Cerebral Oxygen Saturation Responsiveness During Cardiopulmonary Resuscitation After Prolonged Ventricular Fibrillation: A Porcine Study

Background/Objectives: Near-infrared spectroscopy (NIRS) enables the monitoring of cerebral tissue oxygen saturation (ScO2) during cardiopulmonary resuscitation (CPR). In this study, we aimed to investigate ScO2 responsiveness during CPR initiated 14 min following the induction of ventricular fibrillation (VF) in a porcine model. Methods: Ten female pigs underwent electrically induced VF. CPR was initiated 14 min later using mechanical chest compressions. ScO2 was continuously monitored using NIRS. Return of spontaneous circulation (ROSC), movement recovery, and ScO2 dynamics were evaluated. Results: ScO2 reached its minimum value at 3.3 min (interquartile range [IQR], 2.8–4.3) following VF induction and remained suppressed for 10.8 min (IQR, 9.6–11.3) prior to CPR initiation. Although ScO2 reached its maximum value at 3.8 min (IQR, 2.8–4.3) following CPR initiation, the median ScO2 during CPR remained below 50% (49.0% [IQR, 48.3–50.5]). Initial mean arterial pressure during CPR was 35.5 mmHg (IQR, 31.5–40.3). Seven animals (70%) achieved ROSC, and three survived for 60 min post-ROSC; none of the animals recovered movement. Conclusions: Continuous assessment of ScO2 responsiveness using NIRS from the time of CPR initiation may provide useful physiological information regarding the restoration of cerebral oxygen delivery during resuscitation.