Determination of cerebral venous hemoglobin saturation by derivative near infrared spectroscopy.

An "in vivo" method for non-invasive determination of cerebral venous hemoglobin O2 saturation (SvO2) was developed. A specially designed spectrophotometer recorded the Td near IR spectra of transilluminated brain tissue surrounding the SS. The accuracy of the method, based on the principle of DNIRS was tested on eight pentobarbital anesthetized dogs during hypoxic hypoxia (inspired O2 6-21%). Spectral data were transformed into first derivative for correlation with SvO2 data measured from the SS. Linear regression analyses were applied using data from 5 dogs, with SvO2 ranging from 1.5%-70%, to build a 3 wavelength algorithm for predicting brain SvO2. In three dogs, this regression equation was employed to predict SvO2 in 31 separate spectra of varying HH intensity. The standard deviation of differences between SvO2 and predicted values was 3.2%. The predicted values, when regressed against the sampled SvO2, yielded an r value of 0.97. The results demonstrate that it is possible to noninvasively quantify SvO2 utilizing IR spectroscopy.