EXPANDABLE CANNULA
Cannulas for surgical and medical use expand along their lengths. The cannulas are inserted through tissue when in an unexpanded condition and with a small diameter. The cannulas are then expanded radially outwardly to give a full-size instrument passage. Expansion of the cannulas occurs against the viscoelastic resistance of the surrounding tissue. The expandable cannulas do not require a full depth incision, or at most require only a needle-size entrance opening. In one embodiment of the invention, the cannula includes a number of arcuate plate segments movable with respect to each other for enabling an increase in cross-sectional area of the cannula lumen. In this embodiment, the cannula can be provided with a pointed end portion. The cannula may be expanded by inserting members or by fluid pressure. The cannula is advantageously utilized to expand a vessel, such as a blood vessel. An expandable chamber may be provided at the distal end of the cannula.
This application is a continuation of U.S. patent application Ser. No. 10/242,205, filed Sep. 12, 2002, which in turn is a continuation of U.S. patent application Ser. No. 09/992,211, filed Nov. 16, 2001, which in turn is a continuation of U.S. patent application Ser. No. 08/470,142, filed Jun. 6, 1995, now U.S. Pat. No. 6,338,730 B1. The aforementioned application Ser. No. 08/470,142 is itself a continuation-in-part of U.S. patent application Ser. No. 08/254,368, filed Jun. 6, 1994, now U.S. Pat. No. 5,573,517. The aforementioned application Ser. No. 08/254,368 is a divisional of U.S. patent application Ser. No. 08/013,942, filed Feb. 4, 1993, now U.S. Pat. No. 5,320,611.
BACKGROUND OF THE INVENTIONThe present invention relates to cannulas for surgical and medical use. A typical cannula is a fixed diameter tube which a surgeon uses to maintain an instrument passage through tissue to a subcutaneous working location. The surgeon must first make an incision the full depth of the cannula in order to insert the cannula. This traumatic action damages good tissue in order to get to bad tissue. It would be desirable to provide cannulas which do not require a full depth incision, or at least require only a needle-size entrance opening, and which still allow use of a cannula to maintain an instrument passage.
SUMMARY OF THE INVENTIONIn accordance with one of the features of the invention, cannulas are provided which expand along their length. The cannulas are inserted through tissue when in an unexpanded condition and with a small diameter. The cannulas are then expanded radially outwardly to give a full-size instrument passage. Expansion of the cannulas occurs against the viscoelastic resistance of the surrounding tissue. The cannulas may be expanded by inserting members into the cannulas or by fluid pressure.
In accordance with another feature of the invention, a leading end portion of the cannula is constructed to pierce human body tissue. This enables the cannula to form its own opening in body tissue as the cannula is inserted into the tissue.
In accordance with still another feature of the invention, the cannula can be inserted into a blood vessel and expanded. A flow of fluid can be conducted through the cannula into the blood vessel.
The cannula advantageously includes a sheath which encloses a plurality of wires. A member may be inserted into the sheath and moved along the wires to expand the cannula. Each of the wires may advantageously include a core which is at least partially enclosed by a jacket which is integrally formed as one piece with the sheath. If desired, the cannula may be expanded by fluid pressure rather than inserting a member into the cannula.
BRIEF DESCRIPTION OF THE DRAWINGSThe foregoing and other features of the present invention will become apparent to one skilled in the art to which the present invention relates upon consideration of the following description of the invention with reference to the accompanying drawings, wherein:
FIG, 10 illustrates the cannula of
In a first embodiment of the invention, a cannula 10 (
The wires 16 are preferably made of a material which is flexible, does not break, and does not stretch. A preferred material is music wire, which is thin gauge steel about 0.015″ in diameter. The use of the term “wire” in this application and its claims does not limit the invention to metal wires. The “wires” may also be made of other elongate material such as composites or plastics or other metals. The “wires” may also be coated.
The number of wires may be selected as desired. Applicants have found that 8 to 10 wires will suffice for a cannula expandable up to 7 mm OD, and that 12 wires or more may be necessary for a larger cannula. Ten larger diameter wires (0.025″) may be used rather a larger number of small diameter wires. A greater number of wires 16 can be used if a greater diameter is needed. If not enough wires 16 are used, an instrument (trocar, insert, scope, etc.) inserted through the passage 20 when the cannula 10 is expanded will contact the elastic sheath 18 rather than the wires 16, at locations between the wires.
