Patent Description:
Traditional cannulae used for patient life support generally involve single lumen cannulae at multiple insertion sites, high volume circuits, and cannulae that are not capable of long-term use. Multiple insertion sites increase the risk of bleeding, vessel damage, and infection, as well as pain and discomfort to the patient. These cannulae are designed and built for short-term acute therapies. Additionally, traditional cannulae usually require access sites located in the patient's groin area near the right or left femoral veins.

While multi-lumen cannula assemblies exist in the art in order to avoid the need for multiple insertion sites, the infusion tube and the drainage tube of these cannula assemblies are generally fixed in length relative to one another, as the infusion tube is affixed to the assembly by way of, e.g., an adhesive. This fixed length of the infusion tube relative to the drainage tube may limit the adjustability of cannula assembly placement within the patient's body, thereby making it difficult for the user to account for differences in patient size and/or patient vessel length when positioning the cannula assembly.

Examples of existing cannula devices are described in <CIT>, <CIT>, and <CIT>.

In view of the foregoing, there exists a need for a dual lumen cannula capable of enabling adjustability in the length of an inner infusion tube relative to the outer drainage tube.

Embodiments of the present disclosure are directed to a dual lumen coaxial cannula assembly. The assembly includes a first infusion tube having a first elongate body defining a first lumen therethrough, the first infusion tube having a proximal end, a distal end, and a sidewall extending circumferentially therebetween. The assembly also includes a second drainage tube co-axially aligned with the first infusion tube and having a second elongate body with a second lumen defined by a space between the first infusion tube and second drainage tube, the second drainage tube having a proximal end, a distal end, and a sidewall extending circumferentially therebetween. The assembly further includes a connector assembly, wherein the connector assembly includes an inlet portion through which a portion of the first infusion tube is configured to extend and outlet portion through which a portion of the second drainage tube is configured to extend. Additionally, the connector assembly is configured to enable selective axial displacement of the first infusion tube through the second drainage tube. Furthermore, the connector assembly includes a first valve positioned circumferentially around a portion of the first infusion tube to secure the first infusion tube relative to the connector assembly.

In some embodiments, the first valve is configured as a passive valve.

In some embodiments, the first valve is an O-ring.

In some embodiments, the connector assembly includes a second valve positioned circumferentially around another portion of the first infusion tube to secure the first infusion tube relative to the connector assembly.

In some embodiments, the second valve is configured as an active valve.

In some embodiments, the second valve is a Tuohy-Borst valve.

In some embodiments, the second valve includes at least one sensor configured to provide feedback regarding the securement of the first infusion tube relative to the second valve.

In some embodiments, the at least one sensor includes at least one of a pressure transducer and an axial force strain gauge.

In some embodiments, the assembly further includes a side-port connection positioned between the first valve and the second valve of the connector assembly.

In some embodiments, the assembly further includes an embolic protection device positioned between the first valve and the second valve of the connector assembly.

In some embodiments, the first infusion tube includes at least a first magnet of a first polarity and a second magnet of the first polarity positioned along the first elongate body, and further wherein the second drainage tube comprises a third magnet of a second polarity positioned proximate to a distal end thereof.

In some embodiments, the first magnet is positioned to represent a distal length limit of the first infusion tube and the second magnet is positioned to represent a proximal length limit of the first infusion tube.

In some embodiments, the assembly further includes at least one intermediate magnet positioned between the first magnet and the second magnet on the first infusion tube.

In some embodiments, the first infusion tube includes a plurality of infusion apertures provided at the distal end, the infusion apertures extending through the sidewall of the first infusion tube.

In some embodiments, the second drainage tube includes a plurality of drainage apertures provided at the distal end, the drainage apertures extending through the sidewall of the second drainage tube.

