the sealing relationship between the flange 147 and the elastomeric flange 185. The interrelationships of the various components of the trocar 10 can be best understood with reference to the assembled view of Figure 12. Initially a subassembly can be formed between the end cap 121, the valve assembly 46a and the partition structure 130. In the preferred method of assembly the partition structure 130 is inserted through the opening at the bottom of the valve assembly 46a where the partition 165 extends around the zero closure valves of the assembly. The proximal end wall 161 of the structure 130 is brought into contact with the end wall 172 of the valve assembly 46a. With the projections 170 of the structure 130 extending through concentric holes in the end wall 172. With the partition structure 130 operatively positioned within the valve assembly 46a, the end cap 121 can be moved into position over the top of the valve structure 46a. In this step, the projections 197 of the end cap 121 extend into the buttons 170 associated with the partition structure 130 preferrably in a snap fit relationship. This snap fit completes the subassembly by maintaining the end wall 190 of the end cap 121, the end wall 172 of the valve assembly 46a, and the end wall 161 of the partition structure 130 in a generally fixed relationship. The resulting top view of the subassembly is best illustrated in Figure 4. In this view, the valve sets are not shown in detail, but nevertheless are represented by their reference numerals 52a, 54a and 56a. The subassembly including the end wall 121, the valve assembly 46a, and the partition structure 130 can then be mounted in the housing 23a. This is accomplished in the preferred method by introducing the end of the subassembly including the structure 130 into the top of the housing 23a until the surface 192 of the end wall 190 on the end cap 121 is brought into contact with the proximal surface 145 of the side wall 143. Since the end wall 190 is larger in diameter than the hole at the proximal end of the housing 23a, the end cap 121 cannot pass further into the housing cavity 30a. A particularly advantageous feature biases the end cap 121 in this sliding contact relationship with the surface 145 of the housing 23. This bias is obtained by stretching or tensioning the side walls 176 of the valve assembly 46a. With the end cap 121 fixed axially in the proximal direction, the stretched configuration of the sidewalls 176 can be maintained by fixing the distal end of the valve assembly 46a axially in the distal direction with the sidewall 176 stretched therebetween. In a preferred example the distal end is fixed by fitting the outwardly extending annular flange 185 of the valve assembly 46a over the inwardly extending annular flange 147 associated with the housing 32a. In this step, the distally facing surface 181 of the valve assembly 46a is also brought into contact with the proximal facing surface 152 of the housing 23a. The interlocking relationship of the flange 147 and 185 is assisted by the projection 156 on the annular flange 147 and a similar projection on the flange 185. To further maintain the fixed relationship of the flanges 185 and 147, the cannula 12a can be introduced distally into the channel defined by the skirt 141. This brings the proximal surface 138 of the cannula 12a into abutting relationship with the distally facing surface 187 of the valve assembly 46a. It also sandwiches the elastomeric flange 185 between the surface 154 of the flange 147 and the surface 138 of the cannula 12a. This not only maintains the elastomeric flange 185 in a fixed relationship with the housing 23a and cannula 12a, but also enhances formation of seals between these adjacent elements. As previously discussed, the cannula 12a can be held in its operative position by a quick disconnect structure such as the bayonet fitting formed between the tabs 132 and slots 134. Once the trocar 10 has been assembled, the operative features of the concept become readily apparent. One of these features has to do with the floating relationship between the seal sets, such as the set 54a and 56a illustrated in Figure 13. This floating of the seal sets in order to accommodate the off-axis insertion of instruments was disclosed by Ritchart et al in U. S. Patent No. 5,209,737. In the example of Figure 13, floating of the seal sets 54a and 56a is facilitated by permitting the end cap 121 to move transverse to the axis 21a in sliding engagement with the side wall 143 of the housing 23a. While this floating movement of the end cap 121 could be accomplished in enlarged recess, as taught by Ritchart et al, the size of the housing 23a can be reduced if the end cap 121 is permitted to define the largest diameter of the trocar 10 at its proximal end. In this case, the outside diameter of the side wall 143 of the housing 23a does not exceed the diameter of the end cap 121. While the end cap 121 is permitted to float laterally or radially of the housing 23a, this float must be limited in order to protect the valve sets 54a, 56a. In the illustrated example, this protection is afforded by the annulus 98 which extends into the valve cavity 30a. As the end cap 121 moves laterally, the annulus 198 approaches the sidewall 143 and eventually reaches a point of interference where the end cap 121 cannot be further laterally displaced. Thus the annulus 198 ensures that operation of the seals 54a and 56a is not inhibited by extensive lateral movement of the end wall 121. The medium seal set 54a (including the septum valve 67a and zero closure valve 70a) and the large seal set (including the septum valve 61a and zero closure valve 63a may also benefit from additional isolation. In a typical situation, an instrument will be inserted through one of the seal sets, such as the set 54a, where the associated septum valve forms a seal with the instrument. In this particular valve set, the zero closure valve 70a will be open and non-sealing as long as the instrument is in place. The concern at this point is with the operation of the zero closure valve 63a associated with the other valve set. If the instrument is allowed to tilt or is otherwise brought into contact with the zero closure valve 63a, associated with the other valve set 56a, that valve 63a can be deformed resulting in leaking of the insufflation gas. To prevent