A Simplified System for Urodynamic Observations

Abstract

THE full assessment of a patient presenting with a urological disorder should include not only the commonly undertaken investigations, such as pyelography and cystoscopy, but also studies of the hydrodynamic properties of the lower urinary tract. Such studies of urodynamics have been well documented since Mosso and Pellicani first described the cystometrogram in 1882.The cystometrogram maintains an important place in the investigation of lower urinary tract disorders today (Nesbit and Baum, 1954), despite the fact that it has been said that the interpretation of the pressure-volume curve of the bladder depends on the established diagnosis, rather than the converse (Weyrauch, Lucia and Howard, 1944). It may be that there has been a surfeit of sophisticated literature recently, concerning an investigation which is essentially a simple observation (Hodgkinson and Cobert, 1960). No two published papers conform to a set pattern of technique. Confusion has been created by the controversy concerning the measurement of bladder pressures with urethral or suprapubic cannula: (Sandae, Bryndorf and Gertz, 1959 ; Pekarovic, Robinson and Zachary, 1969); there is no agreement regarding the rate of filling of the bladder; some workers suggest that air should be used instead of water (Bradley et al., 1968). Further complicated techniques made use of the " radio pill " as a method of determining intravesical pressure (Gleason and Lattimer, 1962;Bradley, Chou and French, 1963 ; Gleason, Lattimer and Bauxbaum, 1965).Urethral pressure and resistance were formerly difficult to evaluate, but the introduction of the urethral pressure profile by Brown and Wickham in 1969 offered an alternative technique to those requiring elaborate mathematical calculations (Smith, 1968;Rankin, 1967Rankin, , 1969. The pressure profile has made a valuable contribution to urology; it allows accurate determination of urethral length, localisation of strictures and the evaluation of the success of dilatation in their treatment, and assessment of sphincteric competence and its improvement by electronic stimulation (Riddle, Hill and Wallace, 1969;Harrison, 1970).The urinary flow rate is a third observation which has become too sophisticated to be of value in busy surgical practice. From simple displacement techniques have evolved methods involving transducers, multi-channel recorders, and output integrators, which provide results of incomparable quality, and allow superimposition of the volume voided and the integrated flow rate. The addition of further transducers, and more channels to the recording apparatus allow the voiding pressures in the bladder and rectum to be measured at the same time as the urinary flow rate. Finally, a simple technique has been described (Whitaker, 1969(Whitaker, , 1970, which provides an accurate method of measuring flow rate quickly and economically.These three investigations, the cystornetrogram, the urethral pressure profile, and the urine flow rate, should play a more significant part in urological investigation. The two mai...