A prototype instrument combining laser Doppler flowmetry and reflection pulse oximetry

Abstract

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%.

Review of methodological developments in laser Doppler flowmetry

“…Since the distribution of blood vessels in tissue and optical properties is heterogeneous, it is difficult to calibrate an instrument to measure absolute blood flow per unit volume of tissue. Often, a comparison between laser Doppler flowmetry and an alternative method is complicated, because of the difference in techniques and probed volume [60][61][62][63]. Another approach which was tested for an absolute flow measurement was measuring on either a well-defined tissue preparation [64] or on flow models [26,65].…”

Blood oxygenation and flow measurements using a single 720-nm tunable V-cavity laser

“…The standard deviation (SD) of the calibrating data is 3.2%. As described in [8,22], prolonged breath holding produces characteristically shaped oxygenation responses, so we tested the accuracy of the system by measuring the SpO 2 of a completely new subject . 13, with the reference data measured with the commercial co-oximeter (red line).…”

“…There have been some reports on prototype instruments combining LDF and pulse oximeter. The instrument developed by Dougherty used two LDs to complete the both readings [8]. One LD at 810 nm is used to give a blood flow index and oxygenation information, and the other one at 670 nm to complete the estimation of oxygen saturation.…”

Speckles in laser Doppler perfusion imaging

“…Since the distribution of blood vessels in tissue and optical properties is heterogeneous it is difficult to calibrate an instrument to measure absolute blood flow per unit volume of tissue. Often a comparison between laser Doppler flowmetry and an alternative method is complicated because of the difference in techniques and probed volume [60][61][62][63]. Another approach which was tested for an absolute flow measurement was either measuring on a well defined tissue preparation [64] or on flow models [26,65].…”