Herein described but not part of the invention is a method of assisting a patient's heart. The method includes providing a dual lumen coaxial cannula assembly including a first infusion tube having a first elongate body defining a first lumen therethrough, the first infusion tube having a proximal end, a distal end, and a sidewall extending circumferentially therebetween, a second drainage tube co-axially aligned with the first infusion tube and having a second elongate body with a second lumen defined by a space between the first infusion tube and second drainage tube, the second drainage tube having a proximal end, a distal end, and a sidewall extending circumferentially therebetween, and a connector assembly, wherein the connector assembly comprises an inlet portion through which a portion of the first infusion tube is configured to extend and outlet portion through which a portion of the second drainage tube is configured to extend. The connector assembly is configured to enable selective axial displacement of the first infusion tube through the second drainage tube. The method further includes inserting the dual lumen coaxial cannula into an internal jugular vein of the patient, the dual lumen coaxial cannula having a length to extend from the patient's neck area to the patient's heart. The method includes maneuvering the dual lumen coaxial cannula through the patient's vasculature such that the first distal end of the first infusion tube is at least within proximity of the patient's pulmonary artery and such that the second distal end of the second drainage tube is at least within proximity of the patient's right atrium. The method also includes adjusting an axial position of the first distal end of the first infusion tube relative to the second distal end of the second drainage tube. The method includes securing the first infusion tube in a selected axial position relative to the second drainage tube. The method further includes connecting the dual lumen coaxial cannula to a blood pump for establishing right ventricular support.

In some cases, securing the first infusion tube in the selected axial position includes tightening a valve around a portion of the first infusion tube, wherein the valve is positioned on the connector assembly.

In some cases, the method further includes providing at least a first magnet of a first polarity and a second magnet of the first polarity along the first elongate body of the first infusion tube, and providing a third magnet of a second polarity proximate to a distal end of the second drainage tube, wherein the first magnet and the second magnet provide tactile feedback regarding a position of the first infusion tube relative to the third magnet of the second drainage tube.

In some cases, blood from the blood pump is delivered to the patient's pulmonary artery through a plurality of infusion apertures of the first infusion tube, and blood is withdrawn from the patient's right atrium through a plurality of drainage apertures of the second drainage cannula.

Further details and advantages of the present disclosure will be understood from the following detailed description read in conjunction with the accompanying drawings.

For purposes of the description hereinafter, the terms "end," "upper," "lower," "right," "left," "vertical," "horizontal," "top," "bottom," "lateral," "longitudinal," and derivatives thereof shall relate to the invention as it is oriented in the drawing figures. However, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments or aspects. Hence, specific dimensions and other physical characteristics related to the embodiments or aspects disclosed herein are not to be considered as limiting.

As used herein, the term "at least one of" is synonymous with "one or more of'. For example, the phrase "at least one of A, B, and C" means any one of A, B, and C, or any combination of any two or more of A, B, and C. For example, "at least one of A, B, and C" includes one or more of A alone; or one or more B alone; or one or more of C alone; or one or more of A and one or more of B; or one or more of A and one or more of C; or one or more of B and one or more of C; or one or more of all of A, B, and C. Similarly, as used herein, the term "at least two of" is synonymous with "two or more of'. For example, the phrase "at least two of D, E, and F" means any combination of any two or more of D, E, and F. For example, "at least two of D, E, and F" includes one or more of D and one or more of E; or one or more of D and one or more of F; or one or more of E and one or more of F; or one or more of all of D, E, and F.

When used in relation to a cannula, catheter, or other device inserted into a patient, the term "proximal" refers to a portion of such device farther from the end of the device inserted into the patient. When used in relation to a cannula, catheter, or other device inserted into a patient, the term "distal" refers to a portion of such device nearer to the end of the device inserted into the patient.

Referring to the drawings, in which like reference characters refer to like parts throughout the several views thereof, various embodiments of a coaxial, dual lumen cannula <NUM> (hereinafter referred to as "coaxial cannula <NUM>") are shown. With initial reference to <FIG>, the assembled coaxial cannula <NUM>, according to one embodiment, generally includes a first infusion tube <NUM> and a second drainage tube <NUM>, with the first infusion tube <NUM> configured to pass through the second drainage tube <NUM>. As will be described in further detail hereinbelow, the length of the first infusion tube <NUM> relative to the length of the second drainage tube <NUM> is configured to be adjustable so as to account for patient size and/or patient vessel length.

