Abstract:
Cavity conforming balloons with active pressure gradients are provided to replace passive reliance on gravity flow of fluid from organs, body lumina, cavities and the like for more accurate and timely assessment and analysis of exudates. Diffuse drug delivery to cavities or lumina can be administered as an adjunct to the drainage process, as can application of brachytherapy.

Description:
[0001]     This application claims benefit of provisional application No. 60/751,159, filed Dec. 16, 2005. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The invention concerns apparatus for drainage of liquids from a body cavity or lumen of a living patient, including quantification of liquid flow.  
         [0003]     Today, assessment of fluid exudate outflow from the body is reliant upon collection by devices dependent on gravity flow.  
         [0004]     This flow is therefore often affected either by position of the patient in relation to the collection device, or by pressure exerted by the body on the subject organ or lumina. Quantitative analysis is dependent on constant repetitive observation by nursing staff, and qualitative assessment follows sampling and subsequent analysis, often long after collection.  
         [0005]     A well-known example is urine collection by means of a Foley catheter. Urine pools in the bladder, flows out the Foley through a collection tube into a bag, usually hung on the bed. Nursing staff periodically observes and records volume of urine collected, but dependent on patient position and whether the tube is kinked restricting flow, there is likely a time lag between kidney output to the bladder and collection in the bag. Volume per unit time is therefore inexact. This effect is exacerbated by the fact that the Foley does not completely occupy or reach all the space in the bladder, potentially allowing a pool of urine to accumulate until the level reaches the Foley outlet. This level is very dependent on patient position.  
         [0006]     There is therefore need for a system to more immediately accumulate and account for fluid extraction, making volume collection data and qualitative analysis immediately available. Preferably, this data is sensed automatically at the bedside with the results communicated immediately to a remote site, for example a nursing station, for timely use in therapeutic decision-making. This invention addresses this need, and in addition to providing accurate and timely urine analysis and output data, will free nursing staff from most bedside data collection, so they can provide increased patient care.  
         [0007]     Although this background is presented using urine collection, this invention has applicability to other drainage procedures as well, for example, wound drainage post operatively. As an adjunct to drainage, therapeutic or opaque imaging agents may be administered to the interior surfaces of a cavity or lumen being drained.  
       SUMMARY OF THE INVENTION  
       [0008]     One embodiment of this invention comprises a low-pressure, cavity-filling balloon on a flexible catheter shaft, or alternatively, on a rigid wand, depending on the cavity being drained and its accessability. At the distal end of the catheter or wand is the balloon; and at the proximal end is a multi-entry hub for separate connections to lumina within the shaft of the catheter or wand.  
         [0009]     The catheter or wand comprises two lumina, one for balloon inflation, and one for fluid withdrawal. Preferably, these lumina are coaxial, although they can simply be parallel. More lumina and other configurations of lumina may be provided for other purposes as described below.  
         [0010]     On the outside of the balloon is a continuous surface covering which is capable of expanding with the balloon, and which is permeable or semi-permeable such that the fluids to be extracted, or the agents to introduced, can flow through the layer in response to an actively applied pressure gradient. In an alternate embodiment, the covering is intermittent, and shaped to create channels to decrease resistance to fluid flow of liquids over the surface of the balloon while it is in contact with the cavity or lumen being drained. With channels, the fluids being collected need only pass through the surface covering a short distance, as explained below.  
         [0011]     At the proximal end of the balloon where it meets the catheter or wand, the outer layer, and any channels therein, communicate with a lumen in the shaft of the catheter or wand for withdrawal of fluid from the body of the patient. This lumen is in fluid communication with a collection system comprising a collection receptacle external to the body. The other catheter or wand lumen is for pressurizing the balloon. Sensors are situated along the fluid path between the balloon and the collection receptacle, preferably outside the body, such that volume per unit time can be immediately assessed, and if desired, fluid properties can be analyzed. Results can then be transmitted to a remote site, for example a receiver console or nursing station, for immediate evaluation and use in making therapeutic decisions. A vacuum drawn on the extraction lumen provides a flow gradient drawing exuded fluid through the outer balloon surface layer, and channels if any, to the catheter or wand, through the in-line sensors, and into the receptacle.  
