Formation and informative content of photoplethysmographic signal under the conditions of controllable external compression

The physical nature and quantitative characteristics of the photoplethysmographic (PPG) signal under conditions external compression studied tissue area are theoretically investigated. Dependences constant variable components PPG on applied pressure revealed, which have maxima at certain values. model formation process takes into account optical mechanical properties biological tissues. is based consideration diffuse propagation light in a two-component scattering medium (blood + surrounding tissues) employs Kubelka – Munk two-stream theory; this case, amount blood tissues determined by equilibrium laws deformation.
 It shown that developed correctly describes observed qualitative features signal, condition for best agreement between theoretical experimental curves allows real-time determination peripheral microcirculation (mean value amplitude fluctuations precapillaries, erythrocyte concentration, average degree oxygenation, vessel walls elasticity, etc.). methods determining circulation parameters can be used as basis inexpensive effective express research medical diagnostics, especially useful mass surveys or environmental monitoring.