Physical properties of female urethral wall experimental method for determining relative degree of urethral wall stiffness

Yalla, Subbarao V.; Burros, Harry M.; Ivker, Milton

doi:10.1016/0090-4295(73)90462-7

Cited by 5 publications

(4 citation statements)

References 10 publications

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“…Furthermore, Mijailovich et al [2004] showed that p-A and p-Q hysteresis are correlated suggesting that the viscoelasticity of the FCZ might be important. This idea is further supported by measurements of the time dependence of the p-A relation in resting female urethras, which characterize the elastic and viscoelastic components of the urethra in the continence state (Colstrup [1984b] and Yalla et al [1973]). Unfortunately, no such data are available for the male prostatic urethra.…”

Section: Hysteresis In P-a and P-q Plotsmentioning

confidence: 82%

“…Among them are: (a) the indirect estimation of the pressurearea (p-A) relation exclusively from the lower portion of p-Q plot; (b) a mathematical form of the p-A relation ¢xed to a simple exponential equation ; (c) assumptions that turbulent pressure losses and unsteady £ow e¡ects are negligible; and (d) exclusion of experimentally observed hysteresis and rate dependence in the p-A relation [Yalla et al, 1973;Colstrup, 1984a,b;Bagi et al, 1993].…”

Section: Introductionmentioning

confidence: 99%

“…This implies that turbulent urethral losses are important and should be included in model calculations. Also the hysteresis and rate dependence of the p-A relationship during opening and closing phases of micturition [Yalla et al, 1973;Colstrup, 1984a,b;Bagi et al, 1993] directly a¡ect the p-Q plots and therefore, an assessment of the p-A relation exclusively from the descending phase of micturition (p-Q plot) proposed by SchÌfer [1985], and SpÔngberg et al [1989] may not entirely re£ect the properties of the outlet.…”

Section: Introductionmentioning

confidence: 99%

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Effect of urethral compliance on the steady state p‐Q relationships assessed with a mechanical analog of the male lower urinary tract

Mijailovich

Sullivan

Yalla

et al. 2006

Neurourology and Urodynamics

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Using this mechanical analog, the measurements of p-A and p-Q relationships under various experimental conduit conditions validated our previous theoretical model of the male lower urinary tract. Both the experimental measurements and our previous theoretical model predictions indicate that an increase in opening pressure is associated with an increase in the slope of the p-Q relationship which becomes steeper with decreased cuff compliance. These data are in accordance with urodynamic findings in patients with benign prostatic hypertrophy (BPH) and suggest that a reduction in prostatic compliance exacerbates the severity of obstruction.

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Section: Hysteresis In P-a and P-q Plotsmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of urethral compliance on the steady state p‐Q relationships assessed with a mechanical analog of the male lower urinary tract

Mijailovich

Sullivan

Yalla

et al. 2006

Neurourology and Urodynamics

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“…Studies of the viscoelastic properties of soft tissue have shown that the relative distribution of collagen and elastin in the tissue to a large extent determines its mechanical properties [Yalla et al, 1973;Fung, 19811. Collagen is one of the stiffer biomaterials, with a Young's modulus of elasticity of 1.0 X lo7 N/m2.…”

Section: Biomechanical Considerationsmentioning

confidence: 99%

Quantification of urethral function based on Griffiths' model of flow through elastic tubes

Spångberg

Terió

Engberg

et al. 1989

Neurourology and Urodynamics

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Griffiths' model of flow‐through elastic tubes makes it possible to relate the elastic properties of the flow‐controlling zone to the pressure/flow relation of the urethra. In this work the pressure function p(A) = Pmo + Kn An, where A is cross‐sectional area, Pmo the minimal opening pressure, and Kn and n parameters describing urethral distensibility, describes the elastic properties of the flow‐controlling zone. By curve‐fitting in the pressure/flow plot, the three parameters pmo, Kn, and n can be estimated analytically. Using this model it is possible to identify three different biomechanical changes that may cause obstruction. First, pmo may be elevated. Second, the urethra can be distended to a certain area only, corresponding to high values of Kn and n. Third, the urethra can be distended but a higher‐than‐normal pressure increase above Pmo is needed, Kn is high, and n is low. With this model it is possible to quantify urethral function for both scientific and clinical purposes.

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Conduit and regional compliance of female canine urethra

Yalla

Burros

1974

Urology

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Physical properties of female urethral wall experimental method for determining relative degree of urethral wall stiffness

Cited by 5 publications

References 10 publications

Effect of urethral compliance on the steady state p‐Q relationships assessed with a mechanical analog of the male lower urinary tract

Effect of urethral compliance on the steady state p‐Q relationships assessed with a mechanical analog of the male lower urinary tract

Quantification of urethral function based on Griffiths' model of flow through elastic tubes

Conduit and regional compliance of female canine urethra

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