(1) Mechanotransduction is the process by which cells sense and respond to mechanical stimuli through biochemical signaling. This document discusses several mechanisms of mechanotransduction, including changes in protein conformation and mechanosensitive ion channels.
(2) Areas of disturbed flow, such as at blood vessel bifurcations, are prone to atherosclerosis due to the effects of disturbed flow on endothelial cell signaling and function. Disturbed flow leads to increased monocyte adhesion and LDL permeability.
(3) Mechanotransduction influences atherosclerosis through effects on genes like MCP-1, KLK-2, and lipid metabolism pathways in endothelial cells in response to shear stress and cyclic stretch. Sustained activation of pathways like JNK can
This randomized crossover study compared end-tidal oxygen (ETo2) levels during preoxygenation with a bag valve mask (BVM) alone and with supplemental nasal cannula (NC) oxygen at different flow rates. Healthy volunteers underwent 3 minutes of preoxygenation with a BVM alone or a BVM with NC at 0, 5, 10, or 15 liters per minute. The primary outcome was ETo2 after 3 minutes of preoxygenation. NC flows of 0 and 5 L/min resulted in significantly lower ETo2 levels compared to the other groups. There were no differences in ETo2 between the BVM alone, NC 10 L/min, and NC 15 L/
This study evaluated the pharmacokinetics and safety of polidocanol injectable foam in treating incompetence of the saphenofemoral junction. 21 patients received either 1% or 2% polidocanol foam. Blood samples found polidocanol peaked within 15 minutes and was mostly eliminated within 2 hours. Exposure was higher in females but weight-normalized data found no differences between males and females. Both concentrations were well tolerated with only mild adverse events. The foam demonstrated consistent pharmacokinetics with no effect on electrocardiograms.
This study examined the relationship between volume overhydration and endothelial dysfunction in 81 stable patients on continuous ambulatory peritoneal dialysis. Volume status was assessed by normalized extracellular water and endothelial function was estimated by flow-mediated dilation of the brachial artery. There was an independent correlation between the index of volume status (normalized extracellular water) and endothelial function (flow-mediated dilation), with higher normalized extracellular water related to worse endothelial function. Multiple regression analysis identified calcium-phosphate product, normalized extracellular water, and dialysis vintage as independent determinants of endothelial function. The results suggest that volume overhydration may lead to increased cardiovascular risk in dialysis patients through its effects on endothelial dysfunction.
Notes for Measuring blood flow and reactivity of the blood vessels in the ski...improvemed
This document describes the laser Doppler flowmetry (LDF) method for measuring blood flow in the microcirculation of skin. Specifically, it discusses post-occlusive reactive hyperemia (PORH) testing using LDF to assess microvascular reactivity by inducing a brief occlusion of blood vessels. It also covers iontophoresis of acetylcholine and sodium nitroprusside combined with LDF to evaluate endothelium-dependent and independent vasodilation respectively. Standardization of methods like occlusion duration and probe placement is important for reproducibility. LDF provides a general index of microvascular function rather than direct flow measurements.
This document describes a study that used laser Doppler vibrometry (LDV) to non-invasively measure mechanophysiological activity associated with cardiorespiratory signals. The study validated LDV for measuring cardiovascular variables extracted from the carotid pulse waveform across different phases of the respiration cycle. Data were collected from 32 healthy participants at rest and breathing spontaneously. Measures of cardiac and vascular dynamics across the respiration cycle agreed with established literature and signals recorded simultaneously using conventional sensors. The study demonstrated LDV's effectiveness for extracting key cardiorespiratory signals in a completely non-contact manner suitable for use in psychophysiological research and other settings.
In this paper we present the use of a signal processing technique to find dominant channels in
near infrared spectroscopy (NIRS). Cross correlation is computed to compare measuring
channels and identify delays among the channels. In addition, visual inspection was used to
detect potential dominant channels. The results showed that the visual analysis exposed painrelated
activations in the primary somatosensory cortex (S1) after stimulation which is
consistent with similar studies and the cross correlation analysis found dominant channels on
both cerebral hemispheres. The analysis also showed a relationship between dominant channels
and neighbouring channels. Therefore, our results present a new method to detect dominant
regions in the cerebral cortex using near-infrared spectroscopy. These results have also
implications in the reduction of number of channels by eliminating irrelevant channels for the
experiment.
(1) Mechanotransduction is the process by which cells sense and respond to mechanical stimuli through biochemical signaling. This document discusses several mechanisms of mechanotransduction, including changes in protein conformation and mechanosensitive ion channels.
(2) Areas of disturbed flow, such as at blood vessel bifurcations, are prone to atherosclerosis due to the effects of disturbed flow on endothelial cell signaling and function. Disturbed flow leads to increased monocyte adhesion and LDL permeability.
(3) Mechanotransduction influences atherosclerosis through effects on genes like MCP-1, KLK-2, and lipid metabolism pathways in endothelial cells in response to shear stress and cyclic stretch. Sustained activation of pathways like JNK can
This randomized crossover study compared end-tidal oxygen (ETo2) levels during preoxygenation with a bag valve mask (BVM) alone and with supplemental nasal cannula (NC) oxygen at different flow rates. Healthy volunteers underwent 3 minutes of preoxygenation with a BVM alone or a BVM with NC at 0, 5, 10, or 15 liters per minute. The primary outcome was ETo2 after 3 minutes of preoxygenation. NC flows of 0 and 5 L/min resulted in significantly lower ETo2 levels compared to the other groups. There were no differences in ETo2 between the BVM alone, NC 10 L/min, and NC 15 L/
This study evaluated the pharmacokinetics and safety of polidocanol injectable foam in treating incompetence of the saphenofemoral junction. 21 patients received either 1% or 2% polidocanol foam. Blood samples found polidocanol peaked within 15 minutes and was mostly eliminated within 2 hours. Exposure was higher in females but weight-normalized data found no differences between males and females. Both concentrations were well tolerated with only mild adverse events. The foam demonstrated consistent pharmacokinetics with no effect on electrocardiograms.
This study examined the relationship between volume overhydration and endothelial dysfunction in 81 stable patients on continuous ambulatory peritoneal dialysis. Volume status was assessed by normalized extracellular water and endothelial function was estimated by flow-mediated dilation of the brachial artery. There was an independent correlation between the index of volume status (normalized extracellular water) and endothelial function (flow-mediated dilation), with higher normalized extracellular water related to worse endothelial function. Multiple regression analysis identified calcium-phosphate product, normalized extracellular water, and dialysis vintage as independent determinants of endothelial function. The results suggest that volume overhydration may lead to increased cardiovascular risk in dialysis patients through its effects on endothelial dysfunction.
Notes for Measuring blood flow and reactivity of the blood vessels in the ski...improvemed
This document describes the laser Doppler flowmetry (LDF) method for measuring blood flow in the microcirculation of skin. Specifically, it discusses post-occlusive reactive hyperemia (PORH) testing using LDF to assess microvascular reactivity by inducing a brief occlusion of blood vessels. It also covers iontophoresis of acetylcholine and sodium nitroprusside combined with LDF to evaluate endothelium-dependent and independent vasodilation respectively. Standardization of methods like occlusion duration and probe placement is important for reproducibility. LDF provides a general index of microvascular function rather than direct flow measurements.
This document describes a study that used laser Doppler vibrometry (LDV) to non-invasively measure mechanophysiological activity associated with cardiorespiratory signals. The study validated LDV for measuring cardiovascular variables extracted from the carotid pulse waveform across different phases of the respiration cycle. Data were collected from 32 healthy participants at rest and breathing spontaneously. Measures of cardiac and vascular dynamics across the respiration cycle agreed with established literature and signals recorded simultaneously using conventional sensors. The study demonstrated LDV's effectiveness for extracting key cardiorespiratory signals in a completely non-contact manner suitable for use in psychophysiological research and other settings.
