High flow-low pressure irrigation system

[0001] This application claims benefit to U.S. Provisional Application Ser. No. 60/329,139 filed Oct. 12, 2001.

[0002] 1. Field of the Invention

[0003] The present invention generally relates to renal cooling systems and, more particularly, to a high-flow low-pressure irrigation system for use in minimally invasive surgery.

[0004] 2. Description of Related Art

[0005] Complex renal surgery frequently requires transient interruption of the renal vasculature. Renal hypothermia is known in the field to protect the kidney from ischemia-induced nephron loss and to preserve renal function during partial nephrectomy, renovascular surgery and kidney transplantation. Renal hypothermia is achieved by clamping the renal artery and packing the kidney in ice or slush. Although this practice provides sufficient cooling of the kidney, it presents many drawbacks such as exposing the surrounding structures to the cooling effects of the ice or slush and obscuring the surgical field of view by the ice or slush. Moreover, the practice of packing the kidney in ice or slush is not feasible for minimally invasive or laparoscopic surgery.

[0006] With growing interest in laparoscopic surgery, the inability to achieve renal hypothermia during laparoscopic surgery has become a significant problem. Accordingly, there is a need in the art for a renal cooling system for use during minimally invasive surgery and, in particular, a high-flow low-pressure irrigation system.

[0007] The present invention is directed to a high-flow low-pressure irrigation system for directing a fluid to and recovering the fluid from an area within a body. The irrigation system comprises a sheath defining a sheath lumen and a flexible catheter disposed in and through the sheath lumen. The flexible catheter defines a catheter lumen and comprises a plurality of apertures at a distal portion that extends beyond the sheath lumen and spreads in the body area. The fluid is directed and outputted to the body area through the catheter lumen and the apertures, and the outputted fluid is recovered and returned through the sheath lumen. The irrigation system can be endoscopically placed inside a body cavity such as the kidney prior to laparoscopic surgery. The fluid may be a cooling solution such as saline, which is introduced to the irrigation system to allow for preservation of renal tissue during renal artery clamping. A feature of the invention is that only the lumen being irrigated, the catheter lumen, is exposed to the fluid or cooling solution. An advantage of the system of the invention is the fluid or cooling solution can be delivered directly to a very defined space via the catheter lumen while the pressure is kept low by the sheath recovering the outputted fluid. In a renal application, for example, the catheter lumen can deliver the cooling solution directly to the collecting system of the kidney as the access sheath tamponades the ureter and the bladder is completely bypassed. Another feature of the invention is it can be made as a one-piece system that can be easily deployed.

[0008] Renal applications of the system include alkaline irrigation for dissolution of uric acid stones, chemo-dissolution of cystine stones, irrigation with chemotherapy drugs after ureteroscopic tumor management, antibiotic irrigation of intra-abdominal abscess and severe infection (e.g., fungal and bacterial), and irrigation of thrombotic agents (Alum or direct delivery of Amicar for renal bleeding).

[0009] The accompanying drawings, which are included in and constitute a part of this specification, illustrate the embodiments of the invention and, together with the description, explain the features, advantages and principles of the invention. In the drawings:

[0010] FIG. 1 illustrates a high-flow low-pressure irrigation system in accordance with a first embodiment of the invention;

[0011] FIG. 2 illustrates a flexible catheter of the irrigation system of the invention;

[0012] FIG. 3 illustrates an exemplary access sheath for use in the irrigation system;

[0013] FIG. 4 illustrates the flow of entering fluid and returning fluid in the irrigation system;

[0014] FIG. 5 illustrates the irrigation system flushing out stone fragmentations from a body cavity;

[0015] FIG. 6 illustrates a high-flow low-pressure irrigation system in accordance with a second embodiment of the invention;

[0016] FIG. 7 illustrates a high-flow low-pressure irrigation system in accordance with a third embodiment of the invention;

[0017] FIG. 8 illustrates a high-flow low-pressure irrigation system in accordance with a fourth embodiment of the invention;

[0018] FIG. 9 illustrates another embodiment of the flexible catheter of the irrigation system;

[0019] FIG. 10 illustrates yet another embodiment of the flexible catheter of the irrigation system;

[0020] FIG. 11 illustrates a high-flow low-pressure irrigation system having an integrated catheter and access sheath in accordance with another embodiment of the invention; and

[0021] FIG. 12 illustrates a cross-sectional view of the integrated catheter and access sheath of the irrigation system of FIG. 11.

