Patent Publication Number: US-2023149118-A1

Title: Devices, systems, and methods for fluid delivery

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of and priority to U.S. Provisional Patent Application Ser. No. 63/279,727, filed on Nov. 16, 2021, the disclosure of which is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates generally to the field of medical devices. In particular, the present disclosure relates to medical devices for delivering a fluid to a target location, such as a diseased tissue, e.g., a tumor or the like. 
     BACKGROUND 
     Delivering fluids to treatment sites may include targeting delivery to particular tissues or a portion of a tissue, e.g., a tumor. It may be desirable for the fluid to only be delivered to the target site with minimal fluid engagement with ancillary tissue(s). For example, in oncology, the fluid may have destructive effects on tissue that would be undesirable among healthy tissue. Therefore, targeted percutaneous cannula delivery may be a desirable method of fluid delivery to the site to ensure substantially localized fluid deliver. However, such fluid delivery techniques may have complications. Although the fluid may be delivered to the site, it may be such a low viscosity that it flows and/or leeches outside of the target site upon delivery or over time after delivery. The fluid may have such a high viscosity that the dimensional parameters of the delivery cannula may not effectively deliver, deploy, disperse, or maintain flow of the fluid to the target site. The cannula and/or the target site may also be difficult for a medical professional to visualize and/or navigate for desirable fluid delivery. 
     Accordingly, a variety of advantageous medical outcomes addressing the above deficiencies may be realized by the devices, systems, and methods of the disclosure. 
     SUMMARY 
     Medical devices, systems, and methods are described herein, e.g., for facilitating fluid delivery to a treatment site, such as a tumor. In one aspect, a cannula may comprise a shaft comprising a proximal end, a distal end, and a lumen. A plurality of apertures may be disposed along a delivery portion of the shaft. Each aperture may be in fluid communication with the lumen. Each aperture may extend radially from a central axis of the shaft. At least one echogenic marker may be disposed along the shaft within or adjacent to the delivery portion. A body may be disposed within the distal end of the shaft. The lumen may extend along an axial length of the shaft, and a body may be disposed within a distal end of the lumen, blocking the distal end of the lumen. 
     In the described and other aspects of the present disclosure, the body may comprises a pointed distal tip, a midportion having a diameter larger than the distal tip, and a proximal insertion portion having a diameter smaller than the midportion and dimensioned to fit within the distal end of the shaft. The diameter of the midportion may be greater than or equal to a diameter of the shaft. The cannula may comprise 1 to 100 apertures or more. The plurality of apertures may comprise at least one ringed pattern of apertures at a flexible portion along the shaft. The plurality of apertures may comprise at least one helical pattern of apertures along the shaft. The plurality of apertures may be circular in shape, oblong in shape, ellipsoidal in shape, rectangular in shape, or a combination thereof. The plurality of apertures may comprise at least one proximal aperture having a smaller width than a width of at least one distal aperture of the plurality of apertures. The plurality of apertures may comprise a gradual increase in width along a length of the shaft between a proximal end of the delivery portion and a distal end of the delivery portion. A width of at least one of the plurality of apertures may be about 0.254 mm±0.100 mm to about 0.381 mm±0.100 mm. An axial length of the delivery portion may range from about 1.5 cm to about 2.5 cm. The cannula may comprise one or more echogenic markers disposed adjacent a proximal end of the delivery portion and/or one or more echogenic markers disposed adjacent a distal end of the delivery portion. The cannula may comprise a plurality of echogenic markers in the form of rings disposed adjacent a proximal end of the delivery portion and/or a plurality of echogenic markers in the form of rings disposed adjacent a distal end of the delivery portion. An axial length of the at least one echogenic marker may range from about 2 mm to about 10 mm. 
