Patent Publication Number: US-11395869-B2

Title: Arterial cannula which allows perfusion along opposing directions within a cannulated vessel

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. patent application Ser. No. 14/419,431, which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     Aspects of the present disclosure are directed to a cannula having at least one opening at a distal tip, and which further includes multiple fenestrations that are maintainable in position substantially immediately or slightly beyond a site or point of cannula entry into a vessel. The fenestrations, in combination with the opening(s) at the cannula&#39;s distal tip, facilitate or enable the simultaneous perfusion of blood into the cannulated vessel along multiple directions, including opposing or anti-parallel blood flow directions relative to a central axis of the cannulated vessel. Blood introduced into a vessel such as the femoral artery by way of the cannula can thus exit the cannula in a manner that provides concurrent blood flow in a first direction towards the heart and a second direction away from the heart. 
     BACKGROUND 
     Patients with cardiopulmonary failure can be treated with mechanical circulatory support, such as veno-arterial extra-corporeal membrane oxygenation (VA ECMO). In association with VA ECMO, a cannula having a proximal end and a distal tip is placed in an artery, which is commonly the femoral artery, to infuse oxygenated blood into the body. The cannula can be inserted into the artery by way of open surgical or percutaneous puncture, such as through the Seldinger technique. Blood that is directed into the cannula&#39;s proximal end exits the cannula at its distal tip, and is directed up the aorta towards the heart. 
     In order to supply an adequate amount of blood, the cannula needs to be sufficiently large in diameter. As a result, the cannula itself obstructs blood flow into the extremity or limb that is cannulated, which is commonly a leg. For patients on long-term support, the potential for ischemia to the cannulated limb arises due to this obstruction of blood flow. Attempts to solve this ischemia problem include the insertion of a second arterial cannula into the artery, limb-wise distal to the site of cannulation and directed downwards. This second cannula is taken off of the cardiopulmonary circuit by a Y connector and a tube. Unfortunately, this requires a second cannulation in an often sick and anticoagulated patient. 
     A need exists for an arterial cannula that provides adequate blood flow into the body, but which also enables blood flow into the cannulated body extremity. 
     SUMMARY 
     In accordance with an aspect of the present disclosure, a process or method of cannulating an anatomical vessel of a patient through a vessel entry point and introducing concurrent flows of oxygenated blood into the anatomical vessel in opposing flow directions during a veno-arterial extra-corporeal membrane oxygenation (VA ECMO) procedure or a cardiopulmonary bypass procedure includes: 
     (a) providing a cannula structure formed as an elongate tubular structure and having a length, the cannula structure including:
         a proximal opening configured to reside outside of the patient&#39;s body and by which oxygenated blood is introducible into the cannula structure for delivery into the anatomical vessel during the VA ECMO procedure or cardiopulmonary bypass procedure;   a plurality of fluid outputs, each of the plurality of fluid outputs fluidically coupled along the length of the cannula structure to the proximal opening of the cannula structure, the plurality of fluid outputs including:
           a distal opening configured for outputting into the anatomical vessel a first portion of said oxygenated blood in a first flow direction; and   a set of fenestrations that is distinct and spaced proximally away from the distal opening, the set of fenestrations configured for outputting into the vessel a second portion of said oxygenated blood in a second flow direction counter to the first flow direction, simultaneous with the distal opening outputting the first portion of said oxygenated blood in the first flow direction;   
           a first tube disposed distal to the cannula structure&#39;s proximal opening, the first tube having an elongate length along which a plurality of fluidically coupled lumens extend therethrough, the first tube including:
           a first segment configured to entirely reside within the anatomical vessel during the VA ECMO procedure or cardiopulmonary bypass procedure, the first segment including:
               a first lumen having a proximal fluid input fluidically coupled to the proximal opening of the cannula structure and which is configured for receiving said oxygenated blood during the VA ECMO procedure or cardiopulmonary bypass procedure;   an elongate projecting portion through which the first lumen extends; and   the cannula structure&#39;s plurality of fluid outputs,
                   wherein the distal opening resides near or at a distal end of the first tube,   wherein the elongate projecting portion extends between the distal opening and the set of fenestrations,   wherein the set of fenestrations resides on a section of the first segment that is (a) proximal to the elongate projecting portion, (b) configured to remain angulated within the vessel during the VA ECMO procedure or cardiopulmonary bypass procedure, and (c) disposed substantially beneath the vessel entry point such that the set of fenestrations outputs the second portion of said oxygenated blood substantially beneath the vessel entry point during the VA ECMO procedure or cardiopulmonary bypass procedure;   
