A feasibility study of cerebral oximetry monitoring during the post-resuscitation period in comatose patients following cardiac arrest

Background: One of the major causes of death and neurological injury after cardiac arrest is delayed ischemia combined with oxygen free radical mediated reperfusion injury. Consequently determining the optimal balance between oxygen delivery and uptake in the brain using a reliable non-invasive monitoring system during the post-resuscitation period is of importance. In this observational study, we evaluated the feasibility of using cerebral oximetry during the post-resuscitation period in order to identify changes in regional cerebral oxygen saturation (rSO₂) and its association with survival to discharge. Methods: 21 consecutive patients admitted to the intensive care units following cardiac arrest had cerebral oximetry monitoring carried out for 48h. Mean rSO₂ values were collected during the first 24h and then again during the subsequent 24-48h of the post-resuscitation period. Results: 43% (n=9) patients survived to hospital discharge and 57% (n=12) died. Amongst all patients the median (IQR) rSO₂% was 65.5% (62.6-68.2) in the first 24-h following ROSC and increased to 72.1% (64.6-73.7) (p=0.11) in the subsequent 24-48h. The median (IQR) rSO₂% during the first 24h in patients who survived to discharge compared to those who did not survive were significantly higher 68.2% (66.0-71.0) vs. 62.9% (56.5-66.0), p=0.01). During the subsequent 24-48h period, while a difference in the rSO₂ between survivors and non-survivors was noted, this did not achieve statistical significance (median (IQR): 73.7 (70.2-74.0) vs. 66.5 (58.2-72.1), p=0.11). Conclusions: Our study indicates that the use of cerebral oximetry is feasible during the post resuscitation period after cardiac arrest. Further studies are needed to determine whether cerebral oximetry may be used as a novel non-invasive monitoring system to evaluate changes in the balance between cerebral oxygen delivery and uptake during the post-resuscitation period.