Fig. 1

Changes in rSO₂ and flat aEEG pattern in PCAS. A female in her 70s was transferred to the hospital by ambulance with an airway obstruction suffered during a meal. Her initial cardiac rhythm indicated pulseless electrical activity. The time from cardiac arrest to ROSC was 31 min. The initial rSO₂value was 66–75 % (a-a) one hour after ROSC and the aEEG pattern was flat. Her rSO₂ decreased with a decline in blood pressure and rose following dopamine infusion (a-b). However, her rSO₂ gradually decreased (a-c) and she experienced another cardiac arrest (a-d) with a steep decline in rSO₂. Throughout the course of treatment in the ICU, the aEEG maintained a flat pattern regardless of rSO₂ value (b and c). A: rSO₂ (%); B: aEEG, 1 h after ROSC. C: aEEG, 5 h after ROSC. Arrows: (a): BP 112/58 mmHg, arterial gases: PaCO₂ 56.8 mmHg, pH 7.189; (b): sBP 88 mmHg, start dopamine administration, PaCO₂ 42.6 mmHg, pH 7.232; (c): sBP 92 mmHg, arterial gases: PaCO₂ 39.6 mmHg, pH 7.353; d: cardiac arrest, start chest compression. sBP: systolic blood pressure; ROSC: return of spontaneous circulation; rSO₂: regional cerebral oxygen saturation; aEEG: amplitude-integrated electroencephalography (NicoletOne^TM IMI, Japan)