Effects of nasal continuous positive airway pressure on nutritive swallowing in lambs

Current knowledge suggests that, to be successful, oral feeding in preterm infants should be initiated as soon as possible, often at an age where immature respiration still requires ventilatory support in the form of nasal continuous positive airway pressure (nCPAP). While some neonatologist teams claim great success with initiation of oral feeding in immature infants with nCPAP, others strictly wait for this ventilatory support to be no longer necessary before any attempt at oral feeding, fearing laryngeal penetration and tracheal aspiration. Therefore, the aim of the present study was to provide a first assessment of the effect of various levels of nCPAP on bottle-feeding in a neonatal ovine model, including feeding safety, feeding efficiency, and nutritive swallowing-breathing coordination. Eight lambs born at term were surgically instrumented 48 h after birth to collect recordings of electrical activity of laryngeal constrictor muscle, electrocardiography, and arterial blood gases. Two days after surgery, lambs were bottle-fed under five randomized nCPAP conditions, including without any nCPAP or nasal mask and nCPAP of 0, 4, 7, and 10 cmH(2)O. Results revealed that application of nCPAP in the full-term lamb had no deleterious effect on feeding safety and efficiency or on nutritive swallowing-breathing coordination. The present study provides a first and unique insight on the effect of nCPAP on oral feeding, demonstrating its safety in newborn lambs born at term. These results open the way for further research in preterm lambs to better mimic the problems encountered in neonatology

Laryngeal muscle activity during nasal high frequency oscillatory ventilation in non-sedated newborn lambs

Background: We have previously shown that nasal pressure support ventilation (nPSV) can lead to an active inspiratory laryngeal narrowing in lambs. This, in turn, can limit lung ventilation and divert air into the digestive system, with potentially deleterious consequences. On the other hand, nasal high-frequency oscillatory ventilation (nHFOV) is particularly attractive in newborns, especially since, unlike nPSV, it does not require synchronization with the patient's inspiratory efforts. Objectives: The main aim of the present study was to test the hypothesis that glottal constrictor muscle activity (EMG) does not develop during nHFOV. A secondary objective was to study laryngeal EMG during nHFOV-induced central apneas. Methods: Polysomnographic recordings were performed in 7 nonsedated lambs which were ventilated with increasing levels of nPSV and nHFOV at both 4 and 8 Hz, in random order. States of alertness, diaphragm and glottal muscle EMG, SpO2, and respiratory movements were continuously recorded. Results: While phasic inspiratory glottal constrictor EMG appeared with increasing nPSV levels in 6 out of 7 lambs, it was never observed with nHFOV. In addition, nHFOV at 4 Hz dramatically inhibited central respiratory drive in 4/7 lambs, with 64-100% of recording time spent in central apnea in 3 lambs. No glottal constrictor EMG was observed during these central apneas. Conclusion: nHFOV does not induce glottal constrictor muscle EMG in nonsedated newborn lambs, in contrast to nPSV. This may be an additional advantage of nHFOV relative to nPSV

Absence of inspiratory laryngeal constrictor muscle activity during nasal neurally adjusted ventilatory assist in newborn lambs

It has been demonstrated that a progressive increase in nasal pressure support ventilation (nPSV) leads to an active inspiratory glottal closure in non-sedated newborn lambs, which limits lung ventilation (24, 33). Unlike nPSV, the pressure delivered during nasal Neurally Adjusted Ventilatory Assist (nNAVA) is synchronized to the diaphragm electrical activity on inspiration (36). Given the tight neural integration of the glottal dilators and constrictors with diaphragm activity on inspiration and expiration respectively, the aim of the present study was to test the hypothesis that inspiratory glottal closure does not develop during nNAVA. Polysomnographic recordings were performed in eight non-sedated, chronically instrumented lambs, which were ventilated with progressively increasing levels of nPSV and nNAVA, in random order. States of alertness, diaphragm and glottal muscle electrical activity, tracheal pressure, SpO2, tracheal PETCO2 and respiratory inductive plethysmography were continuously recorded. While phasic inspiratory glottal constrictor electrical activity appeared with increasing levels of nPSV in 5 out of 8 lambs, it was never observed at any nNAVA level in any lamb, even at maximal achievable nNAVA levels. In addition, a decrease in arterial PCO2 was neither necessary nor sufficient for the development of phasic inspiratory glottal constrictor activity. In conclusion, nNAVA does not induce active glottal closure in non-sedated newborn lambs at high-pressure levels, in contrast to nPSV

Laryngeal dynamics during non-conventional nasal ventilation by neurally adjusted ventilatory assist (NAVA) and high frequency oscillatory ventilation (HFOV) in non-sedated newborn lambs

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

Laryngeal dynamics during non-conventional nasal ventilation by neurally adjusted ventilatory assist (NAVA) and high frequency oscillatory ventilation (HFOV) in non-sedated newborn lambs

