A system for measurements of micturition urethral cross-sectional areas and pressures
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A system for the measurement of urethral urinary stream cross-sectional areas and pressures is described. The system consists of: (1) A 4 French gauge probe with electrodes for the electrical impedance measurement of cross-sectional areas and side-holes for pressure measurements (2) an electrical field generator and impedance detecting section and (3) a side-hole perfusion and pressure measuring part.
Thein vitro performance of the system is: linear cross-sectional area measurement in the range of 0–38 mm2, independent of the shape of the lumen and with an axial resolution of approximately 7 mm. Measurement of hydrostatic pressures with a time constant of 0·38 s and of closure pressures with a post-occlusion pressure increase rate of 0·85 kPa s−1.In vivo cross-sectional areas are calibrated in a standard made of PVC. The influence of the electrical shunting of the urethral mucosa is shown to permit this, provided that the impedance of the mucosa in the closed urethra is measured in each patient investigated.
KeywordsElectrical impedance Urethral pressure Urinary stream cross-sectional area Urodynamics
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