Patent Publication Number: US-2023149042-A1

Title: Needle and cannula assembly for cannulation and treatment of subcutaneous vessels

Description:
TECHNICAL FIELD 
     The present invention relates to assemblies and methods for use in various procedures in which cannulation of a subcutaneous vessel is needed. More particularly, the present invention relates to a needle that exhibits different reflectance characteristics for improved ultrasound visualization, and a cannula assembly that can be used to treat a puncture site within a wall of a subcutaneous vessel and/or to monitor for the development of a hematoma following cannulation. 
     BACKGROUND 
     Many medical procedures require cannulation of subcutaneous vessels, especially arteries. For example, it may be necessary to perform an arteriogram of a leg or heart artery to determine if blockages are present. Cannulation procedures of this type generally require that a percutaneous tubular cannula be inserted through a patient&#39;s skin and into a subcutaneous vessel. This of course necessitates that an incision or hole be made in the defining wall of the subcutaneous vessel in order to accommodate the cannula body. Various methods exist for accomplishing this task. For example,  FIGS.  1 A- 1 E , in sequence, depict one known cannulation procedure in which a cannula  10  is introduced into a subcutaneous vessel  14  within the body of a patient. As shown, the cannula  10  is of known construction and includes a hollow shaft  12  with a distal end configured to be inserted into the subcutaneous vessel  14  of the patent and a side arm (depicted as a tube), for use in cannulation or catheterization procedures where a passageway is created to a subcutaneous vessel  14 , such as a blood vessel, a vein, or an artery. In the known cannulation procedure, an incision is typically made through a skin layer  20  of the body of the patient adjacent to the subcutaneous vessel  14 , and the skin layer  20  and the subcutaneous tissue  21  are spread apart by forceps (not shown). A hollow needle  16  with a tip  18  is then inserted into the patient&#39;s body through the incision and guided via ultrasonography using an ultrasound device  31  placed on the surface of the skin  20  of the patient until the tip  18  of the needle  16  punctures a wall  22  of the subcutaneous vessel  14 , creating a hole  22   a  (or puncture site  22   a ) through the wall  22  of the subcutaneous vessel  14 , as shown in  FIG.  1 A . Proper placement of needle  16  can then be confirmed by passage of blood coming out of a proximal hub  24  of the needle  16 . 
     Following insertion of the needle  16 , a guidewire  28  is inserted through needle  16  and deposited within the subcutaneous vessel  14 , as shown in  FIG.  1 B . Once the guidewire  28  is deposited, the needle  16  is subsequently removed, as shown in  FIG.  1 C . The cannula  10 , which, in this case, is equipped with a hollow internal dilator  30  is inserted over the guidewire  28  until the distal end of shaft  12  is deposited within the subcutaneous vessel  14 , as shown in  FIG.  1 D . Once the distal end of the shaft  12  of the cannula  10  is deposited within the subcutaneous vessel  14 , the guidewire  28  and internal dilator  30  are removed, leaving only the cannula  10 , as shown in  FIG.  1 E . At this point, the cannula  10  is ready for use in the intended medical procedure. 
     After the medical procedure for which the cannula  10  was inserted is finished, the cannula  10  is removed from the subcutaneous vessel, leaving a puncture site  22   a  in the subcutaneous vessel  14  which must be closed, especially if the subcutaneous vessel is an artery since the pressure of blood inside an artery is much higher than that of a vein, thereby increasing the bleeding risk from the puncture site in the artery as compared to a vein. Many techniques are thus known for closing a puncture site. The simplest technique to close the puncture site is to apply manual pressure (e.g., by two fingers  33 ) to the skin overlying the puncture site, as shown in  FIG.  1 F . Such pressure must be strong enough to be transmitted through the subcutaneous tissue  21  underlying the skin  20  and onto the puncture site  22   a  in the subcutaneous vessel  14  so that the tissue overlying the puncture site prevents the flow of blood out of the puncture site  22   a , thereby leading to formation of blood clot  35  in the puncture site  22   a , as also shown in  FIG.  1 F . Gradually, the blood clot becomes strong enough to keep the puncture site  22   a  closed, even after manual pressure over the skin is removed. The skin  20  and underlying tissue  21  surrounding the skin puncture site are periodically examined after the application of manual pressure to ensure the blood clot  35  has remained intact in the puncture site  22   a  in the subcutaneous vessel  14 . This is done by visual inspection and palpation. If the puncture site  22   a  in the subcutaneous vessel  14  is not completely closed, then bleeding occurs into the subcutaneous tissue  21  overlying the subcutaneous vessel  21 , thus forming a hematoma  34 , palpated as a mass and visualized as a swelling, as shown in  FIG.  1 G . Such bleeding can also extend out of the skin incision. 
     The method of insertion of cannula into a subcutaneous vessel and removal of the cannula from a subcutaneous vessel can thus generally be divided into three steps. First, the needle is inserted into the subcutaneous vessel, commonly with ultrasound guidance, followed by insertion of cannula in the manner described above. Second, the cannula is removed and the puncture site within the subcutaneous vessel is closed by manual application of pressure to the skin overlying the hold. Finally, the puncture site is monitored by intermittently examining the puncture site and the skin around it by visual inspection and palpation in the manner described above. However, there are inherent problems with each of these steps. 
     With respect to visualization of the needle tip using ultrasound guidance, the needle tip and remainder of the shaft of the needle have the same ultrasonic reflectance characteristics, which can mislead a physician to direct the needle tip to the side of a subcutaneous vessel instead of toward the subcutaneous vessel as the needle is advanced. In this regard, the inherent problem of visualizing the tip of the needle is that the tip of the needle and the shaft of the needle are located in a plane different from the plane of the ultrasound waves, thus making it extremely difficult to be certain that the echogenic structure, seen by ultrasound is truly the tip of the needle and not simply a segment of the shaft of the needle. Although attempts have been made in the art to solve this problem (as evidenced, e.g., by U.S. Pat. Nos. 4,401,124, 5,766,135, and 10,188,467), such attempts have not improved the visualization of the tips of needles which are commonly used. Hence, there is a real and unsatisfied need for improving the visualization of the tip of the needle. 
