Monitoring patients with severe traumatic brain injury
Authors: Randall M Chesnut, Robert H Bonow, Walter Videtta
Journal: The Lancet Neurology (2024)

In the OXY-TC study,1Payen JF Launey Y Chabanne R et al.Intracranial pressure monitoring with and without brain tissue oxygen pressure monitoring for severe traumatic brain injury in France (OXY-TC): an open-label, randomised controlled superiority trial.Lancet Neurol. 2023; 22: 1005-1014Summary Full Text Full Text PDF PubMed Scopus (10) Google Scholar Jean-Francois Payen and colleagues have investigated if assessment of brain tissue oxygen pressure (PbtO2) improves outcomes in patients undergoing intracranial pressure monitoring after severe traumatic brain injury, in whom flow-metabolism matching is essential. Pragmatically, the OXY-TC study tested whether a protocol-specific response to data from the PbtO2 monitor produced a superior outcome versus protocol-specific management of intracranial pressure alone. Payen and colleagues presumed that the PbtO2 monitor accurately measured local flow-metabolism balance, which usefully reflect the patient's overall condition, and that their management protocols were safe and effective. They also assumed no significant interactions between PbtO2 and intracranial pressure management. The OXY-TC trial was well designed and executed, and the results do not belie the value of PbtO2 monitoring. However, the findings do mandate rethinking the target population, treatment threshold, and management protocols, among other considerations. Targeted therapy is important for precise neurotrauma care. The OXY-TC findings suggest that a subgroup of patients with early intracranial hypertension might benefit from empirical flow-metabolism matching.1Payen JF Launey Y Chabanne R et al.Intracranial pressure monitoring with and without brain tissue oxygen pressure monitoring for severe traumatic brain injury in France (OXY-TC): an open-label, randomised controlled superiority trial.Lancet Neurol. 2023; 22: 1005-1014Summary Full Text Full Text PDF PubMed Scopus (10) Google Scholar However, the subgroup effect was small, and a benefit was not detectable within the overall study cohort. Once completed, ongoing parallel studies (ie, the BOOST3 trial2Bernard F Barsan W Diaz-Arrastia R Merck LH Yeatts S Shutter LA Brain Oxygen Optimization in Severe Traumatic Brain Injury (BOOST-3): a multicentre, randomised, blinded-endpoint, comparative effectiveness study of brain tissue oxygen and intracranial pressure monitoring versus intracranial pressure alone.BMJ Open. 2022; 12e060188Crossref Scopus (33) Google Scholar and BONANZA trial3Australian and New Zealand Intensive Care SocietyBONANZA-GT: brain oxygen neuromonitoring in Australia and New Zealand—global trial.https://www.anzics.com.au/current-active-endorsed-research/bonanza/Date: 2023Date accessed: October 25, 2023Google Scholar) will allow for an individual participant data meta-analysis, which should provide sufficient power to address questions about subgroups. Together, the findings of OXY-TC, BOOST3, and BONANZA could prompt reconsideration of the ethics of randomising patients with PbtO2 abnormalities, to more directly address the value of PbtO2 monitoring. The negative findings of the BEST TRIP trial,4Chesnut RM Temkin N Carney N et al.A trial of intracranial-pressure monitoring in traumatic brain injury.N Engl J Med. 2012; 367: 2471-2481Crossref PubMed Scopus (931) Google Scholar which compared protocols based on intracranial pressure monitoring with those not based on monitoring, did not result in intracranial pressure monitoring being abandoned in neurotrauma care. Similar concerns regarding subgroup and effect size instead prompted re-evaluation of treatment based on intracranial pressure. PbtO2 monitoring is much less established than intracranial pressure monitoring. Early negative findings from a randomised trial should not cost us this technology. RHB declares grant support from the Garvey Institute for Brain Health. RMC and WV declare no competing interests. Intracranial pressure monitoring with and without brain tissue oxygen pressure monitoring for severe traumatic brain injury in France (OXY-TC): an open-label, randomised controlled superiority trialAfter severe non-penetrating traumatic brain injury, intracranial pressure and PbtO2 monitoring did not reduce the proportion of patients with poor neurological outcome at 6 months. Technical failures related to intracerebral catheter and intracerebral haematoma were more frequent in the intracranial pressure and PbtO2 group. Further research is needed to assess whether a targeted approach to multimodal brain monitoring could be useful in subgroups of patients with severe traumatic brain injury–eg, those with high intracranial pressure on admission. Full-Text PDF Monitoring patients with severe traumatic brain injury – Authors' replyWe fully agree with Randall M Chestnut and colleagues' comments and thank them for underlining important considerations. The findings from OXY-TC trial1 do raise questions on the heterogeneity of patients with severe traumatic brain injury despite comparable Glasgow Coma Scale scores at baseline. Pooled data from the trials OXY-TC, BOOST3, and BONANZA might provide sufficiently robust evidence to identify the patients who most likely benefit from multimodal invasive brain monitoring. Full-Text PDF