Search results for "PhotoPlethysmoGraphy"
showing 10 items of 53 documents
Extended Granger causality: a new tool to identify the structure of physiological networks.
2015
Granger causality (GC) is a very popular tool for assessing the presence of directional interactions between two time series of a multivariate data set. In its original formulation, GC does not account for zero-lag correlations possibly existing between the observed time series. In the present study we compare the GC with a novel measure, termed extended GC (eGC), able to capture instantaneous causal relationships. We present a two-step procedure for the practical estimation of eGC based on first detecting the existence of zero-lag correlations, and then assigning them to one of the two possible causal directions using pairwise measures of non-Gaussianity. The proposed method was validated …
Comparison of short-term heart rate variability indexes evaluated through electrocardiographic and continuous blood pressure monitoring
2019
Heart rate variability (HRV) analysis represents an important tool for the characterization of complex cardiovascular control. HRV indexes are usually calculated from electrocardiographic (ECG) recordings after measuring the time duration between consecutive R peaks, and this is considered the gold standard. An alternative method consists of assessing the pulse rate variability (PRV) from signals acquired through photoplethysmography, a technique also employed for the continuous noninvasive monitoring of blood pressure. In this work, we carry out a thorough analysis and comparison of short-term variability indexes computed from HRV time series obtained from the ECG and from PRV time series …
Tissue optical perfusion pressure: a simplified, more reliable, and faster assessment of pedal microcirculation in peripheral artery disease
2020
Oscillometry is an alternative to continuous-wave Doppler (cw-Doppler) to determine peripheral artery disease (PAD) severity using the ankle-brachial index (ABI). cw-Doppler ABI differentiates systolic pressure of ATP and ADP where either one of both values in most patients is higher (high) and the other value is lower (low). In contrast, oscillometric ABI measures the strongest signal and hence misses the lower value. Both do not take pedal perfusion into consideration. Simultaneous determination of tissue microperfusion cares for pedal PAD. ABI was determined by cw-Doppler and oscillometry. Tissue optical perfusion pressure (TOPP) was taken from the first toe using photoplethysmography. 3…
Simultaneous recording of skin blood pulsations at different vascular depths by multiwavelength photoplethysmography.
2007
A new technique for parallel recording of reflection photoplethysmography (PPG) signals in a broad spectral band (violet to near-infrared) has been developed, and its potential for assessment of blood microcirculation at various depths from the skin surface is discussed. PPG signals have been simultaneously detected at cw laser wavelength sets comprising 405, 532, 645, 807, and 1064 nm. Various signal baseline responses to breath holding and different shapes of the PPG pulses originated from the same heartbeat but recorded at different wavelengths have been observed, indicating a depth variety of the skin blood pulsation dynamics.
PPG embedded system for blood pressure monitoring
2014
In this work, we have designed and implemented a microcontroller-based embedded system for blood pressure monitoring through a PhotoPlethysmoGraphic (PPG) technique. In our system, it is possible to perform PPG measurements via reflectance mode. Hardware novelty of our system consists in the adoption of Silicon PhotoMultiplier detectors. The signal received from the photodetector is used to calculate the instantaneous heart rate and therefore the heart rate variability. The obtained results show that, by using our system, it is possible to easily extract both the PPG and the breath signal. These signals can be used to monitor the patients during the convalescence both in hospital and at hom…
Challenges in automated estimation of capillary refill time in dogs
2018
Capillary refill time (CRT) is a part of the cardiorespiratory examination in dogs. Changes in CRT can reflect pathological conditions like shock or anemia. Visual CRT estimation has low repeatability; therefore, optical systems for automated estimation have recently appeared. Since existing systems are unsuitable for use in dogs, we designed a simple, small and portable device, which could be easily used at veterinary clinic. The device was preliminarily tested on several measurement sites in two dogs. Not all measurement sites were suitable for CRT measurements due to underlying tissue optical and mechanical properties. The CRT measurements were possible on the labial mucosa, above the st…
Attālinātas fotopletizmogrāfijas metode femorāla nerva blokādes monitorēšanai
2020
Virsrakst: Attālinātas fotopletizmogrāfijas metode femorāla nerva blokādes monitorēšanai. Priekšvēsture: Attālināta fotopletizmogrāfija (aFPG) ir neinvazīva ādas mikrocirckulācijas izvērtēšanas metode, ko potenciāli var izmantot reģionālas anestēzijas sekmīguma pārbaudei. Viena no reģionālas anestēzijas problēmām ir vēlīnā un subjektīvā bloka iznākuma prognozēšana. Mērķis: Izvērtēt ādas mikrocirkulācijas izmaiņas ceļa locītavas ādā pēc prolongētas femorāla nerva blokādes ar aFPG metodi. Izvērtēt aFPG metodes efektivitāti diferencēšanā starp placebo un lokālo anestētiķu injekciju femorāla nerva blokādes laikā. Uzdevumi: 1. Izvērtēt aFPG spēju identificēt šļirci ar lokālo anestētiķi vai place…
Use of photoplethysmography to determine gastrointestinal perfusion pressure: an experimental canine model.
2002
<i>Objectives:</i> To develop an experimental model to assess the parietal perfusion pressure (PPP) of the digestive tract using photoplethysmography. <i>Materials and Methods:</i> Twenty-two mongrel dogs were used. Progressive external compression was applied to the intestinal wall and the PPP was assessed with photoplethysmography. The study group was divided into two groups. In group 1 PPP was measured at the levels of the stomach, duodenum, jejunum and transverse colon. In group 2 PPP was measured after temporary occlusion of the truncal and marginal circulation of the jejunum to provide further variables. <i>Results:</i> The PPP decreased significant…
Photoplethysmography In Dogs And Cats: Selection Of Measurement Sites For Pet Monitor
2018
The PPG measurements of the study Cugmas et al, 2018. Notes.txt include all information about the dataset.
Photoplethysmograhic sensors, potential and limitations: Is it time for regulation? A comprehensive review
2023
Healthcare is expected to increasingly shift care out of inpatient settings thanks to wearable monitoring systems. Photoplethysmography (PPG) is an optical technique already integrated into wrist-worn commercial products which presents significant advantages in terms of cost and dimensions. PPG-based devices, despite their ability to detect multiple cardiovascular parameters, are affected by several influencing conditions that depend both on technological or environmental variables, and on intra- and inter-subject variability that influences the whole measurement chain and reliability, hindering an objective characterization of PPG devices. Plus, the lack of standardization for data collect…