Patent Publication Number: US-2004049170-A1

Title: Balloon-free urinary catheter

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
     [0001] The present application claims the benefit f priority of International Application No. PCT/GB01/03434 filed on Jul. 31, 2001 which claims the benefit of GB Application No. 0019107.2 filed on Aug. 3, 2000, the entire contents of which are incorporated herein by reference. 
    
    
     
       BACKGROUND  
       [0002] 1. Technical Field  
       [0003] This invention relates to a balloon-free urinary catheter.  
       [0004] 2. Background of Related Art  
       [0005] Many people suffer from a variety of problems with their urinary system ranging from the inability or difficulty to pass urine to urinary incontinence which can be intermittent or chronic. The most common treatment for many of these disorders is to fit a FOLEY catheter to control drainage of urine from the bladder. A FOLEY catheter is a flexible tube, usually made from latex, which has a central lumen and an inflatable balloon incorporated into a wall of its distal end. With the balloon deflated, the catheter tube can be passed through the urethra into the bladder. Once the balloon at the distal end of the tube is located in the bladder, it is inflated and then rests in the neck of the bladder to provide a seal therewith and prevent the tube from being easily removed. A tubular extension extends a few centimetres beyond the top of the balloon and has holes in its wall to allow urine to pass from the bladder into the central lumen tube. It then flows to the proximal end of the device which is fitted with a connector to inflate the balloon and a second connector to close the central lumen. A collection bag is usually connected to the second connector.  
       [0006] The FOLEY catheter was developed over 40 years ago and has many disadvantages. Firstly, about half of all catheterised patients block their catheters. The FOLEY catheter does not allow for easy removal and cleaning or back-flushing and drainage whilst inserted. Furthermore, it does not deal effectively with those patients whose catheters block and most catheterised patients develop infections of some sort when using a FOLEY catheter which in some cases can be problematic. The FOLEY catheter is very obtrusive, particularly for elderly patients requiring long term catheterisation (the largest group) so its use represents a significant degradation in their quality of life. The major advantage of the FOLEY design is that it is relatively cheap to manufacture, although it does require multiple-dip coatings of latex which can be time consuming. It is also widely available and accepted by the medical profession despite its shortcomings.  
       SUMMARY  
       [0007] Preferably the retention section is made of a braided material including structural filaments that are arranged at an angle such that when the axial force is applied to the retention section, the tube decreases in diameter but returns to its original shape due to the hoop stress within the braid structure. Preferably, the retention section is made of a polymer such as polyurethane, neoprene, styrene ethylene butadienestyrene (SEBS), styrene butadiene styrene (SBS), plasticised PVC or thermoplastic valcanites. The structural filaments can be made of a ceramic material or metallic wires or polypropylene, nylon, polyurethane, polyethylene. The diameter of the retention section increases on the removal of said axial force until the angle of the braids in relation to the longitudinal axis of the catheter reaches a critical angle. The preferred critical angle is tan −1 {square root}2=54.73°.  
       [0008] The tubular drainage section can also be made of a braided material including structural filaments that are arranged at an angle such that when the axial force is applied thereto, the tube decreases in diameter but returns to its original shape due to the hoop stress within the braid structure.  
       [0009] In the preferred embodiment, the braid angle of the filaments in the tubular retention and drainage sections is different so that said tubular sections will expand differentially on release of the axial pressure applied to the retention section.  
       [0010] Preferably the catheter is made of a thin walled elastomeric polymer tubing for example polyurethane, neoprene, styrene ethylene butadiene styrene (SEBS), styrenebutadiene styrene (SBS), plasticised PVC or thermoplastic vulcanites.  
       [0011] Conveniently a valve is located in the proximal end of the catheter which can be of any convenient type. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0012] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which  
     [0013]FIG. 1 is a cross section of the area surrounding the urinary tract showing a prior art FOLEY catheter fitted in the bladder;  
     [0014]FIG. 2 is a side view of a urinary catheter of the present invention in its normal relaxed state;  
     [0015]FIG. 3 is a view of the catheter shown in FIG. 2 in its elongated reduced diameter state ready for insertion into the bladder;  
     [0016]FIG. 4 shows the urinary catheter of FIGS. 2 and 3 but in its relaxed normal state when in position in a patients bladder;  
     [0017]FIG. 5 is an end view of the catheter shown in FIGS.  2 - 4   
     [0018]FIG. 6 is a cross section through the catheter of FIGS.  2 - 5  but including the placement tool;  
     [0019]FIG. 7 is an end view of the catheter of FIGS.  2 - 6  but including a return spring in the retention section; and  
     [0020]FIG. 8 shows the catheter of FIG. 4 in position in a patient&#39;s bladder. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
     [0021] Referring to FIG. 1 of the drawings, there is shown a bladder  1  having a neck  2  which tapers into prostatic part  4  of urethra  3  which is surrounded by prostate gland  5 . The external sphincter  6  is also shown whose normal function is to keep the urethra closed until urination when it opens for emptying the bladder  1 .  
     [0022] A prior art FOLEY type catheter  7  having an elongate body section  8  and a balloon  11  at one end is seated in the tapered neck  2  of the bladder  1  to make a seal therewith. The balloon  11  has a tubular section  12  extending therefrom with holes  13  therein.  
     [0023] To insert the catheter  7  into the bladder  1 , the balloon  11  is collapsed and the catheter  7  is inserted through the urethra  3  until the balloon portion  11  has traveled beyond the tapered neck  2  of the bladder  1 . The balloon  11  is then inflated to its condition illustrated in FIG. 1 as a result of which it makes a seal with the tapered neck  2  of the bladder  1 . The body portion  8  of the catheter  7  is located within the prostatic part  4  of the urethra  3  and its distal end  14  protrudes just beyond the end of the urethra  3 . A valve incorporating a connector (not shown) would normally be attached to the distal end  14 . Urine drains from the bladder  1  through the holes  13