         [0012]     In use, after the catheter is inserted into the patient and properly situated in the target cavity or lumen, controlled pressure is applied to the pressure lumen of the catheter to inflate the balloon such that it fills the target cavity or lumen. Vacuum is then pulled on the extraction circuit to begin active fluid flow and analysis.  
         [0013]     Because empty space within the target cavity outside of the balloon is eliminated, stagnant pooling of exudate in the target cavity or lumen is also eliminated. The pressure gradient created by the vacuum assures fluid extraction is accomplished under all conditions of body attitude or stress in a timely manner. Should the vacuum tend to collapse the thickness of the outer balloon layer, a further lumen can be provided in the catheter or wand which communicates between the proximal hub and the distal-most portion of the outer covering of the balloon in order to provide a vent, relieving the force tending to compress the outer covering. The vent can be used when desired, usually intermittently but possibly continuously, to admit a liquid into the permeable layer to keep the compressible permeable layer expanded or to re-expand it. The liquid could include a therapeutic agent, such as a solution of hydrogen peroxide, in the case of a surgical excision cavity. The more rigid and less compressible the permeable layer, the more a venting liquid flow is useful to maintain a flow of the seroma or other liquid being withdrawn.  
         [0014]     As a separate but related embodiment of this invention, and where appropriate, the outer permeable layer can be coated or imbibed with drugs to be diffusely administered to the interior surface tissues of the target cavity or lumen, before insertion into the body. In a still further embodiment, a lumen may be provided in the catheter or wand which communicates between a separate entry at the proximal hub, and sealingly passes through the distal end of the balloon to communicate with the distal-most portion of the outer permeable/semi-permeable surface layer on the balloon. Using this lumen, drugs or other therapeutic agents may be introduced under pressure to bathe the interior tissues of the subject cavity in a flushing manner.  
         [0015]     A further embodiment of this invention is drainage in combination with brachytherapy utilizing small sources of ionizing radiation. This embodiment could also include application of therapeutic agents as discussed above, including agents to enhance, vary or retard the therapeutic effect of a prescribed dose of radiation therapy. Lumina or channels can be provided to selectively administer such agents prior to or simultaneously with delivery of radiation treatment, providing localized effect. These and other objects, advantages and features of the invention will be apparent from the following description of preferred embodiments, considered along with the accompanying drawings. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a schematic view of the system in relation to a body cavity of the patient.  
         [0017]      FIG. 2  is a side view in cross-section of the balloon section of a catheter of the invention.  
         [0018]      FIG. 3  is a side view of a balloon showing channels in the outer permeable layer.  
         [0019]      FIG. 4A  is a transverse section showing channels through the complete thickness of the permeable layer, whereas  FIG. 4B  is a transverse section through the balloon where the channels are only part way through the permeable layer.  
         [0020]      FIG. 5  is a side view in cross-section of an alternate embodiment of the invention.  
         [0021]      FIG. 6  is a side view in cross-section showing a further embodiment of the invention including a radiation source. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0022]      FIGS. 1 and 2  show a wand or catheter  100  comprising a shaft having two coaxial tubes forming channels or lumina, the inner tube  201  forming a lumen  101  for pressure to inflate an impermeable balloon  103 , and the outer tube  202  forming a lumen  102  for extraction of exuded fluid (liquid). Outside of, and bonded to the outer surface of the balloon  103  is a permeable or semi-permeable layer  104 . The term “permeable” as used in the claims is intended to include both permeable and semi-permeable. The balloon  103  itself is bonded to the shaft portion of the catheter, specifically to the inner tube  201  as shown. The catheter is indicated as inserted into a cavity of the patient and inflated, with the layer  104  in intimate contact with the inner walls of the subject cavity. The inner catheter lumen  101  is connected to a pressure source, for example a squeeze bulb (not shown) outside the body of the patient. The outer lumen  102  passes through sensors  115   a  for volume, and, in this embodiment,  115   b  for qualitative analysis as representative of sensors which might be used to assess-volume flow per unit time and quality of exudate. The outer lumen  102  then continues to the liquid collection receptacle  106  shown with liquid  107  therein. The collection receptacle  106  is sealed from the atmosphere to preserve vacuum, which is controlled by pressure regulation methods.  
