Device for blood staunching
Currently, various branches of medicine use electromagnetic radiation (generated mostly using lasers), which carries on energy, resulting in a local increase of tissue temperature. Normally, radiation from the range of near and medium infrared is used (light wavelength 700 - 3000 nm). Thermal effect of a concentrated beam of light with big power density is used in: surgery, dermatology, ophthalmology, rheumatology or dentistry, e.g. in an ablation process (tissue destruction).
Transmission (permeability) of light through consecutve skin layers (epidermis, dermis, underskin tissue) for different wavelengths. Percentage numbers
Example temperature distribution in a tissue with cut blood vessels after irradiating with blue–violet light
Introduction of a new wavelength of the electromagnetic radiation from the visible range, at the borderline of blue and violet light (wavelength 405 - 460 nm) to medicine allows using a therapy based on prevention of microbleedings in people with haemophilia or using drugs influencing blood clotting (anticoagulants), such as aspirin. In this case it is necessary to limit the effects of small cuts, bruises or blood haemorrhages under skin and into joints (e.g. into knees of elbows), which sometimes arise as a result of a hit (bruise).
The goal of the project was creation of a non-expensive and easy to use device based on LED diodes for performing non-invasive, photothermal coagulation at home or in ambulatory conditions. It is designed for people with blood coagulation disorder for effective staunching of haemorrhages caused by small cuts, bruises or simple medical operation, without causing damage to neighbouring tissues.
The therapy using violet light is based on activation of haemoglobin molecules which has the size of a few nanometers. Haemoglobin is the best absorbent for this range of wavelengths and absorbs much more energy compared to other light types. The energy of electromagnetic radiation absorbed by molecules of haemoglobin is transformed into heat, which heats up the fluid blood tissue and leads to the coauglation itself. This process is based on destruction of protein structure and a total loss of biological activity and creation of permanent clots. The clots of the destroyed protein structure form a structure with mechanical functions, closing the bleeding area.
Within the project SKA Polska developed a device which implements the described concept. It is based on LED technology – a blue-violet diode is the light source. In order to achieve the desired level of light power density, the radiation is focused using special lens. The device is supplied with power using common or rechargeable batteries which make it convenient in use at home. A big challenge was related to construction of the diode controller which has to keep a stable level of radiation over a certain time, maintaining the best possible efficiency. It is particularly important with battery power supply.
The device is characterised by low manufacturing cost, which makes it available for interested patient groups. About 40 thousand people with haemophilia live in European Union, and about 20 million of people taking medications influencing blood coagulation.
Defining parameters of the device, such as power density and lighting time, required a numerical simulations to be performed for the process of conversion of light energy to heat in the skin. Towards this goal, the team of SKA Polska developed a method basing on Finite Elements Method.
Conducted numerical analyses of heating of blood tissue and dermis using blue-violet light have shown that heat exchange processes take place in the surface layers of blood tissue, and the coagulation process is possible with appropriate parameters of the device. This project has been implemented by an international consortium comprised of six companies and two research institutes.