<title>Photonic vascular diagnostics by four-channel photoplethysmography</title>

2005

A four-channel photoplethysmography device was designed and built at University of Latvia to detect signals from different body parts and to analyze the signal shapes. The device consists of optical contact probes, interface, and a standard PC. Clinical tests were performed with occlusion patients having vascular problems at arm or leg arteries. Results showed significant difference in the pulse wave transit time in occluded and nonoccluded part of the body.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Analysis of factors influencing resuscitation success in acute coronary syndrome patients with out-of-hospital cardiac arrest in Latvia in 2010–2015

2016

Micro-circulation of skin blood: optical monitoring by advanced photoplethysmography techniques

2003

Blood micro-circulation in upper skin layers has been studied experimentally in real time by advanced two-channel photoplethysmography (PPG) techniques. The blood volume changes caused by micro-vessel expansion and dilution during the cardiac cycles have been detected by infrared optical contact sensors. A newly developed portable monitoring device comprising a lap-top computer was used for accumulation and processing of the bio-signals. Shapes of the PPG signals detected at different sites of the body were compared with these obtained by computer modeling.

The blood perfusion mapping in the human skin by photoplethysmography imaging

2010

A CMOS camera-based imaging photoplethysmographic (PPGI) system is described to detect the blood pulsations in tissue. Attention of PPGI is drawn to the potential applications in visualized blood perfusion. Intensity variations of three wavelengths (620 nm, 520 nm and 432 nm) were detected and analyzed in each pixel of image. To obtain a twodimensional mapping of the dermal perfusion measurement, custom image-processing software has been developed. The high-resolution PPGI images were derived from human fingers (transmission mode) and face (reflection mode), evaluated at three wavelengths. The newly developed system can be usable in skin blood perfusion monitoring for clinical applications.

Novel laser technologies for human skin in-vivo assessment

2007

Two experimental methodologies for human skin optical non-invasive in-vivo assessment have been developed and clinically tested - imaging of the laser-excited autofluorescence fading rate, and simultaneous recording of the reflectance photoplethysmography signals at several laser wavelengths with different skin penetration depths. Details of both equipments are described along with some measurement results illustrating feasibility of the novel technologies.

Factors influencing myopic shift in children after intraocular lens implantation.

2019

Introduction:Intraocular lenses have always been a controversial topic in pediatric cataract surgery. In the early 1990s in the post-Soviet states of Eastern Europe, intraocular lenses promised an easier full-time correction and amblyopia treatment. Since 1991, ophthalmologists in Latvia have been implanting intraocular lenses in infants. Amount of the postoperative myopic shift and its influencing factors, analyzed in this article, are important indicators of congenital cataract treatment.Materials and methods:A retrospective chart review off 85 children (137 eyes) who underwent foldable posterior chamber intraocular lens implantation at the Clinical University Hospital in Riga, Latvia, fr…

Wearable wireless photoplethysmography sensors

2008

Wearable health monitoring sensors may support early detection of abnormal conditions and prevention of their consequences. Recent designs of three wireless photoplethysmography monitoring devices embedded in hat, glove and sock, and connected to PC or mobile phone by means of the Bluetooth technology, are described. First results of distant monitoring of heart rate and pulse wave transit time using the newly developed devices are presented.

<title>A portable device for optical assessment of the cardiovascular condition</title>

2003

A hand-held prototype device for detection and processing of the tissue-remitted optical signals has been developed and tested. The photoplethysmography (PPG) principle was applied to follow the dilation and contraction of skin blood vessels during the cardiac cycle. Cardiovascular condition of the monitored person was assessed by temporal analysis of the recorded PPG signals as well as by shape analysis of the mean single-period PPG signals.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Bilateral photoplethysmography studies of the leg arterial stenosis.

2005

A newly developed portable multi-channel photoplethysmography (PPG) device has been used for comparative studies of 20 healthy control subjects and 45 patients with diagnosed arterial stenosis in a leg. The peripheral blood pulsations were detected simultaneously at four body sites-the same fingers and toes of both arms and legs. The PPG pulses recorded at the periphery of the stenotic leg, if compared with those of the healthy leg, were much weaker, with delayed arrival as a consequence of increased pulse wave transit time (PWTT) due to higher vascular resistance. The specific PWTT delays for the occluded legs were in the range of 20-80 ms, while in the case of healthy subjects the leg PPG…

Naturalistic follow-up study of rehospitalization rates and assigned disability status of patients with first-episode schizophrenia spectrum psychosi…

2020

Patients with first-episode schizophrenia spectrum psychosis (FEP) are at risk of not visiting an out-patient psychiatrist and are assigned disability status within a short period after diagnosis.The aim of this study was to conduct a naturalistic follow-up of FEP patients to explore their use of mental healthcare services and the rate of assigned disability status after FEP.This was the first study in Latvia to include all consecutive patients with FEP admitted to the largest regional hospital in South East Latvia, Daugavpils Psychoneurological Hospital (DPNH). Patients received standard treatment in a real-world environment. The mean follow-up time was 33 months (Min = 20 months, Max = 40…

Photoplethysmography Device for Detection of Changes in the Vasomotor Parameters of Small Laboratory Animals

2008

A device for observation of changes in vasomotor parameters of small laboratory animals with limited blood amount has been developed. The device contains cw laser sources (635 nm, 650nm or 980 nm), photodetector, amplifier of the absorption photoplethysmography signal and special software for data recording.