In this paper we present the use of a signal processing technique to find dominant channels in
near infrared spectroscopy (NIRS). Cross correlation is computed to compare measuring
channels and identify delays among the channels. In addition, visual inspection was used to
detect potential dominant channels. The results showed that the visual analysis exposed painrelated
activations in the primary somatosensory cortex (S1) after stimulation which is
consistent with similar studies and the cross correlation analysis found dominant channels on
both cerebral hemispheres. The analysis also showed a relationship between dominant channels
and neighbouring channels. Therefore, our results present a new method to detect dominant
regions in the cerebral cortex using near-infrared spectroscopy. These results have also
implications in the reduction of number of channels by eliminating irrelevant channels for the
experiment.
CROSS CORRELATION ANALYSIS OF MULTI-CHANNEL NEAR INFRARED SPECTROSCOPYcscpconf
In this paper we present the use of a signal processing technique to find dominant channels in near infrared spectroscopy (NIRS). Cross correlation is computed to compare measuring channels and identify delays among the channels. In addition, visual inspection was used to detect potential dominant channels. The results showed that the visual analysis exposed painrelated activations in the primary somatosensory cortex (S1) after stimulation which is consistent with similar studies and the cross correlation analysis found dominant channels on both cerebral hemispheres. The analysis also showed a relationship between dominant channels
and neighbouring channels. Therefore, our results present a new method to detect dominant regions in the cerebral cortex using near-infrared spectroscopy. These results have also implications in the reduction of number of channels by eliminating irrelevant channels for the experiment.
CROSS CORRELATION ANALYSIS OF MULTI-CHANNEL NEAR INFRARED SPECTROSCOPYcscpconf
In this paper we present the use of a signal processing technique to find dominant channels in near infrared spectroscopy (NIRS). Cross correlation is computed to compare measuring channels and identify delays among the channels. In addition, visual inspection was used to detect potential dominant channels. The results showed that the visual analysis exposed painrelated activations in the primary somatosensory cortex (S1) after stimulation which is consistent with similar studies and the cross correlation analysis found dominant channels on both cerebral hemispheres. The analysis also showed a relationship between dominant channels and neighbouring channels. Therefore, our results present a new method to detect dominant regions in the cerebral cortex using near-infrared spectroscopy. These results have also implications in the reduction of number of channels by eliminating irrelevant channels for the experiment
The document describes an ultrathin, soft, skin-conforming sensor technology that can noninvasively and precisely map both macrovascular and microvascular blood flow. The sensor consists of an array of thin metallic thermal actuators and sensors that conform intimately to the skin through van der Waals forces. Experimental studies on human subjects demonstrate the sensor's ability to sensitively and accurately measure directional blood flow in large subsurface vessels and changes in near-surface microvascular flow induced by breathing and skin stimulation. An advanced pulsed operation mode offers potential for long-term continuous monitoring by reducing drift and power consumption.
The document describes an epidermal device that can noninvasively map blood flow both macrovascularly and microvascularly in a precise and continuous manner. The device uses an array of thin thermal actuators and sensors that intimately conform to the skin to monitor subsurface blood flow. Experimental studies on humans validate that the device can accurately measure directional blood flow in large veins under various physiological conditions as well as changes in microvascular flow from actions like deep breathing. Quantitative models are used to convert the thermal measurements into estimates of blood flow rates. The low-profile, soft design allows for potential long-term monitoring during daily activities.
The main objective of this project is to measure the heart pumping function continuously and with maximally non-invasive methodology in a medical setting arrangement. Thus this paper is aimed to determine the study of impedance plethysmographic method to evaluate the stroke volume changes. In this paper the blood flow analysis has been carried out with fuzzy logic tool box with various activities such as Dehydration, Physical exercise, Cool skin, Warm Skin and breathes hold activity. Immediately after measuring the blood flow with the help of Impedance plethysmography, the end systolic and end diastolic values are obtained with the help of echocardiogram for the 18 subjects both in the normal condition and immediately after holding the breathe for 25 seconds. For the 18 subjects the correlation coefficient is obtained in a linear fashion between the changes in peak amplitude of forearm impedance plethysmographic waveform and changes in stroke volume before and after the 25 second breathe holding activity. Finally the forearm impedance plethysmographic waveform can be used to analyze the heart beat changes in Correlation with the changes in heart stroke volume. The process could be monitored for the series of cycles in determining the heart pumping performance.
Measurement of blood pressure is one of the oldest physiological measurements. It originates from the heart and depends on three factors: cardiac output, artery diameter, and blood quantity. Normal values are below 120/80 mmHg. Indirect non-invasive methods like auscultation and oscillometry use an occlusive cuff on the brachial artery. Direct invasive methods involve catheter insertion but are needed for continuous accurate readings in dynamic situations. Both methods rely on measuring pressures as a cuff is inflated and deflated over the artery.
This document summarizes a study that quantified wall shear stress (WSS) in human conjunctival pre-capillary arterioles between 6-12 μm in diameter. The study accounted for changes in blood velocity and viscosity throughout the cardiac cycle. Average blood flow was 13-202 pl/s, wall shear rate was 587-3515 s-1, and WSS was 1.7-21.1 N/m2. Power law equations describe the relationships between diameter and flow, wall shear rate, and WSS during systole, diastole, and on average over the cardiac cycle. According to the best-fit WSS equation, average WSS decreases from 10.5 N/m2 at
Blood Sugar (Glucose) Measurement, Monitoring and Data Analysis: A Review on ...Md Kafiul Islam
The presentation reviews the recent development in non-invasive blood sugar measurement and monitoring techniques, their pros and cons, comparative analysis and the key challenges in implementing such technique in continuous and regular health monitoring for wearable biomedical device technology
This document provides an overview of various methods for respiratory monitoring. It discusses physical examination, pulse oximetry, mixed venous oxygen saturation, tissue oxygenation, capnography and blood gas analysis, respiratory mechanics, respiratory rate monitoring, and imaging techniques. Pulse oximetry measures arterial oxygen saturation noninvasively using light absorption. Mixed venous oxygen saturation reflects whole body oxygen uptake. Tissue oxygenation can be assessed using near-infrared or visible light spectroscopy. Capnography monitors exhaled carbon dioxide to evaluate ventilation and cardiac output.
Turbulent blood flow plays an essential localizing role in the development of...SHAPE Society
The study investigated the role of hemodynamic forces in localizing atherosclerotic lesions in hypercholesterolemic rats with abdominal aorta constriction. Doppler ultrasound showed turbulent blood flow downstream of the constriction with lower wall shear stress, while laminar flow and normal wall shear stress occurred upstream. Rats with constriction developed focally distributed atherosclerotic lesions downstream but only diffuse fatty streaks upstream. Immunohistochemistry also showed greater oxidative stress downstream. Thus, turbulent blood flow combined with hypercholesterolemia promotes localized plaque formation, showing hemodynamic forces prime the local vessel wall for lesion development.
INVESTIGATING THE USE OF IMPEDANCE PLETHYSMOGRAPHY FOR DETECTING DECREASED BL...Mirza Baig
Literature Review
According to Isabel Morales’ research, the foot impedance plethysmography was carried out with two distinct kinds of electrodes, using 1mA/10kHz and finding the impedance of the foot.
In this study Piuzzi research is an ultimate technique selected that makes use of a current with a frequency of 50 kHz that is injected into the thorax of the subject using a couple of textile electrodes.
In this study of Ramkumar & Babu, blood flow was performed using a fuzzy logic toolbox with many different activities, measured before and after the 25 seconds of breath-holding activity. The plethysmographic waveform of forearm impedance can be used to analyze the changes in a heartbeat that are correlated with the changes in heart stroke volume.
Contribution
In this work we are investigating using multiple electrodes to see the additional data going to make testing easier.
