The impact of hyperoxemia on mortality and neurological outcomes in traumatic brain injury: a systematic review and meta-analysis

INTRODUCTION: Traumatic brain injury (TBI) is a critical condition where the management of oxygen levels plays a pivotal role in patient outcomes. While hypoxemia is known to worsen outcomes, the impact of hyperoxemia on mortality and neurological outcomes remains controversial. This systematic review and meta-analysis aims to evaluate the effects of hyperoxemia on these outcomes in TBI patients. EVIDENCE ACQUISITION: This study followed PRISMA guidelines and was registered with PROSPERO (registration number: CRD42024537543). A comprehensive search was conducted across MEDLINE, Embase, and SCOPUS databases, identifying relevant studies on hyperoxemia and its impact on mortality and neurological outcomes in TBI patients. Both observational studies and randomized controlled trials were included, and data were synthesized and analyzed using a random-effects model. EVIDENCE SYNTHESIS: Fifteen studies including 38,718 patients were included in the qualitative synthesis, with 13 studies included in the quantitative meta-analysis. Hyperoxemia was not significantly associated with mortality (pooled OR=0.88 [0.66-1.16]; P=0.36; I2=86%) or with unfavorable neurological outcomes (pooled OR=1.04 [0.83-1.29]; P=0.75; I2=67%). Sensitivity analyses limited to studies with low or low/ moderate risk of bias showed a statistically significant association between hyperoxemia and reduced mortality, although with high heterogeneity (OR=0.65 [0.48-0.88]; P=0.005; I2=82%). A subgroup analysis of studies assessing neurological outcome at 6 months suggested a trend toward improved functional outcomes with early moderate hyperoxemia (OR=1.32 [0.99-1.75]; P=0.06). An explorative meta-regression did not show a significant linear association between PaO2 thresholds and outcomes. CONCLUSIONS: This systematic review and meta-analysis do not provide sufficient evidence to discourage the use of moderate hyperoxemia in TBI patients. Exploratory analyses suggesting potential benefits from early moderate hyperoxemia require further validation in selected patients. High-quality prospective studies are urgently needed to determine the optimal use of oxygen therapy in TBI.