Imaging of Laser-Excited Autofluorescence Fading Rates: Novel Technique for Tissue Surface Structure Studies

2008

Experimental methodology for imaging of laser-excited tissue autofluorescence fading rates has been developed and clinically tested. Details of the equipment and image processing are described, along with measurement results confirming feasibility of the novel technology.

Changes in Cognition, Depression and Quality of Life after Carotid Stenosis Treatment

2019

Background:Although several studies have evaluated the change of cognitive performance after severe carotid artery stenosis, the results still remain elusive. The objective of this study was to assess changes in cognitive function, depressive symptoms and Health Related Quality of Life (HRQoL) after carotid stenosis revascularisation and Best Medical Treatment (BMT).Methods:Study involved 213 patients with ≥70% carotid stenosis who underwent assessment of cognitive function using Montreal Cognitive Assessment scale (MoCA), depressive symptoms - using Patient Health Questionnaire-9 (PHQ-9) and HRQoL - using Medical Outcome Survey Short Form version 2 (SF-36v2). The assessment was performed b…

Multi-spectral photoplethysmography biosensor

2011

A photoplethysmography (PPG) signal can provide very useful information about a subject's hemodynamic status in a hospital or home environment. A newly developed portable multi-spectral photoplethysmography device has been used for studies of 11 healthy subjects. The developed optical fiber biosensor comprises one multi-wavelength laser diode (405nm, 660nm and 780nm) and a single photodiode with multi-channel signal output processing and built in Li-ion accumulator; special software was created for visualization and measuring of the MS-PPG signals. ARM7TDMI-S LPC2148, NXP (founded by Philips) 32 bit processor with clock frequency of 60 MHz performs measurement and analysis of the signal.

Optical multichannel sensing of skin blood pulsations

2004

Time resolved detection and analysis of the skin back-scattered optical signals (reflection photoplethysmography or PPG) provide information on skin blood volume pulsations and can serve for cardiovascular assessment. The multi-channel PPG concept has been developed and clinically verified in this study. Portable two- and four-channel PPG monitoring devices have been designed for real-time data acquisition and processing. The multi-channel devices were successfully applied for cardiovascular fitness tests and for early detection of arterial occlusions in extremities. The optically measured heartbeat pulse wave propagation made possible to estimate relative arterial resistances for numerous …

Optical systems for non-invasive cardiovascular biosensing

2005

Three portable prototype devices for cardiovascular biosensing based on reflection-type photoplethysmography (PPG) principle have been designed and clinically tested. The single-channel PPG finger sensor provides real-time measurements with fast calculation of the mean single-period PPG signal shape ("cardiovascular fingerprint", potentially useful for recognition). The dual-channel PPG system gives additional possibility to monitor on-line the arterial pulse wave transit time and its responses to physical exercises. The four-channel PPG system proved to be applicable for fast detection of cardiovascular pathologies, e.g. arterial occlusions in extremities. Design principles and software al…

Influence of Severe Carotid Stenosis on Cognition, Depressive Symptoms and Quality of Life.

2017

Background: Carotid artery disease is not just a causal risk factor of ischemic stroke, but may predispose patients to depressive symptoms and low health related quality of life (HRQoL). Objectives: The objectives of the present study were to assess the association between severe carotid artery stenosis (CAS) and cognitive impairment, frequency of depressive symptoms and status of HRQoL. Methods: Cross - sectional study involved 55 patients with severe CAS and 54 patients with lower extremity peripheral artery disease (PAD). Cognitive impairment was assessed using Montreal Cognitive Assessment Scale (MoCA), depressive symptoms - PHQ-9 scale. HRQoL was measured using Medical Outcome Survey …

Monitoring of blood pulsation using non-contact technique

2009

Time resolved detection and analysis of the skin back-scattered optical signals (reflection photoplethysmography or contact PPG) provide rich information on skin blood volume pulsations and can serve for cardiovascular assessment. The widely used contact PPG technique has many limitations, like high sensitivity to sensor movement etc. The newly developed non-contact PPG technique has been developed in this work. Potential of the new technique for express-assessment of human cardio-vascular condition has been demonstrated.