                   a second segment proximal to the first segment and configured to essentially entirely reside external to the vessel during the VA ECMO procedure or cardiopulmonary bypass procedure, which includes a second lumen aligned with the first lumen of the first segment, and which between the cannula structure&#39;s proximal opening and distal opening is fluidically coupled to each of the cannula structure&#39;s proximal opening, the proximal fluid input of the first segment, the first lumen of the first segment, and the cannula structure&#39;s plurality of fluid outputs, and which is configured for receiving said oxygenated blood from the cannula structure&#39;s proximal opening and delivering said oxygenated blood into the proximal fluid input of the first segment during the VA ECMO procedure or cardiopulmonary bypass procedure; and   an expandable or inflatable cuff which prior to and after expansion or inflation is disposed distal to the second segment and around the first segment at a first segment location slightly proximal to the set of fenestrations, wherein the expandable or inflatable cuff when expanded or inflated has a cross sectional area that is larger than each of a cross sectional area of the vessel entry point and the first segment at the location around the first segment at which the expandable or inflatable cuff is disposed, and wherein the expandable or inflatable cuff includes:
                   a sleeve configured for expansion away from or contraction toward the first lumen; and   an activation member coupled to the sleeve and configured for selectively expanding or contracting the sleeve,   wherein the expandable or inflatable cuff when expanded or inflated is configured to reside entirely within the vessel in a position substantially beneath and immediate to the vessel entry point adjacent to the superficial wall of the vessel, proximal to the set of fenestrations relative to the length of the first tube when the vessel is cannulated and the first tube is in a correct position within the vessel during the VA ECMO procedure or cardiopulmonary bypass procedure;   
                   
               
           (b) introducing the distal end of the first tube into the anatomical vessel through the vessel entry point;   (c) after (b), advancing portions of the first tube into the anatomical vessel until the first segment including the set of fenestrations resides within the anatomical vessel;   (d) after (c), further advancing the first tube into the anatomical vessel, such that the first segment including the set of fenestrations, the expandable or inflatable cuff, and portions of the second segment reside within the anatomical vessel;   (e) after (d), expanding or inflating the expandable or inflatable cuff,   (f) after (e), withdrawing portions of the cannula structure from the anatomical vessel until resistance is felt, indicating the expandable or inflatable cuff has contacted the superficial wall of the anatomical vessel; and   (g) after (f), anchoring portions of the cannula structure to the patient&#39;s skin.       

     The process or method can further include, after (g):
         supplying said oxygenated blood to the cannula structure&#39;s proximal opening; and   discharging the first portion of said oxygenated blood out of the distal opening in the first flow direction simultaneous with discharging the second portion of said oxygenated blood into the anatomical vessel out of the set of fenestrations in the second flow direction.       

     In association with the process or method, a vector flow component along a central axis of the anatomical vessel corresponding to blood output by at least some fenestrations within the set of fenestrations is antiparallel to a vector flow component along the central axis of the anatomical vessel corresponding to blood output by the distal opening. 
     In association with the process or method, the distal opening provides systemic blood flow to the patient&#39;s body, while the set of fenestrations provides blood flow to a limb of the patient&#39;s body during the VA ECMO or cardiopulmonary bypass procedure. 
     In accordance with a further aspect of the present disclosure, supplying said oxygenated blood to the cannula structure&#39;s proximal opening includes includes the proximal end of the cannula structure to a pump circuit. 
     In accordance with a further aspect of the present disclosure, the first segment carries a blood indicator port that is fluidically coupled to a blood indicator interface corresponding to a hub structure associated with the cannula structure, and wherein (c) of the method includes: after (b), advancing the first tube into the anatomical vessel until the blood indicator interface indicates that the set of fenestrations resides within the anatomical vessel. 
     In accordance with a further aspect of the present disclosure, the activation element is fluidically coupled to an activation port carried by the expandable or inflatable cuff, and wherein (e) includes: after (d), expanding or inflating the expandable or inflatable cuff by way of communication of a fluid into the activation port. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a first tube or cannula having multiple fenestrations in accordance with an embodiment of the present disclosure. 
         FIG. 2  is a schematic illustration of a front view of an expandable/inflatable flanged cuff in accordance with an embodiment of the present disclosure. 
         FIG. 3A  is a representative illustration showing portions of first and second segments of the first tube positioned relative to a vessel entry site by which the first segment of the first tube has been positioned within a vessel. 
         FIG. 3B  is a representative top cross sectional illustration at or through an angulatable section in or on which a set of fenestrations resides, illustrating representative blood/fluid flow directions out of the set of fenestrations and into a cannulated vessel. 
