Effects of Continuous Positive Airway Pressure on Cerebral Vascular Response to Hypoxia in Patients with Obstructive Sleep Apnea
Bibliographic record
Abstract
RATIONALE: The mechanism leading to increased risk of stroke in patients with obstructive sleep apnea (OSA) is unknown. It may occur through alteration in the regulation of cerebral blood flow, reflected in part by the response of the cerebral vasculature to hypoxia. We hypothesized that the cerebrovascular response to hypoxia is reduced in patients with OSA. OBJECTIVE: To determine the cerebral blood flow response to hypoxia in patients with OSA. METHODS: The cerebral blood flow response to 20 minutes of isocapnic hypoxia was measured in eight male patients with OSA before and after 4 to 6 weeks of continuous positive airway pressure (CPAP) therapy and in 10 matched healthy control subjects. MEASUREMENTS AND MAIN RESULTS: The cerebral blood flow response to hypoxia was significantly lower in patients with OSA compared with control subjects (0.56 +/- 0.10 vs. 0.97 +/- 0.09% [mean +/- SE] change in blood flow velocity per % desaturation; p=0.007). After CPAP therapy, the cerebral blood flow response to hypoxia was similar between patients with OSA and control subjects (1.08 +/- 0.15 vs. 0.92 +/- 0.13% change in blood flow velocity per % desaturation; p=0.4). Moderately strong correlations were found between the cerebral blood flow response to hypoxia and the apnea-hypopnea index (r=-0.57; p=0.04) and nocturnal oxyhemoglobin saturation (r=0.48; p=0.01). CONCLUSIONS: The cerebral blood flow response to hypoxia is significantly reduced in patients with OSA. Treatment of OSA with CPAP increases the cerebral blood flow response to hypoxia to normal levels. An attenuated cerebrovascular response to hypoxia in patients with OSA may contribute to their elevated risk of stroke.
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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 | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".