DEVELOPMENT OF NEW DIAGNOSTIC EQUIPMENT FOR MEDICINE
Optical noninvasine reflectance tissue oximeter "Spectrotest":
This optical noninvasive reflectance tissue oximeter "Spectrotest", created together with Closed-End Company Association "Istok-EOS" and State Scientific and Production Company "Ciklon-Test", is intended for in vivo functional examination of the system of blood microcirculation, as well as of the oxygen transport in a skin of a patient in real time. The principle of functioning of the device is based on the use of methods of absorbing spectroscopy for the light-scattering media allowing indirectly through an estimation of optical and physical properties of the media to obtain the information on maintenance in a zone of inspection of various biochemical components, allowing to identify these substances among other components in the media using their specific absorption spectra. For the reception of the diagnostic information using the device "Spectrotest", the examened tissue is illuminated by low-intensity optical radiation of visible and near infrared range of wavelengths, and the special photodetector of an optical probe registers the backscattered radiation. During calculations, based on the registered optical density of skin in different spectral wavebands, the contribution to a useful optical signal from blood in the tissue is estimated. The general depth of scanning of a tissue for different types of tissues is an order of 3-5 mm, i.e. small arteries get to an inspection zone, venules, shunts, and also a network of capillaries penetrating the tissue. For the purpose of terminology simplification the blood content in all these links of microcirculation bed in engineering documentation on the device is conditionally named as capillary blood content.
The main measured by the oximeter parameter is:
- the index of capillary blood content in a tested volume of the soft tissue (Vb).
Additional measured parameters are:
- the index of average (per both arterial and venal parts of the blood microcirculation system) saturation of oxyhemoglobin in the peripheral mixed blood (index of hemoglobin oxigenation) in the tested volume of tissue (tissue's saturation SO2 or StO2);
- the index of a melanin content within a skin (Me).
A contribution of capillary blood in a total optical signal from a biotissue generally depends on actually blood volume circulating in a volume of inspection, and on a degree of disclosing of capillaries, especially of superficial. Therefore the relative index Vb displayed by the device is the complex integrated parameter characterizing both these processes. Registration and calculation of the average StO2 is carried out on the basis of a difference in optical properties of oxygenated and reduced hemoglobin fractions. Thus, at work the device perceives the information from all specified above vascular parts of microcirculation bed, therefore the registered index of tissues saturation StO2 is also an integrated parameter characterizing average relative content of HbO2 in the system of microcirculation, averaged on all capillary and arterio-venous channels getting to a zone of inspection. However, as a venal blood on the average in the inspection volume is contained in a general case in 4-6 times more than arterial one, the parameter of tissues saturation is closer to a value of venous saturation SvO2 that allows, knowing an arterial saturation SaO2 (or at least a pulse-saturation SpO2), approximately to estimate an oxygen uptake by tissue's cells. The system of data processing of the oximeter uses a method of the analytical solution of the inverse optical problem for light-scattering media and allows right after the probe positioning on a body of the patient in real time to receive on the screen of the monitor a full diagnostic result. Unlike indirect analogs of this device – pulsoximeters – the parameters of capillary blood volume and oxygenation of peripheral blood are registered by "Spectrotest" without using the registration of blood pulse waves, i.e. any measurements in conditions of occlusion of vessels and of stagnation of blood flow are possible. Oximeter "Spectrotest" is protected by the patent of Russian Federation No. RU2234853 from 26.12.2002. It has the Federal Registration Certificate of Russian Federal Agency of Healthcare Inspection and Social Development No. FS 022a2006/3254-06 from May, 15th, 2006 as well as the Certificate of Safety of Gosstandart of the Russian Federation.
Multipurpose laser noninvasive diagnostic system "LAKK-M":
The multipurpose laser noninvasive diagnostic system (MLNDS) "LAKK-M", created together with SPE "LAZMA" Ltd., functions on a basis of a simultaneous application of methods of Laser Doppler flowmetry (LDF), laser fluorescent spectroscopy (LFS), optical pulsoximetry (OPO) and reflectance tissues oximetry (RTO). It covers today all the most perspective techniques of the modern NMS in a medical science. New technical decisions, optical fiber probe and more developed software allow directly in an doctor's office of any specialization to execute complex in vivo (in situ) functional examinations of patients directed on revealing of thin specific features of microhemodynamics, infringements of a metabolism of oxygen in the system of blood microcirculation and dynamics of relative concentration of oxidation-reduction enzymes (NADH, FAD, lipopigments, porphyrins) in a surveyed site of a biotissue. The optical probe (a fibre optical probe) of the system, used as a diagnostic probe, also is adapted for the usage through the instrumental channel of endoscopes, colonoscopes, etc. allowing a doctor to produce any endoscopic diagnostic procedures.
Registered and determined main medical parameters:
- index of tissue’s blood perfusion (Im) as a function of time;
- functional pulse-saturation of oxyhemoglobin in arterial blood of the system of blood microcirculation (SpO2) as a function of time;
- functional saturation of oxyhemoglobin fraction in a mixed peripheral blood of the system of blood microcirculation (StO2) as a function of time;
- relative volume of all fractions of hemoglobin (volume of blood) in a tested tissue's volume (Vb) as a function of time;
- an index of perfusional saturation of the oxygen in a blood (StO2m);
- parameter of a specific oxygen utilization in a tissue (U);
- frequency rhythms of regulation of microcirculation parameters (miogenic rhythm, neurogenic one, endothelial, etc.) at performance of the base functional test;
- functional reserves in the system of blood microcirculation and the type of blood microcirculation in tissues of the patient (normal type, hyperemic type, spastic one) at performance of loading functional tests with arterial occlusion;
- coefficients of fluorescent contrast of tissue (transcutanous indexes of content of the substances in a tissue) under excitation of fluorescence in ultraviolet (365 nm), green (532 nm) and red (635 nm) spectral wavebands, which indicate a content in the tissue and activity of different tissue’s enzymes and proteins (collagen, elastin, NADH, FAD, lipopigments, porphyrins, etc.).
The design of the system is protected by Russian Patent No. RU2337608 and the international application form on PCT procedure: PCT/RU2008/000275, publishing No. WO/2008/140355. Holder of the patent is SPE "LAZMA" Ltd. The system has passed all official state technical and clinical trials and has got on 05.11.2009 the Federal Registration Certificate of Russian Federal Agency of Healthcare Inspection and Social Development No. FSR 2009/05953 as well as the Certificate of Safety of Gosstandart of the Russian Federation No. ROSS RU.IM18.V01611.
Main areas of application in medicine:
- Oncology and radiology: diagnostics of malignant tumors, an estimation of the oxygen status of tumors;
- Angiology: instrumental registration of blood microcirculation in tissues, an assessment of functioning of shunts and capillaries;
- Endoscopy: an estimation of stages of erosive-ulcer and tumoral processes;
- Endocrinology: an estimation of levels of trophic infringements in extremities at a diabetes;
- Professional pathology: an estimation of vascular and trophic infringements at vibrating illness (white finger syndrome) and bronho-pulmonary pathologies;
- Surgery: a choice of a place of a fence (formation) of a transplant, definition of degree of its viability;
- Surgery: determination of type of a tissue at microsurgery operations with stem cells.