Development of a more clinically relevant bladder and urethral model for catheter testing

Abstract

This paper sets out the rationale and design for a more physiologically representative bladder/urethral model than the current rigid funnel industry standard. We suggest this flexible model can better serve as a basis for evaluating new catheters. We investigated the parameters and the validation tests required to construct and test with more flexible materials. The protocol includes static and impact force tests, while measuring internal retention balloon pressure. We have designed a flexible elastomer bladder floor and urethral model and tested it with a Foley balloon catheter. The tests showed that the model could hold the catheter with static loads up to 0.7 kg, but that the catheter was pulled out by impact forces from dropped weights. The Foley catheter design and its associated standards make no provision to mitigate urethral injury in the surprisingly common event of removal with a filled balloon. Our design is a more realistic model for testing retention and extraction characteristics of a urethral catheter. Validation tests have confirmed the feasibility of measuring urethral dilation and balloon pressure, both under traction and during progressive deflation. We suggest this model improves upon the current standard tests and will enable the design of safer catheters.