The first infusion tube <NUM> is disposed within the second drainage tube <NUM> in a coaxial arrangement centered about a central axis <NUM>. Each of the first infusion tube <NUM> and the second drainage tube <NUM> has a first circumference defining a first lumen and a second circumference defining a second lumen, respectively. The first circumference of the first infusion tube <NUM> is smaller than the second circumference of the second drainage tube <NUM> such that the first infusion tube <NUM> may be placed within the second lumen of the second drainage tube <NUM>. One or both of the first infusion tube <NUM> and the second drainage tube <NUM> may be manufactured from a medical-grade material such as polyurethane. Alternatively, the tubes may be made from PVC or silicone, and may be dip molded, extruded, co-molded, or made using any other suitable manufacturing technique.

The coaxial cannula <NUM> has sufficient placement flexibility adapted for placement of the coaxial cannula <NUM> within a patient's body. Desirably, a vascular insertion site is provided at the internal jugular vein on the patient's neck area. The coaxial cannula <NUM> is adapted for placement above or below the right atrium of the patient's heart. The coaxial cannula <NUM> may be used with an introducer to guide the placement of the coaxial cannula <NUM> as it is inserted within the patient's body.

With continuing reference to <FIG>, the coaxial cannula <NUM> is designed to withdraw blood directly from the patient's heart and return blood back into the patient's heart. The function of the first infusion tube <NUM> is to deliver blood into the blood stream of the patient, while the function of the second drainage tube <NUM> is to drain the blood from the patient's bloodstream as will be described hereafter.

A plurality of infusion apertures <NUM> are provided near a distal end of the first infusion tube <NUM>, and the distal end of the infusion tube includes an infusion opening <NUM>. The plurality of infusion apertures <NUM> are desirably arranged in a circular pattern extending around the outer circumference of the first infusion tube <NUM>. In some embodiments, the plurality of infusion apertures <NUM> may be disposed in multiple groups provided at various sites on the first infusion tube <NUM>. Similarly, the second drainage tube <NUM> includes a plurality of drainage apertures <NUM> provided at a distal end of the second drainage tube <NUM>. The plurality of drainage apertures <NUM> are desirably arranged in a circular pattern extending around the outer circumference of the second drainage tube <NUM>. In alternative embodiments, the plurality of drainage apertures <NUM> may be arranged in groups disposed at various sites along the length of the second drainage tube <NUM>.

The infusion apertures <NUM> are separated from the drainage apertures <NUM> by a variable distance D. In different embodiments of the coaxial cannula <NUM>, the separation of infusion apertures <NUM> from drainage apertures <NUM> determines the amount of mixing of oxygenated blood and unoxygenated blood. As will be described in further detail below, the distance D may be varied by user adjustment of first infusion tube <NUM> with respect to the second drainage tube <NUM> along the central axis <NUM>. The user may axially displace (i.e., push or pull) the first infusion tube <NUM> through the second drainage tube <NUM> until an acceptable and desired distance D is attained. In this way, the distance D may be altered based on, e.g., the age and/or size of the patient, as well as the desired flow rates during the medical procedure where the coaxial cannula <NUM> is used. For example, a distance D may be varied between <NUM> and <NUM>. More specifically, in some embodiments, the distance D may be varied between <NUM> and <NUM>. However, it is to be understood that the distance D is not limited to these lengths, and may be varied between lengths lesser or greater than those described herein.

With continuing reference to <FIG>, a Y-shaped connector assembly <NUM> is provided at the proximal end of the coaxial cannula <NUM>. Portions of the Y-shaped connector assembly <NUM> may be made substantially from polycarbonate as an example, but could also be made from PVC, acrylic, or polyurethane. The Y-shaped connector assembly <NUM> may be constructed using one or more manufacturing techniques including injection molding, machining, or dip forming. One of ordinary skill in the art will understand that a variety of other manufacturing techniques may be used for constructing the Y-shaped connector assembly <NUM> without departing from the intended scope of the invention. Additionally, while a connector assembly <NUM> is shown and described herein as being Y-shaped, it is to be understood that connector assembly <NUM> may be formed in other shapes and configurations.

