Thermistor use to monitor urine flow rates in dogs

The small size of a new thermistor flowmeter facilitated implantation in ureters in anesthetized dogs. It consisted of a self-heating thermistor bead which was suspended centrally within an open catheter and dissipated heat as a function of fluid velocity. A continuous record of instantaneous flow rate was obtained, since the flowmeter catheter maintained a constant cross-sectional area around the thermistor bead. A continuous record of volume output was obtained simultaneously with an additional measurement technique. Spurt volumes of urine delivered in concert with ureter peristalsis were directly correlated to peak flow rates delineated by the flowmeter.