Estimation of elastic properties in the urethral flow controlling zone by signal analysis of urodynamic pressure/flow data

Terió, Heikki; Spångberg, Anders; Engberg, Anders; Ask, Per

doi:10.1007/bf02441491

Cited by 14 publications

(12 citation statements)

References 15 publications

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“…These methods included computerised models as described by Sch/~fer [21][22][23], Spangberg et al [30], Terio et al [31] and Mastrigt and Rollema [18]. Nielsen and coauthors find that these models are too complicated and cumbersome for daily urological practice.…”

Section: Similarities With Other Methodsmentioning

confidence: 99%

The Abrams-Griffiths nomogram

1995

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The treatment of benign prostatic hyperplasia and the definition of bladder-outlet obstruction has preoccupied urologists and researchers in recent years. Bladder-outlet obstruction can be defined only by pressure-flow measurement. Various methods of analysis of pressure-flow data have been proposed. The Abrams-Griffiths nomogram is an easy method of classifying these data to distinguish between the presence or absence of obstruction. Using the values for the maximal flow and the corresponding voiding detrusor pressure a point can be plotted on the nomogram that determines whether the bladder outlet is obstructed, unobstructed, or equivocally obstructed. For those that fall in the equivocal zone, further criteria for the mean slope of the pressure-flow plot and the minimal voiding detrusor pressure are used to determine whether there is obstruction or not. The nomogram's prognostic value in predicting the outcome of prostatectomy has been studied and found to be excellent. The Abrams-Griffiths nomogram can be modified by assigning an Abrams-Griffiths number to each set of pressure-flow data. This number is easy to calculate and use and gives a continuous variable that can be used to evaluate the effects of therapy. Although the Abrams-Griffiths nomogram and number are somewhat simplistic, none of the more complex methods of pressure-flow analysis have been shown to be better predictors of treatment outcome to date.

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Section: Similarities With Other Methodsmentioning

confidence: 99%

The Abrams-Griffiths nomogram

1995

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“…The use of more degrees of freedom, for example, parameters, within an approximation method will likely result in a more accurate method, albeit at increased algorithmic complexity. In the past, any extension beyond a linear fit was found to be not reproducible and not of added value for describing the PURR 14 . However, we showed that a linear fit is rather inaccurate when only based on p detQmax , as all (linear) one‐parameter methods were found significantly less accurate in predicting p muo when compared to the three‐parameter method.…”

Section: Discussionmentioning

confidence: 64%

Quantifying bladder outflow obstruction in men: A comparison of four approximation methods exploiting large data samples

van Dort,

Rosier,

Geurts

et al. 2023

Neurourology and Urodynamics

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IntroductionA pressure flow study (PFS), part of the International Continence Society standard urodynamic test, is regarded gold standard for the classification and quantification of the urethral resistance (UR), expressed in the bladder outflow obstruction (BOO). For men with benign prostatic hyperplasia, the minimum urethral opening pressure (pmuo), found at the end of the passive urethral resistance relation is considered the relevant parameter describing BOO. However, in clinical practice, direct measurements of pmuo are easily confounded by terminal dribbling. For that reason, alternative methods were developed to derive pmuo, and thereby assess BOO using the maximum urine flow rate (Qmax) and the corresponding pressure (pdetQmax) instead. These methods were never directly compared against a large data set. With the increasing variety of treatments becoming available more precise grading of UR may become of relevance. The current study compares four well‐known methods to approximate pmuo and examines the relation between pmuo and pdetQmax.MethodsIn total, 1717 high‐quality PFS of men referred with lower urinary tract symptoms between 2003 and 2020 without earlier lower urinary tract surgery were included. From these recordings, pmuo was calculated according to three one‐parameter methods. In addition, a three‐parameter method (3PM) was used, based on a fit through the lowest pressure flank of the pressure‐flow plot. The estimated pmuo's were compared with a precisely assessed pmuo. A difference of <10 cmH2O between an estimate and the actual pmuo was considered accurate. A comparison between the four approximation methods and the actual pmuo was visualized using a Bland–Altman plot. The differences between the actual and the estimated slope were assessed and dependency on pmuo was analyzed.ResultsA total of 1717 studies were analyzed. In 55 (3.2%) PFS, 3PM analysis was impossible because all pressures after Qmax were higher than pdetQmax. The 3PM model was superior in predicting pmuo, with 75.9% of the approximations within a range of +10 or −10 cmH2O of the actual pmuo. Moreover, pmuo according to urethral resistance A (URA) and linearized passive urethral resistance relation (linPURR) appear equally reliable. Bladder outflow obstruction index (BOOI) was significantly less accurate when compared to all others. Bland–Altman analysis showed a tendency of BOOI to overestimate pmuo in men with higher grades of UR, while URA tended to underestimate pmuo in those cases. The slope between pmuo and pdetQmax‐Qmax increased with larger pmuo, as opposed to the constant relation proposed within BOOI. Although significant differences were found, the clinical relevance of those differences is not known.ConclusionOf the four methods to estimate pmuo and quantify BOO, 3PM was found the most accurate and BOOI the least accurate. As 3PM is not generally available and performance in lower quality PFS is unknown, linPURR is (for now) the most physiologically accurate.

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“…It is true that the reproducibility of the exponent m is far from perfect; however, this parameter is not randomly distributed since the patients tend to have the same shape of urethral resistance relations after performing several micturitions [14,16]. It is true that the reproducibility of the exponent m is far from perfect; however, this parameter is not randomly distributed since the patients tend to have the same shape of urethral resistance relations after performing several micturitions [14,16].…”

Section: Discussionmentioning

confidence: 99%

Estimation of urethral resistance by curve fitting in the pressure-flow plot

Spångberg¹

1995

World J Urol

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The curvature of the urethral resistance relation was estimated in 21 normal men, in 32 prostatism patients, in 60 men with a diagnosis of benign prostatic hypertrophy (BPH) and obstruction, and in 55 men after treatment of BPH. The curvature was determined by curve fitting in the pressure-flow plot using the method of least squares. In all, 58% of the normal men and prostatism patients had a urethral resistance relation with the convexity directed upward, demonstrating a low-compliant type of distensibility. After transurethral resection (TUR), significantly more men had the convexity of the urethral resistance relation directed downward, showing that the distensibility was more of a constrictive type. This change in the elastic properties of the flow-controlling zone can be assessed only by using several curvatures to estimate the urethral resistance relation. Another advantage for the method of using different curvatures is that the effects of bladder contractility are minimized. However, should one use only one form of the urethral resistance relation, it is recommended that a linear relation be chosen.

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Estimation of elastic properties in the urethral flow controlling zone by signal analysis of urodynamic pressure/flow data

Cited by 14 publications

References 15 publications

The Abrams-Griffiths nomogram

The Abrams-Griffiths nomogram

Quantifying bladder outflow obstruction in men: A comparison of four approximation methods exploiting large data samples

Estimation of urethral resistance by curve fitting in the pressure-flow plot

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