         FIG. 4  is a schematic illustration of a second tube  20  provided by a cannula assembly or structure in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the present disclosure, depiction of a given element or consideration or use of a particular element number in a particular FIG. or a reference thereto in corresponding descriptive material can encompass the same, an equivalent, or an analogous element or element number identified in another FIG. or descriptive material associated therewith. The use of “/” in a FIG. or associated text is understood to mean “and/or” unless otherwise indicated. The recitation of a particular numerical value or value range herein is understood to include or be a recitation of an approximate numerical value or value range (e.g., within +/−5% to 10%). 
     As used herein, the term “set” corresponds to or is defined as a non-empty finite organization of elements that mathematically exhibits a cardinality of at least 1 (i.e., a set as defined herein can correspond to a unit, singlet, or single element set, or a multiple element set), in accordance with known mathematical definitions (for instance, in a manner corresponding to that described in  An Introduction to Mathematical Reasoning: Numbers, Sets, and Functions , “Chapter 11: Properties of Finite Sets” (e.g., as indicated on p. 140), by Peter J. Eccles, Cambridge University Press (1998)). In general, an element of a set can include or be a system, an apparatus, a device, a structure, an object, a process, a physical parameter, or a value depending upon the type of set under consideration. 
     As used herein, the term “vessel” is taken to mean an anatomical vessel, passage, channel (e.g., a blood vessel, such as an artery) of a patient or subject, or an anatomical chamber or compartment. As used herein, the term “perfusion” is taken to mean the injection, transfer, or fluid communication of blood and/or one or more other fluids into a blood vessel for purpose of enabling the blood and/or other fluid(s) to reach an organ or tissues (e.g., to supply nutrients and oxygen). The term “fluidically coupled” is taken to mean coupled in a manner that provides for fluid (e.g., liquid or gas) communication. The term “antiparallel” is taken to mean parallel vectors that reside or lie along a common line, but which point in opposite directions. 
     Embodiments in accordance with the present disclosure are directed to a cannula or cannula structure (e.g., an arterial cannula) providing (a) a set of openings at a distal cannula portion, segment, end, or tip that is configured for entry into a vessel (e.g., an artery) at a cannulation site or point, and which is configured for displacement or travel along the vessel and positioning away from the cannulation point; and (b) a set of fenestrations, apertures, or openings configured to be positioned or maintained in position essentially or substantially immediately beyond the cannulation point. The set of fenestrations, in association with the set of openings at the cannula&#39;s distal tip, enable simultaneous perfusion of blood (and/or another fluid) into the cannulated vessel along multiple directions, including, opposing or anti-parallel flow directions relative to a central axis of the cannulated vessel, such that such blood introduced into the vessel by the cannula simultaneously flows towards the heart and away from the heart. 
       FIGS. 1-4  are schematic illustrations showing portions of a cannula assembly, cannula structure, or cannula (e.g., an arterial cannula) in accordance with an embodiment of the present disclosure. As indicated in  FIG. 1 , in an embodiment the cannula includes at least a first tube, tubular member, or tubular structure  10  providing a lumen therethrough and having an elongate first portion  100  coupled to a second portion  200 , where the first portion  100  is distal to the second portion  200 . The first portion  100  spans, extends along, or defines an elongate first fraction of the length of the first tube  10 ; and the second portion  200  spans, extends along, or defines a second fraction of the first tube&#39;s length. The first and second portions  100 ,  200  of the first tube  10  are coupled, joined, or formed together to enable fluid flow from a proximal opening  220  disposed at a proximal end  230  of the fist tube  10  toward, to, and through a set of distal openings  120  disposed at, along, or adjacent to a distal portion, segment, end, or tip  130  of the first tube  10 . One having ordinary skill in the art will understand that the first tube  10  can itself be defined as the cannula, and hence the first tube&#39;s proximal opening  220  can be identified or defined as the cannula&#39;s proximal opening  220 , and the first tube&#39;s distal opening(s)  120  can be defined as the cannula&#39;s distal opening(s)  120 . 
     The first portion  100  of the first tube  10  includes a first or distal segment  110  that spans or extends along a first section of the first tube&#39;s elongate length, and which has a lumen therethrough which forms a portion of the first tube&#39;s lumen. The first segment  110  is coupled (e.g., integrally and fluidically coupled) to a second or proximal segment  115  of the first portion  100 , which spans or extends along a second section of the first tube&#39;s elongate length, and which has a lumen therethrough (that is contiguous or aligned with the first segment&#39;s lumen). The first segment  110  is configured for entering into a vessel (e.g., an artery) at a cannulation site or point, and being positioned or displaced along or within the vessel such that the distal tip  130  of the first tube  10  resides at an intended or predetermined distance away from the cannulation point, at which blood and/or another fluid is intended to be perfused or directed into the cannulated vessel along a first direction through the first tube&#39;s distal opening(s)  120 . 