The wires 16 are self-aligning. When the cannula 10 is in a contracted condition, the wires 16 may overlap. When the cannula 10 is expanded, the wires 16 straighten out as shown.
The elastic sheath 18 is preferably secured to the wires 16 at both proximal and distal ends, to prevent the sheath from sliding off the wires during insertion and removal of the cannula 10. Rubber cement or cyanoacrylate or a similar adhesive can be used to bond the sheath 18 to the wires 16 as shown schematically at 24.
The elastic sheath 18 is preferably made of latex or silicone, or of C-Flex®, a general purpose thermoplastic elastomer sold by Linvatec Corporation of Clearwater, Fla. The sheath 18 is of a diameter such that it is stressed even when the cannula 10 is fully contracted. Thus, the sheath 18 constantly biases the wires 16 radially inwardly toward the axis 22 of the cannula 10.
At the proximal end portion 14 of the cannula 10, the wires 16 are clamped between an inner ring member 30 and an outer ring member 32. The inner ring member 30 has a central opening 34. The inner ring member 30 has a clamping surface 36 including a beveled edge 38 and an annular radially extending surface 40. The outer ring member 32 has a threaded central opening 42 for receiving a standard luer lock 43. The outer ring member 32 has a clamping surface 44 including a beveled edge 46 and an annular radially extending surface 48.
The ring members 30 and 32 can be made of metal, in which case they can be brazed or welded together. The ring members 30 and 32 can be made of plastic, in which case then they can be UV joined or joined by adhesive.
Proximal end portions 50 of the wires 16 are trapped between the ring members 30 and 32. When the ring members 30 and 32 are joined together as in
The sheath 18 has a longitudinally extending circumferential outer surface 54 (
In use of the cannula 10, the surgeon makes a small incision in the epidermis. He inserts a narrow trocar such as the trocar 70 (
The end portion 72 of the trocar 70 may be blunt in order to push away internal tissue. In this case, a small incision would need to be made through the epidermis.
The trocar/cannula assembly is inserted through the incision in the epidermis to the subcutaneous working location. Then, a tubular insert 80 (
Because the insert 80 is larger in diameter than the trocar 70, during insertion of the insert 80, the cannula 10 is expanded radially outwardly, as seen in a comparison of
After the tissue is allowed to relax, the surgeon removes the insert 80. The cannula 10 collapses radially inwardly because of the elastic sheath and because of the force of the tissue around it. But the tissue opening does not necessarily collapse completely, because of the viscoelastic nature of tissue, which tends to maintain its stretched condition for some time.
The surgeon then puts a second insert inside the cannula 10. The second insert is a hollow tube larger in diameter than the first insert 80. Again, the cannula expands radially outwardly, and the tissue stretches.
In this manner, the surgeon continues with larger and larger inserts, until the tissue opening is as large as desired. The cannula may then be in the expanded condition shown in
Items inserted through the central passage 20 of the cannula 10 always contact the inner cylindrical surface 92 of the insert 90. This provides a non-wearing, slippery engagement, which is desirable for insertion and removal of the instruments. An example is illustrated in
Items inserted through the central passage 20 of the cannula 10, such as the inserts 80 and 90, always contact the radially inner surfaces 60 of the wires 16. This also provides a non-wearing, slippery engagement, which is desirable for insertion and removal of the inserts.
The cannula 10 is discarded after use to prevent contamination.
Thus, it is seen that the wires 16 have outer surface portions 60 disposed radially inwardly in the cannula 10 and forming contact surfaces for surgical instruments and the like inserted through the central instrument passage 20 of the cannula. The sheath 18 has an outer circumferential surface 54 engaging tissue when the cannula 10 is in use. The wires 16 block engagement of instruments inserted through the central instrument passage 20 of the cannula 16 with the elastic sheath 18. The sheath 18 blocks engagement of tissue with the wires 16, and the sheath and the wires block engagement of tissue with any instruments inserted through the cannula 10.
The cannula 10 expands radially outwardly along substantially its entire length against the bias of the sheath 18. Thus, the cannula 10 can accommodate through its central instrument passage 20 a surgical instrument or the like having a diameter along its entire length which is greater than the diameter of the cannula in the contracted condition. This is not possible with cannulas which expand only along a portion of their length.
