Nomograms

Development of a Reliable Instrument for Recording and Analyzing Uroflow Procedures that includes the Liverpool (Haylen, et al) Nomograms

A. C. COATS, M.D.

Life-Tech, Inc., Houston, Texas, USA

Summary —The science of analysis of Uroflow recordings has been described at length by the International Continence Society (ICS) and in numerous publications by leading clinicians in the field of Urology 1,2,3 in recent years. The clinical research demonstrated a need for a reliable device for the documentation and an alysis of uroflow results that included the “gold standard” Liverpool Nomograms.

The Microflo ? (Life-Tech, Inc., Houston, TX, USA ) was developed to provide clinicians with a highly accurate system for the recording and analysis of Uroflow procedures, to include the diagnostic reference plotting of the patient on the Liverpool Uroflow Nomograms. The system features a high performance microprocessor, collecting data at 8 samples per second while digitally displaying the

values. The highly advanced load cell technology provides superior accuracy while minimizing maintenance and operating cost. The system is found to be both economical and easy to operate (Figure 1).

Data analysis is automatic and provides for the manual entry of patient information while printing age, sex, position and the Uroflow pattern. The system’s sophisticated algorithms automatically analyze the Uroflow study while virtually eliminating artifacts. High resolution Uroflow recording is automatically printed in the appropriate time scale of 0-60 sec., 0-120 sec., or 0-180 sec. (Figures 2 and 3).

Microflo retains in memory the last recorded Uroflow and with subsequent printout the scale can be changed from 0-50 ml/sec. to 0-25 ml/sec. to improve the resolution of abnormal Uroflow waveforms.

Figure 1: Microflo 2001N.

Figure 2: Microflo Patient Information and analysis result.

Perhaps the most important feature of Microflo is the automatic plotting of the patient’s Uroflow results on the Liverpool Nomograms. These Nomograms are considered world-wide to be the

“gold standard” of Uroflow interp retation,

offering reference ranges for both males and

females, for both maximum and average flow rates, over a wide range of voided volumes

(Figure 4).

Patient's results are plotted as a percentage of

normalcy, by both age and sex, for both Maximum and Average Uroflow. All of the Liverpool Nomograms for all age and sex considerations are included in Microflo’s software package, and are drawn upon as necessary to plot patient percentile of normality.

Abrams, P., Blaivas, J., Stanton, S., and Andersen, J. (1988), Standardisation of Terminology of Lower Urinary Tract Function. Pp. 410-412. Alan R. Liss, Inc . 2

Haylen, B., Ashby, D., et al. (1988), Maximum and average Urine Flow Rates in Normal Mal and Female Populations – the Liverpool Nomograms. British J. of Urol ., 64: 30-38 3

Abrams, P., Fenely, R. and Torrens, M (1983). Urodynamics. Pp. 26-38 Berlin: Springer-Verlag.

Figure 3: Microflo Uroflow tracings. Figure 4: Microflo with Liverpool Nomograms.