     The first segment  110  carries a set of fenestrations  140  and a selectively expandable/inflatable cuff  150 , which is typically flanged. In various embodiments, the first segment  110  includes an elongate projecting portion  114  between the first tube&#39;s distal opening(s)  120  and the set of fenestrations  140 . The fenestrations  140  and the first tube&#39;s distal opening(s)  120  are configured for fluid communication with the first tube&#39;s proximal opening  220  and the second portion  200  by way of the first tube&#39;s first and second segments  110 ,  115 . Blood and/or another fluid supplied to the first tube&#39;s proximal opening  220  flows towards the fenestrations  140  as well as the first tube&#39;s distal opening(s)  120 . As further detailed below, the fenestrations  140  provide fluid entry sites, portals, or points other than the first tube&#39;s distal opening(s)  120  by which such blood and/or another fluid can enter into the cannulated vessel from the first segment  110  (or stated equivalently, the fenestrations  140  provide fluid output or discharge or release sites by which blood/fluid can be output or released or discharged from the first segment  110  into the cannulated vessel), and flow in a direction away from or opposite to a blood flow direction out of and beyond the first tube&#39;s distal opening(s)  120 . Hence, the fenestrations  140  provide access sites through which blood and/or another fluid supplied to the first tube&#39;s proximal opening  220  can flow into the cannulated vessel along a second direction opposite or counter to the aforementioned first direction that is associated with the first tube&#39;s distal opening(s)  120 . 
     For instance, in association with a VA ECMO procedure that employs a first tube  10  in accordance with an embodiment of the present disclosure which is inserted into an artery (e.g., the right femoral artery) of a body extremity (e.g., the right leg, correspondingly), blood supplied to the first tube&#39;s proximal opening  210  can flow through the first tube  10  and simultaneously flow (a) out of the first tube&#39;s distal opening(s)  120  into the body (e.g., directed up the aorta towards the heart); and (b) out of the first tube&#39;s fenestrations  140 , away from the body and into the cannulated extremity. Thus, blood leaving the first tube&#39;s distal opening(s)  120  flows along a first direction (e.g., towards the heart), and blood leaving at least some of the first tube&#39;s fenestrations  140  flows along a second direction counter or opposite to the first direction (e.g., away from the heart). As a result, the risk of ischemia in the extremity is substantially or greatly reduced, or essentially eliminated. 
     Each of the fenestrations  140  can be configured or adapted to provide an intended shape, size, or fluid communication area (and not all fenestrations  140  need to have an identical shape, size, or fluid communication area). The fenestrations  140  are circumferentially or otherwise disposed about the first portion  110 , slightly or very slightly distal or distally adjacent to the flanged cuff  150 . In some embodiments, a boundary or dividing line between the first segment  110  and the second segment  115  can be defined at a proximal edge or border of the flanged cuff  150 . The flanged cuff  150  is configured to facilitate clinician positioning or disposition of the fenestrations  140  at an intended position within the cannulated vessel, as further detailed below. 
     When the cannula is in use (i.e., when the vessel is cannulated/when the first tube  10  has been inserted into a patient or subject such that blood and/or another fluid can flow or is flowing from the first tube&#39;s proximal opening  220  toward its distal opening(s)  120  and out of the fenestrations  140  and the distal opening(s)  120 ), the first segment  110  is configured to reside entirely within the vessel. The second segment  115  and the second portion  200  are configured to almost or essentially entirely reside external to the vessel, outside of the patient&#39;s body. For instance, when the cannula is in use, only that portion of second segment  115  that is proximal to the expandable/inflatable cuff  150  and which is distal to the inner surface of the cannulated vessel&#39;s superficial wall resides within the vessel. The first segment  100  is flexible or pliable, and the second segment  200  is at least generally or somewhat flexible or pliable. 
