Use of Continuous Positive Airway Pressure in Anesthetized Infants
Bibliographic record
Abstract
We thank Dr. Rothstein for his interesting comments regarding our article.1As he correctly points out, the effect of added elastic and/or resistive load on respiratory drive may differ in the awake and anesthetized states. In the awake state, an increase in elastic and/or resistive load is compensated by an increase in neuronal inspiratory drive. This compensatory neuronal drive may be absent or diminished during general anesthesia,2and this may be particularly so in infants who are highly susceptible to anesthesia-induced attenuation of neuronal input. Continuous positive airway pressure (CPAP) may itself reduce inspiratory drive through the Herring-Breuer inflation reflex.3The resulting hypercapnia will depend on the reduction in minute alveolar ventilation. In previous studies in anesthetized children, the impact of CPAP on minute ventilation has been clinically insignificant.4Keidan et al. studied the effect of CPAP (6 cm H2O) on work of breathing and respiratory indices in healthy spontaneously breathing children (median age, 1.0 yr) during halothane–nitrous oxide anesthesia.4Application of CPAP via a facemask significantly decreased the work of breathing but had no significant effect on inspiratory tidal volume, inspiratory minute volume, or end-tidal carbon dioxide tension. To the extent that CPAP relieves existing upper airway narrowing, CPAP can also improve gas exchange, resulting in a reduction of hypercapnia and improved oxygenation. It was the purpose of our study to determine the interaction of propofol anesthesia and CPAP on upper airway caliber and configuration in infants. We considered it neither relevant to the study hypothesis nor ethically justifiable to perform arterial puncture for blood gas analysis in our infant subjects. Given the relatively brief duration of CPAP application, any increase in arterial carbon dioxide tension was likely small; indeed, after removal of CPAP, we observed no outpouring of carbon dioxide as determined by end-tidal measurement.*The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada. mark.crawford@sickkids.ca
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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 | 0.007 |
| 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 | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".