     With respect to the application of manual pressure of the skin overlying the puncture site in the subcutaneous vessel, such pressure can be quite painful. This is especially true when the subcutaneous vessel is deeper and much larger pressure needs to be applied so that enough pressure can be transmitted through flexible subcutaneous tissue. Additionally, in deeper located subcutaneous vessels, the pressure may not necessarily be transmitted in the intended direction and thus may be less effective in closing the puncture site in the subcutaneous vessel. The inherent problems with manual application of pressure thus include discomfort experienced by the patient during the application of pressure and less than desired success in closing the puncture site in the subcutaneous vessel following removal of the cannula. With respect to the former, discomfort is especially noticeable in obese patients who have subcutaneous vessels that are located more deeply beneath the skin. In such patients, the puncture site in the subcutaneous vessel requires a much larger pressure after removal of the cannula due to the larger depth of intermediary subcutaneous tissue and due to the fact that pressure dissipates as depth increases. Additionally, the area of skin on which pressure is applied is proximal to the site of entry into the skin. As such, the area of skin, on which pressure is applied is at best an estimate and may not necessarily correspond to the vertical position over the puncture site in the deeply located subcutaneous vessel. In such cases, blood may thus continue to exit the puncture site resulting in the formation of hematoma in the subcutaneous tissue or bleeding out of the skin incision. 
     Finally, with respect to monitoring the puncture site for bleeding and surrounding skin for formation of hematoma by examining intermittently, bleeding may occur and a hematoma may develop in the subcutaneous tissue overlying the subcutaneous vessel puncture site during the periods between examination. If such bleeding is severe, it could be fatal or require transfusion of blood to patient. The inherent problem with monitoring the skin incision for bleeding and surrounding skin for formation of hematoma is thus due to the lack of continuous monitoring. However, no automated means that would provide desired continuous monitoring currently exist in common use. 
     Accordingly, percutaneous needle and cannula assemblies helping to cure the above-identified problems would be both highly desirable and beneficial. 
     SUMMARY 
     The present invention relates to assemblies and methods for use in various procedures in which cannulation of a subcutaneous vessel is needed. More particularly, the present invention relates to a needle which exhibits different reflectance characteristics for improved ultrasound visualization, and a cannula assembly which can be used to treat a puncture site within a wall of a subcutaneous vessel and/or monitor for the development hematoma following cannulation. 
     An exemplary cannula assembly for treating a puncture site in a subcutaneous vessel of a patient includes a cannula and an elongated sleeve configured to receive the cannula. The cannula includes a shaft which defines a distal end configured to be inserted into the subcutaneous vessel of the patient. The elongated sleeve includes: a proximal end, a distal end that is configured to be inserted into subcutaneous tissue of the patient and proximal to a puncture site of the subcutaneous vessel, and a bore that extends from the proximal end to the distal end of the elongated sleeve and in which the cannula is received. To promote the formation of a seal between the distal end of the sleeve and the subcutaneous puncture site around the puncture site, the elongated sleeve further includes a plurality of channels circumferentially spaced about the bore through which a flow of air can be drawn and/or a plurality of wires can be advanced into the subcutaneous vessel. 
     In some embodiments, the proximal end of the elongated sleeve includes a valve which is configured to form a seal around the cannula when the shaft of the cannula is inserted within the bore of the elongated sleeve. In some embodiments, the sleeve is constructed so that the respective channels are interconnected (i.e., in fluid communication with) one another, such that when a port of the sleeve is placed in fluid communication with a vacuum source, a flow of air is drawn upwardly through the respective channels of the plurality of channels. 
     The cannula assembly can, in some embodiments, further comprises a plug which can be inserted into the bore of the elongated sleeve following removal of the cannula from the sleeve. The length of the plug is such that, in use, the distal end of the plug applies direct pressure to the puncture site when fully inserted into the bore of the elongated sleeve. In some embodiments, a thrombotic material configured to promote thrombosis at the puncture site is deposited on the distal end of the plug. In some embodiments, at least one electrically conductive plate configured to be placed in contact with the puncture site is connected to the distal end of the plug. In such embodiments, the electrically conductive plate(s) is operably connected to an electrical source, such that an electrical current can be selectively applied to the electrically conductive plate(s) to cauterize subcutaneous tissue around the puncture site. 
     In some embodiments, the elongated sleeve includes a slide mounted for movement with respect to a proximal end of a main body of the elongated sleeve. In such embodiments, the slide is connected to a plurality of wires. In use, the slide can be selectively moved in a first direction to advance the plurality of wires into the subcutaneous vessel to promote the formation of a seal between the distal end of the sleeve and the subcutaneous vessel by urging a wall of the subcutaneous vessel toward the distal end of the sleeve. 
     In some embodiments, the sleeve of the cannula assembly includes an electrode (or first electrode) that is disposed on an outer surface of the distal end of the elongated sleeve and is configured to transmit electrical current to another electrode (or second electrode) disposed on an exterior surface of the skin of a patient or receive electrical current from the second electrode. In such embodiments, the first electrode and the second electrode are operably connected to a bioimpedance meter configured to measure impedance between the first electrode and the second electrode. 
