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 a effused material. A wash of saline and anticoagulant agitated by an air-input stream and periodic rotation of the subcutaneous device may be used to reduce clotting.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application 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. 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 venous congestion is through the use of live medicinal leeches. The use of leeches can present a number of problems. For example, leeches can move off of congested tissue and feed on normal skin, they cannot be used 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. 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 punch biopsy wound. A fluid pacing though 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  
         [0005]    The present invention provides an improved device for the treatment of venous congestion. In one non-limiting embodiment, the device consists of a glass shell, which acts as a collection chamber and supports several additional components of the device. These components include a means to 1) supply anticoagulant subcutaneously through a skin incision, 2) supply anticoagulant to the surface of the incision, 3) apply turbulence to the surface of the incision, and 4) supply anticoagulant to the peripheral tissue surrounding the incision. Specifically, the invention provides a shell with a rim adapted to be affixed to the patient&#39;s skin defining a suction area circumscribed by the rim and inner volume of the device. A conduit supported by the shell has a delivery tip placed subcutaneously through a skin incision for the delivery of anticoagulant. This subcutaneous delivery tip may be made out of a porous material such as a microporous polyethylene impregnated with a polyvinyl alcohol hydrogel or possibly hypodermic stainless steel tubing configured into a semispherical wireframe with pinholes spaced along the tubing to allow for anticoagulant egress. The purpose of this delivery tip is to 1) supply concentrated anticoagulant subcutaneously in a controlled fashion, 2) to provide mechanical anticoagulation by automated rotational movement of the delivery tip, 3) to provide subcutaneous tenting so as to keep open (apart) the skin incision edges. Suction is applied to the glass shell via an outflow port allowing recovered blood and anticoagulant to be withdrawn from the inner chamber.  
           [0006]    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.  
           [0007]    Another object of the invention is to provide for improved dispersal of anticoagulants subcutaneously and to allow rotary motion of the tip so as to inhibit clotting. Besides subcutaneous anticoagulant delivery via the delivery tip, additional anticoagulant can be delivered via needle injection around the shell rim at equidistant intervals. This subcutaneous anticoagulant will be delivered peripheral to the skin incision.  
           [0008]    The device may include an inlet port allowing the introduction of an irrigant such as an anticoagulant-saline mixture into the inner volume. The inlet port may carry irrigant to the skin surface. Thus it is another object of the invention to improve blood removal by augmenting the subcutaneous delivery of anticoagulant with a topical irrigant.  
           [0009]    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.  
           [0010]    The device may include a sensor detecting blood outflow concentration such as an optical sensor.  
           [0011]    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 triggers sequences of agitations and air and liquid flows to provide for efficient blood removal.  
           [0012]    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  
       [0013]    [0013]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;  
         [0014]    [0014]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 and showing the placement of air and irrigation tubes and a suction port on and in the collection shell;  
         [0015]    [0015]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;  
         [0016]    [0016]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; and  
         [0017]    [0017]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 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]    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.  
         [0019]    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 nevertheless blocks the opening  18  so as to prevent passage of air or liquid into or out of the opening  18  except through the conduit  22 .  
         [0020]    Referring now also to FIG. 2, attached at a lower end of conduit  22  removed from the sleeve  20  is a microporous disk  24  having an internal structure of pores (not shown) communicating with a central lumen  26  of the conduit  22 . The disk  24  is centered on the conduit  22  extending radially therefrom generally perpendicular to axis  16 .  
         [0021]    A cross incision  28  made in the skin  30  of a patient permits insertion of the disk  24  subcutaneously with the conduit  22  extending upward out of the incision  28 . 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.  
         [0022]    The conduit  22  may be attached at its upper end protruding from the sleeve  20  to a anticoagulant supply hose  46  delivering concentrated Heparin through the conduit  22  into the microporous disk  24  for diffusion subcutaneously in the surrounding area.  
         [0023]    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 .  
         [0024]    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 .  
         [0025]    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.  
         [0026]    Referring still to FIGS. 1 and 2, in operation, the disk  24  is first vacuum impregnated heparin polyvinyl alcohol hydrogel and implanted in the tissue through the cross incision  28  described above. 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.  
         [0027]    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 .  
         [0028]    Concentrated Heparin is next delivered through the conduit  22  into the microporous disk  24  for diffusion subcutaneously in the surrounding area. Encouraged by the anticoagulant, blood in the region of the disk  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 .  
         [0029]    Air entering through an air inlet 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.  
         [0030]    Periodically, the conduit  22  is rotated in alternate directions so as to reduce the formation of clots around the disk  24 . The disk shape and its orientation perpendicular to the axis of rotation facilitate this rotational process.  
         [0031]    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.  
         [0032]    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 so as to permit passage of anticoagulant 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 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 shaft  22  to eliminate the need for manual intervention.  
         [0033]    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 agitate the conduit through the motor shown in FIG. 3.  
         [0034]    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  64  below the rim  14  to provide for the injection of additional anticoagulant subcutaneously around the disk  22 .  
         [0035]    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.