The dissolution of urinary catheter encrustation.

OBJECTIVES: To identify the optimum volume of acidic bladder washout solution to dissolve catheter encrustations and to compare the effectiveness of different bladder washout delivery devices.
MATERIALS AND METHODS: Urinary catheter encrustation was generated in vitro using a model of the catheterized bladder adapted from previous work. An acidic bladder washout solution (Suby G) was applied via the catheter in the model and retained for 15 min. The amount of encrusting material dissolved was measured by colorimetric analysis of the magnesium and calcium content of the solution returned after the washout procedure. The relative effectiveness of different volumes of washout solution and different washout delivery devices (Optiflow, Bard Ltd, Crawley; UroTainer, B/Braun Medical Ltd, Aylesbury; and a bladder syringe) in dissolving catheter encrustations was compared to the 'standardized' conditions commonly used in practice.
RESULTS: There was no statistically significant difference between washouts with 100 mL and washouts with 50 mL for any of the delivery devices tested. Gentle agitation with 50 mL Suby G did not significantly improve the dissolution of encrustation but the total amount of material dissolved when two washouts with 50 mL Suby G were used sequentially was significantly better than a single washout with either 100 mL or 50 mL.
CONCLUSIONS: Under controlled laboratory conditions, smaller volumes of acidic bladder washout solution (50 mL) are as effective as the 100 mL commonly used in practice, but two sequential washouts with 50 mL are more effective than a single washout. The newly designed Optiflow delivery device is at least as effective as the other devices tested. This study provides new evidence which may contribute to decision-making by practitioners in relation to catheter care.