Most catheters are a cannula or tube like device which is inserted into a portion of a person's body in order to transport fluids or gases in or out of that particular portion of the body. In passing through any particular portion of the body in order to reach its destination, the catheter will come into contact with various tissues in the body. For example, a catheter used to drain one'bladder (such as a "Foley" catheter) must pass through the urethral tract in order to reach the bladder. A nasogastric catheter must pass through the nasal passageway and the esophagus in order to reach the stomach. Some catheters, such as these, are inserted through existing passageways in order to reach their destinations, while others are inserted through surgically created passageways.
In virtually every catheterization, there is a significant potential for microbial growth along the exterior surface of the catheter which can lead to serious infections such as urinary tract infections, bladder infections and the like. Such an infection can be encouraged when adjacent tissues are inflamed due to irritation from rubbing a chafing against this catheter. This is because inflamed or irritated tissues may be less apt to respond effectively to suppress local bacterial infection. In such a situation the infection can spread and intensify, placing the patient at further risk. Such infections can lead to sepsis of the bladder particularly in elderly patients who are incontinent and have a chronic need for catheterization with an indwelling self-retaining catheter such as a "Foley" catheter. Long-term use of indwelling urinary catheters in nursing home patients is well known as a potential cause of significant morbidity due to such infections.
This problem is widely recognized and many solutions for this problem have been suggested in the past. None of these solutions, however, have been completely free of secondary complications and/or completely successful in eliminating the problem. For instance, systemic use of antibacterial drugs or agents have been tried. However, these drugs generally have undesirable secondary effects upon the patient when used systemically, especially when there is a chronic need for catheterization and the drug must employed for a long period of time. Local use of such drugs or agents can be effective for a short period of time, but has not been found to be effective for long-term use for a number of reasons. First, the drug or agent is easily washed out if there is a leakage of urine through the urinary track outside of the catheter. Second, the drug or agent may be delivered only to certain areas of the urinary tract and, third, the drug or agent may be absorbed by the body tissues adjacent to the catheter and transported elsewhere within the body.
Other methods of preventing periurethral contamination have been suggested. These include careful cleansing of the periurethral area on a routine basis, impregnating a sponge or the like with an antiseptic solution and retaining it in a position proximate the urethral, apply antimicrobial ointments to an external portion of the urinary tract, intraurethral irrigation of the urinary track through a separate channel, lubrication of the catheter with an antibiotic-containing material and the use of catheters impregnated with antimicrobial agents. Each of these methods has been explored and none have been found to be entirely satisfactory. In vitro tests of impregnated catheters indicate that the antibacterial agents within the catheters have a tendency to leach or diffuse out of the catheters in a short period of time. Often, the antibacterial activity was either gone or markedly diminished within 24 to 48 hours of insertion within the urethral tract. Therefore, it would be appreciated that a sustained release bactericidal cannula or catheter is needed in order to address the needs of patients requiring long-term catheterization or the like.
Accordingly, it will be appreciated that there is a need for a medical device, cannula or catheter which will address these and other problems associated with the prior art devices. The present invention provides advantages over the prior art cannulas and catheters, over the prior art methods for manufacturing the same, and also offers other advantages over the prior art and solves other problems associated therewith.