CHARACTERIZATION OF PRESSURE CHANGES IN THE LOWER URINARY-TRACT DURING COUGHING WITH SPECIAL REFERENCE TO THE DEMANDS ON THE PRESSURE RECORDING EQUIPMENT

The exact demands on urodynamic equipment for measurement of coughs an d cough associated pressure changes in the lower urinary tract have be en analyzed from high-speed pressure recordings using a double microti p transducer and a storage oscilloscope. The equipment was tested in v itro by the step-test method. The natural frequency response was 175.6 Hz and the rise-time 2.5 ms, resulting in accurate measurements of fr equencies up to about 60 Hz, which is way above the clinically measure d frequencies. Four men and 2 women, all of whom were healthy voluntee rs, were examined in the supine position with an empty bladder. Pressu res were measured in the bladder and in the external sphincter zone of the urethra. The spectral power density of the bladder and urethral p ressures were calculated by Fourier analysis. The pressure changes in the urethra were in all volunteers equal to or slower than in the blad der. The analysis of the spectral power density showed that 99% of the pressure changes could be recorded with an instrument capable of reco rding 9 Hz frequencies, i.e., with a sampling rate of 18 Hz or more. ( C) 1994 Wiley-Liss, Inc.