     An exemplary needle for insertion into a subcutaneous vessel made in accordance with the present invention includes a rigid shaft and a hub connected to a proximal end of the rigid shaft. The rigid shaft includes a main body that defines a bore for receiving a guide wire that extends from a proximal end to a distal end of the rigid shaft, which terminates in a tip that is configured to puncture the subcutaneous vessel of the patient. The rigid shaft also includes a segment which is enlarged relative to the main body of the rigid shaft. In some embodiments, the enlarged segment may be rounded. 
     An exemplary method for cannulating a subcutaneous vessel of a patient which utilizes the exemplary needle and cannula assembly of the present invention is also described herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is a partial sectional view illustrating a first step in a prior art method for cannulating a subcutaneous vessel; 
         FIG.  1 B  is a partial sectional view similar to that of  FIG.  1 A , but illustrating a second step in the prior art method for cannulating a subcutaneous vessel; 
         FIG.  1 C  is a partial sectional view similar to that of  FIG.  1 B , but illustrating a third step in the prior art method for cannulating a subcutaneous vessel; 
         FIG.  1 D  is a partial sectional view similar to that of  FIG.  1 C , but illustrating a fourth step of the prior art method for cannulating a subcutaneous vessel; 
         FIG.  1 E  is a partial sectional view similar to that of  FIG.  1 D , but illustrating a fifth step of the prior art method for cannulating a subcutaneous vessel; 
         FIG.  1 F  is a partial sectional view illustrating a prior art method for promoting the formation of a blood clot following cannulation of a subcutaneous vessel; 
         FIG.  1 G  is a partial sectional view similar to that of  FIG.  1 F , but illustrating dislodging of the blood clot of  FIG.  1 F  and the formation of a hematoma; 
         FIG.  2 A  is a partial sectional view illustrating a first step of an exemplary method for cannulating a subcutaneous vessel of a patient in which an exemplary needle made in accordance with the present invention is visualized by ultrasound and inserted through skin, through subcutaneous tissue, and into the subcutaneous vessel of the patient; 
         FIG.  2 B  is a partial sectional view similar to  FIG.  2 A , but illustrating a second step in the exemplary method for cannulating a subcutaneous vessel of a patient in which a guidewire is passed through the exemplary needle of  FIG.  2 A ; 
         FIG.  2 C  is a partial sectional view similar to  FIG.  2 B , but illustrating a third step in the exemplary method for cannulating a subcutaneous vessel of a patient in which the exemplary needle of  FIG.  2 A  is removed, leaving the guidewire of  FIG.  2 B  in place; 
         FIG.  2 D  is a partial sectional view similar to  FIG.  2 C , but illustrating a fourth step in the exemplary method for cannulating a subcutaneous vessel of a patient in which an exemplary cannula assembly made in accordance with the present invention is placed over the guidewire and into place within the subcutaneous vessel; 
         FIG.  2 E  is a partial sectional view similar to  FIG.  2 D , but illustrating a fifth step in the exemplary method for cannulating a subcutaneous vessel of a patient in which the guidewire is removed, leaving the exemplary cannula assembly of  FIG.  2 D  in place; 
         FIG.  2 F  is a partial sectional view similar to  FIG.  2 E , but illustrating a sixth step in the exemplary method for cannulating a subcutaneous vessel of a patient in which a cannula of the exemplary cannula assembly of  FIG.  2 D  is removed, leaving a sleeve of the exemplary cannula assembly in place; 
         FIG.  2 G  is a partial sectional view similar to  FIG.  2 F , but illustrating a seventh step in the exemplary method for cannulating a subcutaneous vessel of a patient in which a plug is inserted through a bore of the sleeve of the exemplary cannula assembly; 
         FIG.  3    is a side view of the exemplary needle of  FIG.  2 A ; 
         FIG.  3 A  is an enlarged partial view of the exemplary needle of  FIG.  3   ; 
         FIG.  3 B  is a sectional view of the exemplary needle taken along  3 B- 3 B in  FIG.  3 A ; 
         FIG.  3 C  is a sectional view of the exemplary needle taken along  3 C- 3 C in  FIG.  3 C ; 
         FIG.  4    is a sectional view of the exemplary cannula assembly of  FIG.  2 E ; 
         FIG.  5    is a sectional view of the sleeve of  FIG.  2 F ; 
         FIG.  6 A  is sectional view of the sleeve of  FIG.  5    in isolation; 
         FIG.  6 B  is a sectional view of the sleeve of  FIG.  6 A  taken along line  6 B- 6 B in  FIG.  6 A ; 
         FIG.  6 C  is a partial perspective view of the sleeve of  FIG.  6 A ; 
         FIG.  6 D  is a side view of two electrodes for depositing on the skin of the patient and which may be utilized in combination with two electrodes provided on an outer surface of the distal end of the sleeve; 
         FIG.  6 E  is a sectional view of the plug of  FIG.  2 G  in isolation; 
         FIG.  6 F  is a sectional view of another plug, which may be utilized in the exemplary cannula assembly of  FIG.  2 D ; 
         FIG.  6 G  is a cross section view of another plug, which may be utilized in the exemplary cannula assembly of  FIG.  2 D ; 
         FIG.  6 H  is a side view an electrically conductive plate deposited on the skin of the patient and which may be utilized in combination with the electrically conductive plate of the plug of  FIG.  6 G ; 
         FIG.  7    is a sectional view of the exemplary cannula assembly of  FIG.  2 G ; 
         FIG.  8    is a sectional view of another sleeve for use in the exemplary cannula assembly; 
         FIG.  9    is another sectional view of the sleeve of  FIG.  8   ; 
         FIG.  10    is another sectional view of the sleeve of  FIG.  8   , but with the sleeve of the exemplary cannula assembly placed in the subcutaneous vessel of the patient; and 
         FIG.  11    is an exploded view of the sleeve of  FIG.  8   . 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The present invention includes assemblies and methods for use in various procedures in which cannulation of a subcutaneous vessel is needed. More particularly, the present invention includes a needle that exhibits different reflectance characteristics for improved ultrasound visualization, and a cannula assembly that can be used to treat a puncture site within a wall of a subcutaneous vessel and/or to monitor for the development hematoma following cannulation. 
