Urinary flow rate recording: The impact of a single dose of a diuretic on clinic logistics and flow rate parameters

Purpose: We determine the impact of a single dose of a diuretic given to patients scheduled for flow rate recording on clinic waiting time and flow rate parameters, and whether such practice induces artifacts in recording independent of those inherent in repeat recordings. Materials and Methods: A total of 99 volunteers with a mean age plus or minus standard deviation of 54 ± 10.9 years with no known urological condition participated in an open label, crossover study. On 2 separate occasions they came to the clinic for a flow rate recording, and were randomized to receive 20 mg. furosemide upon arrival at the first or second visit. Clinic waiting time, pre-void bladder volume, voided volume, maximum flow rate and other parameters were captured in a database and analyzed. Results: Independent of diuretic use an increase in voided volume and maximum flow rate (19.8 to 21.2 ml. per second) was noted from the first to second visit. Diuretic use independent of sequence induced an increase in voided volume and significant reduction in waiting time (155 versus 81 minutes, p <0.001) without affecting maximum flow rate (19.9 versus 21.1 ml. per second, p = 0.058). Diuretic use on the second visit enhanced the learning effect on maximum flow rate, while first visit use negated the learning effect on the second visit. Waiting time reduction was significant independent of sequence. The positive correlation between voided volume and maximum flow rate remained unchanged with or without the diuretic. Conclusions: Repeat flow rate recordings are associated with a measurable learning effect leading to an increase in maximum flow rate. The use of 20 mg. furosemide reduces waiting time without inducing additional artifacts or significant changes in flow rate parameters. This practice is recommended for busy offices or clinical research centers to enhance urine flow, patient satisfaction and ultimately compliance with care.