Quantitative analysis of the effect of pulsatile flow on vascular resistance

Publisher Website
Google Scholar
Abstract
'Pulsatile flow' has been reported to reduce vascular resistance. In this study, the effect of pulsatile flow was assessed quantitatively, using perfusion of canine hindlimb. The perfusion circuit consisted of roller-type pulsatile pump (Cobe Inc., Stockert pump) and bubble oxygenator (Shiley Inc., S-070/s). Each flow curve was quantified with the mean flow rate (F) and pulse power index (PPI). PPI is derived by Fourier transformation of the flow curve and represents the degree of 'pulsation'. Vascular resistance was determined during perfusion with varied flow rate and PPI. The regression formula between vascular resistance (VR) and two parameters was obtained as follows: VR(F,PPI) = 41600x(F-1.37) -0.95+913 - PPIx{(3.99x(F-1.33)-040_0.69} where VR is measured in mmHg. min-1.kg.ml-1; F represents ml.min-1.kg -1 (range from 2.8 to 17.1); and PPI is dimensionless (range from 2.8 to 215.7). Using this formula, vascular resistance at a fixed flow rate and wave form can be predicted. When the flow rate is 6.27 ml.min-1.kg-1 and the PPI is 1466, (measured values under perfusion with own beating heart) the vascular resistance perfused by own beating heart is obtained. The results indicate that the pulsation of own beating heart contributes to a reduction in vascular resistance to 80%. It is also shown that the value of PPI which is necessary to reduce the vascular resistance to 80% is more than 1300 under the normal flow rate range.