245 research outputs found

    A model-based approach for the evaluation of vagal and sympathetic activities in a newborn lamb.

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    International audienceThis paper proposes a baroreflex model and a recursive identification method to estimate the time-varying vagal and sympathetic contributions to heart rate variability during autonomic maneuvers. The baroreflex model includes baroreceptors, cardiovascular control center, parasympathetic and sympathetic pathways. The gains of the global afferent sympathetic and vagal pathways are identified recursively. The method has been validated on data from newborn lambs, which have been acquired during the application of an autonomic maneuver, without medication and under beta-blockers. Results show a close match between experimental and simulated signals under both conditions. The vagal and sympathetic contributions have been simulated and, as expected, it is possible to observe different baroreflex responses under beta-blockers compared to baseline conditions

    Étude des altĂ©rations du contrĂŽle cardiorespiratoire chez des modĂšles ovins de pathologies nĂ©onatales

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    Introduction : L'implication des RGO dans les Ă©vĂ©nements cardiorespiratoires des prĂ©maturĂ©s reste controversĂ©e. Bien que quelques Ă©tudes rĂ©alisĂ©es sur des animaux nouveau-nĂ©s Ă  terme ou adultes aient montrĂ© que la stimulation des rĂ©cepteurs Ɠsophagiens entraine des rĂ©flexes cardiorespiratoires inhibiteurs, l’impact d’une naissance prĂ©maturĂ©e sur ces derniers demeure inconnu. L’article 1 vise Ă  tester l’hypothĂšse selon laquelle la naissance prĂ©maturĂ©e augmente l'inhibition cardiorespiratoire lors d’une stimulation oesophagienne. Le sepsis nĂ©onatal est Ă  l’origine d’une mortalitĂ© substantielle, en partie en raison de ses consĂ©quences sur le contrĂŽle cardiorespiratoire. Les rĂ©ponses au sepsis nĂ©onatal sont variables et peuvent expliquer un faible diagnostic pendant la phase initiale de l'infection. L'implication du sepsis nĂ©onatal sur le contrĂŽle cardiorespiratoire reste mal connue. L’article 2 vise Ă  comprendre davantage le lien entre l’inflammation accompagnant un sepsis nĂ©onatal et les altĂ©rations cardiaques et respiratoires. MĂ©thodes : Article 1. Huit agneaux nĂ©s Ă  terme et dix agneaux nĂ©s 14 jours prĂ©maturĂ©ment ont Ă©tĂ© Ă©tudiĂ©s. Une polysomnographie a Ă©tĂ© rĂ©alisĂ©e pour suivre en continu l’ECG, la respiration, la pression artĂ©rielle systĂ©mique, les stades de conscience et la saturation en O2. Cinq stimulations de l'Ɠsophage supĂ©rieur et/ou infĂ©rieur, incluant l'inflation rapide par ballonnet et/ou l'injection d’HCl, ont Ă©tĂ© effectuĂ©es dans un ordre alĂ©atoire. Article 2. Deux polysomnographies de six heures ont Ă©tĂ© rĂ©alisĂ©es sur deux jours consĂ©cutifs chez huit agneaux. La premiĂšre a Ă©tĂ© effectuĂ©e suivant une injection IV de solution saline, et la deuxiĂšme aprĂšs une injection IV de 2,5 ÎŒg/kg de lipopolysaccharides (LPS). La tempĂ©rature, les gaz du sang artĂ©riel, les stades de conscience, l'activitĂ© locomotrice, les frĂ©quences respiratoire et cardiaque (FR et FC), la variabilitĂ© cardiaque et respiratoire (VFC et VFR), la pression artĂ©rielle systĂ©mique, les apnĂ©es et les ralentissements cardiaques ont Ă©tĂ© Ă©valuĂ©s. RĂ©sultats : Les stimulations Ɠsophagiennes induisent des rĂ©flexes cardiorespiratoires inhibiteurs (apnĂ©es, bradycardies, dĂ©saturations en oxygĂšne) qui sont amplifiĂ©s par la naissance prĂ©maturĂ©e. L'inhibition cardiorespiratoire la plus importante est observĂ©e suite Ă  une stimulation simultanĂ©e de l'Ɠsophage infĂ©rieur et supĂ©rieur. L’injection de LPS induit des altĂ©rations cliniques (augmentation biphasique de la tempĂ©rature et diminution de la mobilitĂ© et de l’éveil agitĂ©) et cardiorespiratoires (augmentation de la FR et de la FC et diminution de la VFC et de la VFR) en plus d’une inflammation du tronc cĂ©rĂ©bral. Conclusion : La stimulation Ɠsophagienne entraine une augmentation des Ă©vĂ©nements cardiorespiratoires chez les agneaux prĂ©maturĂ©s, probablement en raison de l'immaturitĂ© globale du systĂšme nerveux. L'injection de LPS entraine une inflammation systĂ©mique mimant un sepsis bactĂ©rien chez les agneaux avec de multiples consĂ©quences, y compris des altĂ©rations cardiorespiratoires