Our research is primarily focusing on the amount of blood flow through the finger of the upper limb for diabetic patients.
Conclusion
The finger-simplified model was created in model geometry. A framework made up of five parts was used to build the finger. (i.e., skin, fat, artery, muscle, and bone)
The study includes COMSOL simulation results compared with experimental results to obtain the optimum parameters for this technique. The COMSOL simulation uses 4 electrodes in different positions with a current of 10mA giving the optimal frequency of 100Hz.
It was shown that multiple electrodes can be useful in obtaining impedance change.
This is useful because signals can not be obtained from one pair, or to further support the results.
The study was performed under normal resting conditions where an experimental procedure was set up to measure the impedance response from the finger.
Experiment results were not conclusive as more sensitive impedance analyzers are required.
This research will be helpful to find out the heartbeat using impedance plethysmography.
1) EndoPAT is a medical device that noninvasively assesses endothelial function through changes in vascular tone in the fingers in response to induced hyperemia in the arm.
2) It has been validated in studies comparing it to measures of coronary and brachial artery endothelial function and shown to detect a nitric oxide mediated response.
3) Advantages of EndoPAT include simultaneous recording from both arms to control for systemic changes, assessment of occlusion quality, large dynamic range of measurements, and ease of use.
Technologies for assessment of oxygen delivery | Knut Kvernebo at TBS23scanFOAM
This document summarizes technologies for assessing microvascular function and oxygen delivery. It discusses several key issues in microvascular assessment including the tissues that can be examined non-invasively and measuring small tissue volumes. It then introduces the ODIN concept, which uses the ODI Tech platform involving computer assisted video microscopy and diffuse reflectance spectroscopy to measure microvascular parameters in a tissue volume of around 0.1mm3. Examples are given of automated analysis software and proof of concept studies investigating conditions like ECMO treatment, asphyxiated newborns, and COVID-19.
The Pulsatility Index (PI), which quantifies blood flow pulsation, was measured for the first time in the smallest pre-capillary arterioles of the human eye, ranging from 6 to 12 micrometers in diameter. The PI was measured in 30 arterioles from 15 healthy humans. PI values ranged from 0.4 to 1.5 with an average of 0.8. There was no correlation found between PI and arteriole diameter. This study provides the first measurements of PI in the smallest human eye arterioles.
This document summarizes principles and techniques of intracranial pressure (ICP) measurement and waveform interpretation. It discusses the history of ICP monitoring, indications for monitoring, invasive and non-invasive monitoring techniques, optimal sensor locations, ICP waveform analysis in both time and frequency domains, and guidelines for ICP monitoring in traumatic brain injury. The key points covered include different invasive sensor types, complications of external ventricular drainage, interpreting mean ICP and waveform trends, and using indices like pressure reactivity and variability for management.
This document discusses estimating blood volume flow in precapillary microvessels in the rabbit mesentery based on axial erythrocyte velocity measurements. It summarizes:
1) Volume flow was estimated in 30 microvessels with diameters between 5.6-12 μm by measuring instantaneous axial blood velocity throughout the cardiac cycle and averaging. The effect of velocity profile variation with diameter was also taken into account.
2) According to Murray's law, volume flow should be proportional to diameter to the fourth power. Curve fitting to the volume flow and diameter data supported this relationship, validating the hypothesis that the principle of constant longitudinal pressure gradient applies in the precapillary microvasculature.
3) A
Estimation Of Vitamin Content In Fruit Juices By Ultrasonic Techniqueinventionjournals
ABSTRACT : Fruits are more essential and have many health benifits. Fruits has vitaminewihch is made up of an organic compound. Vitamin must be through diet. Vitamin C is required for the properdevelopment& function of many parts of the body . It also plays an important role in maintaining proper immune function. In this research the Selected fruits are apple and orange and they have Vitamin ‘C’. Estimation of Vitamin content have been done by studying Ultrasonic Velocity, Viscosity, Density and adiabatic Compressibility. Further the experimental values are confirmed by FTIR.
1. Perfusion MRI uses specific sequences to generate maps of blood perfusion parameters like blood volume, blood flow, mean transit time, and time to peak in tissues.
2. Diffusion MRI uses diffusion sensitizing gradients to map the diffusion of water molecules in tissues, revealing microscopic details of tissue architecture.
3. Both techniques provide clinically useful information when combined with other MRI sequences. Perfusion and diffusion MRI are important in evaluating acute brain ischemia like strokes to distinguish salvageable tissue.
This document describes various in vitro models and methods that can be used to study hepatotoxicity, including hepatocyte cell cultures, assays to measure cell viability and metabolic activity (trypan blue dye exclusion test, MTT assay), staining to visualize lipid accumulation (Oil Red O), and techniques to examine gene and protein expression changes (RT-PCR, western blotting). Specifically, it discusses using these methods to establish models of non-alcoholic fatty liver disease (NAFLD) by treating hepatocyte cultures with fatty acids like palmitic and oleic acid, and models of drug-induced hepatotoxicity by treating with acetaminophen or amiodarone. Key readouts include lipid accumulation, apoptosis levels
CROSS CORRELATION ANALYSIS OF MULTI-CHANNEL NEAR INFRARED SPECTROSCOPYcscpconf
In this paper we present the use of a signal processing technique to find dominant channels in near infrared spectroscopy (NIRS). Cross correlation is computed to compare measuring channels and identify delays among the channels. In addition, visual inspection was used to detect potential dominant channels. The results showed that the visual analysis exposed painrelated activations in the primary somatosensory cortex (S1) after stimulation which is consistent with similar studies and the cross correlation analysis found dominant channels on both cerebral hemispheres. The analysis also showed a relationship between dominant channels
and neighbouring channels. Therefore, our results present a new method to detect dominant regions in the cerebral cortex using near-infrared spectroscopy. These results have also implications in the reduction of number of channels by eliminating irrelevant channels for the experiment.
CROSS CORRELATION ANALYSIS OF MULTI-CHANNEL NEAR INFRARED SPECTROSCOPYcscpconf
In this paper we present the use of a signal processing technique to find dominant channels in near infrared spectroscopy (NIRS). Cross correlation is computed to compare measuring channels and identify delays among the channels. In addition, visual inspection was used to detect potential dominant channels. The results showed that the visual analysis exposed painrelated activations in the primary somatosensory cortex (S1) after stimulation which is consistent with similar studies and the cross correlation analysis found dominant channels on both cerebral hemispheres. The analysis also showed a relationship between dominant channels and neighbouring channels. Therefore, our results present a new method to detect dominant regions in the cerebral cortex using near-infrared spectroscopy. These results have also implications in the reduction of number of channels by eliminating irrelevant channels for the experiment
The document describes an ultrathin, soft, skin-conforming sensor technology that can noninvasively and precisely map both macrovascular and microvascular blood flow. The sensor consists of an array of thin metallic thermal actuators and sensors that conform intimately to the skin through van der Waals forces. Experimental studies on human subjects demonstrate the sensor's ability to sensitively and accurately measure directional blood flow in large subsurface vessels and changes in near-surface microvascular flow induced by breathing and skin stimulation. An advanced pulsed operation mode offers potential for long-term continuous monitoring by reducing drift and power consumption.
The document describes an epidermal device that can noninvasively map blood flow both macrovascularly and microvascularly in a precise and continuous manner. The device uses an array of thin thermal actuators and sensors that intimately conform to the skin to monitor subsurface blood flow. Experimental studies on humans validate that the device can accurately measure directional blood flow in large veins under various physiological conditions as well as changes in microvascular flow from actions like deep breathing. Quantitative models are used to convert the thermal measurements into estimates of blood flow rates. The low-profile, soft design allows for potential long-term monitoring during daily activities.
