Relationship Between Bladder Neck Diameter and Hydraulic Energy at Maximum Flow

Abstract

A pressure-flow study was performed with a 5-micro-tip transducer catheter in 6 normal male volunteers (bladder neck diameters 0.80 cm. or larger) and 13 male subjects suspected of having bladder neck contracture. Intraurethral pressure was measured at various sites in the urethra at maximum flow to calculate hydraulic energy at these sites using the Bernoulli equation. When the subjects were divided into 2 groups (1 group with a bladder neck diameter of 0.73 cm. or larger and 1 with a bladder neck diameter of 0.60 cm. or smaller), the relative value of energy (ratios to the initial energy generated in the bladder) at the external urethral sphincter was significantly (p < 0.01) greater in the former than in the latter group. Therefore, the "flow rate controlling zone" lies at the external urethral sphincter in the former group and at the bladder neck in the latter group.

Analysis of Energy Loss Mediated by an Alpha-1 Blocker in Patients with Benign Prostatic Hyperplasia Using a Virtual Urethra Processed from an Endoscopic Video Image

“…15 Tojo and associates 16 calculated the urethral pressure at several points and showed that there was a hydraulic energy loss in patients with bladder outlet obstruction (BOO). 16 Using a virtual 3D model, we previously investigated the interference of the urine flow by a vortex in the urethra in patients with BOO and demonstrated the presence of a complex stream. 17 By being able to reconstruct a 3D structure of the urethra, this can potentially provide new methods for estimating the urethral resistance and a better understanding of the voiding function.…”

Non‐invasive estimation of intraurethral pressure profile from uroflowmetric curve

“…2,4 Their method is characterized by the measurement of pressure at the maximum urinary flow rate (Qmax) at different levels of the urethra. Namely, their method measures 'cross-sectional' urinary parameters at Qmax or in the stable phase of urinary flow.…”

“…This phenomenon may be called 'high-pressure low-flow' from the standpoint of the conventional P/F study and the resistance must be great. 5 If both P 1 and the flow rate are high, the residual energy must be great at the portion 2 because of high dynamic pressure (1/2rv 2 2 ), or DP must be small. This condition may be called 'high-pressure high-flow' from the standpoint of the conventional P/F study.…”

“…By differentiating this infinitesimal equation, it is converted into the second-order differential equation in order to calculate Q and P in the following equations: (2) Where l , A, B, a 1 , a 2 are constants and t represents time (3) where and y = CL.…”

Three-Dimensional Image Processing System for the Ureter and Urethra Using Endoscopic Video

“…16 A recent report stressed the relationship between angulation of the prostatic urethra and urine flow rate. 17 Reconstruction of the prostatic urethra introduces an additional method for measuring the obstructive potential of the prostatic urethra, and CT voiding urethrography may offer a technique in this regard.…”