A study of bladder impedance measurements and cystometry.

Tetrapolar impedance is a non-invasive method of measuring urine volume in the bladder. Changes in the urine volume can be measured by alterations in the impedance measurements. Impedance measurements are obtained by using a tetrapolar impedance converter with four electrodes placed on the subject's abdomen. Measuring impedance changes occurs while the bladder fills with urine. An assessment of urine volume and bladder function is essential to determine an index of renal function and urinary stasis in postsurgical patients, paraplegics and those patients with neurogenic bladder dysfunction. The purpose of this investigation was to describe a noninvasive method, tetrapolar impedance, by measuring urine volume and residual. The impedance measurements were obtained on three subjects during cystometry studies. The changes in impedance were compared with the simultaneous changes in bladder fluid volume as the cystometric fluid was instilled. Few clinically and statistically significant results were obtained from the small number of subjects in this investigation. The first two case studies did not show a significant comparison for impedance changes. They did, however, help to verify that there is some relationship between the change in cystometric capacity and cystometric pressure readings. The information obtained from these case studies can be used to help compare impedance measurements with those of cystometry in the future. However, the third can case did show promise of substantial comparison between impedance measurements and cystometry.