Search results for "plethysmography"
showing 10 items of 84 documents
Photoplethysmography for bovine heat detection: the preliminary results
2020
In this study, we applied photoplethysmography (PPG) as an alternative, convenient, and affordable method for bovine heat detection. Heat detection is an essential part of effective herd reproduction management. Currently, there are many different heat detection techniques, but they can be ineffective or impractical to use. Since heat affects local vulvar blood circulation (resulting in swelling and erythema), photoplethysmography could represent an affordable alternative to detect this bovine phenomenon. In this study, we enrolled 20 animals in heat and other stages of the bovine reproduction cycle. We analyzed the PPG signal in terms of baseline (DC component), power, kurtosis, and erythe…
A study on the effect of contact pressure during physical activity on photoplethysmographic heart rate measurements
2020
Heart rate (HR) as an important physiological indicator could properly describe global subject&rsquo
Comparison of region of interest segmentation methods for video-based heart rate measurements
2018
International audience; Conventional contact photoplethysmography (PPG) sensors are not suitable in situations of skin damage or when unconstrained movement is required. As a consequence, remote photoplethysmography (rPPG) has recently emerged because it provides remote physiological measurements without expensive hardware and improves comfort for long-term monitoring. RPPG estimation methods use the spatially averaged RGB values of pixels in a Region Of Interest (ROI) to generate a temporal RGB signal. The selection of ROI is a critical first step to obtain reliable pulse signals and must contain as many skin pixels as possible with a low percentage of non-skin pixels. In this paper, we ex…
Remote Photoplethysmography for Evaluation of Cutaneous Sensory Nerve Fiber Function
2021
About 2% of the world’s population suffers from small nerve fiber dysfunction, neuropathy, which can result in severe pain. This condition is caused by damage to the small nerve fibers and its assessment is challenging, due to the lack of simple and objective diagnostic techniques. The present study aimed to develop a contactless photoplethysmography system using simple instrumentation, for objective and non-invasive assessment of small cutaneous sensory nerve fiber function. The approach is based on the use of contactless photoplethysmography for the characterization of skin flowmotions and topical heating evoked vasomotor responses. The feasibility of the technique was evaluated on volunt…
Changes of arterial hemodynamics in patients with type 2 diabetes mellitus or impaired glucose tolerance
2006
Aim: The aim of our study was to evaluate the arterial hemodynamics in patients with type 2 diabetes mellitus or impaired glucose tolerance without clinical or Doppler evidence of peripheral arterial disease, in order to early detect vascular damage. Methods. We studied 20 subjects (12 men and 8 women, aged between 48 and 62 years) with type 2 diabetes mellitus (Group 1), 20 subjects (11 men and 9 women, aged between 49 and 61 years) with reduced glucose tolerance (Group 2), and 20 normal subjects (10 men and 10 women, aged between 48 and 62 years) (Group 3). Each subject underwent strain-gauge plethysmography and the following parameters were evaluated: rest flow (RF); peak flow (PF); PF/R…
Prevalence and Risk Factors of PAD among Patients with Elevated ABI
2008
ObjectivesTo assess the prevalence and clinical significance of elevated ankle-brachial index (ABI) in patients referred to vascular consultation.DesignRetrospective clinical study.Material and methodsIn 1,762 patients referred with a suspicion of peripheral arterial disease (PAD), ABI and toe brachial index (TBI) were measured by photoplethysmography. ABI≥1.3 was considered falsely elevated and TBI<0.60 was the diagnostic criterion for PAD.ResultsThe prevalence of elevated ABI was 8.4% and that of PAD among these patients 62.2%. PAD was significantly more prevalent among subjects with severe symptoms (rest pain, ulcers or gangrene) than in those with intermittent claudication (83.8% and 45…
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 …
Associations of fat mass and fat-free mass with physical fitness in 4-year-old children: Results from the MINISTOP trial
2016
Physical fitness is a powerful marker of health in youth. Studies in adolescents and adults suggest that higher fat mass is related to worse physical fitness. However, there is limited knowledge whether fat mass and fat-free mass are associated with physical fitness already in preschoolers. Baseline data from the MINISTOP (Mobile-based INtervention Intended to STop Obesity in Preschoolers) trial was utilized for this cross-sectional analysis. Body composition was assessed using air-displacement plethysmography. Fat mass index [fat mass (kg)/height(2) (m)] and fat-free mass index [fat-free mass (kg)/height(2) (m)] were used to provide height-adjusted measures of body composition. Physical fi…
Noradrenaline depleting and blood pressure lowering activity of threo-corbadrine
1968
Abstract Threo-corbadrine caused a long-lasting depletion of noradrenaline in the heart and in mesenteric vessels and lowered the blood pressure of normal and renal hypertensive rats. It is suggested that threo-cobadrine decreases vascular tone by acting peripherally as a substitute adrenergic transmitter.
Measurement of phase I volume breath by breath in spontaneously breathing guinea pigs.
1990
A new method to determine phase I volume in tracheotomized spontaneously breathing guinea pigs is presented. Measurements were performed in three animals weighing 567-896 g. In simultaneous tracings of tidal volume (VT) and expiratory profiles of endogenous gases (PO2 or PCO2), the phase I volume of each breath was determined graphically as the volume expired up to the end of phase I of the expirogram. The mean phase I volume of different animals ranged from 0.29 to 0.43 ml with an arithmetic dispersion between 0.014 and 0.021 ml. Spontaneous sighs sometimes with doubling of the VT caused a significant rise of phase I volume up to 50% of the normal values. The linear regression curve was c…