this leakage and deformation, it is desirable to isolate the zero closure valves 63a and 70a to some extent, from each other. This is the function of the partition 165 in the structure 130. This partition 165 extends generally around each of the zero closure valves 63a and 70a associated with the valve sets 56a and 54a, respectively. When these zero closure valves 63a and 70a are formed in close proximity to each other for example with their respective axes separated by less than the sum of their radii, the partition 165 may be slightly broken immediately between the zero closure valves 63a and 70a. In this case, the partition 165 forms a continuous curtain around the valve sets 54a and 56a typically in the shape of a figure eight as best illustrated in Figure 15. From the foregoing discussion it is apparent that the trocar 10 of this invention can accommodate all sizes of instruments from the smallest instrument, such as the catheter 48, to the largest instrument, such as the obturator 50, which can pass through the associated cannula 12. Multiple septum valves 58, 67 and 61 can be formed in any transverse wall disposed interiorly of the valve housing 23 or at the end wall 38 of the elastomeric housing portion 27. These septum valves 58, 67 and 61 can be formed at different distances from the central axis 21 in the manner previously discussed. For each of the larger valve sets, for example the medium valve set 54a and large valve set 56a, a zero closure valve may be required. These valves, such as the zero closure valves 70a and 63a, can be provided in any form associated with the prior art. Double duck bill valves such as those illustrated in Figures 1-7 are particularly appropriate for this concept. However, a separate flapper valve, such as those designated by the reference numerals 107 and 109 in Figures 8 and 9 can be provided for the respective valve sets 54 and 56. In a example not belonging to the invention, the end cap 121 can be formed in sliding engagement with the housing 23a. This example is enhanced by the small size of the housing 23a which is not greater than the diameter of the end cap 121. The valve assembly 46a can be stretched to maintain the end cap 121 in sliding engagement with the housing 23a. The annulus 98 can be formed to uniformly limit the lateral displacement of the end cap 121 relative to the housing 23a. The partition 165 further protects the zero closure valves 63a and 70a from interference due to operation of an adjacent valve set. The modular concept permits the cannula 12a to be separated from the housing 23a while at the same time providing a quick disconnect fitting which will function to enhance the seal between the valve assembly 46a and the housing 23a. Given these wide variations, which are all within the scope of this concept, one is cautioned not to restrict the invention to the embodiments which have been specifically disclosed and illustrated, but rather encouraged to determine the scope of the invention only with reference to the following claims.

Claims: A trocar assembly (10) including: a cannula (12) having an axis extending between a proximal end (16) and a distal end (14) of the cannula; a rigid housing portion (25) having a distal end and a proximal end, the distal end of the rigid housing portion having a fixed relationship with the cannula; an elastomeric housing portion (27) coupled to the proximal end of the rigid housing portion, the elastomeric housing portion being axially compressible; the rigid housing portion and the elastomeric housing portion forming a valve housing (23) and defining with the cannula a working channel of the trocar; an obturator (50) sized and configured for removable insertion through the working channel via the valve housing (23); a shaft (103) included in the obturator and having an axis extending from a proximal end to a distal tip (104), the shaft being sized and configured for removable insertion into the cannula to an operative position wherein the distal tip of the shaft extends beyond the distal end of the cannula; a handle (102) of the obturator attached in a fixed relationship to the proximal end of the shaft characterised in that the obturator (50) comprises means (105) located part way along the shaft of the obturator between the proximal end of the shaft and the distal end of the shaft for engaging at least one of the cannula and the rigid housing portion in order to prevent insertion of the obturator into the cannula beyond the operative position of the obturator, said engaging means (105) being arranged for insertion with the shaft of the obturator (50) through the elastomeric housing portion (27), and said engaging means (105) being larger than the inside diameter of the cannula (12). The trocar assembly recited in Claim 1, wherein the engaging means includes: a projection disposed in a fixed relationship with the shaft of the obturator distally of the valve housing and proximally of the shaft distal tip, the projection extending laterally of the shaft a distance sufficient to prevent the projection and the shaft from extending beyond the operative position. The trocar assembly recited in Claim 2, further comprising: a shoulder (34) defined by one of the valve housing and the cannula at the proximal end of the cannula; the shoulder being exposed within the working channel; and forming a stop which engages the projection of the obturator to prevent distal movement of the obturator beyond the operative position. The trocar assembly recited in Claim 1, 2 or 3, including a first valve and a second valve, the first valve and the second valve being integral with the elastomeric housing portion. The trocar assembly recited in Claim 4, wherein: the axis of the cannula is a first axis; the first valve has a second axis; the second valve has a third axis; and at least one of the second axis of the first valve and the third axis of the second valve is offset from the first axis of the cannula. The trocar assembly as claimed in any preceding claim, wherein the cannula (5) is rigid. The trocar assembly of any preceding claim, wherein the distal tip (104) is sharp.

Inventors: HART CHARLES C, TANGHERLINI VINCENT C, HART, CHARLES C., TANGHERLINI, VINCENT C.
Applicants: APPLIED MED RESOURCES, APPLIED MEDICAL RESOURCES CORPORATION
Application year: 1995
Main classification: A61B17
IPC codes: A61B17