     In one aspect, a cannula may comprise a shaft comprising a proximal end, a distal end, and a lumen therethrough. A plurality of apertures may be disposed along a delivery portion of the shaft. Each aperture may be in fluid communication with the lumen. Each aperture may extend radially from a central axis of the shaft. The plurality of apertures may be circular in shape, oblong in shape, ellipsoidal in shape, rectangular in shape, or a combination thereof. A distal marker portion may be longitudinally along the shaft distal to the delivery portion. A proximal marker portion may be along the shaft proximal to the delivery portion. A body may be disposed within the distal end of the shaft. The lumen may extend along an axial length of the shaft, and a body may be disposed within a distal end of the lumen, blocking the distal end of the lumen. The distal body may extend distally from the shaft to a gradually pointed tip. 
     In the described and other aspects of the present disclosure, each of the distal marker portion and the proximal marker portion may comprise a plurality of echogenic ringed grooves. The body may comprise a pointed distal tip, a midportion having a diameter larger than the distal tip, and a proximal insertion portion having a diameter smaller than the midportion and dimensioned to fit within the distal end of the shaft. A width of at least one of the plurality of apertures may be about 0.254 mm to about 0.381 mm. 
     In one aspect, a method of delivering a fluid disclosed herein may include inserting a cannula comprising a shaft, a lumen, and a plurality of apertures disposed along a delivery portion of the shaft into a patient. Each aperture may extend radially from a central axis of the shaft. The plurality of apertures may be circular in shape, oblong in shape, ellipsoidal in shape, rectangular in shape, or a combination thereof. Each aperture may be in fluid communication with the lumen. At least one echogenic marker may be disposed along the shaft within or adjacent to the delivery portion. At least one echogenic marker may be detected with ultrasound. The delivery portion may be positioned within a target tissue with the assistance of the at least one echogenic marker. The fluid may be delivered through the lumen and out of the plurality of apertures such that the fluid is delivered to the target tissue. 
     In the described and other aspects of the present disclosure, the fluid may comprise a viscosity of fluids such as solutions including water, saline and hydrogels that may vary based on composition, temperature, and concentration. The fluid may comprise a viscosity that increases as the fluid approaches a body temperature of a patient. The at least one echogenic marker may be positioned at a border of the target tissue. The fluid may be a gellable fluid. The fluid may be maintained at a temperature below about 37° C. at least until delivery. The delivery portion may be oriented along the target tissue by flexing the delivery portion. The fluid may be maintained within the target tissue for a treatment period of at least 24 hours or more. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting examples of the present disclosure are described with reference to the accompanying figures, which are schematic and not intended to be drawn to scale. In the figures, each identical or nearly identical component illustrated is typically represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component in each embodiment of the disclosure shown where illustration is not necessary to allow those of skill in the art to understand the disclosure. In the figures: 
         FIG.  1    illustrates a perspective view of a cannula delivering a fluid to a target tissue, according to an embodiment of the disclosure. 
         FIG.  2 A  illustrates a perspective view of a shaft, according to an embodiment of the disclosure. 
         FIG.  2 B  illustrates a perspective view of a body, according to an embodiment of the disclosure. 
         FIG.  2 C  illustrates the body of  FIG.  2 B  and a handle in an exploded perspective view with the shaft of  FIG.  2 A , according to an embodiment of the disclosure. 
         FIG.  2 D  illustrates a perspective view of a distal end of the assembled shaft and body of  FIGS.  2 A- 2 C , according to an embodiment of the disclosure. 
         FIG.  2 E  illustrates an alternative perspective view of a distal end of a shaft and body, according to an embodiment of the disclosure. 
         FIG.  3    illustrates a perspective view of an array of bodies, according to an embodiment of the disclosure. 
         FIG.  4    illustrates a perspective view of a fluid delivery system, according to an embodiment of the disclosure. 
         FIG.  5    illustrates a perspective view of a shaft, according to an embodiment of the disclosure. 
         FIG.  6    illustrates a perspective view of a shaft, according to an embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure is not limited to the particular embodiments described. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting beyond the scope of the appended claims. Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure belongs. The detailed description should be read with reference to the drawings, which are not necessarily to scale, depict illustrative embodiments, and are not intended to limit the scope of the invention. 
