Validity of a non-invasive determination of the isovolumetric bladder pressure during voiding in men with LUTS

Invasive pressure flow analysis is the gold standard for discriminating bet ween hypocontractile bladder muscle function and infravesical obstruction i n male patients with lower urinary tract symptoms. Here a non-invasive meth od to determine the isovolumetric bladder pressure to judge contractility i s presented. This is based on interruption of urine flow by sudden occlusio n of a specially fixed condom catheter. The pressure inside the condom is r ecorded and used to estimate the isovolumetric bladder pressure. Combined w ith, for example, home uroflowmetry, this non-invasive method may overcome some of the disadvantages (e.g., invasiveness, cost) of the conventional pr essure flow test. To determine the isovolumetric bladder pressure reliably with this non-invasive method, two constraints have to be met. First, the b ladder neck and urethra have to remain open after occlusion of the condom c atheter. This was tested combining the non-invasive test with radiography i n five patients. Second, a steady state has to be reached, i.e., the flow i n the urethra, due to the elastic properties of the biological and the cond om systems, should come to a stop when the bladder pressure and the condom pressure equilibrate. This was investigated by comparing the non-invasively recorded condom pressure with the simultaneously invasively recorded intra vesical pressure in 52 patients. In these patients, three different methods of condom fixation were evaluated. The results show that the bladder neck and urethra remain open during the test. However, a steady state is often n ot reached. In more than 80% of the cases with the best condom fixation, th e bladder pressure has not stabilized, although the condom pressure reached a plateau. Therefore, this method of sudden occlusion is not yet clinicall y applicable for determining the isovolumetric bladder pressure. (C) 1999 W iley-Liss, Inc.