Étude de la dynamique laryngée au cours de la ventilation nasale non-conventionnelle par Neuro-asservissement de la ventilation assistée (NAVA) et par oscillations à haute fréquence (VOHF) chez l’agneau nouveau-né sans sédation
Bibliographic record
Abstract
Résumé : INTRODUCTION : Il a été démontré que la ventilation assistée nasale (AIn) provoque la fermeture laryngée active chez les agneaux nouveau-nés sans sédation. Ceci pourrait limiter la ventilation alvéolaire, entrainer l’air insufflé dans l’appareil digestif et provoquer des conséquences délétères graves. Le neuro-asservissement de la ventilation assistée nasale (NAVAn) et la ventilation nasale par oscillations à haute fréquence (VOHFn) sont des modes de ventilation attractifs. La NAVA semble être plus physiologique que l’AIn, car elle est synchronisée avec le contrôle neural. Cependant, la VOHF ne nécessite pas de synchronisation et diminue les lésions pulmonaires provoquées par la ventilation mécanique conventionnelle. Le but de mon projet est d’étudier l’effet de la NAVAn et de la VOHFn sur la dynamique laryngée chez les agneaux nouveau-nés sans sédation, en testant l’hypothèse que, contrairement à l’AIn, la fermeture laryngée active n’apparait pas durant la NAVAn et la VOHFn. MÉTHODES : deux groupes d’agneaux nés à terme (NAVAn : 8 agneaux ; et VOHFn : 7 agneaux) ont été instrumentés chirurgicalement à 2 jours de vie, afin de recueillir l’électromyogramme des muscles constricteur et dilatateur laryngés, du diaphragme, les pressions au masque, trachéale, pression de CO[indice inférieur 2] en fin d’expiration (P[indice inférieur ET]CO[indice inférieur 2]) et des gaz sanguins artériels. 48h suivant l’instrumentation, un enregistrement polysomnographique a été réalisé pour chaque groupe (AIn / VOHFn et AIn / NAVAn) dans un ordre randomisé. La pression inspiratoire (AIn & NAVAn) et la puissance des oscillations (VOHFn) ont été progressivement augmentées. RÉSULTATS : Les résultats démontrent que l’augmentation des niveaux de NAVAn et de la puissance de VOHFn n’entraine pas de fermeture laryngée active, contrairement à l’AIn. De plus, la diminution du PaCO[indice inférieur 2] provoquée par l’hyperventilation en AIn pourrait contribuer à la fermeture laryngée active. En VOHFn, la diminution progressive de la fréquence des oscillations jusqu’à 4 Hz induit des apnées centrales. En revanche, aucune fermeture laryngée active n’a été observée à 4 Hz. CONCLUSION : La NAVAn et la VOHFn ne provoquent pas la fermeture laryngée active chez l’agneau nouveau-né, et pourraient constituer des nouvelles alternatives dans le traitement des pathologies respiratoires en période néonatale. //Abstract : INTRODUCTION : We have previously shown that nasal pressure support ventilation (nPSV) can lead to an active laryngeal closure in non-sedated newborn lambs. This, in turn, can limit lung ventilation and divert air into the digestive system, with potentially deleterious consequences. Nasal neurally adjusted ventilator assist (nNAVA) and nasal high frequency oscillatory ventilation (nHFOV) are new attractive non-invasive ventilation modalities in newborns. Neurally adjusted ventilator assist (NAVA) seems to be a more physiological ventilator mode than PSV: it is more synchronized with neural control. However, HFOV is associated with less lung injury and does not require synchronization. Thus, the aim of the present study was to assess the effects of nNAVA and nHFOV on laryngeal dynamics in non-sedated newborn lambs, testing the hypothesis that active laryngeal closure does not develop during both nHFOV and nNAVA. METHODS : Polysomnographic recordings were performed in two groups of non-sedated chronically instrumented lambs (nHFOV, 7 lambs) and (nNAVA, 8 lambs), which were ventilated with progressively increased levels of nPSV and nHFOV or nNAVA, in random order. States of alertness, diaphragm and glottal muscle electrical activity, mask and tracheal pressure, tracheal end tidal CO[subscript 2] (P[subscript ET]CO[subscript 2]) and blood gases were continuously recorded in each group. RESULTS: While active laryngeal closure appeared with increasing levels of nPSV, it was never observed at any nHFOV power or nNAVA levels in any lamb. In addition, a decrease in PaCO[subscript 2] was neither necessary nor sufficient for the development of active laryngeal closure. nHFOV at 4Hz dramatically inhibited central respiratory drive. However, no active laryngeal closure was observed at 4 Hz. CONCLUSION: nHFOV and nNAVA does not induce active laryngeal closure in inspiration in non-sedated newborn lambs, in contrast to nPSV. nNAVA and nHFOV could be an alternatives in the treatment of neonatal respiratory disorders.
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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 | 0.001 |
| 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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".