446 / 492
ICCS S2-6
(P)
A NORMAL VOIDER DERIVED FLOW INDEX CAN BE A MEASURE OF VOIDING
EFFICIENCY
Israel FRANCO
1
, Stephen YANG
2
and Jacob FRANCO
3
1) New York Medical College, Section of Pediatric Urology, Chappaqua, USA - 2) Medical School of Buddhist Tzu Chi
University, Urology, Taipei, TAIWAN - 3) Stonybrook Medical College, Urology, Chappaqua, USA
PURPOSE
We recently derived a Flow index (FI) based on an idealized normal voider. Efficiency is the measure of the ability to
empty the bladder fully and promptly as defined by the physics of voiding. Our hypothesis is that FI can be a proxy
for voiding efficiency and that elevated PVR and high volumes affect efficiency.
MATERIAL AND METHODS
A data set consisting of 1268 presumed normal voiding children who underwent 2 voids was used to calculate our sex
specific quadratic formula for Q. FI (Actual Q/est Q) for each void were compared and tested for accuracy. Non-
parametric testing was done on the different groups to confirm no difference from the first to the second void.
RESULTS
We found that in both sexes that an elevated PVR and a bladder volume in excess of 110% of expected capacity both
impart negative effects on bladder emptying by lowering the FI from its median of 0.97 in normal voiders to 0.53 and
0.72 respectively in females and 0.91, 0.64, and 0.7 in males. Root mean sq error for females was 0.284, 0.12 and
0.26 and males 0.27, 0.16, and 0.12 respectively.
CONCLUSIONS
Our findings show that FI can be a proxy for voiding efficiency since bladder emptying is directly proportional to the
volume in the bladder at the time of micturition. Therefore our FI takes into account the effects of PVR and
overdistended bladder aside from our previous findings that abnormal flow patterns also lower the FI giving us a proxy
for efficiency of voiding.