Non-Invasive Techniques for Multimodal Monitoring in Traumatic Brain Injury: Systematic Review and Meta-Analysis

Monitoring brain oxygenation and intracranial pressure non-invasively and continuously is of paramount importance in traumatic brain injury (TBI). The primary motivation of this study was to identify and provide robust evidence of the most effective techniques for the non-invasive multimodal monitoring for traumatic brain injury. Two reviewers independently searched PubMed, Embase, Scopus, the Cochrane Library, and the Web of Science between January 15, 2010, and January 22, 2020. Cohort studies assessing correlation or accuracy of non-invasive techniques for intracranial pressure (ICP) and/or brain oxygenation monitoring in TBI patients were included. The Newcastle-Ottawa Scale was used to assess the methodological quality of the studies. PROSPERO registration ID is CRD42020164739. Eight out of the 12 studies selected focused on the non-invasive measurement of ICP. Near-Infrared spectroscopy was the main technology for brain oxygenation, whereas ultrasound-based techniques were also used for ICP monitoring. PbtO2 monitoring through near-infrared spectroscopy showed low correlation and limited accuracy in detecting hypoxic events. A meta-analysis on non-invasive ICP monitoring revealed a strong pooled correlation coefficient of 0.725 (95 % confidence interval [CI]: 0.450-0.874; I2 91.31%) between transcranial Doppler and the gold standard ICP monitoring. The current meta-analysis has shown that the two most prominent and widely used technologies for non-invasive monitoring in TBI are near-infrared spectroscopy and transcranial Doppler. Both techniques could be considered for the future development of a single non-invasive and continuous multimodal monitoring device for TBI.