The main objective of this project is to measure the heart pumping function continuously and with maximally non-invasive methodology in a medical setting arrangement. Thus this paper is aimed to determine the study of impedance plethysmographic method to evaluate the stroke volume changes. In this paper the blood flow analysis has been carried out with fuzzy logic tool box with various activities such as Dehydration, Physical exercise, Cool skin, Warm Skin and breathes hold activity. Immediately after measuring the blood flow with the help of Impedance plethysmography, the end systolic and end diastolic values are obtained with the help of echocardiogram for the 18 subjects both in the normal condition and immediately after holding the breathe for 25 seconds. For the 18 subjects the correlation coefficient is obtained in a linear fashion between the changes in peak amplitude of forearm impedance plethysmographic waveform and changes in stroke volume before and after the 25 second breathe holding activity. Finally the forearm impedance plethysmographic waveform can be used to analyze the heart beat changes in Correlation with the changes in heart stroke volume. The process could be monitored for the series of cycles in determining the heart pumping performance.
Measurement of blood pressure is one of the oldest physiological measurements. It originates from the heart and depends on three factors: cardiac output, artery diameter, and blood quantity. Normal values are below 120/80 mmHg. Indirect non-invasive methods like auscultation and oscillometry use an occlusive cuff on the brachial artery. Direct invasive methods involve catheter insertion but are needed for continuous accurate readings in dynamic situations. Both methods rely on measuring pressures as a cuff is inflated and deflated over the artery.
This document summarizes a study that quantified wall shear stress (WSS) in human conjunctival pre-capillary arterioles between 6-12 μm in diameter. The study accounted for changes in blood velocity and viscosity throughout the cardiac cycle. Average blood flow was 13-202 pl/s, wall shear rate was 587-3515 s-1, and WSS was 1.7-21.1 N/m2. Power law equations describe the relationships between diameter and flow, wall shear rate, and WSS during systole, diastole, and on average over the cardiac cycle. According to the best-fit WSS equation, average WSS decreases from 10.5 N/m2 at
Blood Sugar (Glucose) Measurement, Monitoring and Data Analysis: A Review on ...Md Kafiul Islam
The presentation reviews the recent development in non-invasive blood sugar measurement and monitoring techniques, their pros and cons, comparative analysis and the key challenges in implementing such technique in continuous and regular health monitoring for wearable biomedical device technology
This document provides an overview of various methods for respiratory monitoring. It discusses physical examination, pulse oximetry, mixed venous oxygen saturation, tissue oxygenation, capnography and blood gas analysis, respiratory mechanics, respiratory rate monitoring, and imaging techniques. Pulse oximetry measures arterial oxygen saturation noninvasively using light absorption. Mixed venous oxygen saturation reflects whole body oxygen uptake. Tissue oxygenation can be assessed using near-infrared or visible light spectroscopy. Capnography monitors exhaled carbon dioxide to evaluate ventilation and cardiac output.
Turbulent blood flow plays an essential localizing role in the development of...SHAPE Society
The study investigated the role of hemodynamic forces in localizing atherosclerotic lesions in hypercholesterolemic rats with abdominal aorta constriction. Doppler ultrasound showed turbulent blood flow downstream of the constriction with lower wall shear stress, while laminar flow and normal wall shear stress occurred upstream. Rats with constriction developed focally distributed atherosclerotic lesions downstream but only diffuse fatty streaks upstream. Immunohistochemistry also showed greater oxidative stress downstream. Thus, turbulent blood flow combined with hypercholesterolemia promotes localized plaque formation, showing hemodynamic forces prime the local vessel wall for lesion development.
INVESTIGATING THE USE OF IMPEDANCE PLETHYSMOGRAPHY FOR DETECTING DECREASED BL...Mirza Baig
Literature Review
According to Isabel Morales’ research, the foot impedance plethysmography was carried out with two distinct kinds of electrodes, using 1mA/10kHz and finding the impedance of the foot.
In this study Piuzzi research is an ultimate technique selected that makes use of a current with a frequency of 50 kHz that is injected into the thorax of the subject using a couple of textile electrodes.
In this study of Ramkumar & Babu, blood flow was performed using a fuzzy logic toolbox with many different activities, measured before and after the 25 seconds of breath-holding activity. The plethysmographic waveform of forearm impedance can be used to analyze the changes in a heartbeat that are correlated with the changes in heart stroke volume.
Contribution
In this work we are investigating using multiple electrodes to see the additional data going to make testing easier.
Our research is primarily focusing on the amount of blood flow through the finger of the upper limb for diabetic patients.
Conclusion
The finger-simplified model was created in model geometry. A framework made up of five parts was used to build the finger. (i.e., skin, fat, artery, muscle, and bone)
The study includes COMSOL simulation results compared with experimental results to obtain the optimum parameters for this technique. The COMSOL simulation uses 4 electrodes in different positions with a current of 10mA giving the optimal frequency of 100Hz.
It was shown that multiple electrodes can be useful in obtaining impedance change.
This is useful because signals can not be obtained from one pair, or to further support the results.
The study was performed under normal resting conditions where an experimental procedure was set up to measure the impedance response from the finger.
Experiment results were not conclusive as more sensitive impedance analyzers are required.
This research will be helpful to find out the heartbeat using impedance plethysmography.
1) EndoPAT is a medical device that noninvasively assesses endothelial function through changes in vascular tone in the fingers in response to induced hyperemia in the arm.
2) It has been validated in studies comparing it to measures of coronary and brachial artery endothelial function and shown to detect a nitric oxide mediated response.
3) Advantages of EndoPAT include simultaneous recording from both arms to control for systemic changes, assessment of occlusion quality, large dynamic range of measurements, and ease of use.
Technologies for assessment of oxygen delivery | Knut Kvernebo at TBS23scanFOAM
This document summarizes technologies for assessing microvascular function and oxygen delivery. It discusses several key issues in microvascular assessment including the tissues that can be examined non-invasively and measuring small tissue volumes. It then introduces the ODIN concept, which uses the ODI Tech platform involving computer assisted video microscopy and diffuse reflectance spectroscopy to measure microvascular parameters in a tissue volume of around 0.1mm3. Examples are given of automated analysis software and proof of concept studies investigating conditions like ECMO treatment, asphyxiated newborns, and COVID-19.
The Pulsatility Index (PI), which quantifies blood flow pulsation, was measured for the first time in the smallest pre-capillary arterioles of the human eye, ranging from 6 to 12 micrometers in diameter. The PI was measured in 30 arterioles from 15 healthy humans. PI values ranged from 0.4 to 1.5 with an average of 0.8. There was no correlation found between PI and arteriole diameter. This study provides the first measurements of PI in the smallest human eye arterioles.
This document summarizes principles and techniques of intracranial pressure (ICP) measurement and waveform interpretation. It discusses the history of ICP monitoring, indications for monitoring, invasive and non-invasive monitoring techniques, optimal sensor locations, ICP waveform analysis in both time and frequency domains, and guidelines for ICP monitoring in traumatic brain injury. The key points covered include different invasive sensor types, complications of external ventricular drainage, interpreting mean ICP and waveform trends, and using indices like pressure reactivity and variability for management.
This document discusses estimating blood volume flow in precapillary microvessels in the rabbit mesentery based on axial erythrocyte velocity measurements. It summarizes:
1) Volume flow was estimated in 30 microvessels with diameters between 5.6-12 μm by measuring instantaneous axial blood velocity throughout the cardiac cycle and averaging. The effect of velocity profile variation with diameter was also taken into account.
2) According to Murray's law, volume flow should be proportional to diameter to the fourth power. Curve fitting to the volume flow and diameter data supported this relationship, validating the hypothesis that the principle of constant longitudinal pressure gradient applies in the precapillary microvasculature.
