Background: The increase of regional brain oxygen saturation (rSO2) levels measured with Near-infrared-Spectroscopy during advanced life support in patients with out-of hospital cardiac arrest (OHCA) is associated with a higher likelihood of Return of Spontaneous Circulation (ROSC) and can predict neurological outcome. 
However, optimal procedures and values remain vague, since several studies have yielded varying results. The need for continuous data analysis is important and has to be linked to in-hospital measurements in order to obtain outcome values.
Methods: Regional oxymetry measurements were obtained using two oximetry systems for the out-of-hospital and in-hospital settings (SenSmart Model X100, Nonin Medical, Amsterdam; and Foresight Elite, Casmed, Branford, USA). Patients were included upon ambulance arrival at the OHCA-site or after hospital admission. Neurological outcome parameters such as Cerebral Performance Category (CPC) was assessed directly after ROSC and up to 6 months after.
Results: From November 2016 until September 2017, 27 OHCA patients were included. Of those, 10 were enrolled out of hospital, 17 after hospital admission (70% cardiac origin), Eighteen patients (67%) obtained ROSC. At the last observational interval, 11 patients (41%) were alive (7 or 26% with CPC 1-2). Higher mean rSO2-values in the out-of-hospital setting were associated with a significantly higher likelihood of ROSC (rSO2 69.9% ±15.6% vs. 43.7% ±6.5%, p= .004). We observed a similar trend in the in-hospital setting (69.5% ±7.1% vs. 66.2% ±7.5%, p= .673). In addition, we observed a trend towards higher mean rSO2-values, better neurological outcome, and reduced mortality in patients receiving targeted-temperature-management in the out-of-hospital and in-hospital setting.
Conclusion: Combined measurement of regional cerebral oximetry in the out-of-hospital and in-hospital settings is feasible. Higher rSO2 values were associated with a higher probability of ROSC in both settings. The association of higher rS02 values and improved neurologic outcomes needs to be confirmed in a larger study.

Comprehensive Pre- and In-Hospital Near-Infrared-Spectroscopy can predict Outcome Parameters in Patients after Out-of-Hospital Cardiac Arrest - A Feasibility Study