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

A cannula includes at least one opening at a distal tip, and 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's distal tip, 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. During a medical procedure (e.g., an extra-corporeal membrane oxygenation (ECMO) procedure) 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.

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'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'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 cannula structure configured for cannulating an anatomical vessel within which a central axis is definable includes a first tube having a lumen therethrough and an elongate length, the first tube having a proximal fluid input configured for receiving a fluid and a plurality of fluid outputs configured for outputting or discharging the fluid into the vessel, the proximal fluid input fluidically coupled to the plurality of fluid outputs, the plurality of fluid outputs including: (a) a set of fenestrations disposed along the elongate length of the first tube, the set of fenestrations configured for outputting or discharging fluid into the vessel in a first flow direction; and (b) a set of distal openings disposed near or at a distal end of the first tube, the set of distal openings configured for outputting or discharging fluid into the vessel in a second flow direction counter to the first flow direction, concurrent with output of fluid in the first direction. A vector flow component along the vessel's central axis corresponding to fluid output by at least some fenestrations within the set of fenestrations is antiparallel to a vector flow component along the vessel's central axis corresponding to fluid output by the set of distal openings.

The first flow direction can be away from the heart (e.g., toward/into an extremity of limb), and the second flow direction can be toward the heart (e.g., into the body) to support continuous blood circulation. The cannula structure can greatly reduce the risk of extremity or limb ischemia during extra-corporeal membrane oxygenation (ECMO) support by way of concurrent fluid flow in the first and second directions, where fluid flow in the first flow direction is counter to fluid flow in the second direction.

The set of fenestrations and the set of distal openings are configured to reside entirely within the vessel when the vessel is cannulated. A ratio of a total fenestration area through which fluid can exit the set of fenestrations to a total distal opening area through which fluid can exit the set of distal openings is typically not less than 10% and between 20%-40%. The set of fenestrations is typically disposed on an angulatable material, which can be structurally reinforced by way of at least one of material composition, material thickness, and incorporation of natural or synthetic fibres therein.

The first tube can include at least one graduated scale disposed along the elongate length thereof for indicating a depth to which the first tube has been inserted into the vessel.

The first tube includes (a) a first portion having (i) a first segment having a lumen and carrying the set of fenestrations and the set of distal openings, the first segment configured to entirely reside within the vessel when the vessel is cannulated; and (ii) a second segment having a lumen aligned with the lumen of the first segment, the second segment proximal to the first segment, the second segment configured to essentially entirely reside external to the vessel when the vessel is cannulated; and (b) a second portion carrying the proximal opening of the first tube and including a hub structure. The first segment typically includes a blood/fluid indicator port formed therein, which is fluidically coupled to a hub corresponding to the hub structure.

The first segment further carries an expandable or inflatable cuff disposed around the first segment slightly proximal to the set of fenestrations. The expandable or inflatable cuff is configured to entirely reside within the vessel when the vessel is cannulated. The expandable or inflatable cuff includes a set of flange members configured for expansion away from or contraction toward the lumen of the first segment. The expandable or inflatable cuff has a cross sectional area that is larger than a cross sectional area of the first segment at a location around the first segment at which the expandable or inflatable cuff is disposed.

In an embodiment, the expandable or inflatable cuff includes a sleeve that carries the set of flange members; and an activation member carried by the sleeve and configured for selectively expanding or contracting the set of flange members. The activation member can include an activation port that is fluidically coupled to a hub corresponding to the hub structure.

In accordance with a further aspect of the present disclosure, the cannula structure includes a second tube that is configured for mating engagement with the first tube and which serves as a dilator relative to the first tube.

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 least1(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 inAn 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'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. 1-4are 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 inFIG. 1, in an embodiment the cannula includes at least a first tube, tubular member, or tubular structure10providing a lumen therethrough and having an elongate first portion100coupled to a second portion200, where the first portion100is distal to the second portion200. The first portion100spans, extends along, or defines an elongate first fraction of the length of the first tube10; and the second portion200spans, extends along, or defines a second fraction of the first tube's length. The first and second portions100,200of the first tube10are coupled, joined, or formed together to enable fluid flow from a proximal opening220disposed at a proximal end230of the first tube10toward, to, and through a set of distal openings120disposed at, along, or adjacent to a distal portion, segment, end, or tip130of the first tube10. One having ordinary skill in the art will understand that the first tube10can itself be defined as the cannula, and hence the first tube's proximal opening220can be identified or defined as the cannula's proximal opening220, and the first tube's distal opening(s)120can be defined as the cannula's distal opening(s)120.

