Assessment of spatially resolved spectroscopy during cardiopulmonary bypass

Controversy remains about which tissue is primarily responsible for light attenuation of near infrared spectroscopy (NIRS) in the adult, the spatial resolution provided and the preferred algorithm for quantification. Until recently, changes in NIRS have not been fully quantified and have been difficult to interpret without sophisticated computation. A new development by Hamamatsu Photonics, the spatially resolved spectrometer (SRS), may be able to give a quantitative measure of oxygen saturation. We have incorporated the SRS into a multimodality monitoring system for the purpose of direct validation against jugular bulb oxygen saturation (SjO2) in patients undergoing routine cardiopulmonary bypass (CPB). The importance of this investigation is in the development of the SRS machine which shows potential as a useful clinical tool. The results demonstrated good correlation between SRS and SjO2 in 12 out of the 24 patients studied. Although these results are encouraging, this study suggests that the SRS, in its present form, is not a reliable clinical monitor of cerebral oxygen saturation during CPB. © 1999 Society of Photo-Optical Instrumentation Engineers.