The purpose of this study was to introduce and validate a new algorithm to estimate instantaneous aortic blood flow (ABF) by mathematical analysis of arterial blood pressure (ABP) waveforms. The algorithm is based on an auto-regressive with exogenous input (ARX) model. We applied this algorithm to diastolic ABP waveforms to estimate the auto-regressive (AR) model coefficients by requiring the estimated diastolic flow to be zero. The algorithm incorporating the coefficients was then applied to the entire ABP signal to estimate ABF. The algorithm was applied to six Yorkshire swine data sets over a wide range of physiologic conditions for validation. Quantitative measures of waveform shape (standard deviation, skewness, and kurtosis) as well as stroke volume (SV) and cardiac output (CO) from the estimated ABF were computed. Values of these measures were compared with those obtained from ABF waveforms recorded using a Transonic™ aortic flow probe placed around the aortic root. The estimation errors were compared with those using Windkessel model. The ARX algorithm achieved significantly lower errors in the waveform measures, SV, and CO than those obtained using a Windkessel model (P<0.05).
- aortic blood flow
- arterial blood pressure
- cardiac output
- stroke volume
- Copyright © 2012, Journal of Applied Physiology