Modeling of Pulse Transit Time under the Effects of Hydrostatic Pressure for Cuffless Blood Pressure Measurements

Continuous Blood Pressure Measurement From Invasive to Unobtrusive: Celebration of 200th Birth Anniversary of Carl Ludwig

“…On the basis of this approach, researchers have calibrated the patient-dependent coefficient; that is, by using changes in hydrostatic pressure under some assumptions [21,70,71]:…”

Using the Changes in Hydrostatic Pressure and Pulse Transit Time to Measure Arterial Blood Pressure

“…We modified our model described in [4] by substituting the V-P curve presented in [7] into the B-H equation [5] and integrating for an artery segment to give the PTT needed to travel along an artery where the transmural pressure changes linearly with height due to an induced hydrostatic component. The two characterising parameters are: k, a constant related to the elasticity of vessel wall and surrounding tissue and K 0 , a constant derived from boundary condition.…”

“…The model is distinct from the hydrostatic pressure approach proposed by Shaltis et al [6], where a protocol that involves arm movements is used to calibrate salient features of the photoplethysmogram (PPG) for the estimation of BP. Based on our model [4], we found that when a hydrostatic component is introduced, the overall time taken for a pulse to travel along the artery will be a function of both the initial BP and hydrostatic component. In addition, due to the relatively small variation of blood density between subjects, the hydrostatic component depends only on the height difference between two points.…”

“…One common method is to characterise individuals' parameters using the conventional cuff-based devices [1]- [3]. Another method we are currently studying is based on a model of PTT under the effects of hydrostatic pressure due to hand elevation [4]. In this study, we aim to further explore the possibility of using the changes in hydrostatic pressure and PTT for estimating BP on individual persons without calibration.…”

“…We previously proposed [4] to substitute a mathematical representation of the volume-pressure (V-P) relationship of artery into the Bramwell and Hill's (B-H) equation [5] under the effects of hydrostatic pressure. The model is distinct from the hydrostatic pressure approach proposed by Shaltis et al [6], where a protocol that involves arm movements is used to calibrate salient features of the photoplethysmogram (PPG) for the estimation of BP.…”