This paper presents experimental studies on high-speed co-flow jets from orifice models with various annular gaps between the primary jet orifice and surrounding secondary orifices. Co-flow models with annular gaps of 1.5mm, 2.5mm, 3.5mm, and 4.5mm were tested. The co-flow was found to reduce the potential core length of the primary jet for all Mach numbers tested from 0.2 to 1.0. The 4.5mm annular gap model was the most effective at promoting mixing of the primary jet with the surrounding flow. Centerline velocity measurements showed successively greater reductions in potential core length and faster characteristic decay with increasing annular gap
This summary provides an overview of the document:
1) The document studies the effect of geometrical shape (rectangular vs circular) on hydrodynamic focusing in microfluidic flow cytometry through simulation.
2) The results show that a circular shape maintains a higher concentration at the center of the channel and produces higher fluid velocity compared to a rectangular shape.
3) A circular shape also better sustains the focused stream and peak concentration across the length of the channel compared to the decreasing concentration profile seen in a rectangular channel.
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.
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.
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
This paper presents experimental studies on high-speed co-flow jets from orifice models with various annular gaps between the primary jet orifice and surrounding secondary orifices. Co-flow models with annular gaps of 1.5mm, 2.5mm, 3.5mm, and 4.5mm were tested. The co-flow was found to reduce the potential core length of the primary jet for all Mach numbers tested from 0.2 to 1.0. The 4.5mm annular gap model was the most effective at promoting mixing of the primary jet with the surrounding flow. Centerline velocity measurements showed successively greater reductions in potential core length and faster characteristic decay with increasing annular gap
This summary provides an overview of the document:
1) The document studies the effect of geometrical shape (rectangular vs circular) on hydrodynamic focusing in microfluidic flow cytometry through simulation.
2) The results show that a circular shape maintains a higher concentration at the center of the channel and produces higher fluid velocity compared to a rectangular shape.
3) A circular shape also better sustains the focused stream and peak concentration across the length of the channel compared to the decreasing concentration profile seen in a rectangular channel.
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.
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.
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
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.
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
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.
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.
This paper reviews recent developments in the design of microfluidic concentration gradient generators for biological applications. It discusses how gradient generator designs leverage mass transport principles like diffusion and convection to control gradients. The review provides guidance on design considerations for different biological assays and summarizes factors to account for when using gradient generators. It also outlines perspectives on future improvements to gradient generator technology.
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.
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
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.
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.
The document discusses acute normovolemic hemodilution (ANH), a blood saving technique where blood is removed and replaced with fluids to dilute the blood volume. The authors conducted a study comparing ANH patients monitored with the Vigileo system to a control group. Both groups underwent ANH for hip surgery. The Vigileo system continuously monitored cardiac output, stroke volume variation, and other parameters to ensure hemodynamic stability during ANH. Results showed hematocrit and oxygen delivery dropped as expected with ANH but remained within safe limits. No complications occurred, suggesting ANH can be performed safely when carefully monitored with Vigileo.
Acute normovolemic hemodilution g. orianianemo_site
1) The document discusses acute normovolemic hemodilution (ANH), a blood saving technique where blood is removed and replaced with fluids to dilute the blood volume while maintaining normal circulation volume.
2) The study compares outcomes between a group that underwent ANH with continuous hemodynamic monitoring and a control group that underwent standard ANH monitoring.
3) Results showed lower transfusion risks in the continuously monitored group, suggesting continuous monitoring allows for safer ANH by ensuring normovolemic conditions are maintained throughout the procedure and surgery.
Gender Influence on the Performance of Chest Compressions in Simulated Hypogr...Mehdi Kordi
This study investigated whether there are gender differences in performing effective chest compressions using the Evetts-Russomano method to simulate lunar, Martian, and microgravity conditions. The volunteers, both male and female, performed 3 sets of 30 chest compressions under each condition. The results showed that males achieved significantly deeper compressions than females in the microgravity simulation, with none of the females meeting the required depth standards. Both genders were able to perform effective compressions in the lunar and Martian hypogravity simulations. This suggests a gender difference may exist when using the Evetts-Russomano method to perform chest compressions in microgravity.
