Comparative study on various methods of finger plethysmography.

An attempt was made to analyze differences in the results obtained by various kinds of finger plethysmography, such as penetration photo-electric plethysmograph (penet.-PTG), reflexion photo-electric PTG (refl.-PTG), mechanoelectric PTG (pneumo-PTG and hydro-PTG) and impedance PTG, by taking simultaneous recordings principally from the same finger tip. Comparisons of the time course (onset time and crest time) and the wave form (harmonic analysis and base line deviation) of each pulse wave were made with the standard records of the penet.-PTG depicted simultaneously. Experiments were repeated on 15 healthy adults. No significant differences were observed in the time course and wave form among the records obtained by various kinds of plethysmographs, so far as the records obtained from the finger tip were concerned, whereas appreciable differences were recognized in the time course as well as in the wave form, when the proximal