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- Ask, Per, et al.
(författare)
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A SHORT-TIME-DELAY URINARY FLOWMETER
- 1985
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Ingår i: Neurourology and Urodynamics. - : Wiley. - 0733-2467 .- 1520-6777. ; 4:3, s. 247-256
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Tidskriftsartikel (refereegranskat)abstract
- A urinary flowmeter has been designed, using a quickly rotating disc and a balance principle. The flowmeter has a fast and accurate response to changing flows. The time delay of the flowmeter is less than about 0.25 s. The improved accuracy in recording urinary flow using the presented flowmeter should make it possible to extract more information from the detrusor pressure and urinary flow relations, relevant for assessing lower urinary tract function.
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- Språngberg, Anders, et al.
(författare)
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PRESSURE-FLOW STUDIES PREOPERATIVELY AND POSTOPERATIVELY IN PATIENTS WITH BENIGN PROSTATIC HYPERTROPHY - ESTIMATION OF THE URETHRAL PRESSURE-FLOW RELATION AND URETHRAL ELASTICITY
- 1991
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Ingår i: Neurourology and Urodynamics. - : Wiley. - 0733-2467 .- 1520-6777. ; 10:2, s. 139-167
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Tidskriftsartikel (refereegranskat)abstract
- Pressure/flow studies were performed in 28 men with benign prostatic hypertrophy. Twenty-three of the men were also studied postoperatively. Urethral function during micturition was quantified by the urethral pressure/flow relation, P(det) = P(mo) + L(m) Q(m), where P(det) is detrusor pressure, P(mo) is minimal opening pressure, Q is flow rate, and m and L(m) are parameters. Using this method to quantify urethral function, three urodynamically different types of obstruction can be defined. In the first of these, P(mo) is elevated corresponding to Schafer’s compressive obstruction. The second is a constrictive type of obstruction in which m greater-than-or-equal-to 4/3 and L(m) is elevated and the third is a low-compliant type of obstruction in which m less-than-or-equal-to 1 and L(m) is elevated. The two latter types of obstruction may be combined with a compressive obstruction. The preoperative pressure/flow relations were mostly characterized by a very high P(mo), a moderately elevated L(m), and a low m. Thus the majority of patients had a combination of compressive and low-compliant obstruction. Postoperatively, micturitions were much improved and the pressure/flow relations often had an even lower P(mo) than normal, a normal L(m), and a high m. From the pressure/flow relations, the elasticity of the flow-controlling zone can be estimated and described by the urethral pressure/area relation, p(A) = P(mo) + K(n) A(n), where p(A) is the intrinsic urethral pressure, A is the cross-sectional area of the flow-controlling zone and K(n) and n are parameters describing the distensibility of the flow-controlling zone. Preoperatively, the flow-controlling zone had a low distensibility. The shape of the curve suggested that the urethra could have been distended further by higher pressure. Postoperatively, the urethra was distended to larger cross-sectional areas, but in many cases the shape of the curve suggested that distension was restricted by fibrosis. Median and range values for the model parameters as well as discriminating limits between the preoperative micturitions and micturitions in elderly men without voiding problems are presented. The exponent m is not perfectly reproducible but tends to be the same if a person performs several micturitions. The residual sum of squares is often increased more than 100% if an exponent m value other than the optimal one is used for curve fitting. Results when the micturitions were analysed with Schafer’s model and classified using the maximum flow/pressure at maximum flow diagram recommended by the International Continence Society are also shown.
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- Spånberg, Anders, et al.
(författare)
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QUANTIFICATION OF URETHRAL FUNCTION BASED ON GRIFFITHS MODEL OF FLOW THROUGH ELASTIC TUBES
- 1989
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Ingår i: Neurourology and Urodynamics. - : Wiley. - 0733-2467 .- 1520-6777. ; 8:1, s. 29-52
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Tidskriftsartikel (refereegranskat)abstract
- 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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