Fig. 2
Serial changes in cerebral rSO2 (representative cases). a Type 1: High rSO2 type (around 60 %). One patient (51-year-old woman; patient #1) showed this type. Her initial electrocardiogram was ventricular fibrillation, and ROSC was diagnosed in the pre-hospital setting. Her outcome at discharge was good recovery. b Type 2: Low rSO2 type (around 45-50 %). Three patients (52.7 ± 30.2 years, 1 man and 2 women) showed this type. This graph shows the serial changes in cerebral rSO2 of patient #6. A similar pattern was observed in patients #5 and #7. None attained ROSC even once. c Type 3: gradually decreasing rSO2 type. Two patients (69.5 ± 6.4 years, 2 men) showed this type. Serial changes in cerebral rSO2 from patient #4 are shown. The rSO2 value gradually decreased. ROSC was diagnosed in-hospital 35 min after the start of measurement. His outcome was death. A similar pattern was also observed in patient #2. Both patients attained ROSC, which was diagnosed in hospital but not in the pre-hospital setting. Their outcomes at discharge were death. d Type 4: other type. One patient (86-year-old woman; patient #3) showed this type. In this patient with ROSC, when the ELT started cerebral rSO2 measurement, the cerebral rSO2 was 67.3 %. It dropped gradually to 54.5 % and then rose to 74.3 %. Cerebral oxygenation was impaired due to possible return of cardiac arrest, but after that, ROSC led to the recovery of cerebral blood flow. The shaded area represents the normal cerebral rSO2 range measured from healthy adults. rSO 2 regional saturation of oxygen, ROSC return of spontaneous circulation, ELT emergency life-saving technician