     As used herein, “proximal end” refers to the end of a device that lies closest to the medical professional along the device when introducing, removing, or exchanging the device within a patient, and “distal end” refers to the end of a device or object that lies furthest from the medical professional along the device during implantation, positioning, or delivery. 
     As used in this disclosure and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise. 
     It is noted that references in the specification to “an embodiment”, “some embodiments”, “other embodiments”, etc., indicate that the embodiment described may include one or more particular features, structures, and/or characteristics. However, such recitations do not necessarily mean that all embodiments include the particular features, structures, and/or characteristics. Additionally, when particular features, structures, and/or characteristics are described in connection with one embodiment, it should be understood that such features, structures, and/or characteristics may also be used in connection with other embodiments whether or not explicitly described unless clearly stated to the contrary. 
     All numeric values are herein assumed to be modified by the term “about,” whether or not explicitly indicated. The term “about”, in the context of numeric values, generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (i.e., having the same function or result). In many instances, the term “about” may include numbers that are rounded to the nearest significant figure. Other uses of the term “about” (i.e., in a context other than numeric values) may be assumed to have their ordinary and customary definition(s), as understood from and consistent with the context of the specification, unless otherwise specified. The recitation of numerical ranges by endpoints includes all numbers within that range, including the endpoints (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). 
     Although embodiments of the present disclosure are described with specific reference to cannulas, it should be appreciated that other medical devices may be used in a variety of medical procedures. For example, a cannula described herein may instead be a catheter, or the like, and may be percutaneous or non-percutaneous. 
     As used herein, “fluid” may comprise one or more of a liquid, semi-liquid, super critical fluid, gas, solution, particles, drug carriers, spheres, a combination thereof, or the like. A fluid herein may comprise a viscosity that increases as its temperature increases. For example, a fluid may have a lower viscosity at a first temperature and a higher viscosity at a second temperature. For an even more specific example, a fluid may be delivered at a lower temperature within a cannula and may be deployed at a higher temperature (e.g., at least 37° C.) with a higher viscosity. Once deployed, a lower viscosity fluid may undesirably flow through and among a target site and adjacent tissue compared to a higher viscosity fluid that may desirably not flow substantially away from the target site during and/or after deployment. In some embodiments, a fluid is delivered which is a reverse thermosensitive fluid. These fluids are liquids below body temperature and viscous gels at body temperature. In various embodiments, the fluid is provided external of the body at a temperature below body temperature. The fluid may be further chilled to prolong the time the gel stays in the liquid form upon introduction into the body, in some embodiments. For example, the introduction temperature may be is about 10° C. or more below the gelation temperature of the fluid. 
     Although embodiments of the present disclosure are described with specific reference to oncologic fluid delivery into a tumor, it should be appreciated that embodiments herein may deliver fluid in a variety of medical treatment sites such as tissues, organs, body lumens, ducts, vessels, fistulas, cysts, and spaces (e.g., the dermis, stomach, duodenum, jejunum, small intestine, gallbladder, kidneys, pancreas, biliary trees, pancreatic trees, bladder, ureter, abscesses, walled-off pancreatic necrosis, bile ducts, etc.). Devices herein may be inserted via different access points and approaches, e.g., percutaneously, endoscopically, laparoscopically or some combination thereof. 
     Referring to  FIG.  1 A , a perspective view of a cannula  100  delivering fluid  120  into a target tissue  150  is illustrated, according to an embodiment of the disclosure. The cannula  100  includes a shaft  102  having a proximal end (not shown), a distal end  102   d,  and a lumen  104 . Radial apertures  108  are disposed along a delivery portion  106  of the shaft  102 . The radial apertures  108  are disposed helically about the delivery portion  106  of the shaft  102  and each radial aperture  108  is in fluid communication with the lumen  104 . The fluid  120  is being delivered through the lumen  104  and the fluid  120  is being deployed from the lumen  104  out of the apertures  108 . A body  110  is disposed within the distal end  102   d  of the shaft  102 . The body  110  includes a pointed tip that may assist the cannula  100  with entering one or more tissues such as the target tissue  150  and/or adjacent tissue  152 . The body  110  occludes a distal end of the lumen  104  such that the fluid  120  egresses only through the apertures  108 . There is a proximal echogenic marker  116   p  and distal echogenic marker  116   d  disposed along the shaft  102 , each adjacent to the delivery portion  106 . The echogenic markers  116   p,    116   d  are placed across the border of the target tissue  150  such that the delivery portion  106  of the shaft  102  is located entirely within the target tissue  150 . With this arrangement, the fluid  120  is delivered and deployed into the target tissue  150  while discouraging fluid from entering the adjacent tissue  152 . 
