Prediction of arterial pressure during hemodialysis using electrical impedance

Eight hemodialysis were monitored with the objective of detecting the onset of arterial hypotension. Electrical impedance measurements were obtained from the lower limbs together with body weight changes and arterial pressure at regular time intervals. Heart rate, stroke volume, mean blood flow, peripheral vascular resistance, the peak of the first derivative of the impedance signal and " O " wave amplitude were extracted from dZ/dt Clinical hypotension or drops in mean arterial blood pressure of more than 30 mmHg were observed in 6 HD. A multivariate regression model using body weight changes and peak dZ/dt suggests that it is possible to predict changes in arterial pressure with 6% error with an anticipation of up to 30 minutes in the phase of hemodialysis. The correlation obtained between basal impedance and body weight (r = 0.92, p< 0.001) indicates that the former might be used as a substitute for direct measurements of body weight.