Total and static pressure measurements of the male lower urinary tract

Abstract

AbstractSimultaneous total and static urethral pressure measurements were attempted in 22 male subjects who could void around a 10‐French bilumen urethral catheter. The catheter had an end‐hole at its tip and a side‐hole approximately 1 cm away from the end hole (short catheter‐tip segment). Thus, during a single voiding attempt, simultaneous total and static urethral pressures at two different urethral sites (1 cm distance) could be recorded. In addition, suprapubic vesical pressure monitoring was done in all these subjects. The studies also included a comparison of these recordings with those obtained with a 10‐French catheter that had its side‐hole placed 10 cm away from the tip (long catheter‐tip segment). The studies indicated that (1) the total pressure at a particular region of the urethra was usually higher than its static pressure; (2) the pressure sensing catheters produced “plugging effect” of the narrow segments of the outlet; and (3) the static pressure configurations that were obtained with a catheter having a long catheter‐tip segment were markedly different from those obtained through a catheter that had a short catheter‐tip segment.This presentation also includes observations on static pressure measurements obtained from a crude mechanical model that simulated the geometry of the urinary bladder and its outlet. True lateral pressures of the flowing fluid were obtained via cannulae inserted perpendicularly into the stream, through the wall of the outlet (extraluminal route). A comparison was attempted between the static pressure measurements obtained through the extraluminal route with those obtained through the catheters (10–14 French) that were directly inserted into the lumen of the outlet along its axis (intraluminal route). The studies indicated identical static pressures at the narrowest site (16–18 French) of the outlet recorded through both routes.