    Cardiac vagal tone in complex PTSD : a polyvagal perspective.

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    Differences in functionality, impairment, and symptoms provide support for a nosological distinction between Complex PTSD and PTSD. Based on this information, the next step is to examine biological characteristics between the populations, thus bolstering the evidence supporting the uniqueness of these symptom expressions and associated etiologies. The proposed study is the first of its kind to do this, by examining theoretically derived potential differences between these populations. This investigation proposes the polyvagal theory as a comprehensive model through which one can examine psychological and physiological differences to demonstrate a systemic perspective of Complex PTSD. The primary distinguishing characteristic of Complex PTSD is the global symptom expression, disrupting multiple domains of functionality - relationships, emotions, and self-perception. From a polyvagal perspective, interpersonal problems and affect dysregulation are described by the same affective system -faulty neuroception, causing dysregulation in the hierarchical behavioral strategies. Physiologically, this dysregulation removes the neural inhibitory mechanism (cardiac vagal tone or vagal brake), while promoting one of the primal defensive strategies as autonomic regulator. Observations of the cardiopulmonary oscillator was expected to reveal differences between Complex PTSD, PTSD, and control samples. Hypotheses were confirmed, indicating that vagal brake does not reengage in the post-task resting period in the clinical groups, Complex PTSD and PTSD. Moreover, average RSA is lowest in the Complex PTSD group, as anticipated, given the severe affect dysregulation and social dysfunction evident in the symptomology

    Parental sensitivity, family alliance and infants' vagal tone: Influences of early family interactions on physiological emotion regulation

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    In this study, we investigated the influence of parental sensitivity and family alliance on infants’ vagal tone, considered as a physiological indicator of emotion regulation. Studies on mother–infant interactions have shown that vagal tone can be influenced by the quality of the interaction, such as interacting with a sensitive mother. To date, no study has investigated the influence of paternal sensitivity or family alliance on infants’ vagal tone. We hypothesized that maternal sensitivity, paternal sensitivity, and family alliance would be associated with infants’ vagal tone during dyadic and triadic interactions. We also explored if family alliance would act as a moderator on the association between parental sensitivity and vagal tone and if the sensitivity of both parents would act as a moderator on the association between family alliance and vagal tone. This study took place in Switzerland and included 82 families with their 3–4-month-old infants. Results showed that maternal sensitivity and family alliance were associated with infants’ vagal tone, but paternal sensitivity was not. We found no significant moderation effect. However, result tendencies suggested that the contribution of paternal sensitivity to infants’ emotion regulation could be influenced by family alliance, whereas maternal sensitivity and family alliance have a unique contribution

    Flight simulator for training gynaecologists:a mathematical model of the cardiotocogram for use in simulation training

