What is the value of regional cerebral saturation in post-cardiac arrest patients? A prospective observational study

The aim of this study was to elucidate the possible role of cerebral saturation monitoring in the post-cardiac arrest setting. Cerebral tissue saturation (SctO 2 ) was measured in 107 successfully resuscitated out-of-hospital cardiac arrest patients for 48 hours between 2011 and 2015. All patients were treated with targeted temperature management, 24 hours at 33 °C and rewarming at 0.3 °C per hour. A threshold analysis was performed as well as a linear mixed models analysis for continuous SctO 2 data to compare the relation between SctO 2 and favorable (cerebral performance category (CPC) 1–2) and unfavorable outcome (CPC 3–4–5) at 180 days post-cardiac arrest in OHCA patients. Of the 107 patients, 50 (47 %) had a favorable neurological outcome at 180 days post-cardiac arrest. Mean SctO 2 over 48 hours was 68 % ± 4 in patients with a favorable outcome compared to 66 % ± 5 for patients with an unfavorable outcome ( p = 0.035). No reliable SctO 2 threshold was able to predict favorable neurological outcome. A significant different course of SctO 2 was observed, represented by a logarithmic and linear course of SctO 2 in patients with favorable outcome and unfavorable outcome, respectively ( p < 0.001). During the rewarming phase, significant higher SctO 2 values were observed in patients with a favorable neurological outcome ( p = 0.046). This study represents the largest post-resuscitation cohort evaluated using NIRS technology, including a sizeable cohort of balloon-assisted patients. Although a significant difference was observed in the overall course of SctO 2 between OHCA patients with a favorable and unfavorable outcome, the margin was too small to likely represent functional outcome differentiation based on SctO 2 alone. As such, these results given such methodology as performed in this study suggest that NIRS is insufficient by itself to serve in outcome prognostication, but there may remain benefit when incorporated into a multi-neuromonitoring bedside assessment algorithm.