The Y-shaped connector assembly <NUM> includes an inlet portion <NUM> in fluid communication with the first infusion tube <NUM> to transfer blood from a blood pump (not shown) to the first infusion tube <NUM>. An outlet portion <NUM> of the Y-shaped connector assembly <NUM> is in fluid communication with the second drainage tube <NUM> to transfer blood from the second drainage tube <NUM> to the blood pump. The outlet portion <NUM> and the inlet portion <NUM> of the Y-shaped connector assembly <NUM> are arranged such that the fluid pathways leading from the second drainage tube <NUM> and to the first infusion tube <NUM> transition from a coaxial arrangement at a distal end of the Y-shaped connector assembly <NUM> to an axially-offset arrangement at a proximal end of the Y-shaped connector assembly <NUM>.

Referring to <FIG>, the details of Y-shaped connector assembly <NUM> and the coupling of coaxial cannula <NUM> with Y-shaped connector assembly <NUM> are shown. As described above, the first infusion tube <NUM> is configured to extend through inlet portion <NUM> of Y-shaped connector assembly <NUM>, while the outlet portion <NUM> acts as the fluid pathway for second drainage tube <NUM>. The first infusion tube <NUM> is configured to be capable of user-controlled axial displacement through inlet portion <NUM> in both the distal and proximal directions. That is, the user may feed the first infusion tube <NUM> through the inlet portion <NUM> and the second drainage tube <NUM> in the distal direction, thereby increasing the length of the first infusion tube <NUM> relative to the distal end of the second drainage tube <NUM>. Conversely, if the user pulls the first infusion tube <NUM> in the proximal direction, the length of the first infusion tube <NUM> relative to the distal end of the second drainage tube <NUM> decreases. Accordingly, the Y-shaped connector assembly <NUM> and coaxial cannula <NUM> enables user adjustment of the length of the first infusion tube <NUM> relative to the second drainage tube <NUM>.

In one embodiment, the first infusion tube <NUM> includes a first helical coil <NUM> extending through at least a portion of the length thereof, while the second drainage tube <NUM> includes a second helical coil <NUM> extending through at least a portion of the length thereof. The first helical coil <NUM> and/or the second helical coil <NUM> may be manufactured from medical-grade metal or plastic and may act to minimize kinking and/or collapse of the first infusion tube <NUM> and/or the second drainage tube <NUM>.

In addition to serving as a junction for the first infusion tube and second drainage tube <NUM> to form coaxial cannula <NUM>, the Y-shaped connector assembly <NUM> further includes a valve system configured to both control movement of first infusion tube <NUM> and enable blood management by, e.g., minimizing thrombus formation, controlling blood loss, etc..

Specifically, as shown in <FIG>, Y-shaped connector assembly <NUM> includes a distal valve <NUM> located at or near the location where inlet portion <NUM> and outlet portion <NUM> meet to form a common lumen portion <NUM>. The distal valve <NUM> is positioned and configured to provide a smooth transition between the inlet portion <NUM> and the common lumen portion <NUM> of Y-shaped connector assembly <NUM>, thereby minimizing blood flow disruption and potential thrombus formation due to such blood flow disruption.

Additionally, distal valve <NUM> is configured to at least partially secure the first infusion tube <NUM> relative to the Y-shaped connector assembly <NUM>, while still allowing for selective axial movement of the first infusion tube <NUM> through the Y-shaped connector assembly <NUM> and the second drainage tube <NUM>. For example, in one embodiment, distal valve <NUM> is configured to function passively as an O-ring, wherein the opening of the O-ring is slightly smaller in diameter than the outer diameter of first infusion tube <NUM>. The O-ring may be formed of any appropriate medical grade material such as, e.g., polyurethane, PVC, or silicone. In this way, the O-ring forming distal valve <NUM> provides a friction fit over the outer diameter of first infusion tube <NUM>, both securing the first infusion tube <NUM> and preventing blood to flow past distal valve <NUM>, thereby mitigating thrombus formation, blood loss, etc. However, the friction fit of the distal valve <NUM> is configured to allow axial movement of first infusion tube <NUM> upon user-directed force on the first infusion tube <NUM>, thereby allowing the overall length of first infusion tube <NUM> to be adjusted relative to second drainage tube <NUM>, as described above.