     Referring to  FIGS.  2 A- 2 D , parts and assembly of a cannula  200  for delivering fluid are illustrated, in accordance with an embodiment of the disclosure. The cannula  200  includes a shaft  202  having a proximal end (not shown), a distal end  202   d , and a lumen  204 . Radial apertures  208  are disposed along a delivery portion  206  of the shaft  202 . The radial apertures  208  are disposed helically about the delivery portion  206  of the shaft  202  and each radial aperture  208  is in fluid communication with the lumen  204 . 
     A body  210  (as best illustrated in  FIG.  2 B ) includes a pointed distal tip  210   d  and a midportion  210   m  having a diameter larger than the distal tip  210   d.  The distal tip  210   d  gradually widens from a point to the midportion  210  in a proximal direction along a conical convex surface therebetween that may promote a steady increase in peak axial force as the body  210  is axially inserted into tissue substantially along axis α. The pointed distal tip  210   d  that widens to the midportion  210   m  may promote dilation of the tissue that the body  210  is inserted into. The body  210  includes a proximal insertion portion  210   p  having a diameter smaller than the midportion  210   m  and dimensioned to fit within the lumen  204  of the shaft  202 . The diameter of the midportion  210   m  is substantially equivalent to an outer diameter of the shaft  202 , but in various embodiments, the diameter of the midportion  210   m  may be greater than the diameter of the shaft  202 . A transition between the diameters of the midportion  210   m  to the proximal insertion portion  210   p  includes a mid bevel  210   a.  The mid bevel  210   a  may promote an interference fit and/or seal with the distal end  202   d  of the shaft  202  with the body  210  inserted within the lumen  204 . Additionally or in the alternative, if the midportion  210   m  has a diameter larger than the outer diameter of the shaft  202 , the mid bevel  210   a  may promote a smooth transition from the larger diameter midportion  210   m  to the smaller diameter of the shaft  202 . The proximal insertion portion  210   p  includes a proximal bevel  210   b  at the proximal tip of the proximal insertion portion  210   p,  which may promote ease of insertion of the body  210  into the lumen  204  of the shaft  202 . The body  210  may be secured within the shaft  202  by, e.g., swaging, welding, adhering, interference fit, a combination thereof, or the like. The body  210  may comprise a material different from or the same as that of the shaft  202 . For example, in various embodiments, the body  210  may comprise a polymeric material, for example, an epoxy such as EPX 82, available from Carbon, Inc. (Redwood City, Calif., USA), carbon steel, stainless steel, nickel, gold, platinum, an alloy, a combination thereof, or the like. In various embodiments, the body  210  may be formed with or formed from the shaft  202 , e.g., the distal end  210   d  may be formed into a pointed tip such as the portion of the body  210  between the midportion  210   m  and the distal tip  210   d,  and the lumen will not extend to the distal end of the shaft. 