The first portion100of the first tube10includes a first or distal segment110that spans or extends along a first section of the first tube's elongate length, and which has a lumen therethrough which forms a portion of the first tube's lumen. The first segment110is coupled (e.g., integrally and fluidically coupled) to a second or proximal segment115of the first portion100, which spans or extends along a second section of the first tube's elongate length, and which has a lumen therethrough (that is contiguous or aligned with the first segment's lumen). The first segment110is 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 tip130of the first tube10resides 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's distal opening(s)120.

The first segment110carries a set of fenestrations140and a selectively expandable/inflatable cuff150, which is typically flanged. In various embodiments, the first segment110includes an elongate projecting portion114between the first tube's distal opening(s)120and the set of fenestrations140. The fenestrations140and the first tube's distal opening(s)120are configured for fluid communication with the first tube's proximal opening220and the second portion200by way of the first tube's first and second segments110,115. Blood and/or another fluid supplied to the first tube's proximal opening220flows towards the fenestrations140as well as the first tube's distal opening(s)120. As further detailed below, the fenestrations140provide fluid entry sites, portals, or points other than the first tube's distal opening(s)120by which such blood and/or another fluid can enter into the cannulated vessel from the first segment110(or stated equivalently, the fenestrations140provide fluid output or discharge or release sites by which blood/fluid can be output or released or discharged from the first segment110into the cannulated vessel), and flow in a direction away from or opposite to a blood flow direction out of and beyond the first tube's distal opening(s)120. Hence, the fenestrations140provide access sites through which blood and/or another fluid supplied to the first tube's proximal opening220can flow into the cannulated vessel along a second direction opposite or counter to the aforementioned first direction that is associated with the first tube's distal opening(s)120.

For instance, in association with a VA ECMO procedure that employs a first tube10in 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's proximal opening210can flow through the first tube10and simultaneously flow (a) out of the first tube's distal opening(s)120into the body (e.g., directed up the aorta towards the heart); and (b) out of the first tube's fenestrations140, away from the body and into the cannulated extremity. Thus, blood leaving the first tube's distal opening(s)120flows along a first direction (e.g., towards the heart), and blood leaving at least some of the first tube's fenestrations140flows 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 fenestrations140can be configured or adapted to provide an intended shape, size, or fluid communication area (and not all fenestrations140need to have an identical shape, size, or fluid communication area). The fenestrations140are circumferentially or otherwise disposed about the first portion110, slightly or very slightly distal or distally adjacent to the flanged cuff150. In some embodiments, a boundary or dividing line between the first segment110and the second segment115can be defined at a proximal edge or border of the flanged cuff150. The flanged cuff150is configured to facilitate clinician positioning or disposition of the fenestrations140at 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 tube10has been inserted into a patient or subject such that blood and/or another fluid can flow or is flowing from the first tube's proximal opening220toward its distal opening(s)120and out of the fenestrations140and the distal opening(s)120), the first segment110is configured to reside entirely within the vessel. The second segment115and the second portion200are configured to almost or essentially entirely reside external to the vessel, outside of the patient's body. For instance, when the cannula is in use, only that portion of second segment115that is proximal to the expandable/inflatable cuff150and which is distal to the inner surface of the cannulated vessel's superficial wall resides within the vessel. The first segment100is flexible or pliable, and the second segment200is at least generally or somewhat flexible or pliable.

