Estimation of systolic blood pressure variations from pulse arrival time using a narrow-band filter

A narrow-band filtering method was explored to improve the correlation between systolic blood pressure (SEP) and pulse arrival time (PAT). The raw correlation coefficients among them on 15 subjects vary from 0.19 to 0.95. When the uncorrelated components in both signals were suppressed, the remained narrow-band components showed a fairly good linear correlation. The average correlation coefficient was up to 0.87 from 0.69, and the most striking one reached 0.99. The study implies that the narrow-band PAT may be used as a promising indicator of detecting the changes in systolic blood pressure and other physiological characteristics.