Extracranial contribution to cerebral oximetry in brain dead patients: A report of six cases

The near infrared spectroscopy offers a noninvasive method to monitor regio nal brain oxygenation. The problem with the technique appears to be possibl e extracranial contribution to the measurements. As a part of another study , we monitored regional saturation (rSO(2)) in six brain dead patients eith er during the test for spontaneous respiration or in those not eligible for organ donation, after discontinuation of mechanical ventilation. Relativel y normal rSO(2) values were obtained after brain death, and the values decr eased concomitantly with the hemoglobin saturation of oxygen (SpO(2)) after the discontinuation of mechanical ventilation. A corresponding decrease in SpO(2) and rSO(2) suggests extracranial contribution to the measured rSO(2 ). The diagnosis of brain death cannot be made based on this technology; fu rthermore the presence of extracranial contribution may limit its potential value even in other applications.