FIG. 2is a schematic illustration of a front view of an expandable/inflatable flanged cuff150in accordance with an embodiment of the present disclosure. In various embodiments, the expandable or inflatable cuff150is configured to provide a cross sectional area that is larger than a cross sectional area of the first segment110at a location around the first segment at which the expandable or inflatable cuff is disposed. In an embodiment, the flanged cuff150includes an elliptical or circular ring or sleeve152that is shaped and dimensioned to surround an external, outer, or exterior diameter of the first tube's first segment110, as indicated inFIG. 1and as further indicated inFIG. 3A. The flanged cuff150carries a set of expandable/inflatable flange elements or members154(e.g., a plurality of flange members154) peripherally (e.g., circumferentially) disposed about the sleeve152. Each flange member154is coupled to an activation element/structure156corresponding to or carried by the cuff150, which facilitates or enables selective outward expansion of the flange members154away (e.g., radially outward) from the sleeve152, and hence away from the interior or lumen of the first segment110; or inward contraction of the flange members154toward the sleeve152, and hence toward the interior or lumen of the first segment110. For instance, the activation element156can include or be an activation port155carried by the cuff150, which is configured to facilitate or enable the communication of a fluid (e.g., air or a liquid) into or out of the flange members154to thereby inflate/expand or deflate/shrink the flange members154, respectively. In some embodiments, flange members154can be carried by or form portions of a single shaped expandable structure. The activation element156when activated via the activation port155facilitates 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 members154.

When the cannula is in use, at least a portion of the flanged cuff150is intended to reside adjacent to or in contact with the superficial wall of the cannulated vessel. After the first tube's first segment110has been inserted into a vessel through an appropriate entry point, the flanged cuff150can be expanded/inflated. Following such expansion or inflation, partial or slight withdrawal of the first tube10from the vessel causes portions of the flanged cuff150to contact the vessel's superficial wall, which imparts a resistive force that impedes the partial withdrawal of the first tube10, and which identifies to a clinician a position at which the fenestrations140are 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 tube10slightly and gently until a resistive force that impedes the partial withdrawal of the first tube10is felt. Subsequent anchoring of the first tube's second segment115to the patient's skin secures the first tube10in an intended or correct position. In various embodiments, the flanged cuff150is configured for allowing blood flow around unflanged portions thereof. The sleeve152prevents total blockage of blood flow distally. Should the first tube10be advanced inadvertently, blood continues to flow distally between the deployed set of flange members. The flanged cuff150or a flange member154can include or be, for instance, an inflatable balloon or wire mesh structure.

Referring again toFIG. 1, radio-opaque markers170can be positioned proximal and/or distal to the set of fenestrations140to facilitate cannula positioning under fluoroscopic guidance. However, one having ordinary skill in the relevant art will understand that the cannula10can be positioned without fluoroscopic guidance. The cannula10can further include at least one graduated scale disposed on the exterior of the first tube10along portions of the first tube's elongate length, where the graduated scale includes graduated markings or indices180that can indicate a depth to which the cannula10has been positioned or placed within the cannulated vessel.

The second portion200of the first tube100proximally extends away from the first tube's second segment115toward and to the first tube's proximal opening220. A proximal section230of the second portion200can 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 tube100.

The first tube's second portion200is coupled to or includes a hub assembly210, which in various embodiments includes a main hub210a, a first auxiliary hub structure210b, and a second auxiliary hub structure210c. The main hub210aproximally extends away from the second segment115of the first tube's first portion100. In several embodiments, the first auxiliary hub structure210bincludes a flange member activation control interface/port250that is fluidically coupled to the flanged cuff's activation element or port156. More particularly, the flange member control interface250can be fluidically coupled to the flanged cuff's activation port156by way of a first passage or channel155and a second passage or channel255. The first passage155is carried by the first tube's second segment115, for instance, along a portion of an interior or inner surface of the second segment115. In some embodiments, the first tube's second segment115can be inserted further into and within the walls of the first tube10. The second passage255provides a fluid communication pathway between the first passage155and the flange member control interface250, and can extend away the first tube10(e.g., at, near, or generally near an interface between the first tube's first and second portions100,200) to the flange member control interface250.

FIG. 3Ais a representative illustration showing portions of the first tube's first and second segments110,115positioned relative to a vessel entry site or point8by which the first segment110of the first tube10has been positioned within a vessel2. The vessel includes a superficial wall4and a deep vessel wall6, in a manner readily understood by one having ordinary skill in the relevant art. A central axis5(e.g., a curvilinear axis) can be defined within the vessel2, which passes through a center point or centroid of the vessel's cross sectional area.