3) A
Estimation Of Vitamin Content In Fruit Juices By Ultrasonic Techniqueinventionjournals
ABSTRACT : Fruits are more essential and have many health benifits. Fruits has vitaminewihch is made up of an organic compound. Vitamin must be through diet. Vitamin C is required for the properdevelopment& function of many parts of the body . It also plays an important role in maintaining proper immune function. In this research the Selected fruits are apple and orange and they have Vitamin ‘C’. Estimation of Vitamin content have been done by studying Ultrasonic Velocity, Viscosity, Density and adiabatic Compressibility. Further the experimental values are confirmed by FTIR.
1. Perfusion MRI uses specific sequences to generate maps of blood perfusion parameters like blood volume, blood flow, mean transit time, and time to peak in tissues.
2. Diffusion MRI uses diffusion sensitizing gradients to map the diffusion of water molecules in tissues, revealing microscopic details of tissue architecture.
3. Both techniques provide clinically useful information when combined with other MRI sequences. Perfusion and diffusion MRI are important in evaluating acute brain ischemia like strokes to distinguish salvageable tissue.
This document describes various in vitro models and methods that can be used to study hepatotoxicity, including hepatocyte cell cultures, assays to measure cell viability and metabolic activity (trypan blue dye exclusion test, MTT assay), staining to visualize lipid accumulation (Oil Red O), and techniques to examine gene and protein expression changes (RT-PCR, western blotting). Specifically, it discusses using these methods to establish models of non-alcoholic fatty liver disease (NAFLD) by treating hepatocyte cultures with fatty acids like palmitic and oleic acid, and models of drug-induced hepatotoxicity by treating with acetaminophen or amiodarone. Key readouts include lipid accumulation, apoptosis levels
This document summarizes various liver diseases and their etiologies. It discusses alcoholic liver disease, drug-induced liver injury, viral hepatitis infections from hepatitis B, C, and D viruses, autoimmune disorders like autoimmune hepatitis and primary biliary cirrhosis, genetic disorders, non-alcoholic fatty liver disease, cirrhosis, and hepatocellular carcinoma. The liver's important functions are outlined. Causes, pathogenesis, clinical features, diagnosis, and treatment approaches are described for each disease.
An introduction to experimental epidemiology improvemed
This document provides an overview of experimental epidemiology methods. It discusses the key features and types of experimental epidemiology studies, including controlled field trials and community trials. Controlled field trials involve dividing healthy subjects into an exposed group that receives an active substance (like a vaccine) and an unexposed control group that receives a placebo. Community trials involve entire exposed and unexposed communities. Randomized controlled trials, which assign individual subjects randomly to intervention or control groups, are described as the most common experimental method but are covered in more depth separately. Overall, the document outlines the design and purpose of various experimental epidemiology study types.
Genotyping methods of nosocomial infections pathogenimprovemed
Nosocomial infections afflict around 2 million patients in the US each year, resulting in around 88,000 deaths and $4.5 billion in excess healthcare costs. Understanding the distribution and relatedness of pathogens that cause these infections is important for designing effective control methods. Historically, phenotypic characterization was used, but increasingly molecular or genotyping techniques are being used, including pulsed-field gel electrophoresis, multilocus sequence typing, and polymerase chain reaction-based methods. Studies have shown that integrating molecular typing into infection control programs can significantly reduce infection rates and healthcare costs.
Use of MALDI-TOF in the diagnosis of infectious diseasesimprovemed
MALDI-TOF MS has revolutionized clinical microbiology by drastically improving the time needed to identify bacterial cultures from over 24 hours to just a few minutes. Whereas the entire process from sampling to results previously took 2-3 days or more, new methods like MALDI-TOF MS and molecular technology have reduced this to just a few hours or one day. MALDI-TOF MS is a powerful, cost-effective, and easy to implement technique that provides rapid and reliable identification of bacteria and yeast from clinical samples at the genus and species level through analysis of their protein mass spectral signatures.
1. Molecular microbiology methods like PCR and hybridization have revolutionized clinical diagnostics by enabling fast and direct detection of pathogens from clinical samples.
2. PCR in particular has become a mainstay technique, allowing amplification of specific DNA sequences from small amounts of input DNA. Variations like real-time PCR, multiplex PCR, and broad-range PCR further expanded diagnostic capabilities.
3. Emerging technologies like DNA microarrays promise even greater multiplexing, with the ability to simultaneously genotype large genomic regions or measure expression of many genes, positioning them as promising future molecular diagnostic tools.
This document provides information about setting up and conducting experiments with isolated organs and tissue rings, including:
1. Describing the mechanical setup for a four-channel system bath for isolated organs.
2. Explaining the preparation of Krebs-Hanseleit solution and common drugs used.
3. Outlining typical experiment protocols, including stabilizing tissues, pre-contraction testing, and assessing endothelial function.
4. Noting that each experiment begins by preparing Krebs-Hanseleit solution and activating the system before surgery and setting rings in wells.
This document describes the components, work principles, and experimental protocols for using a pressure myograph system to study isolated blood vessels. The system allows measuring vessel diameter in response to drugs and stimuli while maintaining constant temperature. Experiments involve isolating small arteries from rats and attaching them to glass micropipettes in a chamber filled with physiological salt solution. Vessel diameter is recorded under varying pressures and drug exposures to study endothelial function and vasoactive mechanisms. Statistical analysis of diameter changes under different conditions uses repeated measures ANOVA to compare responses between experimental groups.
Notes for STAINING AND ANALYSIS of HISTOLOGICAL PREPARATIONSimprovemed
This document provides an overview of histological staining techniques. It discusses how histological preparations are stained using interactions between dyes, solvents, and tissue components. Different staining methods result in different colors that highlight various structures. A classic example is hematoxylin and eosin staining, where hematoxylin stains acidic components blue and eosin stains basic components pink. Specialized staining techniques also exist, such as immunohistochemistry. Proper staining selection depends on the tissue and research goals. Histological preparations are then analyzed under a microscope to study cell and tissue morphology.
Notes for Fixation of tissues and organs for educational and scientific purposesimprovemed
Fixation of tissues and organs is done to preserve them for scientific and educational purposes. Various chemical fixatives are used including formaldehyde, alcohols, and acids. Formaldehyde cross-links proteins to harden the tissue while maintaining the original structure. Several fixation protocols are used for different purposes, balancing preservation of color and long-term durability. Key steps include diffusion or injection of fixatives, followed by storage in preservative solutions. Proper fixation and storage are necessary to prevent degradation over time.
The document summarizes the process of preparing tissue samples for histological analysis, including fixation, dehydration, infiltration/embedding, sectioning, staining, and examination. Key steps involve fixing tissues to prevent degradation, dehydrating using increasing alcohol concentrations, infiltrating with paraffin wax or resin for structural support during sectioning, precisely cutting thin sections, mounting them to glass slides, staining, and examining under a microscope. The quality of prepared samples depends on carefully following each step of the preparation process.
Notes for The principle and performance of capillary electrophoresisimprovemed
This document provides an overview of capillary electrophoresis (CE). It begins by introducing CE and its advantages over other separation techniques. It then describes the basic theory behind CE, including electrophoretic mobility, electroosmotic flow, and how samples migrate through the capillary when an electric field is applied. The document details the key components of a CE instrument and various CE separation techniques such as capillary zone electrophoresis, micellar electrokinetic chromatography, and capillary isoelectric focusing. It focuses on the principles and applications of CE.
Notes for The principle and performance of liquid chromatography–mass spectro...improvemed
This document provides an overview of liquid chromatography-mass spectrometry (LC-MS). It describes the basic components and functioning of an LC-MS system, including the liquid chromatograph and mass spectrometer connected by an interface. The document discusses various ionization sources like electrospray ionization and atmospheric pressure chemical ionization, as well as mass analyzers like quadrupoles and time-of-flight analyzers. It also covers detectors used in LC-MS like electron multipliers and photomultipliers. Overall, the document serves as a technical introduction to the principles and components of LC-MS.
