Catheterization is required in post operative patients either to assist monitoring of the urine output or because they cannot release the sphincter muscle which has been traumatized by shock of an operation. Long term indwelling catheters are required by paraplegic patients whom have no control over their bladder. At least 50% of long term care residents in nursing homes are identified as incontinent and the problem is frequently managed with indwelling catheters.
Most paraplegic patients develope chronic bladder and kidney infections, and in the end succumb to infection or toxins produced by the infection which cause failure of other organs. Therefore, many paraplegics die from an infection which starts in the urethra or bladder as a result of infections introduced by the use of the catheter.
Urine and other body fluids excreted through the urethra are mediums in which a number of organisms can flourish. Therefore, even when the most sterile techniques are employed during the insertion of a catheter, there is still a path through which infectious organisms can enter the body, that being through the inside of the catheter directly into the bladder.
Yet another path by which infectious organisms can enter the body is along the outside surface of the catheter. Although sterile techniques may temporarily eliminate this path during catheter insertion, it is possible for such organisms to migrate along the outside of the catheter when the antiseptic effect of such techniques has worn off.
Bacterial sepsis can generally be treated successfully with antibiotics, but a complete treatment regimen can be expensive and time consuming. In addition, antibiotic therapy is often complicated by superinfections and increasingly, the appearance of antibiotic-resistant pathogenic strains. Mycotic infections (fungi, molds, yeasts), typically occasioned by extremely high fevers, are usually refractory to commonly employed antibiotics and as a result are often fatal.
One of the largest problems and the greatest dangers to the patient that exist when using an indwelling urethral catheter, such as a Foley catheter, is infection that occurs after the catheter has been indwelling for a few days. Clinical studies have shown that the catheter, both internally and externally, provides an avenue for entry of pathogenic organisms. In the former instance, with respect to organisms gaining access through the interior of the catheter, it is commonplace to provide means for killing organisms that would otherwise multiply in a urine drainage bag operatively connected to the catheter. In the latter instance, attempts have been made to prevent organisms from entering the urethral passage between the wall of the urethra and the exterior surface of the catheter. However, such attempts with respect to providing a barrier that would prevent organisms from entering the urethral passage between the urethra and catheter can result in introducing additional problems not the least of which is increased irritation and inflammation of tissue by prior art catheters, which condition materially enhances the likelihood of infection attendant the use of an indwelling catheter or the like. An indwelling catheter, such as a Foley catheter, is merely an example and the same problem exists with respect to other drainage tubes as well as venous catheters.
Generally, the attempts of the prior art to provide catheters intended to eliminate or minimize infection comprise catheters in which a microbiocide capable of withstanding the conditions attendant the manufacture of the catheter are actually incorporated in a composition comprising the catheter. Such catheters normally achieve a microbiocidal effect by virtue of the fact that in use the microbiocidal agents in the base material bleed to the surface. In the case of urethral catheters this results in irritation of the wall of the urethra. It is believed that catheters with such a construction are no longer in use.
A subsequent generation of indwelling catheters resorted to a somewhat different approach in an attempt to reduce infection. In this regard, and since the tubular body portion of most catheters is formed of a natural or synthetic elastomer that is hydrophobic, prior art catheters such as those formed of silicone rubber have had substantially their entire surfaces, both interior and exterior, coated with a hydrophillic polymer to enable the absorption of aqueous solutions of suspensions of microbiocide, including antibiotics into the coating.
In this regard U.S. Pat. No. 4,055,682 to Merril is directed to a catheter having a silicone body portion rendered hydrophillic by contacting it with N-vinyl pyrrolidone (NVP) and exposing the catheter and NVP to ionizing radiation. U.S. Pat. Nos. 3,566,874 and 3,695,921 to Shepherd et al are representative of indwelling Foley urethral catheters made of natural or synthetic rubber and having an external coating of a hydrophillic acrylate or methacylate polymer grafted thereto for reducing irritation and infection. The hydrophillic polymer may be impregnated with an antibiotic or germicide.
There are several problems encountered by the systems of Merril and Shepherd et al in that if a microbiocide is applied to substantially the entire surface of a catheter, in use it will cause irritation and probably do more damage to the patent than if a standard untreated catheter were used. Further, if an antibiotic is impregnated in the surface of a catheter then only those organisms that are rendered dormant or killed by the particular antibiotic would be effected. The protective flora would be damaged with a possibility that other organisms normally subdued by the flora would run rampant. Thus the use of an antibiotic impregnated catheter could tend to induce rather than prevent infection.
Rendering a surface of a catheter hydrophillic causes other problems. One of the most significant problems in this regard is brought about by the very nature of the coatings, its hydrophillicity, that provides a wettable surface. Once such a wettable surface is in contact with a physiological fluid such as urine, for example, which has dissolved salts and other solid compounds in its composition, the hydrophillic coating, by virtue of uptake of the aqueous moiety of such physiological fluid, provides a nucleus for the accretion of salt due to a supersaturated condition adjacent the coating as well as accretion of other solid components of the composition. An unfortunate end result is a plugged catheter or a catheter with a sharp accretion of salts and the like on the exterior surface of the catheter. Needless to say, in the instance of an urethral catheter having such an accretion on the exterior thereof, the removal of the catheter brings about a situation not unlike the passing of a jagged kidney stone through the urethra.
The U.S. Pat. No. 4,878,901 to Sachse, issued Nov. 7, 1989 discloses an indwelling urethral catheter arrangement for the prevention of ascending bacterial infection which flushes downwardly the bacteria by urine permitted to flow along the inside of the urethral wall, the entire urinary stream being conducted with aid of a condom like sheath fittable over the tip of the penis to the outside of the catheter arrangement. The condom is necessary to prevent soiling of the patient's clothing. This arrangement is only suitable for male patients and further requires the uncomfortable situation of the continual need for the condom-like sheath.
The present invention provides a catheter assembly which is maintained completely within the urethra and includes means which prevent leakage without requiring an external fluid catch, such as a condom like member.