Comprehensive pre-and in-hospital near-infraredspectroscopy (NIRS) after return of spontaneous circulation predicts neurological outcome after out-ofhospital cardiac arrest -A prospective observational study and literature review

Sebastian Schnaubelt^1*Andrea Kornfehl¹Felix Eibensteiner¹Christoph Veigl¹Florian B Mayr²Patrick Aigner³Mathias Gatterbauer³Michael Girsa³Daniel Grassmann³Andreas Zajicek³Alexander Spiel⁴Wolfgang Schreiber¹Michael Holzer¹Heidrun Losert¹Mario Krammel³Thomas Uray¹

• ¹Medical University of Vienna, Vienna, Austria
• ²University of Pittsburgh, Pittsburgh, Pennsylvania, United States
• ³Emergency Medical Service Vienna, Vienna, Austria
• ⁴Klinik Ottakring, Vienna, Austria

Background: An increase in regional cerebral oxygen saturation (rSO2) levels during advanced life support in patients with out-of hospital cardiac arrest (OHCA) is associated with return of spontaneous circulation (ROSC) and can predict neurological outcome. Data from the post-ROSC phase are scarce but may predict clinical outcomes as well.Methods: For this prospective observational study, we measured rSO2 via near-infraredspectroscopy (NIRS) in patients after ROSC following OHCA in both the pre-and in-hospital setting for up to 72 hours. Patients were followed up for their post-ROSC treatment and outcomes. NIRS values were then compared between patients with favourable and nonfavourable neurological outcome, and cut-off values were assessed via Receiver Operating Characteristic (ROC) and Classification and Regression Trees (CART) analyses. In addition, a narrative review on the topic was performed.Results: Of the 27 included patients, 37% survived to hospital discharge, and 26% showed favourable neurological outcomes (CPC 1 or 2). RSO2 was significantly higher in individuals with CPC 1/2 (67 [60-69] % vs. 59 [50-70] %; p = 0.049). This was even more pronounced for initial (= a mean of the first five minutes) NIRS values (70 [65-77] % vs. 57 [49-68] %; p = 0.025) and NIRS values rising in the first 10 minutes (43% vs. 5% of patients; p = 0.042). A ROC analysis for initial rSO2 showed a significant discriminatory power to predict CPC 1/2 (AUC = 0.789, p = 0.025), and both ROC and CART analyses suggested an optimal cut-off of around 62% rSO2.We identified a potential RSO2 cut off measured via NIRS in the post-ROSC phase after OHCA to predict favourable neurological outcome. Initial values and rising dynamics could be more useful for prognostication than a prolonged measurement at the ICU.These findings fit into previous literature and should trigger larger respective trials on the one, and the technology being addressed by resuscitation societies on the other hand.