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

Maintenance of a Spanning Tree For Dynamic Graphs by Mobile Agents and Local Computations

The problem of constructing and maintaining a spanning tree in dynamic networks is important in distributed systems. Trees are essential structures in various communication protocols such as information broadcasting, routing, etc. In a distributed computing environment, the solution of this problem has many practical motivations. To make designing distributed algorithm easier, we model this latter with a local computation model. Based on the mobile agent paradigm, we present in this paper a distributed algorithm that maintain a hierarchical spanning tree in dynamic networks. We study all topological events that may affect the structure of the spanning tree: we address the appearance and the disappearance of places and communication channels

Codage d'algorithmes distribués d'agents mobiles à l'aide de calculs locaux

De nos jours, les systèmes distribués doivent répondre de plus en plus à de nouvelles exigences de qualité de service et à l émergence de nouvelles applications comme le calcul sur la grille ; ce qui généralement se traduit par des impératifs de dynamicité et de mobilité. Si des solutions satisfaisantes existent pour des environnements distribués statiques, elles sont inadaptées dans le cas où le système devient dynamique (mobilité, évolution, modification de composants). En effet, la conception d algorithmes distribués est traditionnellement fondée sur l hypothèse d un réseau dont la topologie est statique. Notre objectif dans cette thèse est de définir et d étudier un modèle à base d agents mobiles pour l implémentation et l exécution d algorithmes distribués codés par des calculs locaux.Ce modèle doit tenir en compte des pannes qui peuvent altérer le fonctionnement du système distribué. Il doit aussi améliorer les performances vis-à-vis des modèles classiques (à envoi de messages)Today, distributed systems must satisfy increasinglynew requirements for quality of service and the emergence ofnew applications such as Grid Computing, whichgenerally results in requirements of dynamicity andmobility. If satisfactory solutions exist forstatic distributed environments, they are inadequate in the casewhere the system becomes dynamic (mobility, evolution,components change). Indeed, the design of distributed algorithms istraditionally based on the assumption of a network whosetopology is static. Our goal, in this thesis, is to defineand study a model based on mobile agents to implementand execute distributed algorithms encoded by local computations.This model must take into account failures that can alter thethe distributed system operation. It should also improveperformance vis-à-vis the classical models (message passing systems)BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF

Characterization of Fluorescent Rhizobacteria Isolated From Oleander (Nerium oleander L.) and Olivier (Olea oleaster L.) With Antagonistic Effect Against Fusarium oxysporum f. sp. radicis-lycopersici

This study aims to characterize the biocontrol potential of two fluorescent rhizobacteria isolated from Oleander (Nerium oleander L.) and Olivier (Olea oleaster L.). The isolation was done in Cetrimide agar. The fluorescing strains at 366 nm were selected for the dual plate assay against the tomato pathogen Fusarium oxysporum f.sp. radicis-lycopersici. The two best strains showing the highest inhibition rates (Pa2 and S2Pf1 with 31.36% and 51.42% respectively) were chosen to be identified and characterized for their production of antifungal molecules. The taxonomical determination based on macro and micromorphological observations in addition to the biochemical tests of the API 20E and API 20NE strips analyzed by the heuristic soft "PIBwin 2.0.0" suggests the strain Pa2 as a Pseudomonas aeruginosa while the strain S2Pf1 belongs to the Burkholderia cepacia species. The antifungal potential was assessed through the quantification/detection of the following bioactive molecules: salicylic acid, hydrogen cyanide, rhamnolipids, chitinases, and cellulases. The strain Burkholderia cepacia S2Pf1 showed a better antifungal profile in comparison to Pseudomonas aeruginosa Pa2. The determination of the growth kinetics parameters of Burkholderia cepacia S2Pf1 based on observed OD600 data, DModel data fitting, and Gompertz model data fitting highlighted a relatively good ability to quickly reach high bacterial densities in both nutrient and seed broths. Thus, Burkoledria cepacia S2Pf1 is suggested as a good candidate to be further assessed for its biocontrol proprieties against Fusarium oxysporum f.sp. radicis-lycopersici

Abstracts of 1st International Conference on Computational & Applied Physics

This book contains the abstracts of the papers presented at the International Conference on Computational & Applied Physics (ICCAP’2021) Organized by the Surfaces, Interfaces and Thin Films Laboratory (LASICOM), Department of Physics, Faculty of Science, University Saad Dahleb Blida 1, Algeria, held on 26–28 September 2021. The Conference had a variety of Plenary Lectures, Oral sessions, and E-Poster Presentations. Conference Title: 1st International Conference on Computational & Applied PhysicsConference Acronym: ICCAP’2021Conference Date: 26–28 September 2021Conference Location: Online (Virtual Conference)Conference Organizer: Surfaces, Interfaces, and Thin Films Laboratory (LASICOM), Department of Physics, Faculty of Science, University Saad Dahleb Blida 1, Algeria