This document provides an overview of basic cell culture techniques. It discusses the history of cell culture, defining primary and secondary cell cultures. It describes different types of cell lines and how cells grow as monolayers or in suspension. The document outlines the key equipment needed for a cell culture laboratory, including biosafety cabinets, CO2 incubators, centrifuges, microscopes, and supplies. It emphasizes the importance of aseptic technique to prevent microbial contamination when working with cell cultures.
This document discusses systems biology and its goals of understanding how biological molecules interact and systems function as a whole. It covers:
1) Systems biology uses large datasets from "omics" experiments and computational models to understand complex biological interactions beyond individual molecules.
2) Pioneering work used microarrays to measure thousands of genes in serum-stimulated cells, finding over 500 changed in proliferation.
3) The field aims to discover emergent system properties and functions not evident from separate parts, like switches that change cell behavior.
Systems biology for Medicine' is 'Experimental methods and the big datasetsimprovemed
This document discusses experimental methods used in systems biology to generate large datasets, including microarrays, sequencing-based methods, mass spectrometry, and liquid chromatography. It explains that systems biology studies must be quantitative and enable computational modeling. Key methods covered are microarrays, RNA-seq, ChIP-seq, whole-genome sequencing, whole-exome sequencing, proteomics using mass spectrometry, and combining liquid chromatography with mass spectrometry for lipidomics, metabolomics and glycomics. Sources of variation are also discussed for genomic and proteomic studies.
Systems biology for medical students/Systems medicineimprovemed
Systems biology takes a holistic approach to studying biological systems by considering all the interactions within a system and how they generate complex behaviors. Lecture 1 introduces key concepts in systems biology like how increasing levels of biological organization give rise to new system properties like robustness. Lecture 2 discusses experimental methods like genomics, proteomics, and metabolomics that generate large data sets for systems analysis. Lecture 3 covers mathematical and statistical tools for analyzing these data sets, such as using differential equations to model signaling networks. Lecture 4 provides examples of medical applications of systems biology in finding diagnostic markers, personalizing therapy, and predicting disease interactions from human disease networks, with the future of medicine taking a more predictive, preventive, and personalized approach
The document discusses several use cases for applying data mining and machine learning techniques in healthcare and biomedical research. Three examples are:
1) Early diagnosis of cancers like lung cancer and breast cancer through predictive modeling of patient data to detect cancers at earlier stages when survival rates are higher.
2) Predicting patient responses to drug therapies for cancers like breast cancer by combining different types of molecular profiling data using techniques like support vector machines and random forests.
3) Using imaging data and temporal analysis of metrics like medication purchases to better understand and predict chronic diseases like diabetes and associated health complications.
The document discusses various data mining methods. It describes data mining as seeking patterns within large databases. Common data mining methods mentioned include clustering, regression, rule extraction, and data visualization. Machine learning algorithms often used for health data include logistic regression, support vector machines, decision trees, and neural networks. The document also discusses newer techniques like graph-based data mining, topological data mining, and data visualization for exploring complex data.
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Strategies for Effective Upskilling is a presentation by Chinwendu Peace in a Your Skill Boost Masterclass organisation by the Excellence Foundation for South Sudan on 08th and 09th June 2024 from 1 PM to 3 PM on each day.
ISO/IEC 27001, ISO/IEC 42001, and GDPR: Best Practices for Implementation and...PECB
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Tags: Information Security, ISO/IEC 27001, ISO/IEC 42001, Artificial Intelligence, GDPR
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it describes the bony anatomy including the femoral head , acetabulum, labrum . also discusses the capsule , ligaments . muscle that act on the hip joint and the range of motion are outlined. factors affecting hip joint stability and weight transmission through the joint are summarized.
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How to Manage Your Lost Opportunities in Odoo 17 CRMCeline George
Odoo 17 CRM allows us to track why we lose sales opportunities with "Lost Reasons." This helps analyze our sales process and identify areas for improvement. Here's how to configure lost reasons in Odoo 17 CRM
Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
This document provides an overview of wound healing, its functions, stages, mechanisms, factors affecting it, and complications.
A wound is a break in the integrity of the skin or tissues, which may be associated with disruption of the structure and function.
Healing is the body’s response to injury in an attempt to restore normal structure and functions.
Healing can occur in two ways: Regeneration and Repair
There are 4 phases of wound healing: hemostasis, inflammation, proliferation, and remodeling. This document also describes the mechanism of wound healing. Factors that affect healing include infection, uncontrolled diabetes, poor nutrition, age, anemia, the presence of foreign bodies, etc.
Complications of wound healing like infection, hyperpigmentation of scar, contractures, and keloid formation.
2. Measurement of blood flow and reactivity blood vessels
in microcirculation skin method laser Doppler
(eng. laser DopplerFlowmetry - LDF)
Anna Stupin
3. In the last few decades developed large No functional method for Research and Measurement
(pato) Physiological functions endothelial in people (Flammer & Luscher, 2010; Ludmera et al. 1986)
Intensified scientific research in vascular plant physiology and pathophysiology
These methods are have not been implemented as a useful diagnostic tool in routine clinical
practice
All approaches to the study endothelial tool designed on way to provide insight in vascular /
endothelial function in different places (vascular basins) in different types of blood vessels
(conductive, resistor blood vessels, microcirculation)
earlier methods invasive (Eg. intracoronary infusion acetylcholine) recent methods less invasive
/ non-invasive and directed the study of peripheral circulation as surrogates system circulation
(Linder et al. 1990;Panza et al. 1990;Celermajer et al. 1992)
4. Because of its accessibility skin represents the perfect place for testing human features
microcirculation (Roustit & Cracowski, 2012)
Open question is whether microvascular function leather representative and appropriate
indicator microvascular other functions organ
IN the last three decades Leather has become a place of intense study microvascular functions
in health and disease, including hypertension (Antonios et al., 1999; Feihl et al., 2006) obesity (Levy et al.,
2006). diabetes (Chang et al., 1997; Yamamoto-Suganuma & Aso, 2009). aging, kidney disease (Kruger et al., 2006)
etc.
5. often used techniques for studying functions microcirculation skin is Laser Doppler (LD)
LD technique estimated size flow in microcirculation skin based on the rejection of the laser
beam of the erythrocytes present in microcirculation in which changes its wavelength (Doppler
effect) (stern, 1975)
computer program determines the size flow - before index perfusion skin (Eng. flux) Rather than
a direct measure of the flow microcirculation skin (Eng. flow)
the results you express in arbitrary units (perfusion unit, PU, 1 PU = 10 mV) Or CVC (index
perfusion divided by the value of blood pressure, mV/ MmHg) (147)
Method flow measurement based on techniques LD (Eng. laser Doppler flowmetry, LDF)
measure blood flow at a single point, and thus in a small volume, but with a high frequency
sampling
7. often mentioned limit LDF methods - pronounced spatial variability which occurs due to regional
heterogeneity perfusion skin and the blood flow measurement at a single point (Roustit et al., 2010)
Tthe restriction may be waived by setting laser probe always the same (marked) in the skin,
especially when you methods used in repetitive measurements
linear the ratio between the laser and the Doppler signal microvascular flow is shown in the
range from 0 to 300 mL/ Min per 100 g tissue (Ahn et al., 1987)
LDF does not give an accurate measure of flow (ie. mL/ Min) !!!
8. LDF is most commonly used to assess microvascular reactivity the responsible to different
stimuli (vascular occlusion. vasoactive medicines, Temperature challenges etc..)