       FIG. 2  is a schematic illustration of a front view of an expandable/inflatable flanged cuff  150  in accordance with an embodiment of the present disclosure. In various embodiments, the expandable or inflatable cuff  150  is configured to provide a cross sectional area that is larger than a cross sectional area of the first segment  110  at a location around the first segment at which the expandable or inflatable cuff is disposed. In an embodiment, the flanged cuff  150  includes an elliptical or circular ring or sleeve  152  that is shaped and dimensioned to surround an external, outer, or exterior diameter of the first tube&#39;s first segment  110 , as indicated in  FIG. 1  and as further indicated in  FIG. 3A . The flanged cuff  150  carries a set of expandable/inflatable flange elements or members  154  (e.g., a plurality of flange members  154 ) peripherally (e.g., circumferentially) disposed about the sleeve  152 . Each flange member  154  is coupled to an activation element/structure  156  corresponding to or carried by the cuff  150 , which facilitates or enables selective outward expansion of the flange members  154  away (e.g., radially outward) from the sleeve  152 , and hence away from the interior or lumen of the first segment  110 ; or inward contraction of the flange members  154  toward the sleeve  152 , and hence toward the interior or lumen of the first segment  110 . For instance, the activation element  156  can include or be an activation port  155  carried by the cuff  150 , which is configured to facilitate or enable the communication of a fluid (e.g., air or a liquid) into or out of the flange members  154  to thereby inflate/expand or deflate/shrink the flange members  154 , respectively. In some embodiments, flange members  154  can be carried by or form portions of a single shaped expandable structure. The activation element  156  when activated via the activation port  155  facilitates or enables the communication of the fluid (e.g., air or a liquid) into the single shaped expandable structure to thereby inflate/expand or deflate/collapse the plurality of flange members  154 . 
     When the cannula is in use, at least a portion of the flanged cuff  150  is intended to reside adjacent to or in contact with the superficial wall of the cannulated vessel. After the first tube&#39;s first segment  110  has been inserted into a vessel through an appropriate entry point, the flanged cuff  150  can be expanded/inflated. Following such expansion or inflation, partial or slight withdrawal of the first tube  10  from the vessel causes portions of the flanged cuff  150  to contact the vessel&#39;s superficial wall, which imparts a resistive force that impedes the partial withdrawal of the first tube  10 , and which identifies to a clinician a position at which the fenestrations  140  are disposed near, very near, or just beyond the cannulation point, slightly or very slightly past the superficial vessel wall. More particularly, the clinician will partially withdraw the first tube  10  slightly and gently until a resistive force that impedes the partial withdrawal of the first tube  10  is felt. Subsequent anchoring of the first tube&#39;s second segment  115  to the patient&#39;s skin secures the first tube  10  in an intended or correct position. In various embodiments, the flanged cuff  150  is configured for allowing blood flow around unflanged portions thereof. The sleeve  152  prevents total blockage of blood flow distally. Should the first tube  10  be advanced inadvertently, blood continues to flow distally between the deployed set of flange members. The flanged cuff  150  or a flange member  154  can include or be, for instance, an inflatable balloon or wire mesh structure. 
     Referring again to  FIG. 1 , radio-opaque markers  170  can be positioned proximal and/or distal to the set of fenestrations  140  to facilitate cannula positioning under fluoroscopic guidance. However, one having ordinary skill in the relevant art will understand that the cannula  10  can be positioned without fluoroscopic guidance. The cannula  10  can further include at least one graduated scale disposed on the exterior of the first tube  10  along portions of the first tube&#39;s elongate length, where the graduated scale includes graduated markings or indices  180  that can indicate a depth to which the cannula  10  has been positioned or placed within the cannulated vessel. 
     The second portion  200  of the first tube  10  proximally extends away from the first tube&#39;s second segment  115  toward and to the first tube&#39;s proximal opening  220 . A proximal section  230  of the second portion  200  can provide or be a standard physical interface, coupling, or connection configured for mating engagement with and receiving blood and/or another fluid from a structure or device (e.g., a portion of a VA ECMO system) that is separate or separable from the first tube  10 . 
     The first tube&#39;s second portion  200  is coupled to or includes a hub assembly  210 , which in various embodiments includes a main hub  210   a , a first auxiliary hub structure  210   b , and a second auxiliary hub structure  210   c . The main hub  210   a  proximally extends away from the second segment  115  of the first tube&#39;s first portion  100 . In several embodiments, the first auxiliary hub structure  210   b  includes a flange member activation control interface/port  250  that is fluidically coupled to the flanged cuff&#39;s activation element or port  156 . More particularly, the flange member control interface  250  can be fluidically coupled to the flanged cuff&#39;s activation port  156  by way of a first passage or channel  155  and a second passage or channel  255 . The first passage  155  is carried by the first tube&#39;s second segment  115 , for instance, along a portion of an interior or inner surface of the second segment  115 . In some embodiments, the first tube&#39;s second segment  115  can be inserted further into and within the walls of the first tube  10 . The second passage  255  provides a fluid communication pathway between the first passage  155  and the flange member control interface  250 , and can extend away the first tube  10  (e.g., at, near, or generally near an interface between the first tube&#39;s first and second portions  100 ,  200 ) to the flange member control interface  250 . 
