Effect of confounding factors on blood pressure estimation using pulse arrival time

Abstract

Two confounding factors were selected and analyzed in blood pressure estimation using pulse arrival time (PAT) for each individual. The heart rate was used as the confounding factor for the cardiac cycle, and the duration from the maximum derivative point to the dicrotic peak (TDB) in the photoplethysmogram was used as another confounding factor representing arterial stiffness. By considering these factors with PAT in multiple regression analysis, the performance of blood pressure estimation is enhanced significantly in the diastolic phase as well as in the systolic phase. The reproducibility of this method was also validated with formerly obtained regression equations from the training set. The correlation between estimated and measured blood pressure decreased a little, but the validity was still maintained (r congruent with 0.8). This shows the value of the method in non-intrusive blood pressure estimation for individual patients and may be useful for various applications.

Cuff-Less and Continuous Blood Pressure Monitoring: A Methodological Review

“…The arterial stiffness affecting cushioning of arteries has been found to have implications on systolic hypertension [53,118]. Structural changes, such as those related to vascular aging and atherosclerosis, along with functional changes like increased BP or higher sympathetic activity, can impact the arterial stiffness [115]. Baek et al described a method of estimating arterial stiffness index (ASI) as the time delay between the mid-point of the rising edge (incident) and characteristic point on the "dicrotic notch" (reflecting wave) of the PPG (Figure 3c) [84,115].…”

“…Structural changes, such as those related to vascular aging and atherosclerosis, along with functional changes like increased BP or higher sympathetic activity, can impact the arterial stiffness [115]. Baek et al described a method of estimating arterial stiffness index (ASI) as the time delay between the mid-point of the rising edge (incident) and characteristic point on the "dicrotic notch" (reflecting wave) of the PPG (Figure 3c) [84,115]. Shaltis et al estimated the impact of hydrostatic pressure by varying the position of subject and measuring changes in PTT and BP, and through experimental data they concluded that gravity has a significant impact on BP [119].…”

“…Heart rate (HR) represents the cardiac cycle and determines the heart's preload and the cardiac output (CO), which positively impact BP as the pressure on the arterial walls. HR is proportional to the volume of blood ejected [115,116]. HR and BP are also regulated by the autonomic nervous system which has been found to be inversely related, depending on the baroreflex activity [117].…”

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

“…where parameter can be the heart rate (HR) or other BP-related features extracted from the pulse signal (e.g., arterial stiffness, cardiac output, and pulse width) [64][65][66]. Because the vascular smooth muscle tone can affect the relationship between BP and PTT (9), Liu et al [67] suggested that the vascular tone should be further considered into PTT-based BP estimation.…”

Photoplethysmographic signals to predict the success of lumbar sympathetic blockade for lower extremity pain

“…For PPG recording, a device of our own design was used. 27 The output signal from the pulse oximetry sensor was converted into a voltage and amplified, then filtered with a band-pass of 0.05-10 Hz to separate the pulsatile AC signal, with an analogue low-pass cut-off at 1 Hz to separate the DC signal. A constant current source circuit was used to drive the LED and the amplification ratio was kept constant.…”