The most common used tests vascular reactivity in microcirculation skin are (Cracowski et al. 2006):
fast-occlusive reactive hyperemia (porho)
iontophoresis vasoactive drugs
exposure Skin temperature changes - warming or cooling
9. first Postokluzivna reactive hyperemia (Pörhö)
Postokluzivna reactive hyperemia (Pörhö) an increase (Micro) vascular blood flow caused by
short-term occlusion blood vessels
Test which is commonly used to assess microvascular reactivity (Cracowskiet al. 2006)
mechanisms that mediate the formation Porho in microcirculation skin:
• activity a sensory nerve neural axonal reflexes (Larkin & Williams, 1993)
• production on endothelium subsidiary vasodilators
• EDHF (Lorenzo & Minson, 2007)
• the role prostaglandin still not fully understood (Dalle-Ave et al. 2004; Medow et al. 2007th
• inhibition COX-a reveals potential addiction Porho-on The NO in human leather microcirculation
(Medowet al. 2007)
ONva methods use you for estimate and testing microvascular reactivity generally, And not as
direct test for estimate microvascular endothelial functions (Roustit & Cracowski2012)
10. first Postokluzivna reactive hyperemia (Pörhö)
The parameters that quantify the analysis porho CDs:
peak hyperemia (eng. peak hyperemia)
• can be expressed or as a raw data as function basal flow
• surface under the curve,
• top minus basal flow rate, or
• relative changes between the top and the basal flow rate expressed as a percentage [(top protoka- basal flow) /
baseline flow rate] x 100
• inRSNA perfusion one can compare in relation to the so-called. Maximum vasodilation was
achieved by heating at 42 ° skinC or more (Charkoudian2003)
Time to peak perfusion (Eng. In this peak)
• still not determined its importance as a marker microvascular reactivity
11. first Postokluzivna reactive hyperemia (Pörhö)
Figure 2. Parameters to be quantified in the analysis Porho a
(Roustit & Blaise, 2010; Roustit & Cracowski, 2012)
12. first Postokluzivna reactive hyperemia (Pörhö)
Inter-day reproducibility Porho a
• When the variable Pörhö LDF is measured in a one point
• depends on place the skin on which is mounted probeon mode data interpretation, and on
basal skin temperature
Largest number of studies that questioned reproducibility Porho a used volar sides forearm
(inconsistent results)
• reproducibility excellent (OR 6% to 22%) when the location shooting accurately labeled and Asked probe every
day at the same place (Yvonne-Tee et al. 2005)
• reproducibility only good (eng. fair thatgood) (CV 20%) when the probe is approximately given on the same
location, but with less full precision (Agarwal et al. 2010)
• reproducibility bad if the place Posted probes chosen randomly from day to day (CV> 40%) (Roustit et al. 2010)
Pleaving the probe in exactly the same place on the skin is a key factor that improves Industry-
living reproducibility Porho's (excellent)
13. first Postokluzivna reactive hyperemia (Pörhö)
The temperature of the skin and the environment
During shooting Porho's needs take account of homogenization to skin and ambient
temperature (rooms)
Temperature plays a key role in regulating the size of the basal flow in microcirculation skin
(Roustit et al. 2010a)
Acceptable repeatability (reproducibility) Measurement times when Pörhö is skin temperature
during shooting maintained at 33 ° C (Roustit et al. 2010)
14. first Postokluzivna reactive hyperemia (Pörhö)
duration vascular occlusion
ANDexcept Heterogeneity in the design of the measurement in different studies - especially
lasting vascular occlusion (1 to 15 minutes) (Yvonne-Tee et al. 2008)
Cause of analogy with the method of flow-mediated vasodilatation (eng. Flow-mediated
dilation, FMD) of the brachial artery, usually the used vascular occlusion for 5 minute
Usually are used, shorter periods of vascular occlusion
Doils vascular occlusion contributes to the accumulation metabolite ischemia (Eg. adenosine)
That could potentially contribute to hyperemic flow blood
15. first Postokluzivna reactive hyperemia (Pörhö)
The pressure cuff which causes vascular occlusion
ANDexcept Heterogeneity in the design of the measurement in different studies and varying
pressure comprising Cufflinks which causes occlusion (In the range 160-220 mm Hg) (KEYMILE et al.
2010)
The most commonly used 30-50 mm Hg cuff pressure exceeds the systolic blood pressure of the
person is measured Pörhö
16. first Postokluzivna reactive hyperemia (Pörhö)
Abstract
porho measured by LDF is a widely used test who provides a general (overall) index
microvascular function - a combination of neural axonal reflexes, COX-dependent paths and
likely effects EDHF a
when use of this test should be careful to avoid methodological bias or error in measurement
(duration occlusion, Basal skin temperature and the location of measurement)
Therefore, Despite being porho in conjunction with the LDF a good and widely used assessment
tool microvascular reactivityThis method still requires standardization
17. 2. iontophoresis acetylcholine (ACh) and sodium nitroprusside (SNP)
iontophoresis is a method for non-invasive transdermal delivery vasoactive substances (Charged
molecules) by using a small electrical current strength
Application methods depends on several methodological factors (Kalia et al 2004):
• concentration and pH solution is applied,
• strength applied current,
• duration iontophoresis and
• properties skin surface (skin thickness, skin skins or)
18. 2. iontophoresis acetylcholine (ACh) and sodium nitroprusside (SNP)
In combination with a LDF (Cracowski et al., 2006; Turner et al., 2008) -
iontophoresis acetylcholine (ACh) Test for assessing endothelium-dependent vasodilation
microcirculation skin
sodium nitroprusside (SNP) test for assessment endothelium-independent vasodilatation
microcirculation skin
Application ACh-a induces predominantly endothelium-dependent dilation:
• COX-dependent metabolites (although the results are not unambiguous) (Durand et al., 2004; Holowatz et al.,
2005)
• NO does not contribute significantly (Noon et al., 1998)
A less significant endothelium-independent dilation
• neural axon reflex (Berghoff et al., 2002)
19. 2. iontophoresis acetylcholine (ACh) and sodium nitroprusside (SNP)
Methodological issues related to iontophoresis:
a) on her own current can induce nonspecific vasodilation which could interfere with the
vasodilatory potency applied drug
• depends on the:
• supplied electrical charge and
• sample the which is the current supplied (For a similar charge, repeated applications cause more
nonspecific vasodilation than continuous iontophoresis) (Durand et al., 2002)
• on particles of the medium used for dissolving and diluting the applied vasodilatorsora (eg. tap
water, distilled water, deionized water, physiological saline);
• distilled Water causes pronounced nonspecific vasodilation caused by electricity rather than salt solution
• iontophoresis ACh-And or SNP causes vasodilation in a similar microcirculation skin, whether ACh or SNP
and dissolved diluted in distilled water or saline) (Farrell et al., 2002)
20. 2. iontophoresis acetylcholine (ACh) and sodium nitroprusside (SNP)
Methodological issues related to iontophoresis:
b) natural resistance of the skin can also affect the delivery vasoactive substance
• recommended to reduce resistance of the skin at the site of application
• treasure removal of the surface layer epidermis adhesive tape or alcohol (Turner et al. 2008)
c) spatial variability Affects on reproducibility ACh- or SNP-dependent vasodilation
• be careful to place the application is the same with repeated measurements (Agarwal et al. 2010;
Blaise et al. 2010)
d) vasodilation depends on site iontophoresis
• npr. SNP-induced dilatation could not be induced to volarnojBut only on the dorsal side
finger (Roustit et al. 2009)
21. 2. iontophoresis acetylcholine (ACh) and sodium nitroprusside (SNP)
Abstract
ANDontoforeza ACh-ai SNP widely apply to assess endothelium-dependent and -neovisne
vasodilatation microcirculation skin and in health and disease
Pri interpretation of results should take into account the complexity of the mechanisms involved
in this answers
Studies that use iontophoresis should be carefully designed to minimize current induced
nonspecific dilatation:
• use of low current strength
• physiological solution (rather than distilled water) should be used as a solvent and dilution vasoactive
substances
• place on the skin where it will be made iontophoresis be cleaned alcohol to reduce the natural resistance
of the skin as possible
22. Third Local thermal hyperaemia (LTH)
Local thermal hyperaemia (LTH) is peripheral microvascular response of the skin to the local
heating
The mechanisms that mediate LTH (Cracowski et al. 2006):
• neuralni axon reflex and
• on The NO dependent endothelial vasodilatation
LTH characterized (Minson et al., 2001):
• initial peak hyperemia (The first 5 min) - depends the sensory nerves, and then
• ondržavanim plateau - largely dependent on The NO
23. Third Local thermal hyperaemia (LTH)
Plato appears 20-30 minutes after the start of heating (Minson2010) and when the heating period
extended, observed the phenomenon of "removal" (ie. slow return perfusion the baseline basal
flow).