Microvascular oxygen delivery | Knut Kvernebo at TBS23scanFOAM
This document discusses microvascular oxygen delivery and circulatory failure. It begins with an overview of the evolution of life and the importance of oxygen delivery. It then discusses monitoring of respiratory and cardiovascular function as well as microvascular dysfunction. Extracorporeal membrane oxygenation for acute heart failure is discussed, noting short term survival rates are less than 50% and costs are high. Circulatory failure is defined as the failure to deliver sufficient oxygen to cells. The basics of microcirculation and its regulation are covered. Diffuse reflectance spectroscopy for measuring microvascular oxygen saturation is introduced, with an example using COVID-19 patients showing significant differences in oxygen saturation between groups.
The evaluation of peritoneal membrane is very important for selection of appropriate modality of peritoneal dialysis. Peritoneal membrane is a living membrane so periodic evaluation is important.
Limitations and Advantages in Assessing Adenovirus Homogeneity by Laser Light...KBI Biopharma
The document discusses methods for characterizing the homogeneity of adenovirus preparations using analytical techniques like light scattering and analytical ultracentrifugation. It finds that light scattering has limitations in accurately assessing particle size distribution and aggregation when measuring large virus particles like adenovirus. Analytical ultracentrifugation is able to provide higher resolution information about the adenovirus particle size distribution and detect different forms of structural heterogeneity.
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
More Related Content
Similar to The measurement of blood flow and blood vessel reactivity in skin microcirculatioin with Laser Doppler Flowmetry - LDF
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.
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
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.
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.
This paper reviews recent developments in the design of microfluidic concentration gradient generators for biological applications. It discusses how gradient generator designs leverage mass transport principles like diffusion and convection to control gradients. The review provides guidance on design considerations for different biological assays and summarizes factors to account for when using gradient generators. It also outlines perspectives on future improvements to gradient generator technology.
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.
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
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.
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.
The document discusses acute normovolemic hemodilution (ANH), a blood saving technique where blood is removed and replaced with fluids to dilute the blood volume. The authors conducted a study comparing ANH patients monitored with the Vigileo system to a control group. Both groups underwent ANH for hip surgery. The Vigileo system continuously monitored cardiac output, stroke volume variation, and other parameters to ensure hemodynamic stability during ANH. Results showed hematocrit and oxygen delivery dropped as expected with ANH but remained within safe limits. No complications occurred, suggesting ANH can be performed safely when carefully monitored with Vigileo.
Acute normovolemic hemodilution g. orianianemo_site
1) The document discusses acute normovolemic hemodilution (ANH), a blood saving technique where blood is removed and replaced with fluids to dilute the blood volume while maintaining normal circulation volume.
2) The study compares outcomes between a group that underwent ANH with continuous hemodynamic monitoring and a control group that underwent standard ANH monitoring.
3) Results showed lower transfusion risks in the continuously monitored group, suggesting continuous monitoring allows for safer ANH by ensuring normovolemic conditions are maintained throughout the procedure and surgery.
Gender Influence on the Performance of Chest Compressions in Simulated Hypogr...Mehdi Kordi
This study investigated whether there are gender differences in performing effective chest compressions using the Evetts-Russomano method to simulate lunar, Martian, and microgravity conditions. The volunteers, both male and female, performed 3 sets of 30 chest compressions under each condition. The results showed that males achieved significantly deeper compressions than females in the microgravity simulation, with none of the females meeting the required depth standards. Both genders were able to perform effective compressions in the lunar and Martian hypogravity simulations. This suggests a gender difference may exist when using the Evetts-Russomano method to perform chest compressions in microgravity.
Microvascular oxygen delivery | Knut Kvernebo at TBS23scanFOAM
This document discusses microvascular oxygen delivery and circulatory failure. It begins with an overview of the evolution of life and the importance of oxygen delivery. It then discusses monitoring of respiratory and cardiovascular function as well as microvascular dysfunction. Extracorporeal membrane oxygenation for acute heart failure is discussed, noting short term survival rates are less than 50% and costs are high. Circulatory failure is defined as the failure to deliver sufficient oxygen to cells. The basics of microcirculation and its regulation are covered. Diffuse reflectance spectroscopy for measuring microvascular oxygen saturation is introduced, with an example using COVID-19 patients showing significant differences in oxygen saturation between groups.
