In patients with cardiac arrest (CA) near infrared spectroscopy (NIRS) enables non-invasive monitoring of the regional haemoglobin oxygen saturation in the brain (rSO2) and has emerged as a real time indicator of oxygen delivery to the brain which could be used to optimise cerebral oxygenation during and after cardiopulmonary resuscitation (CPR). Unlike arterial pulse oximetry, rSO2 can still be measured when blood flow is nonpulsatile or even absent, enabling NIRS to be used during CA. Higher rSO2 values during CPR are associated with significantly higher rates of return of spontaneous circulation (ROSC). However, there is a wide overlap of rSO2 values between ROSC and no-ROSC patients. In patients with in-hospital CA (IHCA) a 25% rSO2 cut-off predicted no ROSC with 100[94-100]% specificity, and 13[8-21]% sensitivity. In addition, time with rSO2 >50% during CPR best predicted favourable neurological outcome after resuscitation (cerebral performance category 1-2), suggesting that rSO2 may reflect the quality of cerebral oxygenation and perfusion during CPR. In patients who are comatose after resuscitation from CA, rSO2 has been used to detect the optimal mean arterial pressure (MAP) as the one that optimises cerebral perfusion. In clinical studies, the time spent below the optimal MAP was associated with a lower likelihood of survival (OR 0.97 [0.96:0.99]. p=0.02). Further research is required to determine if cerebral oximetry is of real value in resuscitation but based on current evidence it is not ready for routine clinical use.
- Cardiac arrest
- Cardiopulmonary resuscitation
- Cerebral Oximetry