Alternatively, in another embodiment, and in lieu of a passive configuration, distal valve <NUM> may be configured as an active valve incorporating, e.g., a dial or button (not shown) located outside of the Y-shaped connector assembly for manipulation by the user in order to selectively secure and/or release the first infusion tube <NUM>.

Referring still to <FIG>, in addition to distal valve <NUM>, Y-shaped connector assembly <NUM> may further include a second, proximal valve <NUM> positioned along the inlet portion <NUM>. Proximal valve <NUM> is configured to provide redundancy and a factor of safety with respect to securement of first infusion tube <NUM>, working in conjunction with distal valve <NUM> to secure first infusion tube <NUM> in place once the user has positioned the first infusion tube <NUM> at a desired length relative to second drainage tube <NUM>.

In one embodiment, proximal valve <NUM> is a manually activated valve such as, e.g., a Tuohy-Borst valve. Accordingly, proximal valve <NUM> includes a rotatable cap <NUM>, which surrounds the first infusion tube <NUM>. If the user rotates the cap <NUM> in a clockwise direction, an inner ring (not shown) of the proximal valve <NUM> compresses along the outer surface of the first infusion tube <NUM>, thereby acting to secure the first infusion tube <NUM> in place. Conversely, if the user rotates the cap <NUM> in a counterclockwise direction, the inner ring releases from the outer surface of the first infusion tube <NUM>, thereby allowing first infusion tube <NUM> to be axially displaced relative to the Y-shaped connector assembly <NUM>. In this way, the proximal valve <NUM> may act as the primary means for securement of the first infusion tube <NUM>, particularly if distal valve <NUM> is configured as a passive valve (e.g., an O-ring).

In addition to providing securement of the first infusion tube <NUM>, in one embodiment, proximal valve <NUM> also serves as a secondary source of blood management within the Y-shaped connector assembly <NUM>. That is, when the inner ring of the proximal valve <NUM> is tightened around the first infusion tube <NUM> in order to secure first infusion tube <NUM> prior to use, blood is prevented from traveling through (and potentially leaking from) the inlet portion <NUM> of the Y-shaped connector assembly <NUM>. As such, thrombus formation and/or blood loss within the valve system of Y-shaped connector assembly <NUM> is substantially prevented, particularly when proximal valve <NUM> is utilized in series with distal valve <NUM>.

The proximal valve <NUM> may include one or more means for providing pressure or axial force feedback indicative of a sufficient securement and/or seal around the first infusion tube <NUM>. For example, in one embodiment, the proximal valve <NUM> includes at least one sensor <NUM>, wherein the at least one sensor <NUM> is configured to provide feedback regarding the securement of the proximal valve <NUM> around the first infusion tube <NUM>. In one embodiment, the at least one sensor <NUM> may be configured as a pressure transducer. In another embodiment, the at least one sensor <NUM> may be configured as an axial force strain gauge. The at least one sensor <NUM> may transmit the feedback relating to securement of the first infusion tube <NUM> to a remote controller and/or user interface via either a wired or wireless connection. Alternatively, the proximal valve <NUM> may incorporate one or more indicators (e.g., LEDs) capable of communicating the feedback from the at least one sensor <NUM> to the user.

In another embodiment, in lieu of (or in addition to) the distal valve <NUM> and/or the proximal valve <NUM>, the Y-shaped connector assembly <NUM> may include a toothed ring (not shown) sized and configured to contact and surround the first infusion tube <NUM>. The toothed ring includes a plurality of teeth directed radially inward and angled in a distal direction relative to the Y-shaped connector assembly <NUM>. With this configuration, the toothed ring enables the first infusion tube <NUM> to be axially moved/adjusted in the distal direction, as the first infusion tube <NUM> is able to pass through the opening formed by the plurality of teeth due to the tooth angulation in the distal direction. However, the toothed ring is configured to substantially restrict or prevent movement of the first infusion tube <NUM> in the opposite (i.e., proximal) direction, as such movement causes the plurality of teeth to bend in the proximal direction, thereby reducing the circumference of the passage formed by the toothed ring around the first infusion tube <NUM>, which causes the plurality of teeth to "bite" into the outer sidewall of the first infusion tube <NUM>. In this way, the toothed ring may provide for at least supplemental securement of the first infusion tube <NUM> relative to the Y-shaped connector assembly <NUM>.

