Abstract:
A device for treatment of venous congestion provides for subcutaneous introduction of anticoagulant through an incision positioned within a collection shell for withdrawal of an effused material. A widened delivery tip provides dispersal of the anticoagulant and may be agitated to disrupt clot formation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation in part of U.S. application Ser. No. 09/745,298 filed Dec. 20, 2000 which is based on and claims the benefit of U.S. provisional application No. 60/171,351 filed Dec. 22, 1999. 
     
    
     
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       BACKGROUND OF THE INVENTION  
         [0002]    The invention relates generally to medical devices to remove excess blood from congested tissue and particularly to a simple mechanical device to replace medicinal leeches.  
           [0003]    A potential post-surgical complication of reconstructive or microvascular surgery is venous congestion. Replanted tissue may become congested due to blood clot formation in the venous outflow of the tissue, or in any situation where arterial inflow exceeds venous outflow. Furthermore, venous stasis or pooling caused by an arterial supply, which is insufficient for the reconstructed tissue can also occur following microvascular surgery. Venous congestion, if not corrected by surgery or some other means, can result in tissue death.  
           [0004]    If surgical correction fails, the current method of treating either venous congestion or venous stasis is with live medicinal leeches. The use of leeches can present a number of problems. For example, leeches can move off congested tissue and feed on normal skin, they are difficult to use in or near orifices of the body because of their potential for migration, the quantity of blood removable by a leech is very limited, and leeches may harbor serious pathogens.  
           [0005]    Cursory attempts have been made to develop mechanical or chemical replacements for the live medicinal leech. A simple mechanical device was used by Smoot et al. in 1995 (Smoot E C, Ruiz-Inchaustegui J A, Roth A C (1995) Mechanical Leech Therapy to Relieve Venous Congestion. J Reconstr Microsurg 11: 51-55). This device consisted of a small glass bell that was placed over a punch biopsy wound. A fluid passing through an inlet port irrigated the wound and was suctioned off via a suction port at −80 mmHg. Chemical replacements for leech therapy have also been studied. The “chemical leech” involved subcutaneous injections of calcium heparin into the reattached fingers of three patients, with drainage into dressings over the surgical site. (Barnett G. R., Taylor G. I. and Mutimer K. L. (1989). The “chemical leech:” Intra-replant subcutaneous heparin as an alternative to venous anastomosis. Report of three cases.  Br J Plast Surg  42:556-558. These subcutaneous injections of anticoagulant were used to promote drainage of excess blood into the dressings of the surgical site. However, prior work has not provided an adequate clinical solution for the post-surgical complication of venous congestion. The need for the development of new techniques is clearly indicated.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention provides an improved device for the treatment of venous congestion. In one non-limiting embodiment, the device consists of a shell, which acts as a collection chamber and which supports a conduit terminating in a widened delivery tip which supplies anticoagulant subcutaneously through a skin incision.  
           [0007]    Specifically, the invention provides a shell having a rim adapted to abut the patient&#39;s skin to define a suction area circumscribed by the rim and enclosed by an inner volume of the shell. A conduit is supported by the shell having a delivery tip for the delivery of anticoagulant and saline irrigation positionable subcutaneously below the rim within the suction area when the shell is positioned against the patient&#39;s skin, the delivery tip having a larger cross-sectional area than the conduit to disperse the anticoagulant beneath the skin and provide subcutaneous agitation as a means of discouraging or breaking up clot formation. A suction port is attached to the shell through which recovered anticoagulant and blood may be drawn from the inner volume.  
           [0008]    Depending on the embodiment, the delivery tip may  1 ) supply anticoagulant subcutaneously in a controlled fashion,  2 ) disperse the anticoagulant,  3 ) provide mechanical anticoagulation by automated rotational and vertical movement of the delivery tip,  4 ) provide subcutaneous tenting so as to create a subcutaneous pocket and keep open (apart) the skin incision edges,  6 ) provide mechanical abrasion to the wound edges,  7 ) irrigate the wound. Suction is applied to the shell via an outflow port allowing recovered blood and anticoagulant/irrigant to be withdrawn from the inner chamber.  
           [0009]    It is one object of the invention to provide for improved removal of blood from congested tissue through the combination of subcutaneous delivery of anticoagulant and topical recovery.  
