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1

Ocena sztywności tętnic na podstawie analizy kształtu fali tętna obwodowego

100%

Wilk B.

Pomiary Automatyka Kontrola

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2009

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tom R. 55, nr 12

1001-1003

PL

W artykule przedstawiono metodę oceny sztywności naczyń tętniczych na podstawie analizy sygnału fotopletyzmograficznego (tzw. PPG) reprezentującego falę tętna obwodowego. Do rejestracji fali tętna zastosowano czujnik fotopletyzmograficzny (wariant prześwietleniowy) umieszczony na palcu. W pracy opisano algorytm opracowany do przetwarzania sygnału PPG, który umożliwia wyznaczenie parametrów przydatnych do oceny sztywności ścian tętnic. Omówiono także problemy detekcji charakterystycznych punktów fali tętna.

EN

Arterial stiffness is a well-known risk factor of cardiovascular dise-ase and a predictor of cardiovascular events. Recent studies have shown that the arterial pulse waveform provides a great deal of information on arterial stiffness. Vascular stiffness plays an important role in controlling the speed of aortic wave propagation. In young healthy subjects, the central aortic wave generated by left ventricular ejection is reflected from the periphery in diastole maintaining a normal coronary flow rate. When the wall stiffness of large arteries increases, the reflected wave appears earlier in the aorta, raising central aortic pressure during systole. In this paper the method for estimating arterial stiffness from the peripheral pulse waveform is described. Peripheral pulse waveforms were recorded at the finger using a transmission-type, photoplethysmographic sensor. Pho-toplethysmo-graphy is a non-invasive optical technique sensitive to variations in blood volume and perfusion in the tissue. Fig.1 shows a typical peripheral volume pulse wave shape represented by the AC component of the photoplethysmographic signal (the so-called PPG signal). The purpose of this study was to develop a simple and effective method for analysis of the PPG signal later used for extracting features for assessment of the arterial stiffness. The following parameters widely used to quantify the arterial stiffness were calculated (see Tab. 1): the crest time, the reflection index (RI), and the time between the systolic and diastolic peaks (related to the transit time of the pressure waves from the root of the aorta to the site of reflection and back). The crest time and the reflection index (RI) are related to the pulse wave velocity in large arteries. In this paper some problems of detection of the characteristic points from the PPG signal are also discussed.

2

Validation of a new device for photoplethysmographic measurement of multi-site arterial pulse wave velocity

84%

Sondej T. , Jannasz I. , Sieczkowski K. , Dobrowolski A. , Obiała K. , Targowski T. , Olszewski R.

Biocybernetics and Biomedical Engineering

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2021

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tom Vol. 41, no. 4

1664--1684

EN

Pulse wave velocity (PWV) is commonly used for assessing arterial stiffness and it is a useful and accurate cardiovascular mortality predictor. Currently, many techniques and devices for PWV measurement are known, but they are usually expensive and require operator experience. One possible solution for PWV measurement is photoplethysmography (PPG), which is convenient, inexpensive and provides continuous PWV results. The aim of this paper is validation of a new device for PPG sensor-based measurement of multisite arterial PWV using a SphygmoCor XCEL (as the reference device) according to the recommendations of the Artery Society Guidelines (ASG). In this study, 108 subjects (56 men and 52 women, 20–91 years in 3 required age groups) were enrolled. The multi-site PWV was simultaneous measured by 7 PPG sensors commonly used in pulse oximetry in clinical settings. These sensors were placed on the forehead, and right and left earlobes, fingers and toes. Pulse transit time (PTT) was measured offline as the difference of time delay between two onsets of the pulse wave determined by the intersecting tangent method. The PWV was calculated by dividing the distance between PPG sensors by PTT. During PPG signals measurement, reference carotid to femoral PWV (cfPWV) was performed with a SphygmoCor XCEL system. The Pearson correlation coefficient (r) between the obtained PWV results was calculated. The Bland-Altman method was used to establish the level of agreement between the two devices. Mean difference (md) and standard deviation (SD) were also calculated. The multi-site PWV was highly correlated with accuracy at the ASG-defined level of ‘‘Acceptable” (md < 1.0 m/s and SD ≤ 1.5 m/s) with cfPWV: forehead - right toe (r = 0.75, md = 0.20, SD = 0.97), forehead - left toe (r = 0.79, md = 0.18, SD = 0.91), right ear - right toe (r = 0.79, md = 0.11, SD = 0.96), left ear - left toe (r = 0.75, md = 0.43, SD = 0.99), right ear - left toe (r = 0.78, md = 0.40, SD = 0.93), left ear - right toe (r = 0.78, md = 0.11, SD = 0.96), right finger - right toe (r = 0.66, md = 0.95, SD = 1.29), left finger - lefttoe (r = 0.67, md = 0.68, SD = 1.35). This study showed that PWV measured with the multisite PPG system, in relation to the obtained numerical values, correlated very well with that measured using the commonly known applanation tonometry method. However, it should be noted, that the measured PWV concerns the central and muscular part of the arterial tree while the cfPWV is only for the central one. The best results were obtained when the proximal PPG sensor was placed on the head (ear or forehead) and the distal PPG sensor on the toe. PPG sensors can be placed in many sites at the same time, which provides greater freedom of their configuration. Multi-site photoplethysmography is an alternative method for PWV measurement and creates new possibilities for the diagnostics of cardiovascular diseases.

3

Correlations between vascular properties and mental dysfunctions in long-COVID-19 support the vascular depression hypothesis

67%

Gólczewski T. , Plewka K. , Michnikowski M. , Chciałowski A.

Biocybernetics and Biomedical Engineering

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2024

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tom Vol. 44, no. 3

461--469

EN

Objectives: Vascular depression hypothesis (VDH) bases on co-occurrence of vascular and mental dysfunctions in advanced age; however, there may be still a controversy about whether there is some direct association between vascular and mental properties or the co-occurrence is only a statistical artifact caused by commonness of these dysfunctions in the elderly. COVID-19 gave opportunity to test VDH under conditions different from aging. Methods: 25 patients were examined 3-6 month after SARS-CoV-2 infection. Subjective worsening of mental functions, presumably caused by the disease, was quantified with three psychometric tests. Blood flow wave-forms were obtained for the left brachial and common carotid arteries. The waveform shape changes continuously with age; therefore, an individual shape can be characterized by the index WA being the calendar age (CA) of the average healthy rested subject having the most similar shape (consequently, in healthy rested subjects WACA = 0, in average). The mathematical functional analysis was used to calculate WA. Results: Brachial WA-CA = 13 yrs, in average (p < 0.00005; Cohen’s d = 0.99), and was correlated with tests scores (r = 0.55, 0.65, 0.46). Mean carotid WA-CA were smaller (7.2 and 1.6) but they were also correlated with the scores (right: r = 0.44, 0.55, 0.32; left: r = 0.49, 0.51, 0.38). Scores of two tests were inversely correlated with the systolic (r = -0.54, - 0.58) and diastolic (r = -0.46, - 0.56) pressures. Conclusions: Since neither vascular nor mental problems are common after COVID-19, these relatively high correlations indicate that vascular and mental properties are not independent, i.e., they support VDH. Note that this not only concerns cerebral vasculature.