The aim of this study was to examine the relationship between early arterial oxygenation thresholds and long-term outcome after severe traumatic brain injury (TBI).
In a post hoc analysis of a randomized trial, adults with severe TBI were classified based on exposure to different levels of arterial oxygenation as measured using the average of arterial partial pressure of oxygen (PaO2) values obtained within 24 hours of admission. Potentially important PaO2 thresholds were defined a priori. The primary outcome was Glasgow Outcome Scale–Extended (GOSE) score at 6 months. Secondary outcomes were cognitive outcomes measured using a battery of 9 neuropsychological tests administered at 6 months, and 6-month mortality.
In adjusted analyses, oxygenation thresholds of 150 and 200 mm Hg were associated with better functional outcome at 6 months (adjusted OR for better functional outcome on GOSE 1.82 [95% CI 1.12–2.94] and 1.59 [95% CI 1.06–2.37], respectively) and improved cognitive outcome at 6 months (adjusted beta coefficients for better cognitive percentile across 9 neuropsychological tests: 6.9 [95% CI 1.3–12.5] and 6.8 [95% CI 2.4–11.3], respectively). There was no significant association between oxygenation level and 6-month mortality except at a PaO2 threshold of 200 mm Hg (OR for death 0.36, 95% CI 0.18–0.71). Higher or lower oxygenation thresholds were not associated with functional or cognitive outcome.
In this observational study, the relationship between early arterial oxygenation and long-term functional and cognitive TBI outcomes appears to be U-shaped. Mild levels of hyperoxemia within the first 24 hours after injury were associated with better long-term functional and cognitive outcomes. These findings highlight the importance of examining balanced oxygen supplementation as a potential strategy to improve TBI outcomes in future research.
BrattonSLChestnutRMGhajarJMcConnell HammondFFHarrisOAHartlR: Guidelines for the management of severe traumatic brain injury. I. Blood pressure and oxygenation. J Neurotrauma24 (Suppl 1):S7–S132007(Erratum in J Neurotrauma 25:276–278 2008)
GlennTCKellyDFBoscardinWJMcArthurDLVespaPOertelM: Energy dysfunction as a predictor of outcome after moderate or severe head injury: indices of oxygen, glucose, and lactate metabolism. J Cereb Blood Flow Metab23:1239–12502003
MenzelMDoppenbergEMZaunerASoukupJReinertMMClausenT: Cerebral oxygenation in patients after severe head injury: monitoring and effects of arterial hyperoxia on cerebral blood flow, metabolism and intracranial pressure. J Neurosurg Anesthesiol11:240–2511999
RinconFKangJVibbertMUrtechoJAtharMKJalloJ: Significance of arterial hyperoxia and relationship with case fatality in traumatic brain injury: a multicentre cohort study. J Neurol Neurosurg Psychiatry85:799–8052014
RockswoldSBRockswoldGLZaunDALiuJ: A prospective, randomized Phase II clinical trial to evaluate the effect of combined hyperbaric and normobaric hyperoxia on cerebral metabolism, intracranial pressure, oxygen toxicity, and clinical outcome in severe traumatic brain injury. J Neurosurg118:1317–13282013
RockswoldSBRockswoldGLZaunDAZhangXCerraCEBergmanTA: A prospective, randomized clinical trial to compare the effect of hyperbaric to normobaric hyperoxia on cerebral metabolism, intracranial pressure, and oxygen toxicity in severe traumatic brain injury. J Neurosurg112:1080–10942010
SteyerbergEWMushkudianiNPerelPButcherILuJMcHughGS: Predicting outcome after traumatic brain injury: development and international validation of prognostic scores based on admission characteristics. PLoS Med5:e1652008
ToliasCMReinertMSeilerRGilmanCScharfABullockMR: Normobaric hyperoxia—induced improvement in cerebral metabolism and reduction in intracranial pressure in patients with severe head injury: a prospective historical cohort-matched study. J Neurosurg101:435–4442004
ZafonteRDBagiellaEAnselBMNovackTAFriedewaldWTHesdorfferDC: Effect of citicoline on functional and cognitive status among patients with traumatic brain injury: Citicoline Brain Injury Treatment Trial (COBRIT). JAMA308:1993–20002012