The urethral pressure profile during flow. An experimental study.

As part of a project aimed at developing a method for accurate evaluation of the position and significance of infravesical outflow obstructions, a technique for recording urethral pressure profiles during flow in male patients was tested in a rigid bladder-urethral model. The catheter which proved to give the most accurate recording of the static pressure in the urethral model had a measuring eye about 250 mm from the tip. With this arrangement, the tip of the catheter did not leave the bladder until the measuring eye had passed the whole length of the urethra and the effective diameter of the urethra and the flow did not change during the recording. The pressure profiles for the different urethral models closely resembled the theoretically calculated curves. Furthermore, the constant recording conditions made it possible to compensate for the influence of the measuring catheter and to calculate the "true" diameter as well as the "true" resistance in different segments of the models.