Uroflowmetry is important in the evaluation of prostatism. We have investigated 93 men, selected at random from the National Register, who had no subjective voiding problems but who fell within the appropriate age range. The sample was representative of the male metropolitan population. Uroflowmetry was carried out and the data are presented graphically in nomograms where the Q max/volume, Q average/volume and Q max time/volume relations are given. Flow variables were evaluated to delineate possible correlations to age. It was found that the median Q max decreased from 18.5 ml/s at the age of 50 years to 6.5 ml/s at 80 years. Only one-third of the group had a Q max exceeding 15 ml/s. The median voided volume was 208 ml. Half of the subjects voided less than 200 ml and one-third less than 150 ml.

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Cardiac output estimates by the principle of thermodilution (COth) was compared with dye-dilution estimates (COdye) in pigs. For COth estimates a Swan-Ganz 7 F floating thermodilution catheter and a 9500 Edwards Computer, were used. The COdye estimates were obtained by the apparatus constructed by Zijlstra and Mook. The effect of the thermistor position in the pulmonary artery on the COth estimates was also investigated. The reproducibility of COth was examined by duplicate determinations. Based on 101 simultaneous estimates of COth and COdye the correlation was found COth = 1.020 COdye + 0.2378, r = 0.971 for cardiac outputs between 0.65 l/min and 11 l/min. For 111 duplicate determinations of COth between 2 and 9 l/min the coefficient of variation was 4.74%. The thermistor position in the pulmonary artery had no influence on the COth estimates provided an undamped pressure curve could be monitored from the tip of the catheter. Cardiac output can thus be measured rapidly with good accuracy also for low values by means of a blindly inserted thermistor catheter positioned without x-ray control and a computer with digital display.

A random sample of 200 males aged 50 years or more was selected from the National Register in order to investigate various aspects of spontaneous uroflowmetry and to estimate the frequency of prostatism and symptoms of lower urinary tract dysfunction. All in all the data from 112 persons were analysed. The prevalence of prostatism was found to be 17% (95% confidence limits 11-26%), while 88% (95% confidence limits 83-95%) experienced various degrees of symptoms. Only few associations between single symptoms and uroflowmetry variables were demonstrated. However, statistically significant correlations were revealed between obstructive and total symptom scores on one hand and maximum and average flow rates on the other hand. As the correlations were modest and a considerable overlap of uroflow variables in persons with and without prostatism were proved, the diagnostic specificity and sensitivity of maximum flow rate as well as other uroflow variables were low in the screening for prostatism. In conclusion uroflowmetry appears inefficient to confirm a clinical impression of prostatism.