A relatively inexpensive dual beam optical absorbance monitor was tested and adapted to measure arteriovenous oxygen difference ((a-v)ΔO2). Since the molar extinction coefficients of oxy and deoxyhemoglobin are markedly different at 660 nm, the difference in optical density between arterial and venous blood, as measured by the absorbance monitor, was shown to be linearly related to (a-v)ΔO2. When appropriate cuvettes (optical path length = 0.5 mm) were used, the instrument's 90% response time (4.4 sec) was sufficiently rapid for most physical applications such as Fick determinations of the rate of an organ's oxygen consumption. The theoretical basis of this spectrophotometric (a-v)ΔO2 measurement and sources of error are discussed in detail.
ASJC Scopus subject areas
- Physiology (medical)