Referring still to <FIG>, and in accordance with another aspect of the present disclosure, Y-shaped connector assembly <NUM> further includes a side port connection <NUM> positioned between the distal valve <NUM> and the proximal valve <NUM>. The side-port connection <NUM> is configured to enable proper management of the space between the respective valves <NUM>, <NUM> by way of, e.g., a barb connector accessible to the user. More specifically, during initial set-up of the coaxial cannula <NUM>, the side-port connection <NUM> can be utilized for de-airing the space between the respective valves <NUM>, <NUM>. Additionally and/or alternatively, the side-port connection <NUM> can be used to establish a heparin lock in the space between valves <NUM>, <NUM> in order to minimize or prevent blood stasis. By injecting heparin, an anti-coagulant, into the space between the valves <NUM>, <NUM> via the side-port connection <NUM>, blood is able to flow more smoothly through the space, and potential clotting may be better prevented. Furthermore, in one embodiment, the side-port connection <NUM> can be used during patient support in order to manage the valve space as needed to minimize or prevent blood stasis.

Next, referring to <FIG>, another aspect of the present disclosure with respect to Y-shaped connector assembly <NUM> is shown. Specifically, an embolic protection device <NUM> may be deployed within the valve space between respective valves <NUM>, <NUM>. Embolic protection device <NUM> may be in the form of, e.g., a filter or basket capable of capturing a thrombus or clot before the thrombus or clot enters the patient's blood stream. That is, if a thrombus or clot were to form in the space between the distal valve <NUM> and the proximal valve <NUM> of Y-shaped connector assembly <NUM> due to blood stasis, the embolic protection device <NUM> serves to substantially prevent the thrombus or clot from traveling beyond the valve space, thereby substantially reducing the risk of an embolic event. While embolic protection device <NUM> is shown as a filter or basket in <FIG>, it is to be understood that embolic protection device <NUM> may be any appropriate device capable of filtering. Furthermore, while shown as placed in the space between the distal valve <NUM> and the proximal valve <NUM> in <FIG>, it is to be understood that embolic protection device <NUM> may be situated elsewhere in the Y-shaped connector assembly <NUM> and/or the coaxial cannula <NUM>.

With reference to <FIG>, another aspect of the present disclosure is shown. As described above, the first infusion tube <NUM> is capable of axial adjustment/movement relative to second drainage tube <NUM>. However, in order for the user to establish the desired position of the infusion apertures <NUM> of the first infusion tube <NUM> relative to the drainage apertures <NUM> of the second drainage tube <NUM> when such axial adjustment is made with the coaxial cannula <NUM> within the patient's body, there is a need for the user to receive feedback as to the position of the first infusion tube <NUM>. Accordingly, in one embodiment, the coaxial cannula <NUM> may include a plurality of magnets configured to provide incremental tactile feedback to the user as the first infusion tube <NUM> is moved through the second drainage tube <NUM>.

Specifically, as shown in <FIG>, the second drainage tube <NUM> includes a first magnet <NUM> having a first polarity positioned at or near a distal end portion <NUM> thereof. In one embodiment, the first magnet <NUM> may be ring-shaped and may extend circumferentially around (or within) the sidewall of the second drainage tube <NUM>. Alternatively, the first magnet <NUM> may include one or more distinct magnets placed along the circumference of the second drainage tube <NUM>. The first infusion tube <NUM> includes a second magnet <NUM>, a third magnet <NUM>, a fourth magnet <NUM>, and a fifth magnet <NUM>, with each of magnets <NUM>, <NUM>, <NUM>, <NUM> having a second polarity opposite that of the first polarity of first magnet <NUM>.