           [0010]    The device may include an air inlet port allowing the introduction of air into the inner volume and down to the skin surface. Thus, it is another object of the invention to both provide a path of air entry to the skin surface. This air flow will create turbulence in the irrigant flowing through the shell at the skin surface, thus creating mechanical anticoagulation at the skin surface and elsewhere within the shell preventing clot formation.  
           [0011]    The device may include a sensor detecting blood volume outflow via the use of weight measurements of the inflow and outflow fluids or optical sensor measurement of outflow concentration.  
           [0012]    Thus, it is another object of the invention to provide for semiautomatic operation in which a sensor provides an indication to the operator of successful operation or trigger sequences of agitations and air and liquid flows to provide for efficient blood removal.  
           [0013]    The foregoing objects and advantages may not apply to all embodiments of the inventions and are not intended to define the scope of the invention, for which purpose claims are provided. In the following description, reference is made to the accompanying drawings, which form a part hereof, and in which there is shown by way of illustration, a preferred embodiment of the invention. Such embodiment also does not define the scope of the invention and reference must be made therefore to the claims for this purpose.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is an exploded perspective view of the device of the present invention showing its disassembly prior to insertion of a subcutaneous conduit into a cross incision in the patient&#39;s skin and the placement of a collection shell over the conduit, and prior to attachment with various input lines and outflow lines;  
         [0015]    [0015]FIG. 2 is an elevational cross sectional view of the device of FIG. 1 assembled and attached to the patient&#39;s skin and showing the subcutaneous location of the delivery tip of the conduit formed from a microporous disk (subcutaneous dispenser) and showing the placement of air and irrigation tubes and a suction port on and in the collection shell;  
         [0016]    [0016]FIG. 3 is a fragmentary cross-sectional view similar to that of FIG. 2 showing an alternative embodiment wherein the subcutaneous conduit is attached to a motor for automatic periodic motion;  
         [0017]    [0017]FIG. 4 is a fragmentary view of FIG. 2 showing the use of an optical sensor for detecting blood outflow such as may be used to control various aspects of the invention;  
         [0018]    [0018]FIG. 5 is a perspective view similar to that of FIG. 1 showing the addition of a series of needles positioned within the rim of the collection shell for injecting additional anticoagulant around the shell rim at predetermined intervals;  
         [0019]    [0019]FIG. 6 is a perspective view of a kit version of an alternative embodiment of the device of FIG. 1 showing the shell assembly as attached to supply and return lines terminating in a multi-line connector and housed in a sterile package for one time use;  
         [0020]    [0020]FIG. 7 is a simplified, block diagram of the embodiment of FIG. 6 showing the relationship of pneumatic axial and pneumatic rotational actuators for combined rotational and axial movement of the conduit and showing an alternative delivery tip;  
         [0021]    [0021]FIG. 8 is a detailed cross-sectional view of the rim of the embodiment of FIG. 6 showing the location of pressure sensitive adhesive on the rim allowing the rim to adhere to the patient&#39;s skin and showing partial removal of a release liner protecting that adhesive;  
         [0022]    [0022]FIG. 9 is a detailed perspective view of the delivery tip of FIG. 7 showing its wedge shape such as provides tenting of the incision; its wide cross-sectional area having multiple orifices for dispersion of anticoagulant and its incorporation of axially extending abrading edges along the outer circumference for breaking up clots; and  
         [0023]    [0023]FIG. 10 is a block diagram of a control unit suitable for the embodiment of FIG. 6 showing provisions for microprocessor control of filtered and actuating air supplies; the anticoagulant and microprocessor monitoring of the flow of recovered anticoagulant and blood. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]    Referring now to FIG. 1, the device  10  of the present invention includes generally a hollow, bell-shaped shell  12  symmetric generally about vertical axis  16  and having an open lower rim  14 . The shell  12  may be constructed of plastic or glass and is preferably of clear material to allow visual inspection of its internal volume.  
         [0025]    At the apex of the shell  12  is an opening  18  surrounded by a cylindrical sleeve  20 . The sleeve  20  is sized to receive along axis  16 , a conduit  22 , the latter being preferably a stainless steel tube having a height greater than that of the shell  12 . The conduit  22  may freely rotate within the sleeve  20 , but blocks the opening  18  to prevent passage of air or liquid into or out of the opening  18  except through the conduit  22 .  
