Research on the main elements influencing blood pressure measurement by pulse wave velocity

There have been considerable errors in non-invasive continuous beat-by-beat blood pressure (BP) measurement using the pulse wave velocity (PWV). To solve the problem, an in vivo study using 10 dogs was performed. The PWV-BP correlation under intact neuro-humoral factors was compared with that under the factors to be partly eliminated and the PWV-BP regularities were investigated using 10-beat average data. It was confirmed that the vasomotion and the viscoelasticity of vascular smooth muscles are the main elements influencing PWV-BP correlation through changing the elasticity of the arterial wall, and result in a 'shift' and 'zigzag swings' in the PWV-BP relationship so as to lower the PWV-BP correlation. By choosing large arteries and modifying the PWV algorithm, linear correlation coefficients of 0.97 +/- 0.027 and standard errors of the BP estimate of 5.29 +/- 2.84 mm Hg were obtained. The study suggests that the error could be further reduced by simultaneously measuring some related parameters.