Current Methods for the Assessment of Oxygen Status and Biotissue Microcirculation Condition: Diffuse Optical Spectroscopy (Review)
Sovremennye tehnologii v medicine
The problem of studying the oxygen status and biotissue microcirculation is of special interest for many directions in medical science since one of the causes of hypoxia development as a typical pathophysiological process is a microcirculatory "failure" associated with the impairment of normal anatomy of the capillary wall, changes in the rheological blood properties, acceleration or slowdown of the blood flow. Current imaging techniques enable the researchers to study the processes of
... ocesses of biosystem vital activity at various levels: from organs and tissues to the substance molecular composition. Methods of functional bioimaging implemented into clinical practice provide the opportunity of watching online the processes of substance movement in the body, monitoring blood flow parameters, assessing hypoxia level, characterizing metabolism in greater detail, and, at the same time, correcting timely pathological conditions. The main advantages and disadvantages of bioimaging examination methods such as BOLD functional magnetic resonance tomography, positron emission tomography, optical imaging, laser Doppler flowmetry, and transcutaneous oximetry are considered in the present review. Special attention is paid to diffuse optical spectroscopy as a noninvasive method of lifetime study of substance content in biotissues. The principle of diffuse optical spectroscopy is based on the ability of tissue chromophores (oxyhemoglobin, deoxyhemoglobin, fatty acids, collagen) to absorb diffusely scattered light of a definite wavelength. Their concentrations are calculated with the allowance for the absorption coefficients of chromophores. Diffuse optical spectroscopy is being introduced in clinical practice to diagnose the degree of tumor malignization, evaluate vascularization in reconstructive operations, diagnose hypoxic tissue conditions, monitor intraoperatively blood flow parameters, measure hypoxia levels in diabetes mellitus. It provides the possibility to define and make clear indications to skin plastic surgery and, conceivably, to develop new methods of skin plasty.