Optical methods of noninvasive examination of the peripheral blood circulation

Practical vascular medicine get benefits from noninvasive, atraumatic, and monitoring-enabling nature of the optical methods that ensure analyzing arterial, venular, and microvessel blood flow; controlling chemical composition of the blood; and assessing the level of blood saturation with oxygen. Currently the most required methods are photoplethysmography, laser Doppler flowmetry, and pulse oximetry. This report highlights the history of the method development, their physical Grounds, technical realization, modern state, application fields, the measurement precision, and further prospects. The methods of studying the peripheral blood flow are grounded on the modern achievements of fundamental physics. The discoveries in physics and technologies (photoeffect, photodetecting, optical mixing, photoemission, lasers, etc.) resulted in development of photoplethysmography, laser Doppler flowmetry, and pulse oximetry. Among the major research directions related to the application of these methods are the study of transcapillary exchange, tomography of microcirculation system, and visualization of the rnicrovessels. Further development of the conventional methods, first of all, in direction of raising the precision of the measurement and development of the controlling instruments is of a great importance as well.