     As best illustrated in  FIGS.  2 C and  2 D , the cannula assembly includes a handle  254 , e.g., a luer lock manifold or the like, coupled to the proximal end  202   p  of the shaft  202  with luminal access to the lumen  204 . A deliverable fluid may be introduced through the handle  254 , delivered along the lumen  204 , and deployed through the apertures  208  along the delivery portion  206 . The cannula may be inserted into/across a target tissue by distally leading insertion of the cannula with the body  210  disposed within the lumen  204  at the distal end  202   d  of the shaft  202 . The distal echogenic marker  216   d  and the proximal echogenic marker  216   p  may assist with navigating, locating, and/or positioning of the cannula and/or the delivery portion  206  with respect to the target tissue. An alternative embodiment in  FIG.  2 E  illustrates a body  210  having a pointed distal tip  210   d,  distal echogenic marker  216   d,  and delivery portion  206 , including radial apertures  208 . There is expected to be some tissue resistance during side hole injection. To address this effect, the radial apertures  208  open into small reservoirs in the form of concavities  206   c  in the delivery portion  206 . In addition, a series of longitudinal overflow tracks  206   t  are provided adjacent to the concavities  206   c  to allow for longitudinal migration of the injected deliverable fluid from the concavities  206   c  along a length of the delivery portion  206 . Such features may be configured to leave a small residue of deliverable fluid upon removal of the needle, for example, to treat the needle track and prevent cancer cell seeding of the track. 
     In various embodiments, one or more dimensions of features or axial lengths along a longitudinal axis l of the cannula may be variable depending on anatomy, size of target tissue, location of target tissue, target tissue border arrangements, deliverable fluid, type or procedure, etc. The shaft  202  has a length s, e.g., about 18 in. (about 457.2 mm) for accessing a liver, but may be shorter, e.g., for accessing skin or breast tissue. For further examples, a length of a shaft may be less than about 500 mm such as about 5 mm, 10 mm 20 mm, 50 mm, 100 mm, 200 mm, 250 mm, 400 mm, etc. The shaft  202  has a gauge, e.g., about 21.5 gauge (about 0.7 mm). The distal echogenic marker  216   d  has an axial length d and the proximal echogenic marker  216   p  has an axial length p, which may be substantially similar to or different from each other, and may be, e.g., about 5 mm. A length m of the delivery portion  206  may be, e.g., about 20 mm, or about 10 mm for a 20 mm target tissue dimension. A diameter of one or more of the apertures  208  may be about 0.010 inches (about 0.254 mm) to about 0.015 inches (about 0.381 mm). 
     In various embodiments, a shaft may be a laser cut or otherwise machined tube. One or more features of the shaft may also be laser cut or otherwise machined, e.g., apertures, echogenic markers, lumens, pointed tips, etc. A shaft may comprise variable materials depending on parameters of a procedure such as, e.g., an epoxy such as an epoxy such as EPX 82, a polymer, carbon steel, stainless steel, nickel, gold, platinum, an alloy, a metal, a combination thereof, or the like. 
     In various embodiments, an echogenic marker may include one or more features that assist with visual and/or ultrasonic locating of at least a portion of a device. An echogenic marker may comprise a groove, deformation, etching, carving, or removal of material at a location of a device of interest for tracking during a procedure. An echogenic marker may include a single marker (e.g., a continuous circumferential band) or multiple markers (e.g., multiple continuous bands axially aligned with respect to each other and discontinuous with each other). One or more echogenic markers may be tracked during a procedure such as for delivery, navigating, positioning, locating anatomy, etc. 
     In various embodiments, radial apertures of a shaft disclosed herein may be disposed along the shaft in various patterns, e.g., arranged as helices, circumferential bands, axial lines, a combination thereof, or the like. Radial apertures of a shaft may be substantially similar to each other or vary. Radial apertures herein may comprise one or more shapes, e.g. circular, oblong, ellipsoidal, rectangular, slotted, a combination thereof, or the like. Some apertures of a shaft may have a smaller dimension and be configured to deploy a fluid while other apertures may have a larger dimension configured to deploy a fluid as well as to elastically and/or plastically deform to assist with navigation and positioning on the shaft during a procedure. In various embodiments, any number of apertures may be used, e.g., 1, 2, 4, 6, 10, 15, 20, 25, 50, 100, etc., or about 20 to about 100 or the like. 