In the example shown in <FIG>, the second magnet <NUM> is positioned to represent the distal length limit of first infusion tube <NUM> (i.e., the greatest allowable length between the distal end of the first infusion tube <NUM> and the distal end of the second drainage tube <NUM>), while the third magnet <NUM> is positioned to represent the proximal length limit of the infusion tube <NUM> (i.e., the least allowable length between the distal end of the first infusion tube <NUM> and the distal end of the second drainage tube <NUM>). The distal length limit of the first infusion tube <NUM>, represented by second magnet <NUM>, may be defined to minimize pressure drop and enable the coaxial cannula <NUM> to achieve blood flows needed to provide adequate circulatory support. In some embodiments, the maximum length of first infusion tube <NUM> may be <NUM>, while the minimum length of first infusion tube <NUM> may be <NUM>. However, it is to be understood that the maximum and minimum lengths of first infusion tube <NUM> are not limited to the above range.

The fourth magnet <NUM> and fifth magnet <NUM> are incrementally positioned between the second magnet <NUM> and the third magnet <NUM>. Similar to the first magnet <NUM>, each of magnets <NUM>, <NUM>, <NUM>, <NUM> may be ring-shaped and may extend circumferentially around (or within) the sidewall of the first infusion tube <NUM>. Alternatively, the magnets <NUM>, <NUM>, <NUM>, <NUM> may include one or more distinct magnets placed along the circumference of the first infusion tube <NUM>. Furthermore, while four total magnets are shown in <FIG>, it is to be understood that more or fewer magnets may be utilized.

During use of the coaxial cannula <NUM> and axial displacement of the first infusion tube <NUM> relative to the second drainage tube <NUM>, the user will receive tactile feedback as each of the magnets <NUM>, <NUM>, <NUM>, <NUM> of the first infusion tube <NUM> pass the first magnet <NUM> of the second drainage tube <NUM> due to the magnets' opposing polarities. In this way, the user receives a tactile indication of the precise position of the first infusion tube <NUM> relative to the second drainage tube <NUM>, including the proximal length limit (from third magnet <NUM>) and the distal length limit (from second magnet <NUM>). The magnets <NUM>, <NUM>, <NUM>, <NUM> may be spaced apart at known increments (e.g., <NUM>) such that the user can precisely position and secure the first infusion tube <NUM> at a desired length relative to the second drainage tube <NUM>.

While the example described with respect to <FIG> utilizes magnets to provide tactile feedback to the user regarding the positioning of the first infusion tube <NUM>, it is to be understood that other forms of tactile and non-tactile feedback may be utilized for such purposes. For example, in lieu of magnets, a plurality of rings or ridges may be provided at spaced-apart locations on the first infusion tube <NUM>, and the distal end of the second drainage tube <NUM> may be slightly undersized as compared to other portions of the second drainage tube <NUM>. Thus, as the rings/ridges pass the undersized portion of the second drainage tube <NUM>, the user would sense a slight interference fit, thereby providing for tactile feedback as the first infusion tube <NUM> is positioned relative to second drainage tube <NUM>. Alternatively, instead of the rings/ridges being located near the distal end of first infusion tube <NUM> and the tactile feedback being provided by passage through the undersized distal end of the second drainage tube <NUM>, the rings/ridges may be provided nearer the proximal end of the first infusion tube <NUM>, with the undersized portion of the second drainage tube <NUM> also being provided at or near a proximal end thereof. With this configuration, direct blood flow over the rings/ridges on first infusion tube <NUM> may be avoided.

Claim 1:
A dual lumen coaxial cannula assembly (<NUM>) comprising:
a first infusion tube (<NUM>) having a first elongate body defining a first lumen therethrough, the first infusion tube having a proximal end, a distal end, and a sidewall extending circumferentially therebetween;
a second drainage tube (<NUM>) co-axially aligned with the first infusion tube and having a second elongate body with a second lumen defined by a space between the first infusion tube and second drainage tube, the second drainage tube having a proximal end, a distal end, and a sidewall extending circumferentially therebetween; and
a connector assembly (<NUM>), wherein the connector assembly comprises an inlet portion (<NUM>) through which a portion of the first infusion tube (<NUM>) is configured to extend, an outlet portion (<NUM>) through which a portion of the second drainage tube (<NUM>) is configured to extend, and a first valve (<NUM>) positioned circumferentially around a portion of the first infusion tube (<NUM>) to secure the first infusion tube relative to the connector assembly;
wherein the connector assembly is configured to enable selective axial displacement of the first infusion tube through the second drainage tube.