Arterial pulsatility and the modeling of reflectance pulse oximetry

Several methods have been used to model the behavior of light in tissue in order to better understand pulse oximetry. Homogeneous or two-layer tissue descriptions used to predict the surface reflectance recorded as photoplethysmographic signals yield approximations at best. A multi-layer tissue description was employed in a Monte Carlo simulation of reflectance pulse oximetry to study the importance of localization of the arterial pulsatility. The results from the multi-layer tissue model indicate a stronger dependence of calibration upon arterial pulsatile amplitude than suggested by homogenous tissue models.