A second embodiment of the invention is illustrated in
Specifically, the member 102 includes a longitudinally extending arcuate segment 110 and a widened proximal end portion 112. The member 104 includes a longitudinally extending arcuate segment 114 and a widened proximal end portion 116. The member 106 includes a longitudinally extending arcuate segment 118 and a widened proximal end portion 120. The member 108 includes a longitudinally extending arcuate segment 122 and a widened proximal end portion 124.
The members 102,104, 106, and 108 each subtend an angle of 90°. When the members 102, 104, 106, and 108 are placed together, their longitudinally extending arcuate segments 110, 114, 118, and 122 form a tubular expandable cannula structure 130.
The distal ends 132 of the members 102, 104, 106, and 108 are tapered inwardly for ease of entrance through tissue. The widened proximal end portions 112, 116, 120, and 124 together form a handle for the cannula 100 which also allows entry of an instrument therethrough. The end portions have angled inner surfaces 134 to guide an instrument into the longitudinally extending central instrument passage 136 of the cannula 100 in the direction indicated by the arrow 138. The handle (proximal end) portion of the cannula 100 can be configured to attach instruments to it, or to have a cap screwed onto the end to close the cannula.
The arcuate segments 110, 114, 118, and 122 are surrounded for most of their length by an overlying elastic sheath 140. The elastic sheath 140 is secured to the segments 110, 114, 118, and 122 at proximal and distal locations 142 and 144, to prevent the sheath from sliding off the segments during insertion and removal of the cannula 100. Rubber cement or cyanoacrylate or a similar adhesive can be used to bond the sheath 140 to the segments. The elastic sheath 140 is preferably made of latex or silicone, or of the C-Flex® material described above. The sheath 140 is of a diameter such that it is stressed even when the cannula 100 is fully contracted. Thus, the sheath 140 constantly biases the segments radially inwardly toward the center of the cannula 100.
One cannula that has been constructed is 90 mm in length, and about 5 mm in diameter when aligned in a tube form as shown in
In use of the cannula 100, the surgeon makes a small incision in the epidermis. He inserts a narrow trocar such as the trocar 70 (
A trocar should be used with the cannula 100 only when needed. The distal end portion of the cannula 100 is preferably used alone to push through internal tissue once an epidermal incision has been made.
The trocar/cannula assembly is inserted through the incision in the epidermis to the subcutaneous working location. Then, a tubular insert 80 (
As the insert 80 is inserted in the cannula 100, the outer surface of the insert engages longitudinally extending radially inner edges 148 of the members 102, 104, 106, and 108. Because the insert 80 is larger in diameter than the trocar 70, during insertion of the insert, the cannula 100 is expanded radially outwardly, as seen in a comparison of
After the tissue is allowed to relax, the surgeon removes the insert 80. The cannula 100 collapses radially inwardly because of the elastic sheath and because of the force of the tissue around it. But the tissue opening does not necessarily collapse completely, because the tissue is viscoelastic.
The surgeon then puts a second insert 90 (
The cannula 100 expands radially outwardly along substantially its entire length against the bias of the sheath 130. Thus, the cannula 100 can accommodate through its central instrument passage 136 a surgical instrument or the like having a diameter along its entire length which is greater than the diameter of the cannula in the contracted condition. This is not possible with cannulas which expand only along a portion of their length.
It is contemplated that one would use two different size cannulas 100 to obtain a desired range of expansion. A first, smaller size, would extend from an OD of 2.5 mm to an ID of 7 mm, being about 70 mm in length. A second, larger size, would extend from an OD of 6 mm to an ID of 12 mm, being about 150 mm in length.
The expandable cannulas of the present invention may be designed to selectively expand at a location at or near the distal end. This is illustrated in
The inner sheath member 306 is of a double-walled construction, including an inner wall 310 and an outer wall 312. An inflation volume 314 separates the inner wall 310 and the outer wall 312. Fluid under pressure such as air, saline, etc. may be introduced into the inflation volume 314 through a fluid port 316. The inner sheath member 306 overlies the wires 302.
When fluid under pressure is introduced into the inflation volume 314 through the fluid port 316, the outer wall 312 of the inner sheath member 306 expands radially outwardly, as shown in
The notch 320, or any similar opening in the outer sheath member 308, may be placed at or near the distal end of the cannula 300. This will stabilize the cannula 300 in the tissue, at the closest possible location to the work area off the distal end of the cannula.