       FIGS.  2 A- 2 G , in sequence, show an exemplary method for cannulating a subcutaneous vessel  14  of a patient, which utilizes an exemplary needle  62  ( FIGS.  2 A and  2 B ) and an exemplary cannula assembly  80  ( 2 D- 2 G) made in accordance with the present invention.  FIGS.  3  and  3 A -C show various views of the exemplary needle  62  or portions thereof. The needle  62  generally comprises a rigid shaft  64  and a hub  66  that is connected to a proximal end of the rigid shaft  64 . The rigid shaft  64  defines, and thus can be characterized as including, a main body  64   a  that defines a bore  71  which extends from the proximal end  70   a  of the rigid shaft  64  to a distal end  70   b  of the rigid shaft  64 . The distal end  70   b  of the rigid shaft  64  terminates in a tip  74  to facilitate puncturing of the wall  22  of the subcutaneous vessel  14 , as further described below. In this exemplary embodiment, the bore  71  of the rigid shaft  64  is of sufficient diameter to receive a guidewire  28 . The hub  66  of the needle  62  defines a lumen, which feeds into the bore  71  of the rigid shaft  64 , such that the lumen of the hub  66  and the bore  71  of the rigid shaft  64  define a pathway through which the guidewire  28  can travel through the needle  62  for deposit into the subcutaneous vessel  14 . Unlike needles of known construction, the rigid shaft  64  of the needle  62  further includes a segment  68  (or enlarged segment  68 ), which is enlarged relative to the remainder of the main body  64   a  of the rigid shaft  64 , and is positioned a predetermined distance  72  from the tip  74  of the rigid shaft  64 . 
     Referring now more particularly to  FIGS.  2 A,  2 B,  3 , and  3 A- 3 C , in this exemplary embodiment, the enlarged segment  68  is rounded and generally has the shape of a sphere with a radius ranging from about 2 mm-4 mm. Of course it is appreciated that the shape and size of the enlarged segment  68  can vary to accommodate different subcutaneous environments and applications without departing from the spirit and scope of the present invention, but the enlarged segment  68  generally exhibits a diameter, d 1 , which is greater than the diameter, d 2 , than the distal end  70   b  of the rigid shaft  64 , as shown in  FIGS.  3 B and  3 C . Further, it should be appreciated that the predetermined distance between the tip  74  of the rigid shaft  64  and the enlarged segment  68  may also vary depending on the known thickness of the wall  22  of the subcutaneous vessel  14  intended for cannulation. For instance, the enlarged segment  68  may be spaced a predetermined distance of approximately 2.5 mm for implementations in which the subcutaneous vessel  14  is a femoral artery, while the enlarged segment  68  may be spaced a predetermined distance of approximately 2 mm for implementations in which the subcutaneous vessel  14  is a radial artery. 
     Referring still to  FIGS.  2 A,  2 B,  3 , and  3 A- 3 C , the exemplary method for cannulating a subcutaneous vessel  14  of a patient (or exemplary method) commences with the tip  74  of the rigid shaft  64  of the needle  62  being inserted through the wall  22  and into the subcutaneous vessel  14  of the patient. As in the prior art method described above with reference to  FIGS.  1 A- 1 E , in this implementation, an ultrasound device  31 , or component thereof, such as a wand, is placed on the skin layer  20  overlying the subcutaneous vessel  14 , is utilized to help visualize and assist a physician in guiding the needle  62  into the subcutaneous vessel  14  until the tip  74  of the needle  62  punctures the wall  22 , thus creating a puncture site  22   a  through the wall  22  of the subcutaneous vessel  14 . Ultrasound devices which may be utilized in the above-described manner are readily known within the art, and, as such, are not described herein. 
     Referring still to  FIGS.  2 A,  2 B,  3 , and  3 A- 3 C , unlike the prior art method described above with reference to  FIGS.  1 A- 1 E , the enlarged segment  68  of the rigid shaft  64  of the needle  62 , exhibits different ultrasound reflectance characteristics than the main body  64   a  of the rigid shaft  64 . In other words, the enlarged segment  68  will reflect sound waves back to the ultrasound device  31  in a manner that is different from the manner in which the other portions of the main body  64   a  reflect the sound waves and thus will appear as a different visual profile (echogenic structure) on a display (not shown) of the ultrasound device  31  than the other portions of the main body  64   a  of the rigid shaft  64 . Accordingly, because the enlarged segment  68  is a known, predetermined distance  72  from the tip  74  of the rigid shaft  64 , the enlarged segment  68  thus provides an approximation as to where the tip  74  of the rigid shaft  64  is relative to the subcutaneous vessel  14 , thereby enabling a physician to more accurately direct the tip  74  into the subcutaneous vessel  14 . Furthermore, because the enlarged segment  68  of the rigid shaft  64  is larger than the puncture site  22   a  created by the distal end  70   b  of the rigid shaft  64 , the enlarged segment  68  also lowers the risk of the needle  62  penetrating beyond the lumen of the subcutaneous vessel  14  by offering resistance. 