The evaluation of peritoneal membrane is very important for selection of appropriate modality of peritoneal dialysis. Peritoneal membrane is a living membrane so periodic evaluation is important.
Limitations and Advantages in Assessing Adenovirus Homogeneity by Laser Light...KBI Biopharma
The document discusses methods for characterizing the homogeneity of adenovirus preparations using analytical techniques like light scattering and analytical ultracentrifugation. It finds that light scattering has limitations in accurately assessing particle size distribution and aggregation when measuring large virus particles like adenovirus. Analytical ultracentrifugation is able to provide higher resolution information about the adenovirus particle size distribution and detect different forms of structural heterogeneity.
Similar to The measurement of blood flow and blood vessel reactivity in skin microcirculatioin with Laser Doppler Flowmetry - LDF (20)
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.
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2. The measurement of blood flow and blood vessel
reactivity in skin microcirculatioin with Laser Doppler
Flowmetry - LDF
Anna Stupin
3. In the last few decades, a large number of functional methods for research and measurement
(pato) of endothelial physiological function in humans have been developed (Flammer &
Luscher, 2010; Ludmer et al., 1986)
Intensified scientific-research work in the field of vascular physiology and pathophysiology
These methods have not yet been implemented as a useful diagnostic tool in everyday clinical
practice
All approaches to endothelial function study are designed to provide insight into vascular /
endothelial function at different sites (vascular basins) and in various types of blood vessels
(conductive, resistive blood vessels, microcirculation)
Earlier invasive methods (eg intracoronary infusion of acetylcholine), newer methods of less
invasive / noninvasive and directed to the study of peripheral circulation as surrogate of
systemic circulation (Linder et al 1990, Panza et al 1990, Celermajer et al 1992)
4. Because of its accessibility, the skin is a perfect place to investigate the function of human
microcirculation (Roustit & Cracowski, 2012)
The open question is whether microvascular function of the skin is representative and
appropriate indicator of microvascular function of other organs
In the last three cases the skin has become a place for intensive study of microvascular function
in health and illness, 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)
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. The often mentioned limitation of the LDF method - expressed spatial variability due to regional
heterogeneity of skin perfusion and blood flow metering at one point (Roustit et al., 2010)
This limit can be eliminated by placing the laser probe always at the same (marked) place on the
skin, especially when the method is used in repeated measurements
The linear relationship between the laser Doppler signal and the microvascular flow was in the
range of 0 to 300 mL / min per 100 g of tissue (Ahn et al., 1987)
The LDF does not give the exact flow rate (i.e. 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. 1. Postocluctive Reactive Hyperemia (PORH)
Post-occlusive reactive hyperaemia (PORH) is an increase in (micro) vascular blood flow caused
by short-term occlusion of the blood vessel
A test that is commonly used to estimate microvascular reactivity (Cracowski et al., 2006)
Mechanisms mediating the formation of PORH in the microcirculation of the skin:
The activity of the sensory nerves through the neural axon reflex (Larkin & Williams, 1993),
Production of endothelium dependent vasodilators EDHF (Lorenzo & Minson, 2007),
The role of prostaglandins has not yet been fully clarified (Dalle-ave et al., 2004; Medow et al.,
2007).