In the embodiment of the invention illustrated in
The cannula 400 (
In accordance with one of the features of the embodiment of the invention illustrated in
The jacket 412 around the core 410 of each of the wires 404 is integrally formed as one piece with the sheath 402. Thus, each of the jackets 412 is formed of the same elastic material as the sheath 402. The elastic polymeric material of the sheath and the jackets 412 may be molded or extruded around the cores 410 during formation of the cannula 400.
Each of the jackets 412 has a longitudinal central axis which extends parallel to a longitudinal central axis 418 of the cannula 400. The jackets 412 extend throughout the entire length of the sheath 402. Since the jackets 412 are integrally formed as one piece with the sheath 402, the wires 404 are maintained in a parallel relationship with the longitudinal central axis 418 of the cannula 400. The parallel wires 404 extend from the opening 416 at the distal end of the sheath 402 to the location where the proximal end of the sheath is clamped between ring members in a manner similar to that illustrated in
Central cores 410 of the wires 404 may be formed of any desired material. In the embodiment of the invention illustrated in
In the illustrated embodiment of the invention, the parallel cores 410 of the wires 404 have a cylindrical configuration. Thus, each of the cores 410 has a circular cross sectional configuration as viewed in a plane extending perpendicular to a longitudinal central axis of the core. In the embodiment of the invention illustrated in
The surface portions of the cores 410 which do not engage the sheath 402 are enclosed by the jackets 412. Since the jackets 412 are integrally formed as one piece with the sheath 402, there is no precise line of demarcation between the jackets and the sheath. However, the jackets 412 extend inward from the sheath 402 toward the central axis 418 of the cannula 400 and cooperate with the sheath to enclose each of the cores 410. If desired, the jackets 412 could extend completely around the cores 410.
Circular axial end faces 424 of the cores 410 are exposed at opposite ends of the sheath 402. Thus, at the distal end of the cannula 400, the circular end faces 424 (
The cannula 400 is expandable throughout its length from a contracted condition (
As the tubular member 430 is axially moved into the cannula 400 from the proximal end portion (not shown) of the cannula to the distal end portion, the wires 404 are forced radially outward away from the longitudinal central axis 418 of the cannula. Thus, the cylindrical outer side surface 432 of the member 430 applies radially outward force against the wires 404. This radially outward force is transmitted through the wires 404 to the sheath 402. As this occurs, the elastic material of the sheath 402 is resiliently stretched and the distance between the wires 404 increases.
There is minimal resistance to axial sliding movement of the tubular member 430 into the cannula 400. This is because the tubular member 430 is engaged by only the jackets 412 on the wires 404 along very thin linear areas. The outer side surface 432 of the tubular member 430 is maintained in a spaced apart relationship with the inner side surface of the sheath 402 by the wires 404. Once the tubular member 430 has been inserted into the cannula 400, the sheath 402 presses the jackets 412 on the wires 404 against the outer side surface 432 of the tubular member 430. The first tubular member 430 has a length which is greater than the length of the sheath 402 and extends axially outward from opposite ends of the sheath.
If the central passage through the tubular member 430 has sufficient cross sectional area, the cannula 400 may be used with the tubular member 430 holding the cannula in an expanded condition. However, it is believed that it may be desirable to further expand the cannula 400. Therefore, a second cylindrical tubular member 436 is inserted into the cannula 400 through the proximal end of the cannula to further expand the cannula. The second tubular member 436 has an inside diameter which is larger than the outside diameter of the first cylindrical tubular member 430.
As the second tubular member 436 is inserted into the proximal end of the cannula 400, a cylindrical outer side surface 438 on the second tubular member 436 slides along the wires 404. The second tubular member 436 forces the wires 404 radially outward away from the cylindrical outer side surface 432 of the first tubular member 430. As this occurs, the elastic material of the sheath 402 is further resiliently stretched by the force applied against the wires 404 by the tubular member 436.
As the resilient material of the cylindrical sheath 402 is circumferentially stretched, the distance between the parallel wires 404 increases. Sliding of the tubular member 436 from the proximal end to the distal end of the cannula 400 is relatively easy since the tubular member slides along the jackets 412 on the wires 404 and does not engage the inner side surface of the sheath 402. The second cylindrical tubular member 436 extends axially outward from opposite ends of the sheath 402.
Once the second cylindrical tubular member 436 has been telescopically inserted into the cannula 400 around the first or inner tubular member 430, the first tubular member can be axially withdrawn from the cannula 400. This results in the cylindrical central passage 406 through the cannula 400 having a diameter equal to the inside diameter of the relatively large second tubular member 436.
