Photoplethysmographic evaluation of the relationship between skin reflectance and skin blood volume.
Although photoplethysmography can be used successfully to determine venous recovery time, it cannot be used in tests which rely on a determination of the blood volume change (e.g. maximum venous outflow). In seeking an explanation for this inadequacy it was shown that although the photoplethysmograph is able to indicate changes in reflectance, it is incapable of measuring reflectance, per se; information which is essential for an accurate calculation of venous volume decrease. A minor modification of the system enables relative reflectance measurements to be made. Measurements were performed under in vitro conditions to establish the skin-reflectance/skin-blood volume relationship; photon diffusion theory is then used to describe the skin-reflectance/skin-blood volume relationship and to determine the scattering and absorption coefficients of skin and whole blood.
Higgins
J L
JL
Fronek
A
A
D001810:Blood Volume; D005374:Filtration / Q000295:instrumentation; D008027:Light; D008433:Mathematics; D008962:Models, Theoretical; D010991:Plethysmography; D012542:Scattering, Radiation; D012879:Skin Physiological Phenomena