         [0026]    Referring now also to FIG. 2, attached at a lower end of conduit  22  removed from the sleeve  20  is a delivery tip  24  constructed of a microporous disk having an internal structure of pores (not shown) communicating with a central lumen  26  of the conduit  22 . The delivery tip  24  is centered on the conduit  22  extending radially therefrom generally perpendicular to axis  16 .  
         [0027]    A cross incision  28  made in the skin  30  of a patient permits insertion of the delivery tip  24  subcutaneously with the conduit  22  extending upward out of the incision  28 . Before insertion of the delivery tip  24 ′ into the incision  28 , a small volume bolus of anticoagulant may be administered including possibly other agents such as vasodilators. The portion of the conduit  22  extending out of the incision  28  is received by the sleeve  20  so that the shell  12  moves downward to abut the skin  30  and cover the cross incision  28 . The diameter of the rim  14  of the shell  12 , in the preferred embodiment, is approximately  1 . 3  centimeters.  
         [0028]    The conduit  22  may be attached at its upper end protruding from the sleeve  20  to an anticoagulant supply hose  46  delivering concentrated heparin or other anticoagulant or thrombolytic substance (such as streptokinase) through the conduit  22  into the microporous delivery tip  24  for diffusion subcutaneously in the surrounding area.  
         [0029]    Extending radially near the rim  14  of the shell  12  outside of the shell  12  is an exhaust port  31  sized to receive a suction hose  32  and providing an exhaust path indicated by arrow  34  in FIG. 2 from an inner volume  36  of the shell  12  (defined by the inner walls of the shell  12  and the upper surface of the skin  30 ) to the suction hose  32 . The exhaust port  31  is positioned to draw effluent liquid  44  collecting on the upper surface of the skin  30  out of the shell  12 .  
         [0030]    An air inlet port  38  extends vertically upward from a top of the shell  12  to receive an air supply hose  42  and to communicate air therefrom through the shell  12  to a central air tube  40  extending downward within the shell to a point immediately above the surface of the skin  30 . Ideally the opening of the tube  40  is slightly below the opening of the exhaust port  31  so as to ensure the tip of the air inlet port  38  is immersed in any unexhausted effluent liquid  44 .  
         [0031]    Similarly, an irrigation port  52  extends vertically upward from a top of the shell  12  opposed to the air inlet port  38  about the sleeve  20  to receive an irrigation hose  50  and to communicate irrigation liquid therefrom through the shell  12  to an irrigation tube  54  similar to the air tube  40  extending downward within the shell to a point immediately above the surface of the skin  30 . Tubes  40  and  54  may be stainless steel hypodermic needle tubes.  
         [0032]    Referring still to FIGS. 1 and 2, in operation, the delivery tip  24  is first vacuum impregnated with heparin polyvinyl alcohol hydrogel and implanted in the tissue through the cross incision  28  described above. The shell may also be constructed of other materials, such as Teflon or other biocompatible nonthrombogenic substance, with appropriate inset channels to allow subcutaneous delivery of liquid substances. The shell  12  is then be placed over the conduit  22 , the latter fitting through sleeve  20 , and positioned to cover the incision  28  with the rim  14  resting on the surrounding skin. The rim  14  of the shell  12  is attached to the skin  30  using a surgical adhesive, or an outer flange extension on the shell  12  may be captured beneath the specially designed adhesive strip in the form of an annular ring.  
         [0033]    Anticoagulant supply hose  46  is then attached to the portion of the conduit  22  extending out of the shell  12  through sleeve  20 , while hoses  32 ,  42 , and  50  may be pre-attached to the shell  12 .  
         [0034]    Concentrated Heparin, or other substance, is next delivered through the conduit  22  into the microporous delivery tip  24  for diffusion subcutaneously in the surrounding area. Encouraged by the anticoagulant, blood in the region of the delivery tip  24  is drawn up through the incision  28 . The extracted blood and anticoagulant then mixes with the irrigant introduced through tube  54 . The irrigant is preferably a wash of dilute anticoagulant and saline solution and serves to further inhibit the formation of clots in the resulting effluent liquid  44 .  
         [0035]    Air entering through an air supply hose  42  through the tube  40  percolates air bubbles through effluent liquid  44 , the bubbles serving further to inhibit the formation of clots on the incision surface. Pulsations of pressure, air, and irrigant may also be used to improve blood flow.  
