Cerebral Oxygen Saturation Responsiveness During Cardiopulmonary Resuscitation After Prolonged Ventricular...

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.