Abstract Sa1006: Association between Increment of Near-Infrared Spectroscopy-Derived Cerebral Perfusion Index and Return of Spontaneous Circulation in Out-of-Hospital Cardiac Arrest Patients: A Prospective Observational Study

Introduction: Maintaining cerebral blood flow during cardiopulmonary resuscitation (CPR) is vital, yet establishing a dynamic indicator of cerebral blood flow during CPR remains challenging. Near-infrared spectroscopy (NIRS) is a non-invasive technique capable of continuously detecting changes in cerebral blood volume and has the potential to assess cerebral blood flow in real-time during cardiac arrest. Despite its potential, limited research exists on cerebral perfusion indexes measured by NIRS during CPR and their clinical outcomes. Research Questions: Can assessing cerebral perfusion indices (CPI) using NIRS during CPR in out-of-hospital cardiac arrest patients serve as a prognostic indicator? Aims: To evaluate the association between increased CPI measured by NIRS during CPR by EMS personnel on-scene and return of spontaneous circulation (ROSC) after adult out-of-hospital cardiac arrest (OHCA). Methods: Between January 2021 and March 2023, we included consecutive out-of-hospital cardiac arrest patients due to internal causes who were attempted resuscitation by emergency medical services (EMS) in Sapporo city, Japan. EMS placed a NIRS monitor probe (NIRO 200-NX; Hamamatsu Photonics, Japan) on the patient's forehead and began measurements simultaneously upon contact with the patient. Patients treated with a mechanical chest compression device were excluded. We focused on the change of NIRS pulse waves during CPR at the scene and analyzed the values of NIRS pulse waves at two points: patient contact and scene departure by EMS. NIRS technology measures changes in total hemoglobin (ΔcHb) and oxygenated hemoglobin (ΔO2Hb) concentrations. Patients were divided into groups based on whether their ΔcHb and ΔO2Hb levels increased or decreased between patient contact and scene departure. The primary outcome was prehospital ROSC, and no cases of ROSC were observed at the scene. Results: During the study period, 91 patients were included. The prehospital ROSC rate was 16.4% (11/67) in the group with an increasing ΔcHb trend, compared to 0% (0/24) in the group with no increasing trend (p = 0.034). Regarding ΔO2Hb, the rate was 14.7% (10/68) in the group with an increasing trend and 4.3% (1/23) in the group with no increasing trend (p = 0.279). Conclusion: The increase in CPI measured by NIRS during CPR on-scene was associated with ROSC. Further research is warranted to determine whether CPI can aid in predicting the prognosis of cardiac arrest patients.