     Referring to  FIG.  3   , a perspective view of an array of bodies  310  is illustrated, according to an embodiment of the disclosure. The bodies  310  are disposed along a stage  340 . This arrangement of the stage  340  and array of bodies  310  may be beneficial for manufacturing the bodies  310  in a batch of multiple bodies  310 , compared to a single body  310 . For example, the array of bodies  310  may be additively manufactured (e.g., three-dimensionally printed, or the like) by establishing the stage  340  at the bottom of the manufactured structure. The stage  340  may include apertures  342  or other voids or thinning of material to decrease material, weight of the structure, cost of the structure, and time to manufacture the structure. The bodies  310  are manufactured on top of the stage  340  and are arrayed in rows and columns along an x-axis and a y-axis, respectively. The bodies  310  are formed from proximal insertion portions  310   p  on the stage  340  towards distal tips  310   d  along a z-axis. The bodies  310  may be removed from the stage  340  for assembling into shafts of cannulas described herein. A bevel of a proximal-most portion of the proximal insertion portion  310   p  of each body  310  may assist with severing each body  310  from the stage  340 . Although  50  bodies  310  are illustrated, in various embodiments, any number of bodies  310  on a stage  340  may be formed, e.g., 1, 2, 3, 4, 5, 6, 10, 15, 20, 25, 50, 100, 1000, etc. 
     Referring to  FIG.  4   , a perspective view of a fluid delivery system is illustrated, according to an embodiment of the disclosure. A cannula  400  is illustrated including a proximal handle  454  with luminal access to a lumen of a shaft  402 . The shaft  402  includes a plurality of apertures  408  disposed along a delivery portion  406  disposed between a proximal echogenic marker  416   p  and a distal echogenic marker  416   d  of the shaft  402 . A body  410  having a pointed tip is disposed at a distal end  402   d  of the shaft  402 . The handle  454  is configured to interface with a variety of injectable reservoirs  456  such that a deliverable fluid therein may be delivered from the reservoir  456 , through the handle  454 , through the shaft  402 , and deploy out of the apertures  408 . 
       FIG.  5    illustrates a perspective view of a shaft  502 , according to an embodiment of the disclosure. The shaft  502  includes a proximal end  502   p , a distal end  502   d , and a lumen  504 . Radial apertures  508  are disposed along a delivery portion  506  of the shaft  502 . The delivery portion  506  is disposed between a distal echogenic marker  516   d  and a proximal echogenic marker  516   p  along a longitudinal axis l of the shaft  502 . The radial apertures  508  are disposed helically about the delivery portion  506  of the shaft  502  and each radial aperture  508  is in fluid communication with the lumen  504 . The radial apertures  508  include proximal apertures  508   p  towards the proximal end  502   p  having a dimension (e.g., a diameter, a width, etc.) smaller than that of distal apertures  508   d  towards the distal end  502   d.  For example, a cross-sectional area (e.g., in a direction normal to flow) of the distal-most aperture may be anywhere from fractions to multiple times larger than a cross-sectional area of the proximal-most aperture. Because the apertures  508  comprises a gradual increase in at least one dimension along the delivery portion  506  from the proximal end  502   p  towards the distal end  502   d , a fluid having a high viscosity (e.g., a viscosity larger than that of water) may more easily deploy out of the larger distal apertures  508   d  than out of the smaller proximal apertures  508   p . Because there is a pressure drop along the length of the shaft  502 , such an arrangement may assist with ensuring substantially uniform deployment of fluid out of the apertures  508  along the longitudinal axis l and the deployment portion  506  (i.e., promoting substantially uniform fluid deployment and flowrate along the target tissue as deployment of the fluid may be more restricted at the proximal apertures  508   p , where pressure is higher, compared to the distal apertures  508   d , where pressure is lower). 
