CO<sub>2</sub> rebreathing: an undergraduate laboratory to study the chemical control of breathing
Bibliographic record
Abstract
The Read CO2 rebreathing method (Read DJ. A clinical method for assessing the ventilatory response to carbon dioxide. Australas Ann Med 16: 20-32, 1967) provides a simple and reproducible approach for studying the chemical control of breathing. It has been widely used since the modifications made by Duffin and coworkers. Our use of a rebreathing laboratory to challenge undergraduate science students to investigate the control of breathing provided 8 yr of student-generated data for comparison with the literature. Students (age: 19-22 yr, Research Ethics Board approval) rebreathed from a bag containing 5% CO2 and 95% O2 (to suppress the peripheral chemoreflex to hypoxia). Rebreathing was performed, and ventilation measured, after hyperventilation to deplete tissue CO2 stores and enable the detection of the central chemoreflex threshold. We analyzed 43 data sets, of which 10 were rejected for technical reasons. The mean threshold and ventilatory sensitivity to CO2 were 43.3 ± 3.8 mmHg and 4.60 ± 3.04 l·min(-1)·mmHg(-1) (means ± SD), respectively. Threshold values were normally distributed, whereas sensitivity was skewed to the left. Both mean values agreed well with those in the literature. We conclude that the modified rebreathing protocol is a robust method for undergraduate investigation of the chemical control of breathing.
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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 | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".