Osmotic wound drain
United States Patent 1191 Stepno Apr. 29, 1975 1 OSMOTIC WOUND DRAIN [75] Inventor: Norman Howard Slepno.  
 Alexandria, Va.  
 [73} Assignee: Alza Corporation. Palo Alto, Calif [22] Filed: May 22, 1972 [2]] App]. N0.: 255,438  
 [52] US. Cl. 128/276 [51] Int. Cl A61m 1/00 [58] Field of Search 128/260. 276. 278, 214 R [56] References Cited UNITED STATES PATENTS 3.115.138 12/1963 McElvcnny et al 4. 128/278 3.732.865 5/1973 Higuchi ct a1. 128/260 3.760.804 9/1973 Higuchi ct a1. 128/260 3.760.805 9/1973 Higuchi 128/260 Leepcr 128/260 Theeuncs 128/260 X Primary Eraminer-Richard A. Gaudet Assistant Emminer-J. C. McGowan Anorney, Agent, or Firm-Bacon 81 Thomas [57} ABSTRACT An evacuator device for the extraction of body fluids is comprised of body fluid receiving members adapted to be inserted into the area of the wound and fabricated from membrane material exhibiting controlled permeability to water, and a compartment for collecting such water that flows by osmosis across said membrane in a tendency for osmotic equilibrium with the environment of the device. The body fluid receiving means are advantageously elongated tubes adapted for insertion into the human body.  
 8 Claims, 3 Drawing Figures OSMOTIC WOUND DRAIN FIELD OF THE INVENTION This invention relates to a device for evacuating fluids from the human body, especially from the area of a wound. More particularly, this invention relates to a simple economical evacuator which employs the principle of osmotic diffusion to remove body fluids from the area of a wound.  
 BACKGROUND OF THE INVENTION It is a relatively common surgical procedure to provide for the draining or evacuation of body fluids from the area of a wound or incision incurred during surgery for prevention of fluid build-up, to combat suture pressure, infection, and the like. Ordinary operative wounds are normally drained for a period of about 48 hours after the operation. Some operations, being more extensive and/or requiring more extensive procedures, result in a large build-up of body fluids in the wound area which, as dictated by normal medical practice, should be removed to promote safe, speedy healing.  
  Typical examples of surgical operations which require the removal of body fluids from the wound area during healing are as follows: (I) operations such as radical breast and neck dissections, abdominal, perineal, and certain chest procedures; (2) evacuating hematoma in such operations as upon the hip, femur, tibia, forearm or hand; (3) knee and ankle joint operations and the like; (4) compound fractures; (5) the treatment of large soft tissue abscesses, and the like; (6) treatment of chronic osteomyelitis and septic joints; and (7) various other uses.  
  The use of effective measures to withdraw fluids which accumulate in the area of the wound or incision in such operations results in a number of improved conditions. Swelling is kept at a minimum and suture tension is markedly decreased with noticeably less postoperative pain, and the wound edges are kept white, flat, and quiescent. The elimination of hematoma, swelling, and tension also eliminates some infection promoting factors.  
  U.S. Pat. No. 3,l l5,l38 to McElvenny et al. describes a wound drain device which operates under the principle of applying a negative pressure. In that patent, a device for creating negative pressure is located outside of the body and conncted to tubular means located in the wound area. The pressure acts to withdraw the fluids from the area of the wound and prevents the accumulation of same. While such a device has been found to be an acceptable means to prevent the accumulation of body fluids in the wound area, representing a marked advance over the theretofore known electrical or mechanical evacuators, the manufacture of this prior art device requires certain rigid standards which must be adhered to in order that the device work effectively as desired. For example, the McElvenny et al. device requires that the tubing located within the body in the wound area have openings therein which connect to the central core for evacuation of the body fluids to the collection means. It is ofcourse obvious that should any of these openings occur outside of the body, the negative pressure being applied would be negated by the introduction of air from the atmosphere. Consequently, the openings in the tubular member or members of the McElvenny et al. device must all be located within the body surrounding the wound area. Furthermore, the only means by which the body liquids may be removed from the wound area is through these openings and if accumulation of body fluids occurred at other areas surrounding the tube, the device would not operate to remove such liquids. Also, the collection means or evacuation unit of this prior art device acts as a pump which requires certain specified and rather complex construction features including tension means located around the inside of the pump for applying pressure to the top and bottom of the unit in order that the negative pressure desired may be produced. The top and bottom portions of the evacuating unit of this prior art device moreover require internally disposed shoulders for maintaining the springs in operative position. It can be seen, therefore, that while the McElvenny et al device for draining wounds by the application of negative pressure does result in a degree of effecienty in removing body fluids from the area of the wound, it would be desirable to obtain the same or improved result with a more simplified device.  
