Real-time flow resistance compensation for urodynamic examinations of the upper urinary tract through single lumen catheters.

We developed a special calculation method for the compensation of resistance in urodynamic studies of the upper urinary tract that allows us to use existing single lumen nephrostomy catheters. We integrated a new calibration routine into the setup of our urodynamic equipment. Following the initial calibration procedure using the same size catheter as the previously inserted nephrostomy catheter, our software calculates actual resistance based on actual flowrate and the known linear resistance-flow correlation. Actual resistance and calculated intrapelvic pressure curves are presented in real-time. Using single lumen nephrostomy catheters for pressure-flow studies allows us to consider intrapelvic pressure during the measurement, to adjust filling pressure accordingly. It makes time consuming and sophisticated postprocessing resistance calculation unnecessary and also provides a challenging new method for conventional urodynamic studies of the lower urinary tract.