[0022] FIG. 1 illustrates a high-flow low-pressure irrigation system 10 in accordance with a first embodiment of the invention. System 10 comprises an access sheath 37 and a flexible ureteral catheter 20 disposed inside sheath 37. Sheath 37 includes a sheath outer surface 40 and a sheath inner surface 41 as best illustrated in FIG. 4. Referring back to FIG. 1, a sheath funnel 42 is disposed at a sheath proximal end 38 and includes a sheath proximal opening 44. A sheath tube 46 extends distally from sheath funnel 42 to a sheath distal end 39 where a sheath distal opening 48 is disposed. Sheath tube 46 defines a sheath lumen 49. It is preferable that the length of sheath 37 is less than the length of catheter 20 such that catheter 20 extends through sheath 37 and protrudes out of sheath distal opening 48. In particular, when extended through sheath 37, a distal tube portion 28 of catheter 20 is not enclosed within sheath 37. Referring to FIG. 2, catheter 20 is preferably curled resembling a pigtail at distal portion 28 and may comprise a catheter connector 22 at a proximal end 24. It should be noted that distal portion 28 of catheter 20 may have different configurations to provide optimal irrigation, for example, distal portion 28 may be flared to provide a wide dispersal of irrigant or angled/concentrated to access and irrigate a lower pole stone. Catheter 20 further comprises a thin, flexible tube 25 extending distally from connector 22 and a plurality of distal apertures 26 disposed at distal portion 28.

[0023] Catheter 20 is inserted through sheath 37 such that it extends distally out of sheath distal opening 48 at sheath distal end 39. As stated above, distal tube portion 28 pigtails in a preferred embodiment causing distal apertures 26 to spread circularly. Catheter 20 comprises a catheter outer surface 29 and a catheter inner surface 30 as best illustrated in FIG. 4. Catheter 20 defines a catheter lumen 31 that is in fluid communication with a catheter proximal opening 33 and distal apertures 26. A return passageway 51 is defined between catheter outer surface 29 and sheath inner surface 41. Fluid may be introduced into catheter 20, directed through catheter lumen 31, and outputted at distal apertures 26 to contact the target body organ or body area. As additional fluid is continually directed to the body area through catheter lumen 31, the outputted fluid is recovered from the body area by sheath 37. In particular, the outputted fluid enters sheath distal opening 48 and travels through sheath lumen 49 in a proximal direction. Specifically, returning fluid 57 travels in return passageway 51 between catheter outer surface 29 and sheath inner surface 41. Returning fluid 57 does not disrupt entering fluid 59, which is shielded within catheter 20.

[0024] Sheath 37 may comprise an access sheath similar to those used in connection with dilators or obturators as illustrated in FIG. 3. In a preferred method for irrigating a body organ or cavity, an obturator 55 is inserted through sheath 37 and is manipulated to move and position sheath 37 to a desired location. For example, sheath tube 46 may be placed to extend through a bladder 64 and a ureter 61 as illustrated in FIG. 1. Once sheath 37 is positioned such that sheath distal end 39 is adjacent a target body organ or cavity to be irrigated, obturator 55 may then be removed thereby leaving sheath lumen 49 open for insertion of catheter 20. Catheter 20 is inserted through sheath 37 extending distally from sheath distal end 39.

