Model of the proximal urethra: measurement of the urethral stress profile.

Research on the activity of the urinary tract has led to the creation of a theoretical mechanical model where elastic forces, affecting rigid segments represent the living tissue of the urethral walls whereby it is assumed that the tissue acts as an elastic material. Such a model provides a clearer picture of changes in the physical parameters of the elastic walls of the urethra and facilitates better analysis of measurement errors. Artefacts make it exceptionally difficult to accurately measure the urethral pressure profile. The known methods have a measurement error of at least 30%. We have been trying to eliminate the basic error caused by the size of the measuring sensor. The methods involves measuring the urethral pressure profile in one patients using several sensors of varying diameters. The problem was defined mathematically. By extrapolation of measuring points, the value of elastic force under normal conditions can be obtained. Preliminary results of pressure profile measurements in our patients are much more accurate than those of other currently known measuring techniques. It is too early, however, to predict the extent of increased objectivity in the results of the new method for measuring urethral pressure profile, with and without functional electrical stimulation. The parameters of stimuli produced by our electrical stimulators will be based upon these findings.