       FIG. 3A  is a representative illustration showing portions of the first tube&#39;s first and second segments  110 ,  115  positioned relative to a vessel entry site or point  8  by which the first segment  110  of the first tube  10  has been positioned within a vessel  2 . The vessel includes a superficial wall  4  and a deep vessel wall  6 , in a manner readily understood by one having ordinary skill in the relevant art. A central axis  5  (e.g., a curvilinear axis) can be defined within the vessel  2 , which passes through a center point or centroid of the vessel&#39;s cross sectional area. 
     As indicated in  FIG. 3A , in various embodiments the fenestrations  140  are disposed on a flexible or semi-flexible angulatable section, element, member, or material  112  that is connected to or formed within the first segment  110 . Once the fenestrations  140  have entered into the vessel  2 , a portion of the first segment  110  distally adjacent or very near to the flanged cuff  150  can resemble a curve or an elbow by way of bending provided by the angulatable section  112 . The angulatable section  112  can establish an intended or predetermined angular orientation or angle between the first portion&#39;s first and second segments  110 ,  115 , for instance, approximately 45 degrees. Notwithstanding, the angulatable section&#39;s range of angulation can be from 0 to 180 degrees, or a fraction thereof. The flanged cuff  150  is disposed on the first segment  110 , slightly proximal to the angulatable section  112 . The majority of the length of the first segment  110  extends into the vessel  2 , such that the first tube&#39;s distal opening(s) reside at an intended or predetermined vascular location or target site. In some embodiments, the angulatable section  112  can be structurally reinforced to enhance structural reliability, for instance, by way of one or more of material composition selection, material thickness selection, and/or the incorporation of one or more types of fibrous strands or materials (e.g., biocompatible natural or synthetic bendable fibres such as carbon fibres, optical fibres, or silk fibers), which can be oriented along predetermined directions, such as lengthwise/cross-wise/spiral-wise, relative to the elongate length of the first tube&#39;s first segment  110 ) in and/or through one or more portions of the angulatable section  112 . 
     Referring again to  FIG. 1  in association with  FIG. 3A , the second auxiliary hub structure  210   c  can include a blood and/or fluid indicator interface  260 , which is fluidicially coupled to a blood/fluid indicator port  160  carried by or formed within an interior or inner surface of the first segment  110 . Such fluidic coupling of the blood/fluid indicator interface  260  to the blood/fluid indicator port  160  can be provided by way of a third passage or channel  165  and a fourth passage or channel  265 , in a manner analogous or generally analogous to that described above in relation to the first passage  155  and the second passage  255 , as will be readily understood by one having ordinary skill in the relevant art. In various embodiments, the fourth passage  265  is transparent or translucent, such that the presence of blood therein can be readily visually observed. The fluid indicator interface  260  and the fourth passage  265  can thus provide a visual indication to a clinician of whether the flanged cuff  150  and the fenestrations  140  have entered the vessel  2 . 
     Once the fenestrations  140  and the flanged cuff  150  have entered the vessel  2  (e.g., as indicated by the blood/fluid indicator interface  260 ), the flanged cuff  150  can be expanded or inflated incrementally by the clinician or a machine interfacing with an indicating dial or meter to provide feedback with respect to an amount of air pressure infused into the flanged cuff  150 , such that the flanged cuff  150  expands to have a cross sectional area or diameter that is larger than the entry site  8 . The first tube  10  can then be partially or slightly withdrawn or displaced out of the entry site  8 , causing at least some flange members  154  to contact or abut the inner surface of vessel&#39;s superficial wall  4 . During partial withdrawal of the first tube  10 , such contact of one or more flange members  154  with the superficial wall  4  provides perceptible tactile feedback to a clinician performing the cannulation, such that the clinician knows that the fenestrations  140  are correctly positioned within the vessel  2 . The first tube  10  can then be anchored to the patient&#39;s skin, thereby rendering the first tube  10  substantially or essentially immobile relative to the vessel  2 , in a manner readily understood by one having ordinary skill in the relevant art. 
     When the first tube  10  is in a correct position (and anchored such as described above), blood flowing through the second segment  115  of the first tube  10  toward and into the first tube&#39;s first segment  110  flows into the vessel  2  and exits the first segment  110  by way of (a) the first tube&#39;s distal opening(s)  120 , and (b) the fenestrations  140 . That is, a portion of the blood flowing into the first segment  110  exits the first segment  110  by way of the first tube&#39;s distal opening(s)  120 , while a portion of the blood flowing into the first segment  110  concurrently exits the first segment  110  by way of the fenestrations  140 . 