 SUMMARY OF THE INVENTION Accordingly, it is a primary object of this invention to provide a device for evacuating fluids from the human body, especially from the area of a wound or incision, which device operates in a simple and efficient manner.  
  It is another object of this invention to provide a device for evacuating body fluids from the area of a wound or incision by the application of the principle of osmosis.  
  It is a still further object of this invention to provide a device for the evacuation of body fluids from the area ofa wound or surgical incision which is simple and efficient in operation and which is easily adapted for use by ambulatory patients.  
  These and other objects will become apparent from the description given hereinafter.  
  Briefly, in accordance with this invention, there is provided a device for evacuating body fluids which comprises a conduit member, advantageously tubular, comprised of a material having controlled permeability to water, said conduit member being connected to a collection means or container compartmentalized by means of a flexible water impervious diaphragm. The first compartment of the collection means, to which the conduit member is connected, contains a solution of an osmotically effective solute which exhibits an osmotic pressure gradient against water, and the conduit member contains a like solution. Means are also provided for attaching the collection means firmly to the body, and in the desired position, for use on ambulatory patients. The conduit member is adapted to be inserted into the body in the area of the wound or incision, whereby water of the body fluids, by osmosis, diffuses into the tubular means and passes into the collection means causing the flexible diaphragm to expand upon water uptake into an initially empty space or second compartment in the collection means.  
  In another aspect of this invention, the first compartment of the collection means contains two solutions of osmotically effective solutes each exhibiting an osmotic pressure gradient against water, one being more concentrated than the other, and said solutions themselves being physically separated within the said first compartment by means of a semipermeable membrane. The less concentrated solution also fills the conduit member and that portion of the collection means to which said conduit is connected. The more concentrated solution causes excess water to pass from the less concentrated solution into the chamber containing the more concentrated solution and causes a flexible diaphragm to expand into an initially empty area or second compartment of the collection means.  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view, partially in cross-section, of the wound drain device of the present invention.  
  FIG. 2 is a plan view partially in crosssection, of the modification of from a device of the present invention in which the container has additional means for separating a less concentrated osmotic solution froma more concentrated osmotic solution by means of a semipermeable membrane.  
  FIG. 3 is a view of a front portion of a human body illustrating the application of the present invention thereto in a radical breast dissection or breast removal.  
 DETAILED DESCRIPTION OF THE INVENTION One embodiment of this invention is illustrated in FIG. 1. While FIGS. 1, 2, and 3 all show two tubular conduit members for insertion into the area ofa wound or incision, it is to be understood that one tubular member will in some cases suffice, especially in those operations in which the accumulation of body fluid is slight; it is also envisioned that in some instances more than two conduits or tubes can be employed. Likewise, the tubular members as illustrated in the drawings can be connected to each other via an intermediate portion which in effect would result in one tubular member connected to the collection means. While a Y-shaped connection means is illustrated in the drawings, it will be appreciated that in the case of the use of one tubular member such a connection means would be unnecessary, and, in fact, the tubular member or members may be directly connected to the collection means, if desired.  
