A scoping review protocol on brain PaCO2 levels at altitude
Bibliographic record
Abstract
BACKGROUND: Aeromedical transfer of patients with ischemic stroke to access hyperacute stroke treatment is becoming increasingly common. Little is known about how rapid changes of altitude and atmospheric pressure can impact cerebral perfusion and ischemic burden. In patients with ischemic stroke, there is a theoretical possibility that this physiologic response of hypoxia-driven hyperventilation at higher altitude can lead to a relative drop in PaCO2. This would ultimately result in cerebral vasoconstriction, and therefore worsening of the ischemic burden in patients with ischemic stroke. Currently, there are no specific recommendations in stroke guidelines for optimizing altitude of aeromedical transportation to minimize the rate of ischemic burden. In this scoping review, we aim to map the available literature that addressed whether PaCO2 changes with altitude. This would be the steppingstone for more in-depth analyses into the cerebral autoregulatory consequences of high altitude on cerebral ischemia to form future guidelines. METHODS AND ANALYSIS: We will follow scoping review methods recommended by the Joanna Briggs Institute. Electronic databases MEDLINE, Embase, Web of Science, and Cochrane Central Register of Systematic will be systematically searched to identify articles that report on the acute response of PaCO2 on acute change in altitude. Two independent investigators will perform duplicate title and abstract screening and full-text review, followed by duplicate data extraction. We will present quantitative data using descriptive statistics. Key textual information will be synthesized in a tabular format Simple statistics on the frequency of papers, data will be presented via histogram. ETHICS AND DISSEMINATION: This scoping review does not require ethical approval. The results of our scoping review will be published in academic medical journals and presented at medical conferences. The findings will highlight the current availability of literature on PaCO2 changes with altitude. REGISTRATION: This scoping review protocol has been registered in Open Science Framework (DOI 10.17605/OSF.IO/UVK83).
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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 | 0.106 | 0.106 |
| Meta-epidemiology (narrow) | 0.006 | 0.005 |
| Meta-epidemiology (broad) | 0.016 | 0.012 |
| Bibliometrics | 0.019 | 0.016 |
| Science and technology studies | 0.005 | 0.005 |
| Scholarly communication | 0.010 | 0.010 |
| Open science | 0.006 | 0.008 |
| Research integrity | 0.010 | 0.007 |
| Insufficient payload (model declined to judge) | 0.118 | 0.023 |
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".