     Referring still to  FIGS.  2 A,  2 B,  3 , and  3 A- 3 C , in this exemplary embodiment, the rigid shaft  64  of the needle  62  is constructed of metal (e.g., stainless steel) and the hub  66  is constructed of synthetic resin material. In this exemplary embodiment, the enlarged segment  68  is constructed by welding and then smoothing the surface. However, in alternative embodiments, the enlarged segment  68  may be constructed separately, e.g., as a solid ball, with hollowed lumen  68   a  through which the main body  64   a  of the rigid shaft  64  is inserted and adhered to the main body  64   a  of the rigid shaft  64 . In yet another alternative embodiment, the hollowed out lumen  68   a  of the enlarged segment  68  may include a first set of threading that is configured to interlock with a second set of threading provided on to the distal end  70   b  of the rigid shaft  64  of the needle  62 . 
     Prior to insertion of the needle  62  into subcutaneous vessel  14 , in some implementations, an incision may be made through a layer of skin  20  of the patient&#39;s body adjacent to the subcutaneous vessel  14 . Following the incision, the layer of skin  20  and the subcutaneous tissue  21  may then be spread apart by forceps (not shown) to facilitate insertion of the needle  62  in the manner described above. In some implementations, proper placement of tip  74  of the rigid shaft  64  may be confirmed by passage of blood out of the hub  66  of the needle. 
     Referring now to  FIGS.  2 B and  2 C , following insertion of the needle  62 , in the next step of the exemplary method, a guidewire  28  (represented in  FIG.  2 B  as a mixture of solid and broken lines and in  FIG.  2 C  with only solid lines) is inserted through the lumen of the hub  66  and the bore  71  of the needle  62  until the distal end of the guidewire  28  is deposited within the subcutaneous vessel  14 . Following deposit of the guidewire  28 , the needle  62  is then removed from the patient while leaving the guidewire  28  in place, as shown in  FIG.  2 C . After the needle  62  is removed, the cannula assembly  80  is then inserted into the patient, as further described below. 
     Referring now to  FIGS.  2 D,  2 E,  4 ,  5 , and  6 A ,  FIG.  4    shows a sectional view in which the cannula assembly  80  is inserted within the patient.  FIG.  5    shows a sectional view similar to  FIG.  4   , but with the cannula  10  of the cannula assembly  80  removed.  FIGS.  6 A- 6 C  then show various views of the sleeve  82  of the cannula assembly  80  or portions thereof. The cannula assembly  80  generally comprises a cannula  10  and an elongated sleeve  82  (or sleeve  82 ) configured to receive the cannula  10 . In this exemplary embodiment, the cannula  10  is of the same construction and provides the same functionality as the cannula  10  described above with reference to  FIGS.  1 D and  1 E , and, as such, is provided with the same reference numeral within the drawings. In this regard, like components and environments are provided with like reference numerals throughout the present application. The sleeve  82  defines, and thus can be characterized as including: a proximal end  84 ; a distal end  86  configured to be inserted into the subcutaneous tissue  21 ; and a bore  81  of sufficient dimension to accommodate the shaft  12  of the cannula  10  and extending from the proximal end  84  to the distal end  86  of the sleeve  82 . Preferably, the bore  81  of the sleeve  82  has a diameter which corresponds to that of the shaft  12  of the cannula  10 , such that, when the cannula  10  and sleeve  82  are combined, the shaft  12  frictionally engages an interior surface of the sleeve  82  so that the sleeve  82  is positioned about, and is supported by, the shaft  12  of the cannula  10 . In this exemplary embodiment, the proximal end  84  of the sleeve  82  includes a valve  85 , configured to transition between an open position ( FIG.  4   ) when the shaft  12  of the cannula  10  is inserted into the bore  81  and a closed position ( FIG.  5   ) when the shaft  12  of the cannula  10  is removed from the bore  81 . The valve is preferably constructed in a manner and of a material such that, when the shaft  12  of the cannula  10  is inserted and the valve  85  is in the open position, the valve  85  forms a seal around the shaft  12  of the cannula  10 . 
     Referring now to  FIGS.  4  and  6 A- 6 C , the sleeve  82  further defines, and thus can be further characterized as including, a plurality of channels  88  circumferentially spaced about the bore  81 . The sleeve  82  also includes, in this exemplary embodiment, a tubing  94 , which defines a port  92  that is in fluid communication with the plurality of channels  88 . In this exemplary embodiment, the sleeve  82  is constructed so that the respective channels  88  are interconnected to (i.e., in fluid communication with) one another, such that, when the port  92  is placed in fluid communication with a vacuum source (not shown), a flow of air and/or liquid is drawn upwardly through the respective channels of the plurality of channels  88 . In this exemplary embodiment, the plurality of channels  88  are connected to the tubing  94  at the proximal end  84  of the sleeve  82 , and the tubing  94  is connected to a main body of the sleeve  82  by a connector  96 , which, in this case, defines a port in which the tubing  94  is inserted. Alternative embodiments are, however, contemplated in which the tubing  94  and main body of the sleeve  82  are integrally formed (i.e., of a unitary construction). 
     Referring now to  FIGS.  2 D- 2 G,  4 ,  5 , and  6 A , the distal end  86  of the sleeve  82  terminates at a tip  87 , which is configured to cup the subcutaneous vessel  14  when placed in contact therewith. To this end, in this exemplary embodiment, the distal end  86  of the sleeve  82  defines a 45° angle. In some embodiments, the edges of the tip  87  which, in use, come into contact with the subcutaneous vessel  14  may also be curved or notched to better follow the contours of the subcutaneous vessel  14 . 
     In this exemplary embodiment, the sleeve  82  of the cannula assembly is constructed of a synthetic plastic material via injection molding or three-dimensional printing. 
