A 72-year-old woman with chronic kidney disease (creatinine 3.2 mg/dL) and atrial fibrillation is brought to the ICU after a witnessed out-of-hospital cardiac arrest. She was found in asystole; CPR was initiated by bystanders within 2 minutes. After 20 minutes of advanced life support in the emergency department, including three cycles of adrenaline and two defibrillation attempts, there is still no return of spontaneous circulation (ROSC). The team is considering termination of resuscitation. Which of the following factors MOST strongly predicts a poor neurological outcome and supports the decision to terminate resuscitation efforts?