Hypoxic-ischemic brain injury due to cerebral hypoxia/ischemia is seen in patients within multiple clinical settings across all age groups. Despite uncertainty regarding benefits and harms, cerebral NIRS monitoring is increasingly used as a monitoring tool to guide treatment, in settings where the patients are at risk of cerebral hypoxia/ischemia. It is especially used during aortic and cardiac surgery, but also in the intensive care units, including neonatal, pediatric and adult intensive care. As the rates of hypoxic-ischemic brain injury are typically low in many of these settings, it is difficult for randomised clinical trials to obtain a sufficiently large number of events to evaluate the clinical effect, when conducted in individual clinical settings. This is also seen in the available systematic reviews with meta-analysis including trials within specific clinical settings – numbers are too low and larger/more trials are needed.
The purpose of cerebral NIRS monitoring is the same within the individual clinical settings; to prevent hypoxic/ischemic brain injury. If all trials irrespectively of participant age or clinical setting were pooled in one meta-analysis, we might reach a sufficient information size (evaluated by Trial Sequential Analysis) to evaluate the beneficial and harmful effects of cerebral NIRS monitoring. Thus, we intend to conduct a systematic review with meta-analysis and Trial Sequential Analysis, to evaluate the effects of clinical care with access to cerebral NIRS monitoring versus clinical care without access to cerebral NIRS monitoring, in children and adults across all clinical settings (pooling of trials within surgery, and neonatal-, pediatric-, and adult intensive care).
We are aware that the heterogeneity between the included trials might impair our possibility to interpret the results to specific clinical settings. If the analysis reveals that NIRS has a beneficial effect on any of our predefined outcomes, it will rather be an encouragement to continue the conduct of randomised clinical trials within each clinical setting, in order to reach the sufficient information size (evaluated by a sequential analysis method).
The meta-analyses showed no significant difference for all-cause mortality; moderate or severe, persistent cognitive or neurological deficit; and serious adverse events, when pooling participants from twenty-five randomised clinical trials including a total 2606 participants. All trials were deemed in high risk of bias. The trial sequential analysis demonstrated that the obtained information size was insufficient to detect or reject that adding cerebral NIRS monitoring to clinical care, decreases the risk of death; moderate or severe, persistent cognitive or neurological deficit; and serious adverse events.
To conclude – the evidence on the effects of clinical care with access to cerebral NIRS monitoring is very uncertain. To increase certainty, additional large-scale trials, focusing on lowering their risk of bias, are needed.
Once the results from the SafeBoosC-III trial are published, the systematic review will be updated.