Inhibition of cox reveals the potential dependence of PORH on no in human skin
microcirculation (Medow et al., 2007)
This method is used to evaluate and test microvascular reactivity in general, and not as a direct
test for assessing the microvascular endothelial function (Roustit & Cracowski, 2012
10. 1. Postocluctive Reactive Hyperemia (PORH)
• Parameters that are quantified during PORH analysis:
• Peak hyperemia may be expressed as raw data or as a basal flow function
• the area under the curve,
• peak flow minus basal flow, or
• relative change between peak and basal flow expressed as percentage [(peak flow rate) / basal flow] x 100
• Peak perfusion can be compared with the so-called. maximum vasodilatation achieved by
warming the skin at 42 ° C or more (Charkoudian, 2003)
• Time to peak perfusion (time to peak)
• Its significance as a marker of microvascular reactivity has not yet been determined
11. 1. Postocluctive Reactive Hyperemia (PORH)
Figure 2. Parameters to be quantified in the analysis Porho a
(Roustit & Blaise, 2010; Roustit & Cracowski, 2012)
12. 1. Postocluctive Reactive Hyperemia (PORH)
Inter-day reproducibility of PORH
• it is variable when PORH is measured by LDF at one point
• it depends on the location of the skin on which the probe is placed, how the data is interpreted, and the basal
temperature of the skin
The largest number of studies that examined the reproducibility of PORH used the wool side of the forearms
(results inconsistent)
• Reproducibility is excellent (6% to 22% CV) when the location of the recording is accurately marked, and the
probe is placed every day in the same place (Yvonne-Tee et al. 2005)
• fair to good reproducibility (about 20% CV) when the probe was placed in approximately the same place, but
with a fuller precision (Agarwal et al., 2010)
• reproducibility is poor if the place of probe installation was randomly picked from day to day (CV> 40%) (Roustit
et al., 2010)
Placing the probe in exactly the same place on the skin is a key factor that improves PORH's inter-daily
reproducibility (excellent)
13. 1. Postocluctive Reactive Hyperemia (PORH)
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. 1. Postocluctive Reactive Hyperemia (PORH)
Duration vascular occlusion
Expressed heterogeneity in measurement design in different studies - especially in the duration
of vascular occlusion (from 1 to 15 minutes) (Yvonne-Tee et al., 2008)
Because of the analogy with the flow-mediated dilation (FMD) brachial artery, vascular occlusion
was most frequently used for 5 minutes
Usually, shorter periods of vascular occlusion are also used
Longer vascular occlusion contributes to the accumulation of ischemic metabolites (eg
adenosine) that could potentially contribute to hyperemia blood flow
15. 1. Postocluctive Reactive Hyperemia (PORH)
The pressure cuff which causes vascular occlusion
The expressed heterogeneity in the measurement design in different studies includes a different
cuff pressure causing occlusion (ranging from 160 to 220 mmHg) (Keymel 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. 1. Postocluctive Reactive Hyperemia (PORH)
Abstract
• PORH measured with LDF is a widely used test that provides a general (overall) index of
microvascular function - combination of neural axonal reflexes, COX-dependent pathways
and probably EDHF effects
• When using this test, care should be taken to avoid methodological bias or error in
measurement (occlusion duration, basal skin temperature and metering point)
• Thus, despite the fact that PORH in conjunction with LDF is a good and widely applicable
microvascular reactivity assessment tool, this method still requires standardization
17. 2. Iontoforex acetylcholine (ACh) and sodium nitropruside (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. Iontoforex acetylcholine (ACh) and sodium nitropruside (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. Iontoforex acetylcholine (ACh) and sodium nitropruside (SNP)
Methodological issues related to iontophoresis:
a) the same current can induce nonspecific vasodilation which could interfere with the
vasodilation potency of the drug administered
Depending 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. Iontoforex acetylcholine (ACh) and sodium nitropruside (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. Iontoforex acetylcholine (ACh) and sodium nitropruside (SNP)
Abstract
• Ionophoresis of ACh and SNP is widely applied for the evaluation of endothelium-dependent
and independent vasodilation of microcirculation of the skin and in health and diseases
• In the interpretation of the results, the complexity of the mechanisms involved in these
responses should be taken into account
• Studies using ionophoresis should be carefully designed to reduce current-induced
nonspecific dilation:
• using low power current
• a saline solution (rather than distilled water) should be used as a dissolution and dilution
medium of vasoactive substances
• The place on the skin where iontophoresis will be done should be cleaned with alcohol to
reduce the natural skin resistance as much as possible
22. 3. Local thermal hyperaemia (LTH)
Local thermal hyperaemia (LTH) is peripheral microvascular response of the skin to the local
heating
Mechanisms mediated by LTH (Cracowski et al., 2006):
• neural axonal reflex i
• o NO-dependent endothelial vasodilation
LTH was characterized (Minson et al., 2001):
• Initial peak hyperemia (in the first 5 minutes) - Depends on the sensory nerve and then
• maintained plateau - mostly dependent on NO
23. 3. 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. 3. 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).
