Asymmetric time-dependent model for the dynamic finger arterial pressure–volume relationship

Abstract

The volumetric pulses in the finger PPG signal appear as an information source for several indirect measurement methods. In this study we modelled transformation of pressure pulses into volume pulses in a wide transmural pressure range. The noninvasive finger arterial pressure and photoplethysmographic (PPG) signals were simultaneously registered in 13 healthy subjects while the pressure in the PPG cuff ramped up and down. The nonlinearity of the pressure-volume (P-V) relationship was modelled by an asymmetric function, consisting of two arctangents, each for a different pressure region. The time dependency was described by the first order lag. The disturbing effect of slow creeps in the PPG signal was suppressed by an equal filtering of the measured and model-predicted signal. The differences between the two estimates of the subject's P-V relationship for the increasing and decreasing cuff pressure were small thus showing the repeatability of this method, which can be used for the characterization of individual finger arterial behaviour as well as its changes.

Investigation of photoplethysmographic signals and blood oxygen saturation values on healthy volunteers during cuff-induced hypoperfusion using a multimode PPG/SpO2 sensor

“…Apart from PPG signals being used in estimation of the SpO 2 values, these volumetric changes in the finger PPG signal appear as an information source for several indirect measurement methods [4,7,12]. In a previous study [6], a moderate correlation (r = 0.54) was found between fingertip PPG waveform variability (PPGV) and systemic vascular resistance (SVR).…”

Finger and ear photoplethysmogram waveform analysis by fitting with Gaussians

“…In reality the VP waveform is not exactly same as pressure pulse. This is because the pressure-volume (P-V) relationship is not linear [10]. Nevertheless, time parameters s 1 , s 2 , s 3 , s 4 are not affected by the nonlinearity of the P-V relationship.…”

Experimental Feasibility Study of Estimation of the Normalized Central Blood Pressure Waveform from Radial Photoplethysmogram

“…The arterial wall is essentially composed of viscoelastic tissues consisting mainly of elastin and collagen [13], exhibiting a non-linear behavior in response to the arterial pressure P art [14]. Each left ventricle contraction generates a pulse pressure wave which propagates from the aorta and reaches the extremities through the arterial tree.…”

“…A pressure cuff will apply an external pressure P ext , whereas the relationship between the artery diameter d and the transmural pressure (P tr = P art -P ext ) is given in eqn. 1 [14], where d n is the diameter difference from a fully collapsed state to the inflection point, d p is the diameter difference from the inflection point to a fully expanded size, and C max is the slope of the pressure-diameter curve at the inflection point.…”