     At least some fenestrations  140  have cross sectional areas transverse to the vessel&#39;s central axis  5 , which output, release, or discharge blood/fluid such that vector flow components of blood/fluid output by the fenestrations  140  along the central axis  5  are in opposition to vector flow components of blood/fluid output by the first tube&#39;s distal opening(s)  120  along the central axis  5 . More particularly, blood exiting or output/released/discharged at the first tube&#39;s distal opening(s)  120  has a vector flow component that is tangential/parallel or generally tangential/parallel to the vessel&#39;s central axis  5 , corresponding to a first flow direction. Blood exiting or output/released/discharged at least some of the fenestrations  140  has a vector flow component that is tangential/parallel or generally tangential/parallel to the vessel&#39;s central axis  5 , corresponding to a second flow direction that is at least generally or approximately counter or opposite to (and which can be antiparallel to) the first flow direction. 
       FIG. 3B  is a representative top cross sectional illustration at or through an angulatable section  112  in or on which a set of fenestrations  140   a - d  resides, illustrating representative blood/fluid flow vectors  142  corresponding to the directional flow of blood/fluid through the set of fenestrations  140   a - d  into a cannulated vessel  2 . As indicated in  FIG. 3B , blood/fluid can be output, discharged, or released from each fenestration  140   a - d  into the vessel  2  in which the first tube&#39;s first segment  110  resides. In this representative non-limiting example provided to aid understanding, a first fenestration  140   a  outputs blood/fluid along flow vectors  142   a . 1 - 142   a . 5  that are generally or substantially aligned parallel to the vessel&#39;s central axis  5 , such that blood/fluid output by the first fenestration  140   a  is primarily or substantially discharged along a first flow direction  148 , e.g., toward/into a limb. Second and third fenestrations  140   b - c  output blood/fluid along flow vectors  142   b . 1 - 142   b . 3 ,  142   c . 1 - 142   c . 3  that are generally or substantially oriented toward the vessel&#39;s lateral walls; and a fourth fenestration  140   d  outputs blood/fluid along flow vectors  142   d . 1 - 142   d . 3  that are generally or substantially aligned parallel to the vessel&#39;s central axis  5 , such that blood/fluid output by the fourth fenestration  140   d  is primarily or substantially discharged along a second flow direction  149 , e.g., toward/into the body, which is counter or opposite to the first flow direction  148 . One having ordinary skill in the relevant art will understand that with respect to  FIG. 3B , blood/fluid additionally travels through and along the first segment&#39;s projecting portion  114 , such that blood/fluid is additionally or simultaneously output by the first tube&#39;s distal opening(s)  120  into the vessel  2  generally or substantially along the second flow direction  149 . 
     Any given flow vector  142  can be mapped to or represented as a parallel vector flow component  144  aligned parallel to the vessel&#39;s central axis  5 , and a perpendicular vector flow component  146  aligned perpendicular to the vessel&#39;s central axis  5 , in a manner readily understood by one having ordinary skill in the relevant art. At least some fenestrations  140   a - c  (e.g., at least one fenestration  140   a , and in various embodiments, multiple fenestrations  140   a - c ) output blood/fluid into the vessel  2  such that flow vectors  142   a - c  corresponding to blood/fluid discharged thereby have parallel vector flow components  144   a - c  (e.g., parallel vector flow components  144   a . 1 ,  144   a . 5 ,  144   b .  1 , etc. . . . ) that are oriented along the first flow direction, e.g., toward the limb. Additionally, in some embodiments, particular fenestrations  140   d  output blood/fluid into the vessel  2  such that flow vectors  142   d  corresponding to the blood/fluid discharged thereby have parallel vector flow components  144   d  (e.g., parallel vector flow component  144   d . 1 , etc. . . . ) that are oriented along the second flow direction, e.g., toward the body, i.e., opposite or antiparallel to the parallel vector flow components  144   a - c  oriented toward the limb. Considered collectively, the set of fenestrations  140  provides a net blood/fluid flow that is directed toward the limb, counter or opposite to blood/fluid flow directed toward the body by the first tube&#39;s distal opening(s)  120  and possibly one or more fenestrations  140   d.    
