Abstract

Optical spectroscopy is a routinely used clinical laboratory technique, and since the 1930’s has been used to examine tissue oxygenation in thin tissue sections or from surface reflection measurements. However, in the 1970’s the technique of near infrared spectroscopy (NIRS) of intact organs was first described by Frans Jobsis, a breakthrough that enabled truly non invasive measurements to be made on intact organs, allowing the technique to be applied to patients at the bedside. In the NIR (700-900 nm), oxygenation dependent changes in attenuation can be observed which arise from variations in the concentration of oxy and deoxyhaemoglobin in the blood, and of oxidised cytochrome oxidase in the cell mitochondria. Since the initial report of Jobsis, instrumental improvements now enable us to measure attenuation changes across many centimetres of tissue (most commonly brain or muscle), and techniques to quantify haemodynamic variables such as blood flow and volume have been developed.

© 1998 IEEE