As indicated inFIG. 3A, in various embodiments the fenestrations140are disposed on a flexible or semi-flexible angulatable section, element, member, or material112that is connected to or formed within the first segment110. Once the fenestrations140have entered into the vessel2, a portion of the first segment110distally adjacent or very near to the flanged cuff150can resemble a curve or an elbow by way of bending provided by the angulatable section112. The angulatable section112can establish an intended or predetermined angular orientation or angle between the first portion's first and second segments110,115, for instance, approximately 45 degrees. Notwithstanding, the angulatable section's range of angulation can be from 0 to 180 degrees, or a fraction thereof. The flanged cuff150is disposed on the first segment110, slightly proximal to the angulatable section112. The majority of the length of the first segment110extends into the vessel2, such that the first tube's distal opening(s) reside at an intended or predetermined vascular location or target site. In some embodiments, the angulatable section112can 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's first segment110) in and/or through one or more portions of the angulatable section112.

Referring again toFIG. 1in association withFIG. 3A, the second auxiliary hub structure210ccan include a blood and/or fluid indicator interface260, which is fluidicially coupled to a blood/fluid indicator port160carried by or formed within an interior or inner surface of the first segment110. Such fluidic coupling of the blood/fluid indicator interface260to the blood/fluid indicator port160can be provided by way of a third passage or channel165and a fourth passage or channel265, in a manner analogous or generally analogous to that described above in relation to the first passage155and the second passage255, as will be readily understood by one having ordinary skill in the relevant art. In various embodiments, the fourth passage265is transparent or translucent, such that the presence of blood therein can be readily visually observed. The fluid indicator interface260and the fourth passage265can thus provide a visual indication to a clinician of whether the flanged cuff150and the fenestrations140have entered the vessel2.

Once the fenestrations140and the flanged cuff150have entered the vessel2(e.g., as indicated by the blood/fluid indicator interface260), the flanged cuff150can 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 cuff150, such that the flanged cuff150expands to have a cross sectional area or diameter that is larger than the entry site8. The first tube10can then be partially or slightly withdrawn or displaced out of the entry site8, causing at least some flange members154to contact or abut the inner surface of vessel's superficial wall4. During partial withdrawal of the first tube10, such contact of one or more flange members154with the superficial wall4provides perceptible tactile feedback to a clinician performing the cannulation, such that the clinician knows that the fenestrations140are correctly positioned within the vessel2. The first tube10can then be anchored to the patient's skin, thereby rendering the first tube10substantially or essentially immobile relative to the vessel2, in a manner readily understood by one having ordinary skill in the relevant art.

When the first tube10is in a correct position (and anchored such as described above), blood flowing through the second segment115of the first tube10toward and into the first tube's first segment110flows into the vessel2and exits the first segment110by way of (a) the first tube's distal opening(s)120, and (b) the fenestrations140. That is, a portion of the blood flowing into the first segment110exits the first segment110by way of the first tube's distal opening(s)120, while a portion of the blood flowing into the first segment110concurrently exits the first segment110by way of the fenestrations140.

At least some fenestrations140have cross sectional areas transverse to the vessel's central axis5, which output, release, or discharge blood/fluid such that vector flow components of blood/fluid output by the fenestrations140along the central axis5are in opposition to vector flow components of blood/fluid output by the first tube's distal opening(s)120along the central axis5. More particularly, blood exiting or output/released/discharged at the first tube's distal opening(s)120has a vector flow component that is tangential/parallel or generally tangential/parallel to the vessel's central axis5, corresponding to a first flow direction. Blood exiting or output/released/discharged at least some of the fenestrations140has a vector flow component that is tangential/parallel or generally tangential/parallel to the vessel's central axis5, 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. 3Bis a representative top cross sectional illustration at or through an angulatable section112in or on which a set of fenestrations140a-dresides, illustrating representative blood/fluid flow vectors142corresponding to the directional flow of blood/fluid through the set of fenestrations140a-dinto a cannulated vessel2. As indicated inFIG. 3B, blood/fluid can be output, discharged, or released from each fenestration140a-dinto the vessel2in which the first tube's first segment110resides. In this representative non-limiting example provided to aid understanding, a first fenestration140aoutputs blood/fluid along flow vectors142a.1-142a.5that are generally or substantially aligned parallel to the vessel's central axis5, such that blood/fluid output by the first fenestration140ais primarily or substantially discharged along a first flow direction148, e.g., toward/into a limb. Second and third fenestrations140b-coutput blood/fluid along flow vectors142b.1-142b.3,142c.1-142c.3that are generally or substantially oriented toward the vessel's lateral walls; and a fourth fenestration140doutputs blood/fluid along flow vectors142d.1-142d.3that are generally or substantially aligned parallel to the vessel's central axis5, such that blood/fluid output by the fourth fenestration140dis primarily or substantially discharged along a second flow direction149, e.g., toward/into the body, which is counter or opposite to the first flow direction148. One having ordinary skill in the relevant art will understand that with respect toFIG. 3B, blood/fluid additionally travels through and along the first segment's projecting portion114, such that blood/fluid is additionally or simultaneously output by the first tube's distal opening(s)120into the vessel2generally or substantially along the second flow direction149.