If desired, a still larger tubular member may be telescopically inserted into the cannula 400 around the second tubular member 436 to further expand the cannula and increase the size of the central passage 436 through the cannula. It is possible to expand the cannula 400 to any one of many different sizes depending upon the size of the tubular member which is used to apply force against the wires 404 and resiliently stretch the sheath 402 of the cannula. It is believed that it will be preferred to have the extent of expansion of the sheath 402 be less than the elastic limit of the material forming the sheath.
Since the elastic limit of the material forming the sheath 402 is not exceeded by expanding the cannula 400 by insertion of the members 430 and 436, when the members are withdrawn from the cannula, the sheath will resiliently contract back to the original size shown in
In accordance with one of the features of this embodiment of the invention, the cannula 400 has a pointed distal end portion 442 (
The ends of the wires 404 and the end of the sheath 402 cooperate to provide the cannula 400 with an end portion 442 which can cut body tissue when the end portion of the cannula is pressed against the body tissue. The sheath 402 may advantageously be cut away adjacent to an apex 446 of the pointed end portion 442. Thus, a beveled surface 448 is formed in the material of the sheath 402 adjacent to the apex 446 of the pointed end portion 442. The beveled surface 448 makes the pointed end portion 442 of the cannula sharper to facilitate severing the body tissue. The beveled surface 448 extends outward to a leading end of a wire 404 which extends through the central part of the apex 446 of the pointed end portion 442 of the cannula 400.
In the illustrated embodiment of the invention, the cylindrical cores 410 of the parallel wires 404 are formed by thin gauge steel wire. The leading end of the core 410 of the wire 404 extends through the apex 446 of the pointed end portion 442 of the cannula 400. The leading end of the core 410 of the wire 404 through the apex 446 provides a relatively sharp cutting edge at the axially outer end of the cannula 400. This sharp cutting edge can readily penetrate relatively tough body tissue.
When the pointed end portion 442 of the contracted cannula 400 is pressed against an imperforate surface area on body tissue, force is transmitted axially through the wires 404 and through the sheath 402 to the body tissue. The apex 446 of the pointed end portion penetrates the body tissue and initiates the formation of an opening in the body tissue. The initiating of the opening in the body tissue is facilitated by having the exposed relatively sharp end of the core 410 of the wire 404 which extends through the apex 446 of the pointed end portion 442 of the contracted cannula 400 engage the body tissue to initially cut the imperforate surface area of the body tissue. The leading edge portions of the sheath disposed adjacent to opposite sides of the wire 404 through the apex 446 of the cannula 400 are then effective to sever body tissue to increase the size of the opening in the body tissue.
As the contracted cannula 400 is further inserted into the body tissue, the leading end portions of additional wires 404 and leading edges of segments of the sheath 402 disposed between the wires sever the body tissue to increase the size of the opening. Thus, the sheath 402 and ends of the wires 404 cooperate to form an opening in the body tissue at a location where there was no natural opening. The size of the opening formed in the body tissue by the pointed end portion 442 of the cannula 400 increases until the opening is large enough to accept the cylindrical outer side surface of the cannula when it is in the contracted condition of
Once the contracted cannula 400 has been inserted for a desired distance into the body tissue, the cannula is expanded from the contracted condition of
It is contemplated that the cannula 400 will have many different uses, including the establishment of communication with the interior of many different types of vessels in a human body. For example, the cannula could be used to establish communication with the interior of a vessel such as a lung, heart, endolymphatic duct or sac, a hernial sac, or a bladder. It is also contemplated that the cannula 400 will be used as a passage through body tissue for many different types of instruments and/or fluids. For example, the cannula 400 may be used to facilitate laproscopic or arthroscopic surgery. However, it is believed that the cannula 400 will be particularly advantageous in establishing communication with the interior of a blood vessel.
