Feasibility of absolute cerebral tissue oxygen saturation during cardiopulmonary resuscitation

Abstract

Introduction: Current monitoring during cardiopulmonary resuscitation (CPR) is limited to clinical observation of consciousness, breathing pattern and presence of a pulse. At the same time, the adequacy of cerebral oxygenation during CPR is critical for neurological outcome and thus survival. Cerebral oximetry, based on near-infrared spectroscopy (NIRS), provides a measure of brain oxygen saturation. Therefore, we examined the feasibility of using NIRS during CPR. Methods: Recent technologies (FORE-SIGHT (TM) and EQUANOX (TM)) enable the monitoring of absolute cerebral tissue oxygen saturation (SctO(2)) values without the need for pre-calibration. We tested both FORE-SIGHT (TM) (five patients) and EQUANOX Advance (TM) (nine patients) technologies in the in-hospital as well as the out-of-hospital CPR setting. In this observational study, values were not utilized in any treatment protocol or therapeutic decision. An independent t-test was used for statistical analysis. Results: Our data demonstrate the feasibility of both technologies to measure cerebral oxygen saturation during CPR. With the continuous, pulseless near-infrared wave analysis of both FORE-SIGHT (TM) and EQUANOX (TM) technology, we obtained SctO(2) values in the absence of spontaneous circulation. Both technologies were able to assess the efficacy of CPR efforts: improved resuscitation efforts (improved quality of chest compressions with switch of caregivers) resulted in higher SctO(2) values. Until now, the ability of CPR to provide adequate tissue oxygenation was difficult to quantify or to assess clinically due to a lack of specific technology. With both technologies, any change in hemodynamics (for example, ventricular fibrillation) results in a reciprocal change in SctO(2). In some patients, a sudden drop in SctO(2) was the first warning sign of reoccurring ventricular fibrillation. Conclusions: Both the FORE-SIGHT (TM) and EQUANOX (TM) technology allow non-invasive monitoring of the cerebral oxygen saturation during CPR. Moreover, changes in SctO(2) values might be used to monitor the efficacy of CPR efforts.