A biophysical model of the male urethra: Comparing viscoelastic properties of polyvinyl alcohol urethras to male pig urethras

Idzenga, Tim; Pel, J.J.M.; Mastrigt, Ron van

doi:10.1002/nau.20282

Cited by 17 publications

(18 citation statements)

References 16 publications

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“…The viscoelastic properties of the model urethra have been tuned to those of the male pig urethra in vitro [22]. One of the main diVerences between the model and the urethra in vivo is that the model urethra cannot contract, as muscular components have not been included.…”

Section: Discussionmentioning

confidence: 99%

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Fluid perfused urethral pressure profilometry and Valsalva leak point pressure: a comparative study in a biophysical model of the urethra

2007

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In patient studies the correlation between maximum urethral closure pressure (MUCP) and Valsalva leak point pressure (LPP) is meagre at best (r = 0.22-0.50). We therefore studied the relation between MUCP and LPP in a Xexible and extensible model urethra. We applied diVerently sized pressure zones and diVerent degrees of resistance to a biophysical model urethra by stepwise inXating three types of blood pressure cuV placed around the model. At each degree of resistance we measured detrusor LPP, an in vitro equivalent of Valsalva LPP. Subsequently, we recorded the Urethral Pressure ProWle using a water-perfused 5F end-hole catheter at four withdrawal rates and Wve perfusion rates and calculated MUCP. We tested the dependence of LPP on pressure zone length and MUCP on perfusion rate, withdrawal rate and pressure zone length using analysis of variance. We tested the correlation between LPP and MUCP using Pearson's correlation coeYcient and Linear Regression. LPP did not signiWcantly depend on the pressure zone length (P = 0.80) and increased linearly with increasing cuV pressure. MUCP also increased with increasing cuV pressure, however, MUCP signiWcantly depended (P < 0.01) on perfusion rate, withdrawal rate and pressure zone length. MUCP increased with increasing perfusion rate, and decreased with increasing withdrawal rate. In our model urethra MUCP only accurately reXected urethral resistance for a very limited number of combinations of perfusion rate and withdrawal rate. LPP reXected urethral resistance independent of the type of pressure zone.

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Section: Discussionmentioning

confidence: 99%

“…After 14 h in the freezer the mould was stored at room temperature for 10 h. This freeze-thaw cycle was repeated three times. The urethral model had viscoelastic properties comparable to the male pig urethra [22]. It was placed approximately 1 cm below the water level in a water-Wlled container to prevent dehydration of the PVA.…”

Section: Methodsmentioning

confidence: 99%

Fluid perfused urethral pressure profilometry and Valsalva leak point pressure: a comparative study in a biophysical model of the urethra

2007

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“…For an approximate calculation of the viscoelastic properties of the model and pig urethras from the recorded pressure response a mechanical model of the urethral wall was constructed, consisting of springs, dashpots, and a mass. [15] The simplified analytical solution for the step-response of this model was fitted to 1000 samples (equivalent of 1 s) of the pressure signal.…”

Section: Methods (2)mentioning

confidence: 99%

“…The flexible and extensible biophysical model which we developed[15] was placed in a container filled with water to prevent evaporation. Different degrees of obstruction were imposed by inflating a blood pressure cuff around the model and sound was recorded at different positions downstream of the obstruction.…”

Section: Methods (3)mentioning

confidence: 99%

Perineal sound recording for diagnosis of bladder outlet obstruction

2009

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Objectives:Elderly men are prone to developing lower urinary tract symptoms (LUTS) possibly caused by bladder outlet obstruction (BOO). The most frequently used method to diagnose this condition is an invasive and time-consuming pressure-flow study. We are developing a novel non-invasive method to diagnose BOO in men with LUTS based on perineal sound recording.Methods:A biophysical model urethra was made from polyvinyl alcohol (PVA) cryogel with viscoelastic properties comparable to those of the male pig urethra. To this model different degrees of obstruction were applied and sound was recorded at different positions downstream of the obstruction. In a study in 16 healthy male volunteers the variability and repeatability of perineal sound recording was tested.Results:In the model three parameters, derived from the frequency spectrum of the recorded sound (i.e., weighted average frequency, standard deviation and skewness) are uniquely related to the degree of obstruction (linear regression, P<0.001). The variability of perineal sound recording in healthy male volunteers was found to be smaller within volunteers than between volunteers (Kruskal-Wallis, P<0.001) and the repeatability was comparable to that of the maximum flow rate.Conclusions:We conclude that perineal sound recordings are significantly different between volunteers. In combination with the unique relations found in the model-experiments these results increase the probability that perineal sound recording can be used as a simple and cheap non-invasive method to diagnose BOO. Clinical testing of this method is therefore strongly indicated.

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“…Furthermore, it was not known how the degree of obstruction could be derived from such a sound recording. In an earlier study we have shown in a biophysical model of the male urethra 12 that three parameters, derived from the frequency spectrum of the recorded sound (i.e., the weighted average frequency, the standard deviation and the skewness of the frequency spectrum), were uniquely related to the degree of obstruction. 13 Following this finding we developed a measurement setup for perineal sound recording in patients with LUTS.…”

Section: Introductionmentioning

confidence: 99%

Variability and repeatability of perineal sound recording in a population of healthy male volunteers

Idzenga

2008

Neurourology and Urodynamics

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A biophysical model of the male urethra: Comparing viscoelastic properties of polyvinyl alcohol urethras to male pig urethras

Abstract: We consider the three times freeze-thawed model urethra with a Y-shaped flow channel the best model of the human male urethra. And we therefore use this model urethra for studying the relation between noise recording during urine flow and the degree of bladder outlet obstruction.

Cited by 17 publications

References 16 publications

Fluid perfused urethral pressure profilometry and Valsalva leak point pressure: a comparative study in a biophysical model of the urethra

Fluid perfused urethral pressure profilometry and Valsalva leak point pressure: a comparative study in a biophysical model of the urethra

Perineal sound recording for diagnosis of bladder outlet obstruction

Variability and repeatability of perineal sound recording in a population of healthy male volunteers

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