     Referring now even more specifically to  FIGS.  2 D and  2 E , in the exemplary method, following removal of the needle  62  from the patient, the cannula assembly  80  is inserted into the patient so that the distal end of the shaft  12  of the cannula  10  is inserted into the subcutaneous vessel  14  and the distal end  86  of the sleeve  82  is proximally positioned next to the puncture site  22   a  while the proximal end  84  of the sleeve  82  is positioned outside of the body of the patient. As with insertion of the needle  62 , prior to insertion of the cannula assembly  80 , in some implementations, an incision within the layer of skin  20  of the patient may be spread apart using forceps (not shown) to facilitate insertion of the cannula assembly  80  in the manner described above. In this implementation, and referring now specifically to  FIG.  2 D , the distal end of the shaft  12  of the cannula  10  is inserted into the subcutaneous vessel  14  over an internal dilator  30 , which, in turn, is provided over the guidewire  28  deposited within the subcutaneous vessel  14 . As shown in  FIG.  2 E , once the distal end of the cannula  10  is deposited within the subcutaneous vessel  14 , the internal dilator  30  and guidewire  28  are retracted through the cannula assembly  80  and removed from the patient so that the cannula  10  can be utilized in an intended vascular procedure. 
     Referring now to  FIGS.  2 F,  2 G, and  6 A- 6 C , after the intended vascular procedure is finished, in the exemplary method, the cannula  10  is retracted through the sleeve  82  and removed from the subcutaneous vessel  14 . In this implementation, prior to removal of the cannula  10 , the port  92  of the tubing  94  is placed in fluid communication with a vacuum source (not shown), thus causing a flow of air and/or fluid to be drawn through the openings of the plurality of channels  88  and the sleeve  82  to apply a suction force. The suction force applied by the sleeve  82  promotes anchoring of the distal end  86  of the sleeve  82  to the subcutaneous vessel  14  and the formation of a seal between the distal end  86  of the sleeve  82  and the wall  22  of the subcutaneous vessel  14  around the puncture site  22   a . Alternative embodiments and implementations are, however, contemplated in which the formation of a seal between the sleeve of the cannula assembly  80  and wall  22  of the subcutaneous vessel  14  is achieved by alternative anchoring means, as further described below with reference to  FIGS.  8 - 11   . 
     Referring now to  FIGS.  2 G,  6 E, and  7   ,  FIGS.  6 E- 6 G  are sectional views of various plugs  100 ,  100   a ,  100   b  which may be utilized with the sleeve  82  following removal of the cannula  10 .  FIG.  7    then provides a sectional view of the sleeve  82  and plug  100  inserted within a patient. In the exemplary embodiment shown in  FIGS.  2 G,  6 E, and  7   , the cannula assembly  80  further includes a plug  100 , which is inserted through the proximal end  84  of the sleeve  82  to apply direct pressure around the puncture site  22   a  following removal of the cannula  10  and to promote the formation of a blood clot  35 . As shown, the plug  100  is comprised of an elongated rod  106 , with a distal end  104  that terminates in a tip  107  and an enlarged proximal end  102 , which, in this case, defines a disc  108  with a diameter greater than that of the opening of the bore  81  at the proximal end  84  of the sleeve  82 . The disc  108  of the enlarged proximal end  102  of the plug  100  limits the extent to which the plug  100  can be inserted within the bore  81  of the sleeve  82 . The shape of the of the tip  107  of the distal end  104  is preferably configured to follow the contour of the wall  22  of the subcutaneous vessel  14 , and thus, in some embodiments, may retain a cup-like shape. The length of the plug  100  is such that, in use, the distal end of the plug  100  applies direct pressure to the puncture site  22   a  when fully inserted into the bore  81  of the sleeve  82 , and the diameter of the plug  100  is such that the plug  100  frictionally engages an interior surface of the sleeve  82  within the bore  81  to hold the plug  100  in position and maintain pressure on the puncture site  22   a.    
     As a result of the disc  108  of the enlarged proximal end  102  of the plug  100  limiting the extent to which the plug  100  can be inserted into the bore  81  of the sleeve  82  and the distal end  86  of the sleeve  82  being positioned as to circumscribe the puncture site  22   a , the magnitude of direct pressure applied by the plug  100  to the wall  22  of the subcutaneous vessel  14  is, in turn, limited. The potential magnitude of direct pressure applied by the plug  100  to the wall  22  of the subcutaneous vessel  14  is thus much less than that typically employed using manual pressure ( FIG.  1 F ) to promote formation of a blood clot  35 . In this way, the sleeve  82  and plug  100  of the cannula assembly  80  can thus be used to promote the formation of a blood clot  35  while simultaneously limiting patient discomfort. In addition to promoting the formation of a blood clot  35 , the pressure applied by the plug  100  also serves to reduces the risk of leakage of blood flow from the puncture site  22   a  into the subcutaneous tissue  21  above the subcutaneous vessel  14 . 
       FIG.  6 F  shows another plug  100   a  which may alternatively be utilized in the cannula assembly  80 . As shown, in this exemplary embodiment, the plug  100   a  includes the same features and functions in the same manner as the plug  100  described above with reference to  FIGS.  2 G,  6 E, and  7   . However, in this embodiment, the tip  107  of the plug  100   a  is coated with thrombin  107   a  (i.e., thrombin  107   a  is deposited on the tip  107 ) to promote thrombosis at the puncture site  22   a . Of course, it should be appreciated that other thrombus promoting products (i.e., thrombotic materials), such as fibrinogen, may alternatively be utilized without departing from the spirit or cope of the present invention. 
