The timing of urine passage by bedridden, incontinent elderly persons was studied. Voiding of 7 elderly persons was monitored by an electrolyte sensor for 5 to 7 consecutive days; cumulative measurements were binned at 30min intervals. Both urinary frequency and urinary volume peaked 10 times per day. The timing of the peaks of both urinary frequency and volume coincided well as much as 9 times. There were 2 major peaks after each meal. The first peak occurred within 30min after the meal, while the second peak between 2 and 3hrs thereafter. Two major peaks were also observed about 2 and 6hrs after bedtime respectively. The peaks of both voiding and urinary volume of individual subjects corresponded well to the average by 87.1% for voiding frequency and 82.9% for urinary volume. These results indicate that the patterns of daily voiding of bedridden elderly are regular, rather than random.