         [0023]     The inner lumen  101  exits the outer lumen  102  at a point  108 . If, for example, a turbine type sensor is used to assess fluid flow per unit time, then the sensor  115   a  might advantageously be placed downstream of the exit point  108 , rather than as shown. If quality assessment is spectrographic, the sensor  115   b  would advantageously pass through a section of the catheter or shaft  100  which is transparent to light. Sensor output can be transmitted, for example wirelessly, to a remote location such as a nursing station where monitoring equipment with display is located.  
         [0024]      FIG. 2  shows a cross section in side view of the balloon  103  portion of the catheter or wand. The distal portion  109  of the tube  201  forming the inner lumen  101  extends the length of the balloon  103  to facilitate insertion into the patient. Advantageously, the distal tip  109  is connected to the balloon and rounded to ease insertion of the catheter or wand  100  and to minimize possible damage to the balloon  103  during insertion into the patient. The tube  201  forming the inner lumen  101  has a port  110  opening from the lumen  101  into the balloon  103  to pressurize and expand the balloon. Proximal of the port  110 , the proximal end of the balloon is bonded to the tube  201  forming the lumen  101 . The permeable layer  104  communicates with the lumen  102  for extraction of exudates. As illustrated in  FIG. 2 , the outer permeable balloon layer  104  is bonded to the outside of the tube  201  forming the lumen  101 , and to the inside of the tube  202  forming the lumen  102 .  
         [0025]     The concentric tubes  201  and  202  forming the lumina  101  and  102  may be made of polyurethane, for example. The balloon  103  may be made from silicone rubber, for example. The outer permeable layer  104  can be made from open-cell polyurethane foam, for example. Methods to fabricate these sorts of materials into articles like those described are well known in the art.  
         [0026]      FIGS. 3 and 4 A show in side elevation and transverse cross section, the balloon portion of the catheter or wand  100 , with another form of permeable outer layer  104   a . Channels  111  are formed between and completely through sections of the permeable layer  104   a  attached to the outside of the balloon  103 . These channels  111  may taper down to zero width, merging into a tubular shape where joining tubes  201  and  202  in the way shown in  FIG. 2 , or optionally, the channels  111  may continue into the bond area such that they communicate directly with the lumen  102 . The balloon  103  is visible at the bottom of these channels  111  between sections of the layer  104   a . These channels  111  serve to provide increased fluid flow to the lumen  102  at the proximal end of the balloon. With the channels  111 , the exudate has only to traverse through the permeable layer a short distance rather than through the permeable layer continuously from the fluid source to the lumen  102 . Channel width should be chosen to be narrow enough that tissue of the cavity wall is not attracted sufficiently into the channels so as to block fluid flow.  
         [0027]      FIG. 4B  shows, again in transverse cross section of the balloon  103  portion of the catheter or wand, channels  112  formed between, but only partially through, sections of the permeable layer  104   b  attached to the outside of the balloon. These channels  112  again serve to provide increased fluid flow to the lumen  102  at the proximal end of the balloon, and again may optionally continue into the bond area such that the channels  112  communicate directly with the lumen  102 . The exudate again has only to traverse through the permeable layer  104   b  a short distance into a channel  112 , rather than through the permeable layer continuously from the fluid source to the lumen  102 . This channel construction serves to minimize cavity tissue being drawn into the channels, which could potentially block fluid flow.  