       FIG.  6 G  shows another plug  100   b  which may alternatively be utilized in the cannula assembly  80 . As shown, in this exemplary embodiment, the plug  100   a  includes the same features and functions in the same manner as the plug  100  described above with reference to  FIGS.  2 G,  6 E, and  7   . In this embodiment, however, at least one electrically conductive plate  107   b , such as a metal plate, configured to be placed in contact with the puncture site  22   a  is connected to the distal end  104  of the plug  100   b . Specifically, in this embodiment, a single electrically conductive plate  107   b  is connected to the tip  107  of the plug  100   b . The electrically conductive plate  107   b  is, in turn, operably connected to an electrical source (not shown), such as a cauterization machine of known construction, via an electrically conductive wire  107   c  that extends from the tip  107 , through the body, and out of the distal end  104  of the plug  100   b , such that the electrical source can be selectively activated to supply the electrically conductive plate  107   b  (or electrode) with electrical current to cauterize the tissue of the wall  22  of the subcutaneous vessel  14  surrounding the puncture site  22   a . In this implementation an additional (or second) electrically conductive wire  107   d  is connected to another electrically conductive plate  107   e  deposited on the skin  20  of the patient and is also operably connected to the electrical source, as shown in  FIG.  6 H . In this regard, the skin  20  of the patient thus serves as a second electrode, which, in combination with the electrically conductive plate  107   b  on the tip  107  of the plug  100 , effectively forms a circuit through which an electrical current can travel to and from the electrical source. Alternative embodiments are, however, contemplated in which a second electrically conductive plate is connected to the tip  107  of the plug  100   b  at a predetermined distance, i.e., spaced apart, from the first electrically conductive plate  107   b  to establish a circuit for the flow of electrical current. In such embodiments, the second electrically conductive plate is operably connected to the electrical source via a second electrically conductive wire that extends from the tip  107 , through the body, and out of the distal end  104  of the plug  100   b.    
     Referring now specifically to  FIG.  6 A ,  FIG.  6 C , and  FIG.  7   , in this implementation, following treatment of the puncture site  22   a  in the manner described above, the exemplary method concludes with monitoring of the area around the puncture site  22   a  for the development of a hematoma. To this end, in this exemplary embodiment, the sleeve  82  of the cannula assembly  80  further includes one or more electrodes  110 ,  114 , which are provided on the outer surface of the distal end  86  of the sleeve  82 . Specifically, in this embodiment, the sleeve  82  of the cannula assembly  80  includes two such electrodes: a first electrode  110 ; and a second electrode  114 . In use, the first and second electrodes  110  and  114  are in close proximity to puncture site  22   a  and are operably connected to a bioimpedance meter (not shown) by a first wire  112  and a second wire  116 , respectively, that extend through the main body  82   a  and out of the proximal end  84  of the sleeve  82 . 
     Referring now to  FIGS.  6 A- 6 D and  7   , the one or more electrodes  110 ,  114  provided on the outer surface of the distal end  86  of the sleeve  82  work in conjunction with one or more corresponding electrodes  113 ,  117  attached to a portion of the skin  20  proximal to the puncture site  22   a  of the subcutaneous vessel  14 . For example, in instances where cannulation was performed on the femoral artery, the one or more electrodes  113 ,  117  attached to skin  20  located on the same side of the anterior pelvis, or, alternatively, the same side hip area. In this implementation, there are two electrodes attached to the skin  20  of the patient: a third electrode  113  corresponding to the second electrode  114  provided on the distal end of the sleeve  82 ; and a fourth electrode  110  corresponding to the first electrode  110  provided on the distal end of the sleeve  82 . The third electrode  113  and the fourth electrode  117  attached to the skin  20  of the patient are operably connected to the bioimpedance meter by a third wire  121  and a fourth wire  123 , respectively. In use, the first electrode  110  and the third electrode  113  are configured to send a current to the second electrode  114  and the fourth electrode  117 , respectively, which is subsequently measured by the bioimpedance meter to provide an impedance reading. Such readings may be taken substantially continuously or at predetermined time intervals programmed into the bioimpedance meter or a controller (e.g. microcontroller including a processor configured to execute instructions stored in a memory component) configured to control operation of the bioimpedance meter while the sleeve  82  is present in the patient. 
     To detect the development of a hematoma around the puncture site  22   a , an initial impedance reading or set of impedance readings may be taken to establish a baseline to which subsequent impedance readings can be compared, with a change in impedance (e.g., either generally or within a predefined threshold) signaling the development of a hematoma. In some implementations, the bioimpedance meter may be operably connected to an alarm system, such that when a change in impedance occurs, the alarm system emits a cue to alert a medical professional of the same so that the patient can be treated accordingly. In this way, the cannulation method of the present invention can thus be used to monitor the development of a hematoma during intervals in which the patient is not under observation by a medical professional. 
     Although the sleeve  82  is described as both treating the puncture site  22   a  of the subcutaneous vessel  14  and monitoring the development of a hematoma around the puncture site  22   a  in the exemplary cannulation method described above, it should be appreciated that the sleeve  82  can alternatively be utilized exclusively as a hematoma monitoring device or as a device to treat the puncture site  22   a.    
       FIGS.  8 - 11    show an alternative sleeve  182  which may be utilized in the cannula assembly  80 , in place of the sleeve  82  described above with reference to  FIGS.  2 D- 2 G,  4 ,  5 ,  6 A- 6 C , and  7 . In this exemplary embodiment, the sleeve  182  generally includes the same features and functions in the same manner as the sleeve  82  described above with reference to  FIGS.  2 D- 2 G,  4 ,  5 ,  6 A- 6 C, and  7   , except that, instead of a suction force, the sleeve  182  is configured to be anchored to the wall  22  of the subcutaneous vessel  14  by a pulling force. In this regard, instead of tubing  94  configured to place the sleeve  182  in fluid communication with a vacuum source, the sleeve  182  includes a slide  212  connected (e.g., by adhesion) to a plurality of wires  202  which are configured to engage the wall  22  of the subcutaneous vessel  14 . When the sleeve  182  is assembled, each respective wire of the plurality of wires  202  is inserted, at least partially, in one of the plurality of channels  88 , which, in this case, are defined by a middle segment of the main body  182   a  of the sleeve  182  that is enlarged relative to the proximal end  84  of the main body  182   a  of the sleeve  182 . In this exemplary embodiment, the proximal end  84  of the main body  182   a  of the sleeve  182  is capped with a disc-shaped member  302 , which includes the valve  85 . The slide  212  is mounted for movement with respect to the proximal end  84  of the sleeve  182 , and, in this exemplary embodiment, comprises a tubular member with a central bore  212   a  configured to receive a proximal end of the main body  182   a  of the sleeve  182 . Preferably, the central bore  212   a  has a diameter such that an interior surface of the slide  212  frictionally engages the main body  182   a  of the sleeve  182  as the slide  212  is moved. 