[0025] An advantage of irrigation system 10 of the invention is an irrigant may be introduced into catheter 20 at a high flow rate while maintaining a low pressure in the surrounding area to which the irrigant is directed. For example, an irrigant consisting of H₂O can be pressurized up to 200+ cm while pressure is kept low in the surrounding area by sheath 37 which recovers the outputted irrigant. It will be appreciated that this high-flow low-pressure irrigation system may be used for a multitude of medical and surgical applications. For example, irrigation system 10 may be employed for thermal applications such as renal cooling in laparoscopic surgery. Renal hypothermia may be achieved without incurring the problems of systemic volume expansion or severe hypothermia as commonly found in prior art techniques.

[0026] In another application of the invention, the irrigation system may be employed for warming purposes during surgery. For example, irrigation system 10 may be used in connection with cryogenic ablation of a tumor. In this procedure, the target body organ, such as a kidney, is contacted by a cryogenic probe which freezes the contacted portion and surrounding portions of the body organ. Irrigation system 10 of the invention may be used to deliver warm, or at least warmer, fluid to the surrounding area so as to limit the portions of the body organ being frozen. Irrigation system 10 thus facilitates more localized cryo-ablation to minimize damages to healthy portions surrounding the target body organ. The irrigation system of the invention could also be used to cool the kidney, thereby increasing the ablative capabilities of the cryo-ablation device.

[0027] In a further aspect of the invention, irrigation system 10 may be employed for simply irrigating a body area. For example, irrigation system 10 may be used to flush out stone fragmentations 62 from a particular area as illustrated in FIG. 5. Sheath 37 may be provided with a greater diameter, if necessary, to accommodate recovery of larger fragmentations. Other renal applications include alkaline irrigation for dissolution of uric acid stones, chemo-dissolution of cystine stones, irrigation with chemotherapy drugs after ureteroscopic tumor management, antibiotic irrigation of intra-abdominal abscess and severe infection (e.g., fungal and bacterial), and irrigation of thrombic agents.

[0028] It should be noted that the irrigation system of the invention may be adapted for use outside of the upper urinary tract. For example, system 10 may be used in connection with continuous bladder irrigation and stomach lavage. In another example, system 10 may be used in central nervous applications such as to clear a severe central nervous system infection. In yet another example, system 10 of the invention may be used for intra-uterine irrigation in treating endometriosis. Similarly, system 10 may be used in treating severe hypothermia in connection with a lavage using warmed irrigant to increase core body temperature.

[0029] From the foregoing description, it will be appreciated that the fluid used in the system of the invention may comprise a variety of different types depending upon the application. The fluid may comprise a saline solution set at certain temperatures for thermal applications. For other applications such as dissolution, the fluid may contain a chemical solution adapted to accomplish its specific objective.

[0030] FIG. 6 illustrates a high-flow low-pressure irrigation system 10b in accordance with a second embodiment of the invention. Irrigation system 10b comprises an access sheath 37b and a flexible ureteral catheter 20b disposed inside the access sheath 37b. Sheath 37b is unique in that in that it has a hub 66 at a sheath proximal end 38b. Hub 66 forms a seal with catheter 20b and includes an exit port or exit tube 68 for directing returning fluid 57 outward. In another embodiment of the invention, an irrigation system 10c may include a proximal Y-fitting hub 71 as illustrated in FIG. 7. Y-fitting hub 71 includes a first tube 73 adapted for receiving a flexible catheter 20c and a second tube 75 adapted for directing the returning fluid outward. Both tubes 73 and 75 are in fluid communication with each other and sheath lumen 49c. Tube 73 includes a proximal tube end 77 that forms a seal with flexible catheter 20c to prevent the returning fluid from spilling.

[0031] In a preferred embodiment of system 10c, the system is provided as a one-piece device where a sheath 37c is secured to Y-fitting hub 71 at a sheath proximal end 38c and forms a seal around flexible catheter 20c at a sheath distal end 39c. It is understood that such a seal may be formed in a variety of ways. For example, sheath 37c may be adhered or welded to catheter 20c at sheath distal end 39c. Sheath apertures or ports 79 are provided adjacent to sheath distal end 39c to enable the outputted fluid to return to sheath lumen 49c.

