A cuvette oximeter and an extension to the theory of oximetry

The theory of transmission oximetry is extended to take into account the scattering of light by whole blood, and conditions are formulated under which a single-scale oximeter may be constructed. An instrument is described which has been designed particularly for cardiac catheterization procedures. After setting up on an initial sample of blood, a series of readings can be taken in rapid succession without the need to manipulate controls. The theoretical approach is confirmed by the ability to deduce from the performance curves of the oximeter (operating on whole blood) values for the absorption coefficients of haemolysed blood which agree well with published spectrophotometer values.