Figure 3. A local thermal hyperaemia (LTH). (Roustit & Cracowski, 2012)
24. Third Local thermal hyperaemia (LTH)
Cause of two independent phase LTH, during Data analysis can be quantified by different
parameters
The most common parameters used for interpretation LTH's:
peak perfusion (Vasodilatation dependent axon reflex) and
plateau perfusion (NO-dependent vasodilation in).
Podatci can be expressed:
• in "Raw" (eng. row) As a perfusion units, or
• CVC, Which is perfusion the basal influx or perfusion to the maximum vasodilatation
interesting, Very often as a general indicator endothelial function uses the area under the curve
(eng. area under the curveAUC) measurements of the whole, despite the fact that in this way
conceals the influence of axonal reflexes in the vasodilatorsation (Kruger et al. 2006)
25. Third Local thermal hyperaemia (LTH)
reproducibility LTH LDF recorded a depends the place Posted laser probe (Roustit et al., 2010)
• acceptable interdnevna reproducibility when LTH extent to fingers fist
• bad reproducibility when LTH extent on forearm (Roustit & Cracowski2012 ref 114)
Nhammer the authors have shown much better reproducibility on forearm when to measure
benefit so called. integrative probe.
26. Third Local thermal hyperaemia (LTH)
Heterogenost design study that use LTH:
• different local heating temperature (42-43 ° C) (Johnson et al. 2010)
• različita species devices used to heat the skin (Roustit & Cracowski2012)
Withdravi respondents tolerate local heating at 44 ° C, while participants with impaired
microvascular function (e.g., systemic sclerosis) complaining of pain or a burning sensation in the
heating.
27. 4. Local cooling
Local cooling the temperature stimulus that often used in conjunction with LDF-TV
Different methods cooling:
• immersion hands or fingers in the cold water (Maver & Strucl, 2000).
• alignments cartridges for freezing the skin (Cankar & Finderle, 2003) or
• use carbon dioxide (Lütolf et al. 1993)
Cause of its simplicity, the most widely used method of cooling the immersion in cold water as
in healthy, so and with sick patients (Foerster et al. 2007)
28. 4. Local cooling
Local cooling of the skin encourages (Johnson & Kellogg, 2010 ):
• initial vasoconstriction (Dependent on norepinephrine)
• for followed by transient vasodilatation.
• and in the end extended vasoconstriction (Dependent on norepinephrine NO and inhibition
of the system)
Figure 4. Local cooling. (Roustit & Cracowski, 2012)
29. 4. Local cooling
The best reproducibility these methods:
• when Protocol cooling lasts 30 minutes at 15 ° C (Roustit and al. 2010c)
30. recording postocclusive Reactive hyperemia (Pörhö)
laser Doppler method (LDF)
An example of the Laboratory of Clinical Physiology and Physiology Sports Medicine in Osijek
used device and software: moorVMS-LDF monitor and moorVMS-PC v4.0, Moor Instruments
Limited. Millwey. AxminsterDevon, EX13 5HU, UK
36. 4. Field of interest (eng. Region of interest, ROI)
37. 4. Field of interest (eng. Region of interest, ROI)
38. 4. Field of interest (eng. Region of interest, ROI)
39. 5th Protocol recording porho a
The measurement is performed in a room at room temperature (23.5 ± 0.5 °C)
Examinee should pass through 30 min acclimatization in the room where the measurement is
performed in order to avoid changes in blood flow that can occur in response to temperature
changes during the collection data
when Measurement respondents in supiniranome lying position
Probe the device attached to the volar of the forearm of subjects, 13-15 cm above the wrist
(avoid visible veins) by an adhesive holder that enabled producers devices
convention based on the place in which the lower arm device showing the flow rate between 5
and 10 arbitrary units (perfusion units, PU), so that the measurements uniform
40. 5th Protocol recording porho a
If you are doing repeated tests at a particular respondent, it is necessary to mark the spot on
which it was attached probe devices to avoid changes in the flow resulting from the
heterogeneity of the vascular network of the forearm.
How to avoid the appearance of artifacts in the images, the hand of the respondents placed it
on the cushion to the hand not removed because the device is extremely sensitive to the
slightest movements.
From same reason, patients should be instructed that the uninterrupted rest when measuring to
avoid the appearance of artifacts.
41. 5th Protocol recording porho a
• Measurement begins 5-minute recording of the basal flow
• After that the cuff placed around the upper arm is inflated 30-50 mmHg above systolic pressure of
patients in order to stop the flow in the brachial artery
• First occlusion lasts 1 min
• After that rapidly releases air from the cuff and monitor formed reactive hyperemia on monitor
• At the end, continues with 10 minutes recording basal flow
• This is followed second occlusion for 2 min
• After after cuff release other occlusion, Continues to record 10 minutes of basal flow
• Then, subsequent to the third occlusion for 3 min
• And after the third occlusion continue to take 10 min basal rate.
• After that the measurement is complete.
42. 5th Protocol recording porho a
Figure 5. Schematic representation Protocol.
Laboratory of Clinical Physiology and physiology of
sport Faculty of Medicine Osijek.
43. 6. Data analysis
• Changes in blood flow are expressed in arbitrary units (PU).
• How to determine the relative change in flow during post-occlusive hyperemia, the data is
expressed as the "area under curve" (area under the curve, AUC) over the basal rate,
occlusion and reperfusion.
Figure 6. Measurement flow in microcirculation skin using
methods LDF.
(Source: Jackdaw AND, cosic AND, Jukic AND, Jelakovic
B Lombard JH Phillips WITH, Seric In, Mihaljevic AND,
Drenjancevic AND. The rolls of cyclo-oxygenase-1 and
high-salt diet-induced microvascular dysfunction and
humans. JPhysiol. 2015Dec 15; 593 (24): 5313-24. doi:
10.1113 / JP271631.)
46. 6. Data analysis
• The same process is repeated for period occlusion (1 min) and reperfusion (1 min)
47. 6. Data analysis
• The same process is repeated for the period occlusion (1 min), and reperfusion (1 min)
48. 6. Data analysis
• Since the flow does not reach the zero value, even when the perfusion absent, flow rates are
expressed as a percentage in relation to a particular comparison (In this case the flow of
basal)
• specify We percentage flow during occlusion and reperfusion in relation to the basal flow
• Ultimate the result is expressed as the difference between the percentage change in flow
during occlusion and reperfusion the basal rate (RO)
• The same procedure was repeated for 2-min Pörhö and 3-Pörhö min, provided that the 2-
minute Pörhö denoted ROI for 2 minutes, for a 3-minute Pörhö ROI for 3 minute
49. 7. Experiences from the Laboratory of Clinical Physiology and physiology of
sport School of Medicine, University of Osijek
50. 7. Experiences from the Laboratory of Clinical Physiology and physiology of
sport School of Medicine, University of Osijek
51. 7. Experiences from the Laboratory of Clinical Physiology and physiology of
sport School of Medicine, University of Osijek
52. 7. Experiences from the Laboratory of Clinical Physiology and physiology of
sport School of Medicine, University of Osijek
53. 7. Experiences from the Laboratory of Clinical Physiology and physiology of
sport School of Medicine, University of Osijek
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