Background Noninvasive regional cerebral oxygen saturation (rSO2) measurement
using near-infrared spectroscopy (NIRS) might inform on extent and duration of
cerebral hypoxia during cardiopulmonary resuscitation (CPR). This information
may be used to guide resuscitation efforts and may carry relevant early
prognostic information. Methods We prospectively investigated non-traumatic
out-of-hospital cardiac arrest (OHCA) patients on scene. NIRS was started
either during CPR or shortly after (<2 min) return of spontaneous circulation
(ROSC) by emergency medical service (EMS). Outcome was determined at intensive
care unit (ICU) discharge and 6 months after cardiac arrest. Results A total
of 29 OHCA patients were included. In 23 patients NIRS was started during CPR
and in 6 patients immediately after ROSC. 18 (62.1 %) patients did not reach
ROSC. Initial rSO2 during CPR was very low (<50 % in all 23 patients, < 30 %
in 19 of 23 patients) with no significant difference between patients
achieving ROSC and those who did not. Of five patients with ROSC, in whom NIRS
was recorded during CPR, two reached a good six-months outcome (initial rSO2
22 %) and three died during the ICU stay (initial rSO2 15, 16 and 46 %). In
six patients with NIRS started immediately after ROSC (<2 min), rSO2 was
substantially higher (54–85 %) than in patients during CPR (p = 0.006).
Discussion and conclusion Initial frontal brain rSO2 determined by NIRS during
CPR was generally very low and recovered rapidly after ROSC. Very low initial
rSO2 during CPR was compatible with good neurological outcome in our limited
cohort of patients. Further studies are needed to assess in larger cohorts and
more detail the implications of very low initial rSO2 during CPR on scene