Design and development of a novel automatic valve system for long-term catheterized urinary incontinence patients.

It has been estimated that over 3 million patients in the UK suffer from urinary incontinence, the result of which is often long-term catheterization. However, many catheters block prematurely through encrustation and their continuous drainage limits bladder rehabilitation. Although evidence shows that a catheter valve may overcome such weaknesses, only manual valves are currently available and many patients are not able to benefit from these owing to a lack of manual dexterity. A novel electronically controlled automatic valve system, the Shan-Lai (SL) valve system, has been designed and prototyped. The prototype is compact, reliable, and cost effective, and it has low power consumption. The mass of the overall packaged valve system is 34.2 g and it measures 4.5 cm x 4.5 cm x 1.2 cm. With an orifice of 3 mm diameter, the SL valve has achieved high flowrates with relatively low energy consumption. A flowrate-energy relationship (FER) has been introduced to assess the performance of a catheter valve, and the SL valve system prototype has achieved an FER of 0.66 m/s(-1) mJ(-1) while a commercially available electronic valve has an FER of 0.28 m/s(-1) mJ(-1). The valve demonstrated outstanding mechanical reliability after a series of performance tests and also indicated remarkable encrustation resistance in the vicinity of the valve during an in-vitro test.

Does the valve regulated release of urine from the bladder decrease encrustation and blockage of indwelling catheters by crystalline proteus mirabilis biofilms?

PURPOSE: We tested whether valve regulated, intermittent flow of urine from catheterized bladders decreases catheter encrustation. MATERIALS AND METHODS: Laboratory models of the catheterized bladder were infected with Proteus mirabilis. Urine was allowed to drain continuously through the catheters or regulated by valves to drain intermittently at predetermined intervals. The time that catheters required to become blocked was recorded and encrustation was visualized by scanning electron microscopy. RESULTS: When a manual valve was used to drain urine from the bladder at 2-hour intervals 4 times during the day, catheters required significantly longer to become blocked than those on continuous drainage (mean 62.6 vs 35.9 hours, p = 0.039). A similar 1.7-fold increase occurred when urine was drained at 4-hour intervals 3 times daily. Experiments with an automatic valve in which urine was released at 2 or 4-hour intervals through the day and night also showed a significant increase in mean time to blockage compared with continuous drainage (p = 0.001). Scanning electron microscopy confirmed that crystalline biofilm was less extensive on valve regulated catheters. CONCLUSIONS: Valve regulated, intermittent flow of urine through catheters increases the time that catheters require to become blocked with crystalline biofilm. The most beneficial effect was recorded when urine was released from the bladder at 4-hour intervals throughout the day and night by an automatic valve.