A prototype instrument combining laser Doppler flowmetry and reflection pulse oximetry

A prototype instrument has been developed to combine the monitoring techniques of laser Doppler flowmetry and reflection pulse oximetry, both of which depend on laser light backscattered from the skin tissue. Simultaneous and continuous measurements of both microvascular blood flow and blood oxygen saturation were obtained from the same measurement site. Oximetry readings from the combined instrument were calibrated using a model system, and compared with those determined using a Nellcor N-100 transmission pulse oximeter in a limited clinical study: they showed a variability of +4% and read low by 5-10%.