Brain oxymetry

Abstract

Two main technologies have been proposed to monitor cerebral oxymetry. Near infrared spectroscopy (NIRS) is a non invasive device theoretically dedicated to measure cerebral blood oxygen saturation (ScO₂). The second device allows the invasive measurement of interstitial O₂ partial pressure in brain tissue (PtiO₂). Despite improvements in technologies, NIRS does not allow to measure exclusively cerebral blood saturation since NIRS signal is strongly affected by extracranial tissue blood saturation. In contrast, the invasive measurement of PtiO₂ is reliable and allowed to identify frequent episodic cerebral hypoxic injuries unrelated to known determinants of cerebral O₂ transport. Interestingly, integration of PtiO₂ measurement in multimodal monitoring allowed the identification of a new pathologic entity involved in secondary cerebral ischemic insults.