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Optics to Help Measuring the Blood Flow

Blood flow velocity is an important parameter which doctors need to know to diagnose and treat a number of diseases such as atherosclerosis of the lower limbs or diabetic foot syndrome. Modern tools are not accurate enough to measure it or too expensive. Residents of Technopark ITMO University - VISmart company - offered their device, which is much cheaper counterparts and the rate of blood flow in it is measured by using optics.

According to Yury Emelyanov, CEO VISmart and employee of an international laboratory of ITMO University "Intelligent methods of information processing and semantic technologies", the most common way to measure blood flow velocity is to precisely remove her large arteries using ultrasound Doppler, which is working on the same principles as traffic police radars.

However, in many cases, it is not enough to know only the speed of blood flow in large vessels: a significant portion of blood enters the limb for small vessels, and blood velocity in the peripheral circulatory system is a critical parameter if you want to monitor, for example, the speed of healing of the skin.

In order to find out the average speed of blood flow in the limb, physicians use so-called occlusion method: an arm or leg is clamped by pneumatic cuff, blood flow is reduced, the limb begins to swell, and this swelling rate can be judged on how fast blood is flowing in all vessels simultaneously - without separation for speed in large and small blood vessels.

To obtain the results a tank of water (it’s measured the fact how fast the water level changes) is used. Also it’s possible to use special tube filled with a mixture of indium-gallium, the electrical resistance of which varies depending on the pressure.

However, both of these methods have significant drawbacks.

The method with a tank is not accurate enough and tubes with a mixture, which changes resistance, are too expensive in manufacturing to change them regularly after wear.

To solve this problem and reduce the cost of the blood flow rate diagnostic process, VISmart company offered to track changes in limb volume by optical methods.

"Our solution consists of a system of LED-lasers and light-sensitive elements. The laser creates a light spot on the receiving device, limb casts a shadow, and the position of the border allow to observe the changes in volume which we're shooting in two projections.

Optical methods also allow to obtain the frequency of heartbeat. We conducted a series of measurements, and specialists from the Medical Research Almazov center confirmed the efficiency of our approach", - Yury Emelyanov explains.

Occlusive laser-optical plethysmography allows to register as a bulk flow velocity as the tone and capacity of veins in the studied area.

Method by measuring the flow rate of the change in the electrical resistance in the cuff is developing in the USA, but the USA tool exceeds the cost of the installation, created by scientists from ITMO University.

Analyst of the laboratory "Intelligent methods of information processing and semantic technologies" and commercial director of VISmart company Dmitry Pavlov adds that widespread introduction of the device, which measures the speed of blood flow, can greatly reduce the financial burden on the healthcare system.

"For example, there is such a disease as vegetovascular dystonia. Under this label a whole bunch of diseases may be hiding, which are not diagnosed due to the lack of necessary medical tools. Occlusive plethysmography allows us to understand the nature of the disease and choose appropriate treatment, - Dmitry Pavlov says. - In developed European countries, the direct and indirect losses from these pathologies lead to economic losses of several billion rubles a year because of disability and the lack of treatment of patients who underwent disease diagnostics out-of-time. Our device can help the healthcare system not to lose money. However, this method of diagnosis is not as versatile as, for example, magnetic resonance imaging, therefore, to convince of the need of its implementation is much more difficult."

Now occlusive laser-optical plethysmograph is set in the Federal Almazov North-West Medical Research Centre.

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