     Referring still to  FIGS.  8 - 11   , in use, the slide  212  can be selectively moved in a first (downward) direction to advance the plurality of wires  202  attached thereto within the plurality of channels  88 , thereby directing a distal end  206  of each respective wire into the wall  22  of the subcutaneous vessel  14 , as shown in  FIGS.  8  and  10   . As shown in  FIGS.  8 ,  10 , and  11   , each wire of the plurality of wires  202  is preferably comprised of a semi-rigid material, such as stainless steel, which is biased towards a curved configuration at its distal end  206 , such that, as the plurality of wires  202  are advanced out of the plurality of channels  88  and beyond the tip  87  of the sleeve  182 , the distal end  206  of each respective wire transitions from a straightened to hook-like shape. Accordingly, as the plurality of wires  202  enter the wall  22  of the subcutaneous vessel  14  and transition to the curved configuration, the wall  22  of the subcutaneous vessel  14  is urged toward the sleeve  182  to promote the formation of a seal between the tip  87  of the sleeve  182  and the subcutaneous vessel  14  around the puncture site  22   a , thereby permitting treatment of the puncture site  22   a  in the various manners described herein. Once the distal end  206  of the plurality of wires  202  is deposited within the wall  22  of the subcutaneous vessel  14 , the slide  212  can then be moved in a second (upward) direction to retract the plurality of wires  202  back into the plurality of channels  88  to facilitate removal of the sleeve  182  from the patient. 
     Referring still to  FIGS.  8 - 11   , in this exemplary embodiment, movement of the slide  212  in the upward direction is limited by one or more protrusions  192  (or bars) connected to a first (upper) portion of the main body  182   a  of the sleeve  182 , and movement of the slide  212  in the downward direction is limited by one or more clips  252   a ,  252   b  connected to a second (middle) portion of the main body  182   a  of the sleeve  182 . Specifically, in this embodiment, the sleeve  182  includes two opposing bars  192  which radially extend from an exterior surface of the main body  182   a  of the sleeve  182  and two opposing clips  252   a ,  252   b  attached to the outer surface of the main body  182   a  of the sleeve  182 . In this exemplary embodiment, each clip is substantially T-shaped, with a proximal end  254   a ,  254   b  and an opposing distal end  256   a ,  256   b  interconnected by a middle leg  258   a ,  258   b , which serves as the point of attachment to the main body  182   a  of the sleeve  182 . To maintain the plurality of wires  202  in an advanced position when the slide  212  is moved in the downward direction, in this exemplary embodiment, an inner face of the proximal end  254   a ,  254   b  of each clip  252   a ,  252   b  defines a recess  262   a ,  262   b  configured to receive a circumferential ridge  220  of the slide  212 . To facilitate insertion of the circumferential ridge  220  of the slide  212  into the recess defined in the proximal end  254   a ,  254   b  of each clip  252   a ,  252   b , each clip  252   a ,  252   b  is constructed such that the distal end  256   a ,  256   b  of each clip can be pressed inwardly (i.e., toward the main body  182   a  of the sleeve  182 ) to cause the proximal end  254   a ,  254   b  of each clip  252   a ,  252   b  to move outwardly (i.e., away from the main body  182   a  of the sleeve  182 ) to provide sufficient space for the circumferential ridge  220  to be received. Once received, the pressure on the distal end  256   a ,  256   b  of each clip  252   a ,  252   b  can then be released to maintain the circumferential ridge  220  within the recess  262   a ,  262   b  and prevent the plurality of wires  202  from being inadvertently retracted from the wall  22  of the subcutaneous vessel  14 . In this regard, the circumferential ridge  220  and one or more clips  252   a ,  252   b  can thus be characterized as defining a locking mechanism. 
     Although the various plugs  100 ,  100   a ,  100   b  are described herein primarily in the context of being utilized in combination with the sleeve  82  described herein with reference to  FIGS.  2 D- 2 G,  4 ,  5 ,  6 A- 6 C, and  7   , it should be appreciated that the plugs  100 ,  100   a ,  100   b  may be utilized in the same fashion with the sleeve  182  described herein with reference to  FIGS.  8 - 11   . 
     In this exemplary embodiment, the various components of the sleeve  182  are constructed of a synthetic plastic via injection molding or three-dimensional printing, except for the plurality of wires  202 , which, as noted above are constructed of a metal, such as stainless steel. As perhaps best shown in  FIG.  11   , in this exemplary embodiment disc-shaped member  302 , protrusions  192 , and clips  252   a ,  252   b  are heated and fused to the main body  182   a  of the sleeve  182 . Of course, alternative means of connection may alternatively be employed without departing from the spirit or scope of the present invention. 
     One of ordinary skill in the art will recognize that additional embodiments and implementations are also possible without departing from the teachings of the present invention or the scope of the claims which follow. This detailed description, and particularly the specific details of the exemplary embodiments disclosed herein, is given primarily for clarity of understanding, and no unnecessary limitations are to be understood therefrom, for modifications will become apparent to those skilled in the art upon reading this disclosure and may be made without departing from the spirit or scope of the claimed invention.