Standardization of terminology of the hydrodynamics of the upper urinary tract. International Society for the Dynamics of the Upper Urinary Tract, Subcommittee on Standardization of Terminology

[Quantification of bladder-outlet obstruction in males: standard method vc VBN method]

GOAL

To compare the merits of two methods, standard (Abrams-Griffiths number, Schafer's classification, etc.) and VBN, to study bladder-outlet obstruction in men with benign prostatic hyperplasia (BPH).

MATERIAL AND METHODS

The parameters deduced from both methods and from repeated pressure-flow studies were computed for a population of patients with BPH. Correlation coefficients between standard and VBN parameters were systematically evaluated. Test-retest reliability and inter-rater reliability of the VBN parameters were investigated.

RESULTS

The VBN obstruction parameter was linearly corelated to the A-G number (R = 0.992) and thus is related to the provisional ICS obstruction nomogram. A simple modification to the standard index projected isometric pressure (PIP) yields an mPIP parameter strongly correlated with the VBN detrusor contraction-strength parameter (R = 0.962). VBN analysis reveals minor phenomena such as premature fading of the detrusor contraction to be responsible for much of the void-to-void variability of pressure-flow studies. Consequently, the primary VBN obstruction and contraction-strength parameters exhibit better test-retest and inter-rater reliability than the standard parameters and are less sensitive to changes in testing circumstances (bladder volume, urethral catheter size and psychological factors).

CONCLUSION

With the standard approach to test bladder obstruction, two values: A-G and mPIP, derived from pressure-flow studies, best qualify the patient's voiding status. These parameters are simple to calculate but are sensitive to testing variations and minor phenomena. The VBN approach is more complicated, but its parameters for obstruction and detrusor contraction strength are less dependent on testing variations.

Modelized analysis of pressure-flow studies of patients with lower urinary tract symptoms due to benign prostatic enlargement

AIMS

To gain insight from an adaptable computer model of micturition into the pathophysiological phenomena occurring during voiding in men with lower urinary tract symptoms due to benign prostatic enlargement (BPE).

METHODS

By using the Valentini-Besson-Nelson (VBN) micturition model, we proceeded with an in-depth and systematic analysis of the pressure-flow studies of 71 patients (119 tracings) provided by three different institutions.

RESULTS

The modelized analysis identified and quantified several pathophysiological phenomena during voiding: compressive obstruction, variations in detrusor contraction force (enhanced or reduced), progressive relaxation of the prostatic fossa, occasional detrusor-bladder neck coupling, and sphincteric control dysfunctions. Once these phenomena were taken into account by using a set of new parameters, the computed flow rate and detrusor pressure curves became very similar to the recorded ones.

CONCLUSIONS

The accuracy of this sophisticated analysis allows us to separate and to study during each voiding the phenomena belonging to the urethra, the detrusor, the bladder neck, the prostate, and their neurologic coordination in BPE patients.