A Practical Method of Measuring Urethral Resistance to Micturition

URETHRAL RESISTANCE TO MICTURITION: British Association of Urological Surgeons Prize Essay

“…It has been shown (Smith, 1964) that in all these women the Reynolds number was well in excess of 3,000. If calculations were made for the flow of urine under similar conditions, the Reynolds numbers would be even greater.…”

“…Method.-The method used for calculation of urethral resistance has been described in an earlier paper (Smith, Edwards and Bryant, 1966). Determination was made using a fine indwelling urethral catheter and the majority of measurements were made during micturating cysto-urethrography so that the radiological appearances could be compared with the pressure/ flow results.…”

Review of invasive urodynamics and progress towards non-invasive measurements in the assessment of bladder outlet obstruction

“…However, Smith noted that during voiding flow is likely to be turbulent and the relationship should be:[15] ${\text{R = p/Q}}^{\text{2}}$ …”

Relationship between Perivesical and Intravesical Urinary Bladder Pressures and Intragastric Pressure

“…There have also been numerous attempts to measure the intraabdominal pressure at the same time as the intravesical pressure. Pressures have been recorded by means of a balloon in the stomach (Backman et al 1966, von Garrelts 1957, Sundblad 1971, via a balloon (Gleason and Lattimer 1964, Susset et al 1965, Wise et al 1968), catheter (Claridge and Shuttleworth 1964, Claridge 1966, Frimodt-Moeller 1972 or radiotransmitter (Warrell et al 1963) in the rectum or by means of an extraabdominal tocodynamometer (Smith et al 1966, Rowan et al 1972. Subtraction of the intragastric or intrarectal pressure from the intravesical pressure, in order to obtain the true so-called detrusor pressure, has been done mechanically (Gleason and Lattimer 1964) or by means of subtraction circuits in the recording apparatus (Gleason and Lattimer 1964, Backman et al 1966, Sundblad 1971, Frimodt-Moeller 1972.…”

“…Muscular activity in the wall of the rectum can lead to recording of falsely high pressures (Denny-Brown andRobertson 1933, Rushmer 1946). Extraabdominal pressure recording gives only relative pressures (Smith et al 1966).…”