Bladder contractility and urethral resistance relation: What does a pressure flow study tell us?

Abstract

Abbreviations & Acronyms A = cross-sectional area AG nomogram = Abrams-Griffiths nomogram AG number = Abrams-Griffiths number BCI = bladder contractility index BOO = bladder outlet obstruction BOR = bladder output relation BPE = benign prostatic enlargement BPO = benign prostatic obstruction DAMPF = detrusor-adjusted mean passive urethral resistance relation DESD = detrusor external sphincter dyssynergia FCZ = flow rate controlling zone ICS = International Continence Society LPURR = linearized passive urethral resistance relation LUTS = lower urinary tract symptoms NB = neurogenic bladder P = pressure Pabd = abdominal pressure Pdet = detrusor pressure Pdet.iso = isovolumetric detrusor pressure during isovolumetric contraction Pdet.min.void = minimum voiding pressure PFS = pressure flow study PIP = projected isovolumetric pressure Pmuo = minimum urethral opening pressure POP = pelvic organ prolapse PURR = passive urethral resistance relation PV = prostate volume Pves = intravesical pressure Q = flow rate Qmax = maximum flow rate R = urethral energy loss UD = underactive detrusor UDS = urodynamic studies URA = group-specific resistance factor URR = urethral resistance relation vdet = velocity of shortening of the bladder circumference vest = maximum possible detrusor contraction velocity WF = Watts factor WFmax = point of the maximum value of Watts factor Abstract: Hydrodynamic analysis of a pressure flow study is the only reliable method to determine the presence or absence of a bladder outlet obstruction, especially benign prostatic obstruction. To interpret the results of pressure flow study in benign prostatic obstruction, understanding the outlines of the basic theory about evaluation of the relationship between bladder contractility and urethral resistance relation is of paramount importance. In contrast, hydrodynamic analysis of pressure flow study in conditions other than benign prostatic obstruction is complicated by the limits of theories about the hydrodynamics of the lower urinary tract. In this review, the proposed hydrodynamic theories about the relationship between bladder contractility and urethral resistance relation are outlined. Then, problems encountered in the application of hydrodynamic analysis of pressure flow study to diseases other than benign prostatic obstruction are discussed.

Detrusor contraction power parameters (BCI and W max) rise with increasing bladder outlet obstruction grade in men with lower urinary tract symptoms: results from a urodynamic database analysis

“…It remains controversial which algorithm and threshold value should be used for the diagnosis of DU. Urodynamic experts have proposed a maximum Watt factor (W max ) ≤7-10 W/m 2 or BCI < 100 [15,18,19] for the diagnosis of DU, but these threshold values have never been thoroughly investigated. Therefore, the aim of our study was to (1) evaluate the relationship between BOO and W max or BCI in a large sample of unselected men with LUTS, (2) compare these results with published data obtained from experimental animals, and (3) propose threshold values of W max and BCI for the diagnosis of DU.…”

Bladder Emptying: Contractility

“…where V t = volume of noncontracting bladder wall tissue [7]. Although some studies report WF and WF max , no consensus has been made regarding normative values particularly in female patients [6,8,9]. A WF max of <12 μW/mm 2 for males and <5 μW/mm 2 for postmenopausal females has been used in some studies to define detrusor underactivity [8,10,11].…”

“…A WF max of <12 μW/mm 2 for males and <5 μW/mm 2 for postmenopausal females has been used in some studies to define detrusor underactivity [8,10,11]. Use of WF may not be suitable for practical use due to complexity of the calculation, poor reproducibility, and lack of standardized cutoff values [6,8].…”

“…It is based on detrusor pressure (P det ), flow rate (Q), volume in the bladder (V), velocity of shortening of bladder circumference, and constant values (a = 25 cm H 2 O, b = 6 mm/s) based on in vitro studies [7]. WF max is proposed to represent maximal detrusor contractility and is calculated at maximal flow rate (Q max ) [8]. where V t = volume of noncontracting bladder wall tissue [7].…”

Prediction of sacral neuromodulation treatment success in men with impaired bladder emptying—time for a new diagnostic approach

“…2,3 Except for Sch€ afer's detrusor linearized passive urethral resistance relation (linPURR), all of the existing indicators for contractile function have one fixed threshold value, regardless non-BOO, BOO, or BOO-grade. 4 The Sch€ afer nomogram divides BOO and contractility only in rough classes and, therefore, small changes in BOO or contractility cannot adequately be judged. As a result of these disadvantages, our group has recently developed a BOO-dependent contractility (Maastricht-Hannover) nomogram for detection and classification of small changes.…”