Influence of adipose tissue on near infrared oxygenation monitoring in muscle

The influence of blood content on the sensitivity of a NIR O/sub 2/ monitor is investigated. The simulation model is a semi-infinite medium consisting of skin, adipose and muscle layer. The thickness of adipose layer is varied from 0-10 mm and the absorption coefficient of the muscle layer is changed to realize various conditions of blood content and O/sub 2/ saturation. The optical density (OD) and the partial optical pathlength in the muscle layer are predicted by Monte Carlo simulation. The changes of HbO/sub 2/, deoxyHb, and total Hb are calculated from the predicted OD by reported algorithm for NIR O/sub 2/ monitor. The calculated values are affected by the thickness of adipose tissue.