Thiopurine

2020

Background: Thiopurine methyltransferase (TPMT) plays a significant role in the metabolism of thiopurines, and, for patients with inflammatory bowel disease (IBD), it is useful to perform TPMT genotyping prior to azathioprine (AZA) treatment. In this study, we determined TPMT gene polymorphisms in a cohort of IBD patients in Latvia. Methods: DNA samples were obtained from 244 IBD patients, and qPCR was performed for detection of rs1800462, rs1800460, and rs1142345 single-nucleotide polymorphisms (SNPs). Three common, non-functional TPMT alleles ( TPMT*2, *3B, and *3C) were identified (women, 51%; men, 49%). TPMT*2, *3A, *3B, and *3C allelic variants detected using qPCR were consistent with …

Portable two-channel PPG cardiovascular sensor device

2003

A portable sensor device for simultaneous detection and processing of skin-remitted optical signals from any two sites of the body has been developed and tested. The photoplethysmography (PPG) principle was applied to follow the dilatation and contraction of skin blood vessels during the cardiac cycle. The newly developed two-channel approach allows to estimate the vascular blood flow resistance by analysis of time shifts between the PPG pulses detected at different body sites. Potential of the sensor device for express-assessment of human cardio-vascular condition and for body fitness tests has been demonstrated.

Optical multichannel monitoring of skin blood pulsations for cardiovascular assessment

2004

Time resolved detection and analysis of the skin back-scattered optical signals (reflection photoplethysmography or PPG) provide rich information on skin blood volume pulsations and can serve for cardiovascular assessment. The multichannel PPG concept has been developed and clinically verified in this work. Simultaneous data flow from several body locations allows to study the heartbeat pulse wave propagation in real time and to evaluate the vascular resistance. Portable two- and four-channel PPG monitoring devices and special software have been designed for real-time data acquisition and processing. The multi-channel devices were successfully applied for cardiovascular fitness tests and fo…

Dual channel photoplethysmography studies of cardio-vascular response to the body position changes

2005

The dual-channel photoplethysmography studies of physiological responses during 3-stage orthostatic test were performed. Clear differences in heartbeat rate, pulse wave transit time and blood pressure variations of healthy volunteers and diabetic patients have been observed.

Imaging of laser-excited tissue autofluorescence bleaching rates.

2009

Experimental methodology for imaging of laser-excited tissue autofluorescence bleaching rates has been developed and clinically tested. The fluorescence images were periodically captured from the same tissue area over a certain time, with subsequent detection of the fluorescence intensity decrease rate at each image pixel and further imaging the planar distribution of those values. Spectral features at each image pixel were analyzed with a hyperspectral imaging camera. Details of the equipment and image processing are described as well as some measurement results that confirm the feasibility of the proposed technology.

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.

The analysis of blood flow changes under local anesthetic input using non-contact technique

2010

In this work photoplethysmography imaging (PPGI) technique was used to obtain blood flow changes in human skin under regional anesthesia (RA). PPGI was evaluated from video taken by video camera for 26 patients 2 minutes before and immediately after RA, using custom developed software. Results showed that blood flow obtained by PPGI increases immediately after RA effect and the amplitude of PPGI showed correlation with temperature changes in human skin (r=0.8±0.14, p<0.0001). We found that PPGI technique can be usable for non-contact monitoring of quality of RA.

Wireless photoplethysmography finger sensor probe

2010

A sensitive, digital, wireless sensor probe has been developed for photoplethysmography (PPG) measurements. It uses standard light emitting source and detector. The main advantage of this approach is to measure discharge time of the photodiode as amplitude of PPG signal. It reduces the cost, dimensions, power consumption and filtering of the device. First results of distant monitoring of heart rate using the newly developed sensor probe are presented.

P826 Unexplained higher frequency of mutant thiopurine S-methyltransferase genotypes in inflammatory bowel disease patients of Latvia population

2019

IMPACT OF CAROTID ENDARTERECTOMY ON COGNITIVE PERFORMANCE AND DEPRESSIVE SYMPTOMS

2016

OBJECTIVES: This study aims to evaluate the impact of carotid endarterectomy (CEA) on cognitive performance in patients with severe carotid disease and depressive symptoms, and to explore the possible associations between certain demographics, clinical characteristics, and cognitive function and depression. MATERIALS AND METHODS: The study included 48 patients, who were referred for endarterectomy. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA) scale, while depressive symptoms were assessed using the patient health questionnaire(PHQ-9) scale. An assessment of cognitive and depressive symptoms was performed 1–3 days before surgery, and then six months after. R…

Contact probe pressure effects in skin multi-spectral photoplethysmography

2007

A novel technique ensuring parallel recording of reflection photoplethysmography signals in broad spectral range has been tested for assessment of pressure-induced vascular changes at various depths from the skin surface. PPG signals have been simultaneously detected at three combinations of the cw laser wavelengths 405 nm, 532 nm, 645 nm, 807 nm and 1064 nm. The PPG baseline responses to the probe-skin contact pressure changes and shapes of the PPG pulses originated from the same heartbeat but recorded at different wavelengths have been detected and analyzed.