Data may be expressed:
in "Raw" (eng. row) As a perfusion units, or
• CVC, Which is perfusion the basal influx or perfusion to the maximum vasodilatation
Interestingly, as an overall indicator of the endothelial function, the area under the curve (AUC)
of the whole measurement is often used, despite the fact that it thus disguises the influence of
axonal reflexes in that vasodilation (Kruger et al., 2006)
25. 3. 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)
Some authors showed a much better reproducibility on the forearm when the so-called "
integrative probes.
26. 3. Local thermal hyperaemia (LTH)
Heterogeneity in the design of studies using LTH:
• a different temperature of local warming (42-43 ° C) (Johnson et al., 2010)
• a different type of device used to heat the skin (Roustit & Cracowski, 2012)
Healthy subjects were well tolerated by local warming at 44 ° C, while subjects with impaired
microvascular function (eg systemic sclerosis) complained of pain or choking sensation at the
warming site.
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 for these methods:
• when Protocol cooling lasts 30 minutes at 15 ° C (Roustit and al. 2010c)
30. Recording Post-Occlusive Reactive Hyperemia (PORH)
by Laser Doppler (LDF)
An example of the Laboratory of Clinical Physiology and Physiology Sports Medicine in Osijek
device and software used : 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. 5. Record Protocol of PORH
Measurement is performed in room at room temperature (23.5 ± 0.5 ° C)
The subject should undergo a 30-minute acclimatization in the room where measurement is
performed to avoid changes in blood flow that may arise in response to temperature changes
when collecting data
During the measurements, the subjects were in the supine lying position
The device probe is attached to the shoulder of the forearm of the examinee, 13-15 cm above
the wrist (avoid visible veins) with the adhesive holder provided by the device manufacturer
The place on the forearm on which the device shows a flow between 5 and 10 perfusion units
(PU) is arranged in agreement to make the measurements uniform
40. 5. Record Protocol of PORH
If repeated tests are performed on individual subjects, the location of the device probe should be
marked to avoid changes in the flow resulting from the heterogeneity of the forearm's bloodstream.
In order to avoid artifacts appearing in the footage, the hand of the respondent is placed in the
cushion so that the hand would not fall as the device is extremely sensitive to the least movement.
For the same reason, the respondent should be instructed that he must strictly rest while measuring
to avoid arthropathy.
41. 5. Record Protocol of PORH
• The measurement starts with 5-minute recording of basal flow
• After that, the cuff around the upper arm inflates 30-50 mmHg above the systolic pressure of the
examinee to stop the flow in the brachial artery
• The first occult takes 1 min
• It then releases air from the cuff and follows the resulting reactive hypermeas on the monitor
• Upon completion, 10 minutes of basal flow resumption continues
• Thereafter a second occlusion occurs for 2 min
• After the release of the cuff after the second occlusion, 10 min of basal flow continues
• Then a third occlusion lasts for 3 min
• And after the third occlusion, 10 min of basal flow continues.
• After that the measurement was completed.
42. 5. Record Protocol of PORH
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 procedure is repeated for occlusion (1 min) and reperfusion (1 min)
47. 6. Data analysis
• The same procedure is repeated for occlusion (1 min) and reperfusion (1 min)
48. 6. Data analysis
• Since the flow does not reach a zero value, even when the perfusion is absent, the flow
values are expressed in percentage form relative to some particular comparator (in this case
basal flow)
• We determined the rate of flow during occlusion and reperfusion relative to basal flow
• The final result is expressed as the difference in percentage of change in flow during
occlusion and reperfusion relative to basal flow (R-O)
• The same procedure is repeated for 2-min PORH and 3-min PORH, with 2-min PORH
indicating ROI for 2 minutes and 3-min PORH ROI for 3 minutes
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
54. 8. References
Agarwal SC, Allen J, A Murray, Purcell IF. comparative reproducibility of
dermal microvascular blood flow changes and response it acetylcholine
Iontophoresis. hyperthermia and reactive hyperaemia. Physiol meas 31:
1-11, 2010.
Ahn H, Johansson K Lundgren ON, NilssonGE. in vivoevaluation of signal
processors for laser Doppler tissue flowmeters. HoneyBiol Eng Comput
25: 207-211. 1987
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