Portable urodynamics monitoring system using a personal digital assistance

The conventional urodynamic monitoring is performed by filling artificially the bladder with saline. It is difficult to evaluate the physiological functions of the storage and voiding of the bladder. In this study, we constructed an ambulatory urodynamic monitoring (AUM) system and proposed a novel method for estimating abdominal pressure by bio-impedance changes and EMG activity. The system was evaluated in 10 patients. As the intensity of the abdomen contraction increased, the amplitude of bio-impedance signal and the RMS value of EMG increased as compared to those observed during resting. The correlation coefficient was 0.72 for the "weak" contraction, 0.96 for "strong" contraction, 0.90 for "stronger" contraction, 0.84 for "vigorous" contraction and 0.78 for "maximal" contraction. Also, daily events such as coughing, sneezing and conversation, were sensitively monitored by observing the amplitude change of the bio-impedance signals. However, the EMG signals could not be used to detect these events, therefore, we determined that bio-impedance method was a more useful tool to measure the changes of abdominal pressure noninvasively for urodynamic monitoring.