Non-linear modulation of total peripheral resistance due to pulsatility: a model study

Total Peripheral Resistance (TPR) is the resistance of the arterial tree, defined as the ratio between the mean systemic pressure and the cardiac output. A lumped parameters model of the arterial tree with active and non linear peripheries was developed in order to show how mutual interactions between systemic and local responses characterize non-linear modulations of TPR. Numerical simulations showed that TPR is lower in presence of pulsatile inputs, it decreases with the harmonic content of the input itself, as a consequence of local responses to pulsatility, and it is maximum in absence of pulsatility, a typical condition of Extra Corporeal Circulation (ECC) performed using continuous pumps. TPR is therefore strongly affected by systemic conditions of circulation, but it is mainly determined by the nonlinear behaviour of peripheral networks.