         [0036]    Periodically, the conduit  22  is rotated in alternate directions to reduce the formation of clots around the delivery tip  24 . The disk shape and its orientation perpendicular to the axis of rotation facilitate this rotational process.  
         [0037]    Anticoagulant, irrigation, airflow, and suction are balanced to establish a slight negative pressure within the shell  12  with respect to ambient pressure. The delivery of air, saline and anticoagulant and the application of suction may be performed by an automated control system comprising pumps and pressure transducers and a programmed controller according to techniques well known in the art.  
         [0038]    Referring now to FIG. 3 in an alternative embodiment, a stepper motor  55  may be positioned at the apex of the shell  12  so that its shaft  56  is essentially coaxial with axis  16  and conduit  22 . The shaft  56  may be hollow to permit passage of anticoaguilant therethrough and the lower portion of the shaft may extend through the opening  18  to be attached to the conduit  22 . The opposite, upper end of the shaft  56  may be attached to anticoagulant supply hose  46 . Signals received through motor wires  58  from an automatic controller of a type well known in the art may drive the motor to produce a periodic reciprocating motion of the conduit  22  to eliminate the need for manual intervention.  
         [0039]    Referring now to FIG. 4, an optical sensor  60  may be fit within the wall of the shell  12  to detect color changes in the effluent liquid  44  collecting in the lower portion of the shell adjacent to the skin  30 . Ideally, the sensor  60  is placed near the exhaust port  31  (not shown in FIG. 4) and may include, for example, a light emitter (such as a light emitting diode) and light detector (such as a photo transistor) for evaluating the color or reflectance of the effluent liquid  44 . This measurement may be used to indicate the amount of blood outflow so as to provide a signal through a controller  62  either to attending personnel that rotation of the conduit  22  is required, or an inspection of the device is required, or to automatically actuate changes in the air flow, irrigation flow, or mechanical agitation the conduit through the motor shown in FIG. 3.  
         [0040]    Referring now to FIG. 5 in an additional embodiment, the shell  12  may support a set of vertically disposed hypodermic needles  64  generally parallel to the conduit  22  and spaced at regular angular intervals about the conduit  22  just inside the rim  14  and extending a distance  66  below the rim  14  to provide for the injection of additional anticoagulant subcutaneously around the delivery tips  24 .  
         [0041]    Referring now to FIG. 6, in an additional embodiment, the device  10 ′ may be pre-assembled to the necessary hoses including air supply hoses  42   a ,  42   b , and  42   c , as will be described, anticoagulant supply hose  46 , and the suction hose  32 . Each of these separate hoses may be joined into a single bundle terminating in a multi-hose connector  67  that may be used to rapidly connect the device  10 ′ to the controller  62 . This pre-assembled device  10 ′ and hoses may be sterilized and packaged in sterile condition within a sealed pouch  68  for ready access by the physician.  
         [0042]    Referring now to FIG. 7, the embodiment of FIG. 6 may differ from the previously described embodiment of FIG. 2 by elimination of the irrigation hose  50  and the addition of two additional air supply hoses  42   b  and  42   c  to supplement the air supply hose  42   a , the latter which corresponds to air supply hose  42  of FIG. 2.  
         [0043]    As before, the anticoagulant supply hose  46  attaches to conduit  22  to deliver anticoagulant to delivery tip  24 ′.  
         [0044]    Air supply hose  42   b  provides air to bellows actuator  70  having one portion attached to the shell  12  and the other portion attached to the conduit  22  to cause axial motion  77  of the conduit  22  under varying air pressure from air supply hose  42   b . The axial motion moves delivery tip  24  into and out of the incision to reduce clot formation and to promote bleeding by tenting or flexing of the edges of the incision  28  with the upper part of the delivery tip  24  as will be described. The tenting effect keeps the edges of the wound separated allowing the irrigant to irrigate the entire wound and flow freely to the skin surface.  
         [0045]    Air supply hose  42   c  provides air to a rotary actuator  74  having an internal vane  76  attached to the conduit  22  to provide rotary motion  78  of the conduit  22  back and forth about its axis. These two motions  77  and  78  may be combined to produce a spiraling up and down motion further preventing clot formation.  
