Bibliographic record
Abstract
The focus of this thesis was to systematically examine the effects of sustained hypoxia on ventilation and the function of the primary breathing muscles in an intact awake mammal. Successful execution of this thesis work relied upon the chronically instrumented awake canine model to test the physiologic questions and hypotheses, collaborative team work to execute the experiments, as well as development of appropriate software tools to analyze the immense physiologic dataset amassed over the years. This thesis is organized as a series of related investigative projects overarching the central theme of sustained hypoxia. Ventilation in awake canines exhibited the characteristic biphasic pattern during sustained hypoxia, like that of humans and other mammals, with an initial peak followed by a subsequent decline - “roll-off” or hypoxic ventilatory decline (HVD) - to a lesser intermediate plateau. Our findings directly contest the longstanding canine controversy that ventilation does not roll-off in this species. Examination of the principle inspiratory muscle, the diaphragm, during sustained hypoxia revealed a biphasic contraction and neural activation of the costal and crural, with differential segmental function during initial and sustained hypoxia. Persistent effects of hypoxia caused a dramatic loss of the contractile output of the primary inspiratory chest wall muscle, the parasternal intercostal, accompanied by a decline in EMG activity. Immediate response to hypoxia elicited a marked recruitment of the primary expiratory abdominal muscle, the transversus abdominis, however, sustained hypoxia caused the initial acute expiratory abdominal contribution to be nearly abolished. Excitatory and inhibitory influence of hypoxia may largely account for the past discordance of expiratory activity with hypoxia in mammals. Attenuation of central drive appeared to persist following sustained hypoxia affecting the primary respiratory muscles. We conclude that sustained hypoxic ventilatory roll-off is a universal mammalian characteristic without exception for canines. Attenuation of neural drive with sustained hypoxia is a widespread central phenomenon significantly impacting the primary respiratory muscles of the diaphragm, the chest wall and the abdominal wall, in a distinct and differential manner.
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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 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".