Biomedical subjects
Publications and source records attributed to M Kranse.
Infravesical obstruction can only be diagnosed objectively from a urodynamic pressure-flow study. Analysis of the resulting data is not straightforward. Recently,many methods have been proposed for such analysis. Inevitably most of these methods for pressure-flow analysis are discussed in this contribution, and some results of clinical application of calculated urethral resistance factors are presented.
PURPOSE: The resistance offered to urinary flow by the urethra is one of the factors determining the course of micturition. It was the aim of the present work to study the dependence of urethral resistance on the degree of relaxation of the urethra. MATERIALS AND METHODS: Experiments were done in the guinea pig. Ten animals were used. In 5 animals saline was forced through the (unrelaxed) urethra at imposed flow rates in the range of 1.1 to 43.0 ml. per minute while the urethral pressure was measured. Second degree polynomials were fitted to the pressure/flow data. In the other 5 animals micturition contractions were evoked and pressure/flow plots were derived from the measured signals. A straight line was fitted to the lowest pressure values at each flow rate in these plots. These pressure values represent the most relaxed state of the urethra in these voidings. RESULTS: The pressures measured in the unrelaxed urethra were much higher than the pressures measured during voiding in the same flow rate range, but the intercepts of the mathematical equations fitted to the pressure/flow data on the pressure axis were not significantly different in the 2 groups. CONCLUSIONS: The unrelaxed urethra has a much "steeper" pressure/flow characteristic than the relaxed urethra. However, the urethral closing pressure, that is, the intercept of the pressure/flow characteristic on the pressure axis, does not depend on the state of relaxation of the urethra.
The simultaneous measurement of detrusor pressure and flow rate during voiding is at present the only way to measure or grade infravesical obstruction objectively. Numerous methods have been introduced to analyze the resulting data. These methods differ in aim (measurement of urethral resistance and/or diagnosis of obstruction), method (manual versus computerized data processing), theory or model used, and resolution (continuously variable parameters or a limited number of classes, the so-called monogram). In this paper, some aspects of these fundamental differences are discussed and illustrated. Subsequently, the properties and clinical performance of two computer-based methods for deriving continuous urethral resistance parameters are treated.
In this pilot study on 17 men who underwent urodynamic investigation for various dysuric complaints, real-time transrectal ultrasonography (TRUS) was performed. From the images anatomical parameters were identified that correlated with obstructive urodynamic findings and urethral resistance parameters based on pressure-flow analysis. This study gives support for further clinical investigations to determine the value of TRUS for male patients with dysuric disorders. It also illustrates the anatomical basis of prostatic obstruction as quantified by objective urodynamic parameters.
The measurement of detrusor pressure and flow rate during voiding is the only way to objectively measure or grade infravesical obstruction. The resulting data cannot be interpreted easily. Manual as well as automatic methods have been introduced to derive one or several factors or parameters to quantify urethral resistance. A number of these methods are described in this overview. Since automatic methods involving computers guarantee uniform, unbiased, and objective processing of data, besides enabling the use of (statistical) methods that take into account more than one or two of the measured pressure and flow rate values, emphasis is on these methods. Some clinical results obtained with such automatic methods are discussed to illustrate the clinical value and possible impact on diagnosis and evaluation of treatment of lower urinary tract disorders.