Abstract 219: Cerebral Oximetry Shows The Cardiopulmonary Resuscitation Leading To Return Of Spontaneous Circulation

Purpose: Effectiveness of cardiopulmonary resuscitation (CPR) is associated to return of spontaneous circulation (ROSC), but the alignment of the characteristics of compressions (rate and depth) to AHA recommendations has not been proven to improve outcome. In this study the power of the near infrared spectroscopy to discriminate productive CPR, i.e. chest compression sequences leading to ROSC, was evaluated. Material and methods: The cerebral oxygen saturation (rSO 2 ) measured in both cerebral lobules was recorded with the Nonin SenSmart 100X oximeter by Emergentziak-Osakidetza, the emergency service of the Basque Country, in the out-of-hospital cardiac arrest (OHCA). Concurrently, the ECG and bioimpedance were recorded by the Lifepak 15 desfibrillator. Chest compressions were delivered by Lucas 2 & Lucas 3 devices. Sequences of compressions longer than 30 s were extracted, and changes in the left (rSO 2,L ) and right (rSO 2,R ) lobes were automatically computed by signal processing. The increase of rSO2, measured every 4 s during the CPR-sequence, was adjusted with linear regression and compared for ROSC/no-ROSC patients as registered in the emergency department (ED). Results: Chest compression intervals were identified in the bioimpedance, and 403 CPR-segments were extracted from 115 patients (80 from 43 patients with ED-ROSC) with a mean(std) duration of 2.46(1.07) min. The median(IQR) increase of brain saturation per patient, rSO 2,L and rSO 2,R , were 2.1(1.1-5.5) and 1.9(0.9-3.8) points. The figure shows the linear adjustment of the evolutions for both ROSC/no-ROSC groups, with slopes of: 1.81 vs 1.23 min -1 for ΔrSO 2,L (p>0.05), 1.78 vs 0.95 min -1 (p<0.05) for ΔrSO 2,R, and 2.03 vs 1-08 min -1 (p<0.05) for the combination of both. Conclusions: Cerebral oximetry showed different evolution during mechanical chest compressions for patients with ED-ROSC. Significantly higher slopes in the rSO 2 evolution were observed for patients who achieved ROSC in OHCA.