  Referring specifically to FIG. 1, tubular members 2, comprised of material exhibiting controlled permeabil ity to water and which contain a solution of an osmotically, effective solute which exhibits an osmotic pressure gradient against water and body fluids, are connected via a connector 3 to collection means 4. Of course, both tubular members 2 and connectors 3 are completely filled with the solution of the osmotically effective solute in order to establish the osmotic pressure differential across the membrane of which the tubular members 2 are composed. The tubes 2 are advantageously comprised of semi-permeable, anisotropic cellulose acetate membrane material of the type used in reverse osmosis water desalination. Connection means 3 is illustrated as being Y-shaped having connectors 9 and for connection with tubular means 2 and collection means 4 via lead-away tube 4a, respectively. Connectors 9 and 10 are conveniently of the friction grip type. Collection means 4, advantageously a simple plastic flask, is compartmentalized into compartments 5 and 6 by means of flexible water impervious diaphragm 7. Compartment 6 is initially empty to allow for the expansion therein of flexible diaphragm 7, e.g., to the position exemplified by 7a. Compartment 5 is completely filled with solution 1 of the osmotically effective solute, which solution likewise completely fills the tubular members 2 which are sealed at their distal ends.  
 Plug means 8 is provided for emptying and filling the compartment 5.  
  FIG. 2 shows a device similar to that illustrated in FIG. 1 with tubular members 12 again being connected via Y-shaped connector 13 to collection means 14. The connection means 13 are connected via connectors 20 and 21 to tubular members 12 and lead-away tube 14a, respectively. Again, these connectors are preferably of the friction grip type. Collection means 14 is in this embodiment divided into compartments l5, l7 and 18, with compartments l5 and 17 being separated by means of semi-permeable membrane 16, or other material exhibiting controlled permeability to water. Compartment 18 is initially empty and is separated from the remainder of the collection means 14 by means of water impervious flexible diaphragm 19. Compartment 15 contains a solution 11 of an osmotically effective solute which exhibits an osmotic pressure gradient against water, e.g., normal saline, and which is likewise contained within the confines of tubular members 12 and also connector means 13. Compartment 17 contains a more concentrated solution of osmotically effective solute and, in use, water from solution 11 passes through semi-permeable membrane 16, by osmosis, into the compartment 17, thus causing this compartment and flexible diaphragm 19 to expand, e.g., to the position exemplified by 190. An amount of water corresponding to the volume increase in the compartment 17 also flows from the body, by osmosis, across the membrane comprising the tubes 12 and into the evacuator. Plug means 22 and 23 are provided for the addition or subtraction of materials to sections 15 and 17, respectively.  
  FIG. 3 illustrates the application of the invention to a breast operation. Tubular members 2 are inserted into the wound or incision area exactly as in the McElvenny patent and are operatively connected to collection means 4 via Y-shaped connector member 3. The collection means 4 is firmly strapped to the body via straps 32 attached to collection means 4 by means of, e.g., flaps 31. Straps 32 may be adjusted by buckle or snap means 33.  
  In operation of the device of this invention, with reference to FIGS. 1 and 3, prior to suturing of the wound, the tubes 2 are inserted into the wound as in the McElvenny patent and connected to collection means 4 via Y-shaped connector 3. Sealing means 9 hold tubes 2 in a water tight friction grip and sealing means 10 holds lead-away tube 40 in the same manner. As shown at FIG. 3, the tubular member, or members, are preferably not brought out through the incision 30 but rather at a point or points spaced therefrom, whereby the tube or tubes pass through healthy tissue from which, following completion of the drainage, the tube or tubes may be withdrawn leaving a small opening which will readily heal.  
