The effects of pre-ejection period on the blood pressure estimation using pulse transit time

Owing to the prevalence of hypertension in recent decades, the non-invasive monitoring of blood pressure (BP) using pulse transit time (PTT) has been proposed for better evaluations of cardiovascular diseases. The effects of pre-ejection period (PEP) on the relationship between PTT and BP, however, have not been studied systematically. Our study was to investigate whether the inclusion of PEP in PTT measurement could improve the non-invasive BP estimation. PTTs with and without PEP inclusion were denoted as PAT and TT respectively. Linear regressions were given in the scatter plots, SBP versus PAT and TT, using least-square method. The results of this study showed that (1) only PAT changed significantly (p<0.001) when significant (p<0.001) systolic BP (SBP) change occurred and (2) the standard deviations (SD) of difference between the measured and least-square fitted SBP by PAT and TT were 5.6 mmHg and 8.6 mmHg respectively. The smaller SD of difference between measured and fitted SBP by PAT indicated an inclusion of PEP in the measurement of PTT was necessary to have an accurate PTT-based SBP estimation.