Hypothesis / aims of study
Bladder voiding efficiency (BVE) is defined as the ratio between voided volume and total bladder capacity [1]. Although easy to calculate this index is not widely used and none of the few published studies have addressed the incidence of aging. Recently, the reliability of BVE measurement from a free flow (FF) has been demonstrated in the general population [2]. For the first time, measurement of BVE could be tested in a large cohort of women older than 65 years. Aims of our study were first to search for the condition which had the predominant influence on evaluation of BVE (FF or intubated flow IF)) and second the possible relationships with ageing, complaint and urodynamic diagnosis.
Study design, materials and methods
Urodynamic tracings of non-neurological women referred for investigation of various lower urinary tract symptoms were analyzed. Each session was performed using the Dorado® unit from Laborie. Urodynamic study included one FF in private condition (sitting position) followed by one cystometry (triple lumen urethral catheter 7F allowing for urethral pressure recording) and intubated flow (IF) . Post void residual volumes (PVR) were measured using a Bladder-scan. Exclusion criteria were to be unable to void and/or expelled catheter during IF, voided volume either from FF or IF <100 mL and prolapse of grade ≥ 2.
Results
One hundred and nighty four women met study criteria. Mean age was 74 ± 6 years [65-96 y]. Main complaint was urinary incontinence: stress (31 SUI), urge (59 UUI) and mixed (63 MUI). Forty one women had various complaints without incontinence (among which 19 had frequency (FR) or dysuria (DYS)).
Overall BVE IF (77.60 ± 25.84) was significantly lower than BVE FF (90.38 ± 15.27) (p<.0001). That decrease was observed whatever age sub-groups (table 1) each decrease was significant; decrease of BVE IF with ageing was not significant.
Looking at the complaint BVE IF was significantly lower than BVE FF in women with urinary incontinence whatever the sub-type (table 2):
Urodynamic diagnosis (UD) was posed according to the ICS/IUGA recommendations. From UD, 2 sub-groups were defined according with involvement of detrusor. The first (112 women) had UD related to detrusor dysfunction (21 bladder outlet obstruction BOO, 13 detrusor hyperactivity with impaired contractility DHIC, 29 detrusor overactivity DO, 51 detrusor underactivity DU). The second sub-group (82 women) had UD found “normal” (32 N), related to urethral dysfunction (37 intrinsic sphincter deficiency ISD and 11 voiding triggered by urethral relaxation URA). BVE IF was significantly lower than BVE FF except for DO, ISD, N, and URA urodynamic diagnosis.
Interpretation of results
Main result is the absence of reproducibility between BVE measurement from a FF and from an IF in this post-menopause population, as observed in pre-menopause and peri-menopause populations [2]. That absence of reproducibility is similar in age sub-groups stratification. Decrease of BVE IF with ageing is not significant. The lower values of BVE IF clearly shows an inability of old women to void with a urethral catheter in place. So, BVE FF seems a more reliable index of bladder efficiency.
Complaint of incontinence results of significant decrease in BVE IF which could be useful information for management.
Looking at the urodynamic diagnosis, an unexpected results is observed. For patients with UD diagnosis DO, BVE IF is not different from BVE FF, which can be the consequence of a significant percentage of terminal DO allowing complete bladder emptying.