The cannula 400 can be used to establish communication with the interior of a blood vessel in a human body for an intravenous infusion. When this is to be done, the pointed end portion 442 of the cannula 400 is used to pierce an imperforate surface area on the skin 454 (
When the cannula 400 is to be inserted into the blood vessel 458 for an intravenous infusion or other purpose, the apex 446 of the pointed end portion 442 of the contracted cannula 400 is first pressed against an outer side surface 464 of the skin 454 (
As the axially tapered pointed end portion 442 of the contracted cannula 400 pierces the skin 454, the size of the opening in the skin is increased. A cylindrical outer side surface 468 of the sheath 402 (
After the cannula 400 has pierced the skin 454, the cannula is pressed toward the blood vessel 448 and pierces the body tissue 460 (
The axial force transmitted through the contracted cannula 400 causes the axially tapered leading end of the core 410 of the wire 404 which extends through the apex 446 (
Although the cannula 400 is shown in
Once the contracted cannula 400 has been inserted into the blood vessel 458, the cannula is moved axially along the blood vessel (
Since the cannula 400 is in the contracted condition of
When a relatively large passage 406 is required through the cannula 400 to communicate with the interior of the blood vessel 458, the cannula 400 is expanded from the contracted condition of FIG, 22 to the expanded condition of
As the cannula 400 is expanded, the outer side surface 468 of the cannula is pressed against edge portions of the opening 476 to increase the size of the opening. In addition, the outer side surface 468 of the cannula 400 is pressed against the edge portions of the opening in the skin 454 to increase the size of the opening in the skin. Of course, the outer side surface 468 of the cannula 400 also applies force against the inner side surface of the blood vessel 458 to expand the blood vessel.
The tubular member 436 (
Due to the viscoelastic characteristics of the side wall 456 of the blood vessel 458, the diameter of the blood vessel can be substantially increased by expanding the cannula 400 from the contracted condition of
In the embodiment of the invention illustrated in
In the embodiment of the invention illustrated in
At an apex 446b of the pointed end portion 442b, a core 410b of one of the wires 404b extends past the beveled outer edge surface 448b of the sheath 402b. Thus, an end portion 482 of the core 410b of the wire 404b extends past the opening 416b to the central passage 406b through the cannula 400b. The outwardly projecting core 410b has a pointed end portion 484 which projects axially outwardly from the sheath 402b.
When the contracted cannula 400b is to be used to form an opening in skin 454b, the pointed end portion 484 of the wire core 410b engages the outer side surface 464b of the skin before the sheath 402b engages the skin. This results in the sharp outer end portion 484 of the core 410b piercing the outer side surface 464b of the skin 454b before the skin is engaged by the sheath 402b. By piercing the outer side surface 464b of the skin 454b with the pointed end portion 484 of the core 410b, the forming of an opening in the skin by the contracted cannula 400b is facilitated.
In the embodiment of the invention illustrated in
In addition, in the embodiment of the invention illustrated in
The cannula 400c is inserted into a blood vessel 458c in the manner illustrated in
In accordance with one of the features of the embodiment of the 1invention illustrated in
When the cannula 400c is inserted into a blood vessel 458c (
By aligning the major axis of the oval cross section of the cannula 400c with the longitudinal central axis of the blood vessel 458c, the major axis of the opening formed in the blood vessel 458c extends longitudinally along the side wall 456c of the blood vessel (
It should be understood that when the cannula 400c pierces the side wall 456c of the blood vessel 458c, the cannula is in a contracted condition in which it has a substantially smaller cross sectional configuration than is illustrated in
In accordance with another feature of the present invention, the cannula 400c is expanded throughout its length under the influence of fluid pressure. A pump 490 is connected with the central passage 406c in the cannula 400c through a valve 492 and a conduit 494. Relatively high pressure fluid is discharged from the pump 490 through the valve 492 and conduit 494 into the central passage 406c in the contracted cannula 400c. This fluid pressure is applied against an inner side surface of the sheath 402c and the wires 404c.
The fluid pressure inside the cannula 400c is effective to cause the elastic material of the sheath 402c to expand from a contracted condition to an expanded condition. As this occurs the size of the opening formed in the viscoelastic material of the blood vessel 458c is enlarged. In addition, the outer side surface of the cannula 400c presses against the inner side surface of the side wall 456c to expand the blood vessel 458c downstream from the location where the cannula enters the blood vessel.
The fluid from the pump 490 forms an intravenous infusion of a liquid solution to the blood vessel 458c. Of course, if the cannula 400c is to be used to provide access for surgical tools and/or optical instruments to the interior of the blood vessel 458c or with a part of the body connected with the blood vessel, the cannula 400c could be expanded by using tubular members having an oval cross sectional configuration in the manner described in conjunction with
In the embodiment of the invention illustrated in
In the embodiment of the invention illustrated in
In the embodiment of the invention illustrated in
Each of the wires 404d includes a core 410d and a jacket 412d which extends around the core 410d. Each of the jackets 412d is integrally formed as one piece with the sheath 402d. Each of the jackets 412d extends between opposite ends of the sheath 402d.