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    Due to the high complexity and low incidences of emergencies during labor and delivery, gynaecologists often cannot rely on previous experiences during a crisis. Simulation training can provide both experience and skills in a safe environment, such that complications due to emergencies can be reduced as much as possible. Several simulators are available that support a safe learning environment for obstetric emergency training. However, none provides a realistic and physiology-based (simulation of) the cardiotocogram (CTG), which is a continuous and synchronous registration of uterine contractions and fetal heart rate. However, at the labor and delivery ward, the CTG is widely used as main indicator for fetal welfare. The CTG provides information on the fetal stress reaction to uterine contractions, based on oxygen levels in the fetal blood. Since the CTG is widely available and the only non-invasive method for fetal monitoring, medical decisions are often based on deviations in the CTG. The CTG is therefore an essential part of the clinical environment in medical simulation training. In a one-year clinical project as part of a qualified medical engineer training, a start is made with the development of a CTG simulator. The three main deviations in the CTG were studied: early, late and variable decelerations in fetal heart rate, caused by uterine contractions and complications in labor. The mechanism of these three deceleration types were studied, and each step was quantified for early and late decelerations. In this project, early decelerations were implemented in a mathematical model, based on the underlying physiological principles. In future, implementation of late and variable decelerations are planned within a PhD-project. A validation study was performed for the modeled CTG, where a comparison was made between real and computer-generated CTG tracings from our model, based on experts' opinion. The first results show no significant differences between real and computer-generated CTG tracings. However, the number of clinical experts was low, and a larger study has to be performed to confirm these results. Coupling of the modeled CTG to a simulator interface is planned in future. The model can be implemented in different types of simulators: in a screen-based simulator (individual in-depth training to improve insight into and interpretation of the CTG), as part of a full-body delivery simulator, and as part of a serious game (in these two cases the CTG is part of the clinical environment). Future plans include implementation in a screen-based simulator and a full-body delivery simulato

    The effects of mild hypoxaemia on hypoglossal motoneurone activity in neonates

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    Introduction: Apneic episodes and consequent hypoxaemia are common features of breathing in high- risk neonates. Apneas of central origin (no respiratory effort) usually terminate with an obstructive component due to collapse of the upper airway. The genioglossus muscle, the main protruder muscle of the tongue, plays a crucial role in maintaining upper airway patency by opposing the negative intra-airway pressure generated during contraction of the diaphragm and by preventing the tongue blocking the oropharyngeal opening. In adults, the respiratory-related activity of the hypoglossal nerve (the motoneurone of the genioglossus) increases during hypoxaemia in order to maintain upper airway patency. However, in neonates it has been shown that the genioglossus muscle during hypoxia is age-related and this increased activity is not sustained. In neonates, little is known about how the hypoglossal motoneurones respond to hypoxaemia and the role of hypoglossal motoneurones during hypoxia in the maintenance of upper airway patency. Aim: The aim of this study was to determine the effects of hypoxaemia on hypoglossal motoneurones in neonates. Methods: Extracellular and intracellular recordings were made from hypoglossal motoneurones in vagotomized and vagi-intact neonatal kittens during normoxia and hypoxia. Results: The results showed: (1) the majority of hypoglossal motoneurones either decreased their discharge frequency or had only a transient increase during hypoxia. (2) During intracellular recordings, the membrane potential showed a sustained depolarisation during hypoxaemia in most cases and respiratory-related rhythmic EPSP activity was reduced in amplitude. The membrane impedance of these motoneurones increased and the excitability was reduced. (3) During upper airway stimulation, the amplitude of the laryngeal-evoked potentials was reduced during hypoxia. Conclusions: My results demonstrate that, in neonates, hypoglossal motoneurone activity is inhibited during hypoxia and the hypoglossal-upper airway reflexes are also inhibited. The probable consequence of such inhibition, for the newborn human infant, would be the failure of the maintenance of upper airway patency, thus leading to obstructive apnea. The mechanisms mediating the inhibition of hypoglossal motoneurones during hypoxia remain to be determined
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