  Water, from the objectionable body fluids in the area of the wound, diffuses or is removed from the said area of the wound, by osmosis, into the interior of tubular members 2 in a tendency towards establishing an osmotic equilibrium in the system. The tubes 2 contain a solution of an osmotically effective solute which exhibits an osmotic pressure gradient against water. Inasmuch as body fluids are composed of approximately 98 water, essentially all of the body fluids will be transferred from the area of the wound into the interior of tubular members 2, which members are comprised of osmotic membrane material. This permeation of water causes a corresponding and ultimate increase in the volume of the osmotic solution in compartment 5, which increase in turn results in an expansion of diaphragm 7 into (e.g., to the position shown as 70) the intially empty chamber 6. The osmotic solution 1 in compartment 5 and tubes 2 is preferably a saturated aqueous salt solution. To maintain the solution saturated and therefore to achieve a constant osmotic pressure throughout operation of the evacuator, the compartment containing the solution also contains excess solute in solid form. If desired, additional solute may be added to and/or some of the osmotic solution may be removed from compartment 6 by removing plug 8.  
  The modification of the device, illustrated in FIG. 2, operates in a similar manner, i.e., water, from the wound area passes by osmosis from the body into semipermeable tubes 12, through connector 13 and into collection means 14. In this modification the top section of collection means 14, i.e., the area above flexibie diaphragm 19 (which corresponds to the diaphragm 7 of FIG. 1), is divided into two additional compartments l5 and 17, by means of a semi-permeable membrane 16. A less concentrated solution of osmotically effective solute, e.g., normal saline, is placed in compartment l5 and tubes 12, and a more concentrated solution of osmotically effective solute is placed in compartment 17. Since the concentration of the solution in compartment 17 is greater than the concentration of the solution in compartment 15, water is caused to diffuse, by osmosis, from compartment 15 through semipermeable membrane 16 into compartment 17, since, in relation to the solution in compartment 17, the solution in compartment 15 is hypotonic and, conversely, in relation to the solution in compartment 15, the solution in compartment 17 is hypertonic. This passage of water from body fluids into compartment 15 and thence ultimately into compartment 17 results in the concentration of the solution in compartment 15 and in tubes 12 being maintained substantially equal and sufficiently high to cause body liquids from the wound area to diffuse into the tubes and pass to the collection means 14. As the volume of the concentrated solution in compartment 17 increases with water uptake, flexible diaphragm l9 correspondingly expands into initially empty space 18, e.g., to position [90. Solution, solute or solvent may be added to or removed from compartments l5 and 17 by removing plugs 22 and 23, respectively. In the modification as illustrated in FIG. 2, the solute from the saturated osmotic solution located in compartment 17 does not leave or migrate from the confines of said compartment since it is not necessary for this solution to be present in the interior or tubes 12, and yet since this solution continuously removes water from the solution in compartment 15 and tubes 12, it acts effectively to promote the removal of the body liquids from the wound area. The device of FIG. 2, therefore, is characterized by the phenomenon that all of the pumping&#34; is done at the pump itself, i.e., across the membrane 16, rather than within the body. And in this instance there is no problem whatsoever with salt transport within the tubes 12. in the FIG. 1 embodiment the diffusive flux of the osmotically effective solute towards the extremities of the tubes 2 must be of such velocity as to prevent depletion of such solute therein.  
  The device of this invention is, of course, suitable for bed patients but a particularly desirable feature of the device of this invention is its suitability for ambulatory patients. As shown in FIG. 3, the device may readily be secured to the patients body allowing for a wide range of movement without giving rise to the patients discomfort or affecting the operation of the wound drain device. After the insertion of the semi-permeable tubes 2 into the wound area as in McElvenny and connection thereof to collection means 4, in the manner described above, the collection means is strapped onto a suitable position of the patients body via means such as mounting flaps 31 and straps 32. Such an arrangement results in only minor restrictions on the patients movements and when the draining of the wound is finished, tubes 2 are removed and discarded along with collection means 4.  
