Bladder wall tension during physiological voiding and in patients with an unstable detrusor or bladder outlet obstruction

Abstract

Parts of the study were selected as one of the 120 best poster presentations at the Annual Meeting of the AUA 2000, Atlanta Accepted for publication 2 June 2003 comprised men with bladder outlet obstruction in accordance with the AbramsGriffiths nomogram; group 2 (four men and four women, 56, SD 7.2 years) had detrusor instability; and group 3 (54, SD 9.6 years) had normal bladder emptying. BWT, as the detrusor force per cross-sectional area of bladder tissue (in N/cm 2 ), was calculated after a urodynamic evaluation and ultrasonographic estimate of bladder wall thickness. RESULTSIn all patients it was possible to measure BWT; the mean ( SD ) maximum BWT in group 1 was 9.8 (3.9) N/cm 2 , in group 2 during bladder instability was 11.7 (2.6) N/cm 2 and in group 3 was 2.8 (0.5) N/cm 2 . CONCLUSIONSEstimating BWT in humans is possible by combining a urodynamic evaluation with an ultrasonographic estimate of bladder wall thickness. Further clinical research should elucidate the clinical relevance of BWT under comparable conditions.

Estimation of bladder contractility from intravesical pressure–volume measurements

“…The latter is an alteration of contractile performance independent of resting length and physiologically is defined as a change of contractility: this term therefore has a specific meaning for isometric (muscle tension developed at constant length) or isotonic (muscle shortening at constant load) contractions. Changes of contractility have been demonstrated in the intact heart and isolated cardiac preparations and evaluated in the bladder . To identify patients with reduced cardiac contractility (heart failure), it was important to identify parameters independent of preload and afterload, as these affect muscle fibre length and contractile strength .…”

“…Changes of contractility have been demonstrated in the intact heart and isolated cardiac preparations [5][6][7] and evaluated in the bladder. 8,9 To identify patients with reduced cardiac contractility (heart failure), it was important to identify parameters independent of preload and afterload, as these affect muscle fibre length and contractile strength. 5 The usefulness of indices derived from the rise of isovolumetric ventricular pressure (P) in the cardiac cycle to define cardiac contractility is validated, especially from a plot of (dP/dt).…”

The calculation and comparison of the Detrusor Contractility Parameter and Watts Factor

“…However, a change of contractility specifically reflects a fundamental alteration to excitation‐contraction coupling in muscle tension development. Thus, contractility will be independent of the resting muscle fibre length, innervation of the detrusor, and the composition of bladder wall tissues (eg, detrusor vs connective tissue proportion) . A further complication is that intravesical pressure is often inappropriately used as a surrogate for muscle force (wall tension), yet pressure and tension are proportional only when bladder volume and shape remain constant .…”

“…Thus, contractility will be independent of the resting muscle fibre length, innervation of the detrusor, and the composition of bladder wall tissues (eg, detrusor vs connective tissue proportion) . A further complication is that intravesical pressure is often inappropriately used as a surrogate for muscle force (wall tension), yet pressure and tension are proportional only when bladder volume and shape remain constant . However, detrusor contractility is normally assessed during emptying, when changes to bladder volume and outflow tract resistance impact on pressure development.…”

Bladder wall tension during physiological voiding and in patients with an unstable detrusor or bladder outlet obstruction

“…We read with interest this paper [1] describing ‘a clinical method for measuring bladder wall tension (BWT)’ and a more quantitative approach to elucidate bladder mechanics in vivo from a urodynamic study. The unstated aim of the paper is to provide an estimate of muscle contractility and compare values in different groups of patients.…”