THE SENSITIVITY OF PRESSURE SPECIFIC BLADDER VOLUME VERSUS TOTAL BLADDER CAPACITY AS A MEASURE OF BLADDER STORAGE DYSFUNCTION

Assessment of bladder storage function requires an accurate measure of bladder capacity and pressure. Pressure specific bladder volume is th e volume that a bladder can accommodate at a specified pressure. A tot al of 21 consecutive children with neurogenic bladders who were candid ates for bladder augmentation based on standard clinical criteria (upp er urinary tract deterioration, incontinence and infection) was studie d to determine the efficacy of pressure specific bladder volume as a m easure of bladder dysfunction. Urodynamic indexes were compared to pre viously established nomograms. All 21 patients had bladder volumes at pressures of 30 cm. water or less, which decreased below the 5th perce ntile as determined by the nomogram. In 7 patients (33%) normal total bladder capacity was achieved at the expense of elevated storage press ures. Pressure specific bladder volume provides a better measure of bl adder storage function than total bladder capacity because it relates volume to intravesical pressure, does not rely on a subjective end poi nt to bladder filling, and is objective and reproducible.