Any given flow vector142can be mapped to or represented as a parallel vector flow component144aligned parallel to the vessel's central axis5, and a perpendicular vector flow component146aligned perpendicular to the vessel's central axis5, in a manner readily understood by one having ordinary skill in the relevant art. At least some fenestrations140a-c(e.g., at least one fenestration140a, and in various embodiments, multiple fenestrations140a-c) output blood/fluid into the vessel2such that flow vectors142a-ccorresponding to blood/fluid discharged thereby have parallel vector flow components144a-c(e.g., parallel vector flow components144a.1,144a.5,144b.1, etc . . . ) that are oriented along the first flow direction, e.g., toward the limb. Additionally, in some embodiments, particular fenestrations140doutput blood/fluid into the vessel2such that flow vectors142dcorresponding to the blood/fluid discharged thereby have parallel vector flow components144d(e.g., parallel vector flow component144d.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 components144a-coriented toward the limb. Considered collectively, the set of fenestrations140provides 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's distal opening(s)120and possibly one or more fenestrations140d.

As will be understood by one having ordinary skill in the relevant art, the number of fenestrations140, the positions of the fenestrations140on the angulatable section112, as well as the shapes and/or cross sectional areas of one or more fenestrations140can be selected relative to the shapes and/or cross sectional area(s) of one or more of the first tube's distal openings120in order to provide an intended or expected adequate/appropriate volume and/or rate of blood/fluid flow out of the first tube's distal opening(s)120relative to volume and/or rate of blood/fluid flow out of the fenestrations140. In several representative embodiments, a ratio of a total fenestration area through which blood/fluid can exit the fenestrations140(e.g., a total cross sectional area for blood/fluid flow provided by the fenestrations140) to a total distal opening area through which blood/fluid can exit the first tube's distal opening(s)120is 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 tube10can typically (but not exclusively) have an outer diameter of 3 mm (e.g., for infants) up to 15 mm (for adults).

FIG. 4is a schematic illustration of a second tube20provided 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 tube20corresponds to or is a dilator assembly or dilator20. The second tube20has a diameter smaller than the first tube10, and is engageable therewith. The second tube20includes a central guide wire channel22configured for engaging with or passing a guide wire (not shown), as well as a tapered distal end24having a diameter that occludes the distal opening(s) of the first tube10. The distal end24includes a through hole or opening therein26configured 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 tube20facilitates or enables percutaneous insertion of the first tube10into the vessel2. The second tube20supports and stiffens the first tube10as the first tube10is inserted into the vessel2. The second tube20additionally includes a hub28that is insertable into a main hub210cof the first tube'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 tube10and second tube20, henceforth simply referred to as the cannula10and the dilator assembly20, are inserted into the femoral artery2until the blood/fluid indicator port160carried by the first tube's first segment110is inside the femoral artery2. At this point, blood flows into the third and fourth passages165,265and out through the blood/fluid indicator interface260, thereby visually indicating to a clinician that the blood/fluid indicator port160is inside the femoral artery2.

The cannula10is advanced 1-2 cm further, and the flanged cuff150is inflated or activated. This further advancement of the cannula10into the vessel2ensures that the flanged cuff150is well away from the superficial vessel wall to avoid and prevent accidental damage to the vessel2while inflating the flanged cuff150. The cannula10is then gently pulled back until resistance is felt, which indicates contact of the flanged cuff150with the superficial vessel wall4and thus correct positioning of the cannula10. The cannula10is then anchored into position to the patient's skin. The dilator assembly20is then withdrawn and the proximal end of the cannula10is attached to a pump circuit. Thus, the distal opening120of the cannula provides systemic blood flow to the body, while the fenestrations140provide 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.