In accordance with a feature of the embodiment of the invention illustrated in
When the cannula 404d is to pierce body tissue, the pointed apex 446d of the end portion 442d of the cannula engages the body tissue. In the embodiment of the invention illustrated in
When the cannula 400d is to be inserted into body tissue, the pointed end of the sheath 402d initiates the formation of the opening in the body tissue. The wires 404d stiffen the elastic material of the sheath 402d to enable force to be transmitted through the cannula 400d to the axially outer end of the sheath.
In the embodiment of the invention illustrated in
In the embodiment of the invention illustrated in
Each of the wires 404e includes a core 410e and a jacket 412e (
When the contracted cannula 400e is to be used for form an opening in body tissue, the pointed end portion 442e (
As the contracted cannula 400e is further inserted into the body tissue, the leading end portions of additional wires 404e and leading edges of segments of the sheath 402e disposed between the wires sever the body tissue to increase the size of the opening. The size of the opening is increased until it is large enough to accept the cylindrical outer side surface 468e of the cannula 400e when the cannula is in the contracted condition.
Once the cannula 400e has been inserted for a desired distance into the body tissue, the cannula is expanded by inserting a tubular cylindrical member 430e (
In accordance with a feature of this embodiment of the invention, once the cannula 400e has been positioned in body tissue, a portion 600 of the pointed end portion 442e of the cannula is expandable outward of an outer side surface 468e of the sheath 402e. Thus, the portion 600 is expandable from the configuration shown in solid lines in
When the pointed end portion 442e of the cannula 400e is inserted into body tissue, for example, into a vein, both the cannula sheath 402e and the portion 600 of the cannula are contracted. When the cannula 400e has been inserted a desired distance into the vein, the cannula sheath 402e is expanded by either fluid pressure or by insertion of the tubular member 430e. The portion 600 of the cannula 400e is then expanded radially outward from the cylindrical sheath 402e to grip the inner side surface of the vein. It is contemplated that in certain circumstances it may not be necessary to expand the sheath 402e and the portion 600 will be expanded while the sheath is contracted.
The portion 600 of the cannula 400e includes a resilient panel 604 (
The panel 604 cooperates with the sheath 402e to form a variable volume chamber 610 in the side wall of the sheath. The panel 604 is formed of a polymeric material having a substantially greater elasticity than the material of the sheath 402e. The elasticity of the material of the panel 604 enables the panel to be resiliently expanded from the position shown in solid lines in
The chamber 610 is connected in fluid communication, through an opening 612 in the sheath 402e with a conduit 614. The conduit 614 has a side wall 616 which is integrally formed with the sheath 402e. The side wall 616 of the conduit 614 and the sheath 402e cooperate to form a cylindrical passage 620 which extends between opposite ends of the sheath 402e. An axially outer or distal end portion of the conduit 620 is blocked by a pointed segment 622 of a metal core 410e (
The passage 620 extends to the opposite or proximal end of the cannula 400e. The proximal end of the passage 620 is connected with a pump 626 (
Once the sheath 402e of the cannula 400e has been expanded (
In the embodiment of the invention illustrated in
This results in the conduit 614 being disposed in the longitudinal array of wires 404e and having the same size as one of the wires. When the tubular member 430e (
During construction of the cannula 400e, the recess 606 is formed in the side wall of the sheath 402e. After the opening 612 between the passage 620 and the recess 606 in the sheath 402e has been formed, the panel 604 is electron beam welded or otherwise secured to the sheath.
While various descriptions of the present invention are described above, it should be understood that the various features can be used singly or in any combination thereof. Therefore, this invention is not to be limited to only the specifically preferred embodiments depicted herein.
Further, it should be understood that variations and modifications within the spirit and scope of the invention may occur to those skilled in the art to which the invention pertains. Accordingly, all expedient modifications readily attainable by one versed in the art from the disclosure set forth herein that are within the scope and spirit of the present invention are to be included as further embodiments of the present invention. The scope of the present invention is accordingly defined as set forth in the appended claims.