  While semi-permeable tubular means 2 or 12 may be directly connected to collection means 4 or 14, respectively, in any suitable manner, it is preferred, as illustrated, to employ intermediate connector means 3 and 13. The material employed for connection means 3 and 13 need not be semi-permeable and in fact, it is preferred that this portion of the device of this invention be composed of a material that is not semi-permeable to water. Suitable materials for use in the construction of connector means 3 or 13 would be obvious to those skilled in the art and may be natural or synthetic rubber, polyethylene, polypropylene, vinyl, and other like plastic materials. Likewise, the lead-away members, 4a and 14a, from the collection means may themselves by Y-shaped for receiving tubular members 2 and 12, respectively. The only requirement for the connection means is that it be adapted to suitably grip tubular means 2 or 12 and/or lead-away means 40 and 14a in a suitable friction-type manner to allow the passage of liquid from the tubes 2 and 12 to their respective collection means.  
  It can be seen that the device of the present invention operates to remove fluids from the area about a wound by osmosis, that is, diffusion of the water from the ex cess body fluids into the interior of the semi-permeable tubing members. Since the body fluids in a human body are composed of approximately 98% water, the tubular semi-permeable members are placed in a hypotonic aqueous environment. The osmotic solution located within the interior of the tubular members being correspondingly hypertonic causes water, by osmosis, to be diffused into the interior of the tubular members since it is a well recognized priciple of osmosis that a hypertonic solution tends toward equilibrium, that is, isotonicity. Note especially the embodiment of FIG. 1. In this manner, water is readily removed from the area of the wound and collected at a point outside of the body.  
  It is possible to determine the flux or diffusion of body liquids through the semi-permeable tubing by Ficks Law of Diffusion. Assuming that it is desired to ,remove lSO ccs of body fluid per day and also assum- [0&#34; sec X [5 cm cm sec This amount of flux or difiusion can readily and easily be achieved with common osmotic membranes such as cellulose acetate. In order to provide an even greater surface area available for osmotic diffusion according to the invention, it is contemplated that the tubes 2 and 12 can be fluted or of a star or similar configuration in cross-section.  
  The tubular members can be formed from a wide variety of materials permeable or semi-permeable to sol vent (water) but not to solute, i.e., those suitable for the construction of an osmotic cell. For best results, the membrane should be substantially impermeable to passage of the osmotically effective solute so as to prevent loss thereof. Typical membranes are isotropic membranes such as unplasticized cellulose acetate, plasticized cellulose acetate, reinforced cellulose acetate, cellulose diand tri-acetate. ethyl cellulose; anisotropic reverse osmosis membranes which typically are made of cellulose acetate; silicone rubbers, polyurethanes, natural rubber, and hydrolyzed ethylene/vinyl acetate copolymers. Isotropic membranes have less water permeability than do the anisotropic membranes. Also, with both type of membranes, increasing the acetate content of the cellulose acetate polymer decreases the water permeability. Since, as stated above, it is often important for rapid removal of body liquids from the wound area, membranes allowing relatively rapid water transmission, i.e., anisotropic membranes, are the preferred. A cellulose acetate membrane suitable for this application is available from Eastman Chemical Products. It is of course obvious that the material employed for the semi-permeable tubing should be compatible with human biological tissues so as to avoid irritation, infection, or other complications.  
  There are likewise a wide variety of osmotically effective solutes, that is, those which, when in solution, exhibit an osmotic pressure gradient against water, which can be used in the device of this invention. These include magnesium sulfate, magnesium chloride, sodium chloride, potassium sulfate, sodium carbonate, sodium sulfite, sodium sulfate, sodium bicarbonate, potassium acid phthalate, calcium bicarbonate, potassium acid phosphate, raffinose, tartaric acid, succinic acid, calcium succinate, calcium lactate, magnesium succinate, and the like. The excess solute in solid form located within the chamber containing the saturated osmotic solution can be in the form of dispersed particles or perferably in the form of a pellet. This solution can initially be a solution of the same or of a different osmotically effective solute than the solid excess solute. A particularly effective osmotic solute has been found to be magnesium sulfate, or epsom salts.  