         [0028]     An alternate embodiment of the invention is shown in  FIG. 5 .  FIG. 5  shows the balloon portion of catheter  100  in longitudinal cross-section, including a catheter lumen  105  communicating between the proximal hub and the outer permeable layer  104  after sealingly passing through the distal end of the balloon  103 . The lumen  105  is suitable as a vent or for introduction of therapeutic agents under pressure. As discussed above, the vent can be used, intermittently or continuously, to admit a liquid, and the liquid can carry the therapeutic agents.  
         [0029]     Another therapeutic adjunct is the application of radiation therapy, particularly in intraoperative situations, for example to the cavity created during a breast lumpectomy where both post-operative radiation therapy and drainage are indicated. Therapy of this sort is described in co-pending application Ser. No. 10/683,885, filed Oct. 13, 2003′, herein incorporated in this specification in its entirety. Suitable miniature electronic x-ray sources are known, for example those of U.S. Pat. No. 6,319,188, “Vascular X-Ray Probe”, adapted as to power capability for the intended application. Where radiation is to be applied, it could be applied via the central pressure lumen  101 , or through an auxiliary lumen within the catheter or wand or shaft portion  100  to an axial position within the region encompassed by the balloon  103 . In conjunction with radiation therapy and if desired, balloon or catheter mounted dosimeters  117  can be affixed to the exterior of the balloon outer layer  104  or the catheter  100  to monitor and verify the dose delivered, or to adjust radiation delivery parameters in real time during application of the therapy.  
         [0030]      FIG. 6  shows an embodiment comprising introduction of a probe  113  comprising a source of ionizing radiation  114  into the cavity or lumen through the lumen  101  and a seal  116  at the proximate end of the shaft of the catheter  100 . Advantageously, the lumen  101  is sized to loosely accommodate the probe  113  at and proximal to the port  110  so as to not interfere with balloon inflation. Distal of the port  110 , the lumen  101  may more snugly conform to the probe  113  in order to control the dose distribution of the therapeutic radiation.  
         [0031]     In use, the catheter or wand  100  is prepared and inserted into the patient (perhaps with a slippery coating of hydrogel to facilitate insertion), properly situated in the target cavity or lumen, and then controlled pressure is applied, for example by a squeeze bulb (not shown), to the catheter lumen  101  to inflate the balloon  103  such that it fills the target cavity or lumen. Pressure indicators can be used to sense the pressure rise as the balloon fills and occupies the cavity, or alternately, the balloon may be rendered radio-opaque such that cavity filling can be verified by radio-graphic methods. Vacuum is then pulled on the extraction circuit, for example by regulated wall suction applied to the collection receptacle  106 , to begin active fluid extraction and analysis. Such analysis might include pH or liquid spectroscopy for example, in addition to volumetric analysis.  
         [0032]     If in use the layer  104  loses contact with the issue surrounding the cavity, or the application of vacuum causes partial deflation of the balloon such that it is no longer in contact with the walls of the cavity or lumen, that can be sensed, again by radio-graphic methods if necessary, and the balloon pressure may be increased until contact is again achieved, eliminating dead volume between the cavity and balloon outer surface.  
         [0033]     If desired, the outer layer  104  may be coated or imbibed with drugs before the catheter or wand  100  is inserted into the body and the balloon  103  is expanded, those drugs to be suffused into interior cavity or lumen tissue. Such drug delivery can be useful, for example, in treating an abscessed cavity Subsequent drainage can be analyzed over time as the abscess shrinks, and the results used to determine when the drainage system can be safely removed.  
         [0034]     With this method and apparatus, effective, active drainage of bodily exudate can be achieved, providing timely data for therapeutic decision making, and facilitating a range of proactive treatment regimens which may be applied, including diffuse drug delivery and brachytherapy. In addition, nursing staff are freed from tedious data logging, and are thus able to handle a greater patient load.  
         [0035]     The above described preferred embodiments are intended to illustrate the principles of the invention, but not to limit its scope. Other embodiments and variations to these preferred embodiments will be apparent to those skilled in the art and may be made without departing from the spirit and scope of the invention as defined in the following claims.