Claims
1. A method of accessing an interior portion of a body of a patient, comprising
- inserting an expandable cannula into the body of the patient, the expandable cannula including a tubular sheath defining a passage extending between axially opposite end portions of the tubular sheath;
- expanding the tubular sheath and passage from a first position having a first cross sectional area to a second position having a second cross sectional area, wherein the second cross sectional area is greater than the first cross sectional area; and
- inserting a medical device through the passage into the interior portion of the body of the patient.
2. The method of claim 1, wherein inserting an expandable cannula into the body of the patient comprises:
- piercing the body of the patient with a distal end of the tubular sheath; and
- inserting at least a portion of the tubular sheath through the piercing.
3. The method of claim 2, wherein piercing the body of the patient with a distal end of the tubular sheath comprises:
- inserting a trocar through the passage such that a sharpened tip of the trocar extends past the distal end of the tubular sheath; and
- piercing the body of the patient with the sharpened tip of the trocar; and
- removing the trocar from the expandable cannula.
4. The method of claim 2, wherein the distal end portion of the tubular sheath comprises a pointed end portion when the tubular sheath is in the first position.
5. The method of claim 1, wherein inserting an expandable cannula into the body of the patient comprises:
- making an incision in the body of the patient; and
- inserting at least a portion of the tubular sheath through the incision.
6. The method of claim 1, wherein the first cross sectional area is a first oval cross sectional area.
7. The method of claim 1, wherein the second cross sectional area is a second oval cross sectional area.
8. The method of claim 1, wherein expanding the tubular sheath and passage from a first position having a first cross sectional area to a second position having a second cross sectional area, comprises:
- inserting a first longitudinal expansion member into the passage, the first longitudinal expansion member having a cross sectional area greater than the first cross sectional area, such that the passage expands from the first cross sectional area to the second cross sectional area.
9. The method of claim 1, further comprising expanding the tubular sheath and passage from the second position to a third position having a third cross sectional area, wherein the third cross sectional area is greater than the second cross sectional area.
10. The method of claim 9, wherein expanding the tubular sheath and passage from a first position having a first cross sectional area to a second position having a second cross sectional area, comprises inserting a first longitudinal expansion member into the passage, the first longitudinal expansion member having a cross sectional area greater than the first cross sectional area, such that the passage expands from the first cross sectional area to the second cross sectional area.
11. The method of claim 10, wherein expanding the tubular sheath and passage from the second position to a third position having a third cross sectional area, comprises:
- inserting a second longitudinal expansion member into the passage, the second longitudinal expansion member having a third cross sectional area greater than the second cross sectional area, such that the passage expands from the second cross sectional area to the third cross sectional area; and
- removing the first longitudinal expansion member.
12. The method of claim 11, wherein removing the first longitudinal expansion member comprises:
- removing the first longitudinal expansion member prior to inserting the second longitudinal expansion member, such that the passage radially contracts.
13. The method of claim 12, further comprising allowing tissue surrounding the tubular sheath to relax prior to removing the first longitudinal expansion member.
14. The method of claim 1, further comprising removing the tubular sheath.
15. The method of claim 1, wherein the tubular sheath is resiliently expandable.
16. The method of claim 1, wherein the medical device has a cross sectional area greater than the first cross sectional area of the passage in the first position.
17. A method of accessing an interior portion of a body of a patient, comprising:
- piercing the body of the patient with a distal end portion of an expandable cannula, the expandable cannula including a tubular sheath defining a passage extending between a proximal end portion and the distal end portion of the tubular sheath;
- inserting at least a portion of the tubular sheath through the piercing; and
- expanding the tubular sheath and passage from a first position having a first cross sectional area to a second position having a second cross sectional area greater than the first cross sectional area, wherein the distal end portion of the tubular sheath includes a pointed end portion when the tubular sheath in is the first position.
18. A method of accessing an interior portion of a body of a patient, comprising:
- inserting an expandable cannula into the body of the patient, the expandable cannula including a tubular sheath defining a passage extending between axially opposite end portions of the tubular sheath; and
- expanding the tubular sheath and passage from a first position having a first oval cross sectional area to a second position having a second oval cross sectional area, wherein the second oval cross sectional area is greater than the first oval cross sectional area.
Type: Application
Filed: Oct 31, 2007
Publication Date: Feb 28, 2008
Inventors: Peter Bonutti (Effingham, IL), James Hawkins (Houston, TX)
Application Number: 11/930,332
International Classification: A61M 25/04 (20060101);