[0032] In yet another embodiment of the invention, an irrigation system 10d is provided as one unit including a catheter 20d and a sheath 37d as illustrated in FIG. 8. Specifically, catheter 20d is coupled to sheath 37d at sheath distal end 39d. The cross-sectional area occupied by catheter 20d within sheath 37d may be minimized to optimize the flow of the returning fluid. Similar to irrigation systems discussed above, system 10d may be used for dissolving and recovering stone fragments. Within sheath 37d, recovery of the returning fluid and stone fragments can be optimized by providing a larger gap between an inner surface 41d of sheath 37d and an outer surface 29d of catheter 20d. Outside of sheath 37d, a catheter distal portion may have a wall thickness that is greater than the wall thickness of portion 82 disposed within sheath 37d so as to provide greater column strength and kink resistance.

[0033] It should be reminded that conventional catheters are designed to operate as stand-alone devices. As such, conventional catheters need to have bodies having sufficient column strength and kink resistance. With irrigation system 10d, however, catheter portion 82 within sheath 37d does not need to meet the same performance requirements with regard to column strength and kink resistance as the conventional catheters because portion 82 is protected by sheath 37d. As a result, the wall thickness of shielded portion 82 may be minimized thereby maximizing the cross-sectional area of return passageway 51d.

[0034] FIGS. 9 and 10 illustrate that catheters 20e and 20f for use with separate sheaths 37e and 37f, respectively, may still have thin walls. That is, whether a catheter is affixed to or separate from a sheath, the sheath provides the irrigation system with the necessary column strength and kink resistance so as to enable the catheter to be thinned. In FIG. 9, the wall of catheter 20e has a thickness that expands outside of sheath 37e while in FIG. 10, the wall of catheter 20f has a thickness that remains substantially the same within and outside of sheath 37f.

[0035] FIGS. 11 and 12 illustrate another embodiment of a high-flow low-pressure irrigation system 20g comprising a multi-lumen conduit 84 operating both as a sheath and a catheter. Conduit 84 comprises a common wall 86 that forms a catheter lumen 31g and a sheath lumen 49g (see FIG. 12). Catheter lumen 31g provides a path for the inflow of fluid to a target body area and sheath lumen 49g provides a path for the outflow or returning fluid from the target body area. The outflow of fluid is maximized as catheter lumen 31g can be minimized to occupy a smaller cross-sectional area. Catheter lumen 31g is sealed from sheath lumen 49g and is further defined by a catheter distal portion 28g extending distally from conduit 84. Conduit 84 includes a distal opening 48g in fluid communication with sheath lumen 49g. Blunt obturators and other instrumentation may be inserted through the large sheath lumen 49g defined by conduit 84 for placement of irrigation system 20g.

[0036] It will be appreciated that each embodiment of the invention is preferably configured such that only the target body organ or area being irrigated is exposed to the fluid. An input conduit and an output conduit are provided for flushing and draining, respectively, of the fluid. In the above embodiments, the input conduit is a catheter disposed adjacent to or inside the lumen of the output conduit, which is a sheath. It is anticipated, however, that the input conduit may be a sheath flushing an irrigating fluid and the output conduit may be an internal catheter draining the irrigating fluid. In such an embodiment, a pressure transducer may be used in the internal catheter so if or when the intravenal pressure reaches a set level, e.g., 30 cm H2O, the flow of the irrigating fluid could be automatically stopped. The lumen of the input conduit is shielded from the lumen of the output conduit such that the flushing fluid and draining fluid do not disrupt each other's flow. The input conduit generally has a distal portion that projects out from the output conduit. The distal portion of the input conduit includes apertures for directing the fluid to the target body area. The outputted fluid is recovered through a lumen having an opening or apertures at its distal end. It is foreseeable that the internal catheter and/or sheath is capable of sensing and recording pressure in the renal pelvis so as to adjust the flow of flushing and draining fluid in the irrigation system.

[0037] Many alterations and modifications may be made by those having ordinary skill in the art without departing from the spirit and scope of the invention. Therefore, it must be understood that the illustrated embodiments have been set forth only for the purposes of examples and that they should not be taken as limiting the invention.