R??sum?? : INTRODUCTION : Il a ??t?? d??montr?? que la ventilation assist??e nasale (AIn) provoque la fermeture laryng??e active chez les agneaux nouveau-n??s sans s??dation. Ceci pourrait limiter la ventilation alv??olaire, entrainer l???air insuffl?? dans l???appareil digestif et provoquer des cons??quences d??l??t??res graves. Le neuro-asservissement de la ventilation assist??e nasale (NAVAn) et la ventilation nasale par oscillations ?? haute fr??quence (VOHFn) sont des modes de ventilation attractifs. La NAVA semble ??tre plus physiologique que l???AIn, car elle est synchronis??e avec le contr??le neural. Cependant, la VOHF ne n??cessite pas de synchronisation et diminue les l??sions pulmonaires provoqu??es par la ventilation m??canique conventionnelle. Le but de mon projet est d?????tudier l???effet de la NAVAn et de la VOHFn sur la dynamique laryng??e chez les agneaux nouveau-n??s sans s??dation, en testant l???hypoth??se que, contrairement ?? l???AIn, la fermeture laryng??e active n???apparait pas durant la NAVAn et la VOHFn. M??THODES : deux groupes d???agneaux n??s ?? terme (NAVAn : 8 agneaux ; et VOHFn : 7 agneaux) ont ??t?? instrument??s chirurgicalement ?? 2 jours de vie, afin de recueillir l?????lectromyogramme des muscles constricteur et dilatateur laryng??s, du diaphragme, les pressions au masque, trach??ale, pression de CO[indice inf??rieur 2] en fin d???expiration (P[indice inf??rieur ET]CO[indice inf??rieur 2]) et des gaz sanguins art??riels. 48h suivant l???instrumentation, un enregistrement polysomnographique a ??t?? r??alis?? pour chaque groupe (AIn / VOHFn et AIn / NAVAn) dans un ordre randomis??. La pression inspiratoire (AIn & NAVAn) et la puissance des oscillations (VOHFn) ont ??t?? progressivement augment??es. R??SULTATS : Les r??sultats d??montrent que l???augmentation des niveaux de NAVAn et de la puissance de VOHFn n???entraine pas de fermeture laryng??e active, contrairement ?? l???AIn. De plus, la diminution du PaCO[indice inf??rieur 2] provoqu??e par l???hyperventilation en AIn pourrait contribuer ?? la fermeture laryng??e active. En VOHFn, la diminution progressive de la fr??quence des oscillations jusqu????? 4 Hz induit des apn??es centrales. En revanche, aucune fermeture laryng??e active n???a ??t?? observ??e ?? 4 Hz. CONCLUSION : La NAVAn et la VOHFn ne provoquent pas la fermeture laryng??e active chez l???agneau nouveau-n??, et pourraient constituer des nouvelles alternatives dans le traitement des pathologies respiratoires en p??riode n??onatale. //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.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QSHERU.3/121 |
| Date | January 2014 |
| Creators | Hadj Ahmed, Mohamed Amine |
| Contributors | Praud, Jean-Paul |
| Publisher | Universit?? de Sherbrooke |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | French |
| Detected Language | French |
| Type | Th??se |
| Rights | ?? Mohamed Amine Hadj Ahmed |
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