  The collection means into which the water from the body fluids pass via the semi-permeable tubes, i.e., collection means 4 in FIG. 1 and collection means 14 in FIG. 2, can be formed of polystyrene, polyethylene, polypropylene, polyvinyl chloride, reinforced epoxy resin, polymethyl methylacrylate, styrene/acrylonitrile copolymer, polyamides, polyesters, and other like plastic materials, as well as natural and synthetic rubbers, and metals such as sheet metals (aluminum, copper, steel, etc.). it is of course intended that such collection means act as a barrier to the transport of water and osmotic solution. The diaphragm used to separate the compartments of the collection means must be flexible in order to allow for the increase in volume of the osmotic solution. Suitable materials for use as the flexible diaphragm are natural or synthetic rubbers and certain sheet polyurethanes which are impervious to the passage of water and other liquids. The connection means 3 and 13 may be made from the same materials mentioned in regards to the collection means 4 and 14. It is not necessary that they be of the same material although in most cases it will be preferred. Semipermeable membrane 16, as illustrated in FIG. 2 may be fabricated from those materials mentioned above as being suitable for tubular members 2 and 12.  
  One specific embodiment of the wound drain device fabricated in accordance with this invention and as illustrated in FIG. 2 is as follows:  
 Semi-permeable tubing 12 (two tubes):  
 Composition anisotropic cellulose acetate Cross-section 0.5 cm  
  Length 10 cm Connector 13:  
 Composition opaque polyethylene Length 25 cm Collection flask l4:  
 Composition opaque polyethylene Volume of compartment 15 250 cc Volume of compartment 17 250 cc Volume of compartment 18 250 cc Diaphragm l9 composition styrene-butadiene rubber Semi-permeable membrane 16 anisotropic cellulose acetate This device is capable of removing up to cc per day of water from body fluids accumulating in the area ofa wound in a human body. This has been found quite satisfactory for all but uncommonly large surgical incisions, in which case larger tubes and/or more tubes may be employed to withdraw the necessary amount of body liquid from the wound area.  
  While the invention has been described and illustrated with reference to certain preferred embodiments thereof, those skilled in the art will appreciate that various modifications, changes, additions, and substitutions can be made without departing from the spirit of the invention. It is intended, therefore, that the invention be limited only by the scope of the following claims.  
 What is claimed is:  
  I. An evacuator device for the extraction of body fluids, said device comprising body fluid receiving means adapted to be inserted into the area of a wound and comprised of membrane material exhibiting controlled permeability to water, and means for collecting such water that flows by osmosis across said membrane in a tendency towards osmotic equilibrium with the environment of the device, said body fluid receiving means and said collecting means being filled with a solution of an osmotically effective solute which exhibits an osmotic pressure gradient against water, said water collection means including a freely flexible, water impermeable diaphragm.  
  2. The evacuator device as defined by claim 1, wherein said body fluid receiving means is comprised of elongated tubing.  
  3. The evacuator device as defined by claim 2, wherein said water collection means is comprised of a container which is compartmented by means of said freely flexible, water impermeable diaphragm.  
  4. The evacuator device as defined by claim 3, wherein the elongated tubing communicates with a first compartment of said container, such first compartment and the said tubing being filled with said solution of an osmotically effective solute which exhibits an osmotic pressure gradient against water, and the said freely flexible, water impermeable diaphragm defining wall means comprising said first compartment.  
  5. The evacuatordevice as defined by claim 4, wherein the container is compartmented into three compartments by means ofa membrane exhibiting controlled permeability to water and by said freely flexible, water impermeable diaphragm.  
  6. The evacuator device as define by claim 5, wherein the elongated tubing communicates with a first compartment of said container, such first compartment and the said tubing being filled with said solution of an osmotically effective solute which exhibits an osmotic pressure gradient against water; the said first compartment being separated from the second compartment by wherein the first solution is normal saline.