Françoise Valentini, Brigitte Marti, Gilberte Robain, Pierre Nelson.

UMR S 731 INSERM/Université Pierre et Marie Curie-Paris 6, France.

Introduction and Objectives: Comparison between data from a free flow (FF) and an intubated flow (IF) in women has been little studied [1]. Our purposes were: 1) to search for differences between urodynamic data from FF and IF in women with urinary incontinence and 2) to use a mathematical model of micturition [2] to explain these differences.

Methods: Women with urinary incontinence have been evaluated between July 2002 and December 2004. Exclusion criteria were neurological diseases, diabetes mellitus and grade ≥ 2 prolapse. Urodynamics was performed with the Laborie’s Bonito® unit. Included files consisted of one FF (before cystometry) and one IF (10F triple-lumen urethral catheter) with voided volume >100 mL and continuous flow (voidings in privacy, in seated position). Analyzed parameters were 1) the volumes (initial V_ini, voided V_u, residual V_r), Q_max, the flow time t_mic and the ratios V_r/V_ini, Q_max.IF /Q_max.FF and Q_max/Q_ave, and during IF 2) p_det.open and p_det.Qmax. Voidings with V_r/V_ini > 20% were labelled V+, the others V- .

The VBN® model [2] allowed to evaluate for each recording the detrusor force, the urethra cross-section (each file must be interpreted with the same set of parameters) and to make simulations of pathophysiological hypothesis.

Results: a) Among 217 women, only 102 (47.0%), mean age 54.3 years [24-86], succeeded in FF and IF according to the required criteria. For these 102 women, the values of the voiding parameters are shown in the table.

b) Comparing FF/IF, 69 files were V-/V-, 9 V₊/V₊, 20 V-/V₊ and 4 V₊/V-.

Q_max.IF/ Q_max.FF was .45±.27 for the V-/V₊ group, and .71±.49 for the V-/V- group while its theoretical value, due to the obstructive effect of the catheter, was 0.75: the weak Q_max.IF value in the V-/V₊ group results from an additional phenomenon: fading of the detrusor excitation or/and incomplete sphincter relaxation (abnormal nervous control) due to the catheter in place.

c) No significant difference was found in p_det.open (20.3±16.5 vs 20.0±13.7 cmH₂O) and p_det.Qmax (24.2±13.1 vs 27.2±16.7 cmH₂O) between the IF(V-) and the IF(V+) groups. The increase of detrusor pressure must be sufficient to obtain complete bladder emptying. The theoretical time θ needed for achieve bladder emptying is V_ini/Q_ave ≈ (1.5*V_ini)/Q_max. In the V-/V₊ group t_mic < θ. Modelling shows that this result is consistent with an inhibition of the voiding process for micturition of long duration.

Conclusion: In the population of women able to void during the pressure-flow study, significant differences are found between the data of FF and IF. These differences cannot be explained only by mechanical effects due to the presence of a urethral catheter and could involve, in addition to the anxiety of the patient, a urethral reflex. These findings underline the necessity to combine a FF with an IF during a urodynamic session in order to increase the reliability of the conclusions of the urodynamic investigation.

UroToday.com Coverage of SUFU 2007

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