A technical and clinical evaluation of the Disa uroflowmeter.

This investigation reveals that there is a marked reduction in the rotational speed of the transducer disc as the stream flowrate is increased, although the non-linearity is partly reduced by electronic compensation within the instrument. The inaccuracy at low flowrates is probably unimportant in routine clinical applications. However, significant errors are recorded at high flowrates when the stream strikes the grid intersections or when the point of impact is close to the edge of the rotating disc. For these reasons, it is desirable that the patient should avoid micturating directly on to the grid. To obtain acceptable clinical recordings, an instrument time constant of 0-5 sec must be used. Although some characteristic tracings can be identified, the clinical measurements indicate that the effects of the volume voided and stream movement must be taken into consideration when the flow patterns are being interpreted.