         [0046]    Referring now to FIG. 9, the delivery tip  24 ′ may have a frusto-conical shape with its smaller base facing upward toward the shell  12 . The central lumen  26  of the conduit  22  passes through the narrow top of the delivery tip  24 ′ and opens into a plurality of ports  84  extending out the wider periphery of the lower portion of the delivery tip  24 ′ to better disperse anticoagulant.  
         [0047]    The delivery tip may be constructed of a biologically inert material such as Teflon and attached to the conduit  22  so that its point extends through the incision  28 . The wedge shape of the delivery tip  24 ′ plus the up and down reciprocal action  72  flexes the edges of the incision  28  laterally in and out so as to prevent clot formation and promote bleeding.  
         [0048]    Extending upward from the lower base of the delivery tip  24 ′ are grooves providing axial abrading edges  82 . The rotational movement  78  causes the axial abrading edges  82  to disrupt clot formation and further abrade and promote bleeding.  
         [0049]    Referring now to FIG. 8, a lower planar surface of the rim  14  of the shell  12  may be covered with a pressure sensitive adhesive  86  protected initially by a release liner  88 . The release liner  88  may be peeled back so that the pressure sensitive adhesive  86  is exposed. In this way, when the rim  14  is pressed against the skin  30 , the pressure sensitive adhesive  86  holds the shell  12  in place prior to the creation of a vacuum as has been described. In this embodiment, the shell  12  may be constructed of a lightweight plastic such as polyethylene.  
         [0050]    Referring now to FIG. 10, the controller  62  for the embodiment of FIG. 6 may be self-contained so as to hang on an “IV” pole or the like by hook  89  to attach to the device  10 ′ and hoses  42   a ,  42   b ,  42   c ,  46 , and  32  via a multi-line connector  90  compatible with multi-hose connector  67 . The controller  62  provides for central control of air, anticoagulant, and suction through a microprocessor  100 .  
         [0051]    Air may be provided from a pressurized hospital source  92  or via a selfcontained pump  94  communicating with room air. The air feeding air supply hose  42   a  is micro-filtered by filter  99  to provide a sterile air stream for agitation of the removed anti-coagulant and blood as has been described. This in turn allows for autotransfusion of the recaptured blood as will be described. Air supply hoses  42   b  and  42   c  need not be filtered provided their associated actuators  70  and  74  do not exhaust air into the shell  12 .  
         [0052]    Each of the air supply hoses  42   a ,  42   b , and  42   c  pass through electrically controllable valves  96  allowing air flow to be metered by microprocessor  100 . The valves  96  on air supply hoses  42   b  and  42   a  allow control of the motion of the conduit in rotation and axial translation such as may optimized to minimize damage and maximize the therapeutic effect of this motion. As will be described, this motion may be controlled according to the flow of blood and anticoagulant back to the controller  62  to create a control closed loop system.  
         [0053]    Anticoagulant may be provided from an IV bag  104  such as may be hung on the IV pole flowing under gravity or pumped by internal pump  102  controlled by the microprocessor  100 . The anticoagulant passes through a metering valve  110  (or is controlled by a metering pump  102 ) allowing the microprocessor  100  to control flow of anticoagulant to the anticoagulant supply hose  46 .  
         [0054]    Suction for the suction hose  32  may come from an internal suction pump  112  or may be provided by a connection to the hospital vacuum line  114 . The suction hose  32  passes through a flow meter  106  measuring the flow of returned anticoagulant and blood such as may provide a signal to the microprocessor  100  to control the amount of agitation by means of air supply hoses  42   b  and  42   c  as described above. Ideally, the rate of change of blood volume over time is used to determine the frequency of the actuation.  
         [0055]    The returned blood and anticoagulant may-be collected in a reservoir  116  attached to the IV pole for later autotransfusion.  
         [0056]    In the preferred embodiment, the controller  62  monitors on a continuous basis, the amount of blood and anticoagulant removed from the incision as measured by the flow meter  106  or by a weighing system employing well known strain gauge or other type of weighing systems. The amount of blood alone may be determined by subtracting the amount of anticoagulant delivered by anticoagulant supply hose  46  through metering valve  110  and this information is displayed to the operator to provide a quantitative indication of the correct operation of the device  10 ′.  
         [0057]    The controller  62  may include a battery  118  and/or provision for connection to a low voltage cabling to a transformer attached to the hospital line voltage.  
         [0058]    It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein, but that modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments also be included as come within the scope of the following claims.