       FIG.  6    illustrates a perspective view of a shaft  602 , according to an embodiment of the disclosure. The shaft  602  includes a proximal end  602   p , a distal end  602   d , and a lumen  604 . Radial apertures  608  are disposed along a delivery portion  606  of the shaft  602 . The delivery portion  606  is disposed between a distal echogenic marker  616   d  and a proximal echogenic marker  616   p  along a longitudinal axis l of the shaft  602 . The radial apertures  608  are disposed about the delivery portion  606  of the shaft  602  and each radial aperture  608  is in fluid communication with the lumen  604 . The radial apertures  608  include proximal apertures  608   p  towards the proximal end  602   p  having a dimension (e.g., a diameter, a width, etc.) smaller than that of middle apertures  608   m  and that of distal apertures  608   d  towards the distal end  602   d . The middle apertures  608   m  have a dimension larger than that of the proximal apertures  608   p , and smaller than that of the distal apertures  608   d . Because the apertures  608  comprises a gradual increase in at least one dimension along the delivery portion  606  from the proximal end  602   p  towards the distal end  602   d , a fluid delivered towards the apertures  608  having a high viscosity (e.g., a viscosity larger than that of water) may more easily deploy out of the larger distal apertures  608   d  than out of the smaller proximal apertures  608   p . Because there is a pressure drop along the length of the shaft  602 , such an arrangement may assist with ensuring substantially uniform deployment of fluid out of the apertures  608  along the longitudinal axis l and the deployment portion  606  (i.e., promoting substantially uniform fluid deployment and flowrate along the target tissue as deployment of the fluid may be more restricted at the proximal apertures  608   p , where pressure is higher, compared to the middle apertures  608   m , where the pressure is lower, and the distal apertures  608   d  where the pressure is even lower). The delivery portion  606  also includes a first flex portion  612  and a second flex portion  614  along its length amongst the apertures  608 . The flex portions  612 ,  614  include circumferential and axial etchings (i.e., grooves) that thin and weaken a wall of the shaft  602  of the delivery portion  606 . The flex portions  612 ,  614  are configured to elastically and/or plastically deform during insertion, steering navigation, and/or positioning of the shaft  602  as desired to maneuver the shaft  602  into a position for optimal delivery of a fluid amongst a target tissue. Although two flex portions  612 ,  614  are illustrated, in various embodiments any number of flex portions may be utilized, e.g., 0, 1, 3, 4, 5, 6, 8, 10, 15, 20, 50, etc. Various numbers and lengths of flex portions may be utilized to increase or decrease flexibility as desired. Although the flex portions  612 ,  614  are illustrated with circumferential and axial grooves, a shaft may alternatively include one or more grooves that are solely axial, solely circumferential, solely oblique, solely acute, solely obtuse, and/or a combination thereof In various embodiments, a flex portion may include one or more apertures of various shapes, e.g., circular, oblong, slotted, etc. In various embodiments, it may be desirable for flex portions to minimize curvature of a shaft such that at least some columnar strength of the shaft may be maintained for steering of the device via minute rotational adjustments and distal advances. Repeat adjustments of curvature, advancements, and/or rotation may be made for steering a device towards, within, or around target tissue. 
     Embodiments of methods of delivering a fluid disclosed herein may include inserting a cannula comprising a shaft, a lumen, and a plurality of radial apertures disposed along a delivery portion of the shaft. Each radial aperture may be in fluid communication with the lumen. At least one echogenic marker may be disposed along the shaft within or adjacent to the delivery portion into a patient. At least one echogenic marker may be detected with ultrasound. The delivery portion may be positioned within a target tissue with the assistance of the at least one echogenic marker. The fluid may be delivered through the lumen and out of the plurality of apertures such that the fluid is delivered to the target tissue. The fluid may comprise a viscosity that varies with temperature, for example the fluid may increase in viscosity as temperature rises and approaches a patient body temperature. The at least one echogenic marker may be positioned at a border of the target tissue. The fluid may be a gellable fluid. The fluid may be maintained at a temperature below about 37° C. at least until delivery. The delivery portion may be oriented along the target tissue by flexing the delivery portion. The fluid may be maintained within the target tissue for a treatment period of at least 24 hours. 
     All of the devices and/or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the devices and methods of this disclosure have been described in terms of preferred embodiments, it may be apparent to those of skill in the art that variations can be applied to the devices and/or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the disclosure. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the disclosure as defined by the appended claims.