Nav: Home

Scientists developed new contactless method of measuring blood flow in hands

October 29, 2018

The research team from Russia proposed a new contactless method for measuring blood flow in the upper limbs. The method is based on video recording of the skin surface under green light measuring the absorption of red blood cells. This helps to see how effective the circulatory system and the blood flow regulation are. The experimental results showed that the proposed method is not inferior in accuracy to the traditional one. However, it is easier to use, cheaper and fits more patients. The work was published in Biomedical Optics Express.

Measuring blood flow in the limbs is an important diagnostic indicator. By studying how effectively the heart supplies blood to the limbs, we can see if the the cardiovascular system works well and if the blood flow is regulated effectively. Today, researchers usually use contact (or tensiometric) methods of occlusive plethysmography to measure blood flow in the limbs. Such an approach is based on recording changes in the volume or diameter of a limb due to its filling with blood during venous occlusion.

A way of affecting the blood flow, occlusion happens when venous outflow is stopped by applying a slight pressure on the arm without interrupting the arteries. As a result, it is possible to determine the blood flow equal to the increase in the volume of the limb due to the blood flow from the heart. However, contact measurement systems are difficult to configure and use. In addition, such methods are expensive and require adaptation for each new patient.

To overcome the limitations of standard methods, scientists from ITMO University and Almazov National Medical Research Center developed a contactless system for measuring blood flow in the upper limbs. It is based on photoplethysmography. This technique is capable of tracking changes in the blood supply of the skin using video recording of the absorption of green light. When green light hits a red blood cell, the reflected wave changes its polarization. The camera registers only this modified signal and tracks when it gets most intense. The reason for the increase in light absorption during venous occlusion can be explained by the increase in the number of red blood cells, most likely due to the expansion of the small veins of the upper layer of the skin.

To assess the accuracy of measurements using the new system, scientists conducted a series of experiments and compared the values ??obtained by traditional and new methods. Experimental measurements were performed on healthy volunteers. The signal was recorded for several cycles of venous occlusion. The results of cold stress effect on the vessels work obtained by a new method, almost completely coincided with the results of traditional measurements.

"In this research project, we used four cameras for contactless measurements to ensure the registration of the signal from all sides of the hand. This would allow us to identify the heterogeneity of the signal, if it occurs due to the difference in how capillaries work in different parts of the skin. We developed special software, ordered and assembled the equipment necessary to synchronize and simultaneously process the data stream from the four cameras. Yet, during the study, we saw that the difference was not that great, which means that in the future measurements can be carried out with only one camera," comments Alexei Kamshilin, member of the International Scientific and Technical Center "Computational Optics, Photonics and Image Visualization" of ITMO University.

The proposed method does not directly measure the total skin and muscular blood flow. However, research has confirmed that the measurement of skin blood flow is subject to the same regulatory effects as the general blood flow in a limb. The proposed contactless method is not inferior to the traditional one in accuracy, but it is cheaper, easier to use, suitable for most patients and can be applied not only to the upper but also to the lower limbs without additional optimization. Right now, scientists are working to adapt the proposed method for the legs.

The researchers found that by registering a change in the absorption of green color by the skin during the venous occlusion, it is possible to determine the state of blood flow in its upper layers. Changing the conditions of the experiment influences the tone of blood vessels and affects the speed of the blood flow. This allows assessing the vascular resistance regulation by the nervous system and other control mechanisms. Such regulation flaws are observed in a number of diseases accompanied by damage to nerves and blood vessels.

"Our ultimate goal is the creation of a convenient medical device for assessing blood flow in both upper and lower limbs, since the registration of blood flow disorders in the legs has an important additional diagnostic potential. Thus, in diabetes, complications most often affect the skin of the lower limbs. There is even such term as "diabetic foot". The new technique will be of interest to both endocrinologists and vascular surgeons who are engaged in the treatment of varicose veins of the lower limbs, as well as the restoration of blood flow in patients with atherosclerosis of arteries. At the same time, many changes in the regulation can be established at sufficiently early stages of the disease when prevention and treatment are most effective," notes Oleg Mamontov, member of the Department of Functional Diagnostics of the Almazov Center.
-end-
Reference:

Contactless monitoring of the blood-flow changes in upper limbs
Valeriy V. Zaytsev et. al. Biomedical Optics Express, October 12, 2018
https://www.osapublishing.org/boe/abstract.cfm?uri=boe-9-11-5387

ITMO University

Related Blood Flow Articles:

MRI shows blood flow differs in men and women
Healthy men and women have different blood flow characteristics in their hearts, according to a new study.
Brain blood flow sensor discovery could aid treatments for high blood pressure & dementia
A study led by researchers at UCL has discovered the mechanism that allows the brain to monitor its own blood supply, a finding in rats which may help to find new treatments for human conditions including hypertension (high blood pressure) and dementia.
Blood flow monitor could save lives
A tiny fibre-optic sensor has the potential to save lives in open heart surgery, and even during surgery on pre-term babies.
Changes in blood flow tell heart cells to regenerate
Altered blood flow resulting from heart injury switches on a communication cascade that reprograms heart cells and leads to heart regeneration in zebrafish.
Blood flow command center discovered in the brain
An international team of researchers has discovered a group of cells in the brain that may function as a 'master-controller' for the cardiovascular system, orchestrating the control of blood flow to different parts of the body.
Researchers closer to new Alzheimer's therapy with brain blood flow discovery
By discovering the culprit behind decreased blood flow in the brain of people with Alzheimer's, biomedical engineers at Cornell University have made possible promising new therapies for the disease.
In vitro grafts increase blood flow in infarcted rat hearts
Advances in stem cell research offer hope for treatments that could help patients regrow heart muscle tissue after heart attacks, a key to patients achieving more complete recoveries.
Balloon-guided catheters provide better blood flow following stroke interventions
Patients who have experienced a stroke as a result of blockages of the arteries in the brain have better outcomes with the use of balloon-guided catheter surgery as compared to having a conventional guided catheter procedure.
Scientists developed new contactless method of measuring blood flow in hands
Russian researchers proposed a new contactless method for measuring blood flow in the upper limbs.
Researchers investigate correlation between blood flow and body position
For the first time ever, an international research group detected alterations in capillary blood flow around the face caused by body position change.
More Blood Flow News and Blood Flow Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Teaching For Better Humans 2.0
More than test scores or good grades–what do kids need for the future? This hour, TED speakers explore how to help children grow into better humans, both during and after this time of crisis. Guests include educators Richard Culatta and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#556 The Power of Friendship
It's 2020 and times are tough. Maybe some of us are learning about social distancing the hard way. Maybe we just are all a little anxious. No matter what, we could probably use a friend. But what is a friend, exactly? And why do we need them so much? This week host Bethany Brookshire speaks with Lydia Denworth, author of the new book "Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond". This episode is hosted by Bethany Brookshire, science writer from Science News.
Now Playing: Radiolab

Space
One of the most consistent questions we get at the show is from parents who want to know which episodes are kid-friendly and which aren't. So today, we're releasing a separate feed, Radiolab for Kids. To kick it off, we're rerunning an all-time favorite episode: Space. In the 60's, space exploration was an American obsession. This hour, we chart the path from romance to increasing cynicism. We begin with Ann Druyan, widow of Carl Sagan, with a story about the Voyager expedition, true love, and a golden record that travels through space. And astrophysicist Neil de Grasse Tyson explains the Coepernican Principle, and just how insignificant we are. Support Radiolab today at Radiolab.org/donate.