     As will be understood by one having ordinary skill in the relevant art, the number of fenestrations  140 , the positions of the fenestrations  140  on the angulatable section  112 , as well as the shapes and/or cross sectional areas of one or more fenestrations  140  can be selected relative to the shapes and/or cross sectional area(s) of one or more of the first tube&#39;s distal openings  120  in order to provide an intended or expected adequate/appropriate volume and/or rate of blood/fluid flow out of the first tube&#39;s distal opening(s)  120  relative to volume and/or rate of blood/fluid flow out of the fenestrations  140 . In several representative embodiments, a ratio of a total fenestration area through which blood/fluid can exit the fenestrations  140  (e.g., a total cross sectional area for blood/fluid flow provided by the fenestrations  140 ) to a total distal opening area through which blood/fluid can exit the first tube&#39;s distal opening(s)  120  is not less than 10% and typically between 10%-40% (e.g., 20%-40%, 25%-35%, or 30%). 
     One having ordinary skill in the relevant art will further recognize that cannula assemblies, structures, and portions thereof in accordance with embodiments of the present disclosure can exhibit dimensions which are appropriate for the type of patient or subject (e.g., an infant or child versus a full grown adult) and/or the nature of a clinical situation under consideration. Depending upon embodiment or situational details, the first tube  10  can typically (but not exclusively) have an outer diameter of 3 mm (e.g., for infants) up to 15 mm (for adults). 
       FIG. 4  is a schematic illustration of a second tube  20  provided by a cannula assembly or structure in accordance with an embodiment of the present disclosure. One having ordinary skill in the relevant art will understand that the second tube  20  corresponds to or is a dilator assembly or dilator  20 . The second tube  20  has a diameter smaller than the first tube  10 , and is engageable therewith. The second tube  20  includes a central guide wire channel  22  configured for engaging with or passing a guide wire (not shown), as well as a tapered distal end  24  having a diameter that occludes the distal opening(s) of the first tube  10 . The distal end  24  includes a through hole or opening therein  26  configured for passage of the guide wire. The guide wire can be 0.014 inch or 0.018 inch or 0.035 inch in diameter. Thus, the second tube  20  facilitates or enables percutaneous insertion of the first tube  10  into the vessel  2 . The second tube  20  supports and stiffens the first tube  10  as the first tube  10  is inserted into the vessel  2 . The second tube  20  additionally includes a hub  28  that is insertable into a main hub  210   c  of the first tube&#39;s hub assembly, in a manner readily understood by one having ordinary skill in the relevant art. 
     In a representative example femoral artery cannulation procedure for VA ECMO, the first tube  10  and second tube  20 , henceforth simply referred to as the cannula  10  and the dilator assembly  20 , are inserted into the femoral artery  2  until the blood/fluid indicator port  160  carried by the first tube&#39;s first segment  110  is inside the femoral artery  2 . At this point, blood flows into the third and fourth passages  165 ,  265  and out through the blood/fluid indicator interface  260 , thereby visually indicating to a clinician that the blood/fluid indicator port  160  is inside the femoral artery  2 . 
     The cannula  10  is advanced 1-2 cm further, and the flanged cuff  150  is inflated or activated. This further advancement of the cannula  10  into the vessel  2  ensures that the flanged cuff  150  is well away from the superficial vessel wall to avoid and prevent accidental damage to the vessel  2  while inflating the flanged cuff  150 . The cannula  10  is then gently pulled back until resistance is felt, which indicates contact of the flanged cuff  150  with the superficial vessel wall  4  and thus correct positioning of the cannula  10 . The cannula  10  is then anchored into position to the patient&#39;s skin. The dilator assembly  20  is then withdrawn and the proximal end of the cannula  10  is attached to a pump circuit. Thus, the distal opening  120  of the cannula provides systemic blood flow to the body, while the fenestrations  140  provide blood flow to the limb. The likelihood of limb ischemia is thereby greatly reduced or avoided in patients undergoing extended cardiopulmonary bypass procedures. 
     Aspects of particular embodiments of the present disclosure address at least one aspect, problem, limitation, and/or disadvantage associated with exiting cannula assemblies or structures. While features, aspects, and/or advantages associated with certain embodiments have been described in the disclosure, other embodiments may also exhibit such features, aspects, and/or advantages, and not all embodiments need necessarily exhibit such features, aspects, and/or advantages to fall within the scope of the disclosure. It will be appreciated by a person of ordinary skill in the art that several of the above-disclosed systems, components, processes, or alternatives thereof, may be desirably combined into other different systems, components, processes, and/or applications. In addition, various modifications, alterations, and/or improvements may be made to various embodiments that are disclosed by a person of ordinary skill in the art within the scope of the present disclosure.