Near-infrared spectroscopy (NIRS) during and after cardiopulmonary resuscitation: A systematic review and meta-analysis

Background Outcome prediction during and after cardiopulmonary resuscitation (CPR) poses major challenges for prehospital and in-hospital emergency services. Regional cerebral oxygen saturation (rSO 2 ) measured by near-infrared spectroscopy (NIRS), an emerging technology in emergency medicine, could contribute to prediction approaches. This systematic review evaluated associations between NIRS values during both cardiac arrest (CA) and postresuscitation care and clinical outcomes in nontraumatic adult CA patients. Methods We searched Embase, MEDLINE(R), Cochrane Central Register of Controlled Trials, and Web of Science. Data on study design, population characteristics, and different cerebral oximetry levels in each outcome group were extracted. Risk of bias was assessed using the Quality In Prognosis Studies tool, and a meta-analysis was conducted in groups with at least three studies reporting for the same outcome. Results The search strategy identified 2055 records, and 48 studies with rSO 2 measurements in 3880 patients during or after a cardiopulmonary resuscitation were included for data extraction. In total, we performed 10 different meta-analyses, with four evaluating rSO 2 values during CA and six assessing rSO 2 during postresuscitation care. Overall, delta rSO 2 values during CA had the highest predictive power of return of spontaneous circulation (ROSC) (standardised mean difference=1.61, 95% confidence interval=0.57–2.66; p=0.002). After ROSC, higher rSO 2 values are associated with favourable neurological outcome (standardised mean difference=0.38, 95% confidence interval=0.12–0.65; p=0.004). Conclusion Higher rSO 2 values during CA are consistently associated with increased rates of ROSC, with delta rSO 2 values having the highest predictive power. However, from a practical point of view, retrospectively calculating delta values poses a significant limitation which could be overcome by rather using real-time trends. Also, the implementation of NIRS in postresuscitation care could be an additional component of early multimodal prognostication after CA as we showed that higher initial rSO 2 values after ROSC are associated with a favourable neurological outcome.