Bibliographic record
Abstract
Introduction: The long term detrimental effects of recurrent airway obstruction - such as seen in obstructive sleep apnea (OSA) - on the cardiovascular system have been well described. However, little quantitative evidence is available about acute cardiovascular effects invoked by upper airway obstruction. The effect of acute changes are of importance as they can compound already existing hemodynamic instability, for instance in patients in the intensive care unit or undergoing surgery. We utilized a novel, validated device to perform live measurements of cardiac index during simulated upper airway obstruction in healthy volunteers. Hypothesis: We hypothesized that stroke volume (SV) and cardiac index (CI) would decrease in relation to incremental upper airway resistance, along with compensatory changes in heart rate (HR). Methods: Subjects were asked to lie down supine and monitored with the Non-Invasive Cardiac Output Monitor (NICOM; Cheetah Medical Inc., Vancouver, WA). After collection of baseline data, subjects were asked to breathe through fixed-diameter plastic tubes (Covidien, Mansfield, MA), with decreasing internal diameter (8-3mm) to simulate upper airway obstruction. Each of the five levels was maintained for two minutes. Tubes were attached to spirometry (Datex-Ohmeda, Madison, WI). Left-ventricular SV, HR, CI, brachial blood pressure (BP) and arterial oxygen saturation (SpO2) were continuously recorded using the NICOM device. Results: 6 subjects (2 female, 4 male; mean age 26.0 yrs, mean body mass index 25.4 kg/m2) were enrolled. Baseline SV, HR and CI averaged 91.2ml, 63.3/min and 3.0 l/min/m2. At maximum simulated airway resistance (ID 3), SV and CI decreased significantly by -8% (p=0.015) and -12% (p<0.001), while HR decreased only slightly (-3%; p=0.457). A strong inverse correlation was detectible between calculated airway resistance, SV (R=-0.169, p=0.003), and CI (R=-0.288, p<0.001). BP, SpO2 and spirometry parameters did not differ significantly across tube sizes. Conclusions: We detected significant hemodynamic alterations during simulated upper airway obstruction in healthy volunteers. In our further research, we are going to evaluate the potential impact of these findings in OSA patients.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.476 | 0.364 |
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".