Heart and breathing rate variability in the avian perinatal period: The chicken embryo as a model
Bibliographic record
Abstract
We used the chicken embryo at the internal pipping phase (just after the onset of pulmonary ventilation) as a model to quantify the changes in heart rate (fH), breathing frequency (fB) and their variabilities (heart rate variability and breathing rate variability) during air breathing (21% O 2 ) and successive 20-min periods of 15%, 10% and 5% O 2 and post-hypoxic recovery. For each condition, and for both fH and fB, variability was quantified by time-domain analysis with five standard criteria; these produced qualitatively similar results, which were combined into a single variability index. In normoxia, breathing rate variability was about five times higher than heart rate variability. With 10% O 2 , the embryo’s oxygen consumption ([Formula: see text]) and breathing rate variability decreased while heart rate variability increased. In normoxia, respiratory sinus arrhythmia was recognisable in a minority of embryos; its average value was low (~2%) and decreased further with hypoxia. With very severe hypoxia (5% O 2 ), in some cases, breathing stopped; when it did not, breathing rate variability was high. Within the 20-min post-hypoxia, all embryos recovered, and almost all parameters (fH, heart rate variability, fB, respiratory sinus arrhythmia and [Formula: see text]) were at the pre-hypoxic values; only breathing rate variability remained low. The possibility of simultaneous measurements of fB and fH makes the avian embryo, close to hatching, a suitable model for the investigations of heart rate variability and breathing rate variability in response to hypoxia during the transition from prenatal to postnatal life.
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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 | 0.000 |
| 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) | 0.000 | 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".