Impact of oxygen and carbon dioxide levels on mortality in moderate to severe traumatic brain injury: a systematic review and meta-analysis
Bibliographic record
Abstract
BACKGROUND: Traumatic brain injury (TBI) remains a leading cause of morbidity and mortality worldwide. Secondary brain insults related to oxygenation and ventilation may affect outcomes in this high-risk population. The aim of this study was to perform a comprehensive review examining the relationship between oxygen and carbon dioxide thresholds and mortality to guide clinical care. METHODS: Eleven databases, including: MEDLINE, MEDLINE In-Process, Embase, the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, CINAHL, APA PsycINFO, Web of Science, Biosys, Scopus, and the Global Index Medicus, were systematically searched from inception to October 23, 2024. Included studies reported on adults (≥18 years) with moderate to severe TBI (msTBI) (Glasgow Coma Scale <13 or Head Abbreviated Injury Scale ≥3) and exposure to hypoxia, hypocapnia, or hypercapnia, with mortality or vegetative state data reported within 6 months. Vegetative state data was not reported, so all analyses were based on mortality. Pediatric or mild TBI studies, stroke-focused studies, and studies without mortality outcomes were excluded. The data were screened via Covidence software with multiple reviewers. No language or regional restrictions were applied. This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines. Quality was assessed via the Newcastle-Ottawa Scale (NOS) for Cohort Studies, and certainty of evidence was rated using GRADE. Four authors independently extracted data with verification by a second reviewer. The primary outcome was measured using odds ratios (ORs) with 95% confidence intervals (CIs), calculated separately for crude and adjusted effect estimates. RESULTS: Twenty-one cohort studies with 41,980 patients were included. Hypoxia and hypocapnia were significantly associated with increased mortality (aOR, 1.39; 95% CI 1.11-1.75; p =.005; aOR, 1.64; 95% CI 1.25-2.15; p <.001). Hypercapnia was not significantly associated with mortality (aOR, 1.74; 95% CI 0.91-3.32; p =.09). CONCLUSIONS: In adults with msTBI, hypoxia and hypocapnia were independently associated with increased mortality, underscoring the importance of prompt recognition and targeted management of these secondary injuries. The role of hypercapnia remains unclear, warranting further investigation.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.019 | 0.045 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.024 | 0.055 |
| Bibliometrics | 0.009 | 0.010 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.002 |
| Open science | 0.003 | 0.002 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".