Étude comparative des performances des ventilateurs de domicile et analyse des interactions patient-ventilateur en ventilation non invasive

La ventilation non invasive constitue une modalité de traitement de l’insuffisance respiratoire chronique suffisamment prescrite pour motiver des études sur banc d’essai afin d’évaluer et de comparer les performances des ventilateurs. Pour que les évaluations soient fiables et reproductibles, nous avons revisité de nombreux aspects des études sur poumon mécanique et développé une procédure paramétrique de tests des ventilateurs. Nous avons commencé par modéliser un effort inspiratoire physiologique qui, lorsqu’il gouverne trois modèles pulmonaires physiopathologiques distincts, permet de simuler une cohorte réaliste de patients. L’élaboration de cette procédure a nécessité la définition d’une terminologie claire et motivée, ainsi que l’uniformisation des conditions de tests des ventilateurs. Il a ainsi été rendu possible de caractériser la synchronisabilité des ventilateurs, définie comme leur capacité à se synchroniser aux différents modèles pulmonaires testés. Ces performances dépendent à la fois de la mécanique et de la dynamique pulmonaires. La création de fiches techniques et d’outils de comparaison des ventilateurs, mis à la disposition des praticiens sur un site dédié, devrait faciliter le choix d’un dispositif d’assistance ventilatoire adapté à chaque patient. Ce travail s’appuie en outre sur un modèle dynamique d’interactions patient-ventilateur ayant permis de dresser une revue des asynchronismes mais également d’en comprendre les mécanismes sous-jacents. La mise en relation des résultats théoriques et expérimentaux offre une perspective d’identification des stratégies de fonctionnement des ventilateurs et d’optimisation des interactions patient-ventilateur.Noninvasive ventilation can be defined as a modality of treatment for chronic respiratory failure. Nowadays, it is sufficiently often prescribed to motivate test bench studies whose objectives are to evaluate and compare ventilators performances. To provide reliable and reproducible assessments, we revisited many aspects of test bench studies and developed a parametric procedure for testing ventilators. We initially focused our attention on the modeling of a physiological inspiratory effort which, when driving three pathophysiological lung models, allows to simulate a realistic cohort of patients. The development of this procedure required to introduce a clear and motivated terminology, as well as to unify the parameter settings of the ventilators. It was then possible to characterize the ventilators synchronizability, defined as the ability of the device to synchronize with the different pulmonary models it was connected to. These performances depend on the mechanics and dynamics of the lung model. Providing the practitioners with reports and tools for comparing ventilators on a dedicated website should facilitate the choice of a ventilatory assistance device adapted to each patient. This works was also devoted to the use of a dynamical model for the patient-ventilator system which allowed us not only to review most of the asynchrony events observed in clinics but also to explain their underlying mechanisms. Linking theoretical and experimental results offers us a perspective for identifying the ventilators operating strategies, a required step to improve patient-ventilator interactions

LATE-BREAKING ABSTRACT: A parametric procedure to compare domiciliary ventilator performances

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Performances of domiciliary ventilators compared by using a parametric procedure

WOS:000379882100001International audienceBackground: Noninvasive mechanical ventilation is sufficiently widely used to motivate bench studies for evaluating and comparing performances of the domiciliary ventilators. In most (if not in all) of the previous studies, ventilators were tested in a single (or a very few) conditions, chosen to avoid asynchrony events. Such a practice does not reflect how the ventilator is able to answer the demand from a large cohort of patients with their inherent inter-patient variability. We thus developed a new procedure according which each ventilator was tested with more than 1200 "simulated" patients. Methods: Three lung mechanics (obstructive, restrictive and normal) were simulated using a mechanical lung (ASL 5000) driven by a realistic muscular pressure. 420 different dynamics for each of these three lung mechanics were considered by varying the breathing frequency and the mouth occlusion pressure. For each of the nine ventilators tested, five different parameter settings were investigated. The results are synthesized in colored maps where each color represents the ventilator (in) ability to synchronize with a given muscular pressure dynamics. A synchronizability e is then computed for each map. Results: The lung model, the breathing frequency and the mouth occlusion pressure strongly affect the synchronizability of ventilators. The Vivo 50 (Breas) and the SomnoVENT autoST (Weinmann) are well synchronized with the restrictive model ((epsilon) over bar = 86 and 78 %, respectively), whereas the Elisee 150 (ResMed), the BiPAP A40 and the Trilogy 100 (Philips Respironics) better fit with an obstructive lung mechanics ((epsilon) over bar = 87, 86 and 86 %, respectively). Triggering and pressurization performances of the nine ventilators present heterogeneities due to their different settings and operating strategies. Conclusion: Performances of domiciliary ventilators strongly depend not only on the breathing dynamics but also on the ventilator strategy. One given ventilator may be more adequate than another one for a given patient

Realistic human muscle pressure for driving a mechanical lung

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A dynamical model for patient-ventilator interactions during noninvasive ventilation

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Prediction of severe acute exacerbation using changes in breathing pattern of COPD patients on home noninvasive ventilation

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Defining successful non‐invasive ventilation initiation: Data from a real‐life cohort

International audienceBackground and objective: When home non-invasive ventilation (NIV) is initiated, five goals need to be achieved: a daily use >4 h/day, an improvement in gas exchange, health-related quality of life (HRQL) and sleep quality without side effects. Our aim was to assess how frequently these five goals were reached and the factors predictive of achievement.Methods: We conducted a monocentric cohort study that included patients electively established on home NIV over 2 years. HRQL was assessed at baseline and follow-up by the Severe Respiratory Insufficiency questionnaire. Adequate initiation was defined as the achievement of at least three of five goals and successful initiation as the achievement of all.Results: Two-hundred and fifty patients were included at baseline. NIV was initiated for: obesity hypoventilation syndrome (n = 95; 38%), neuromuscular disease (n = 70; 28%), chronic obstructive pulmonary disease (n = 66; 26%) and chest wall disease (n = 19; 8%). At follow-up, measures of all five goals were available in 141 (56%) patients. NIV initiation was adequate for 96 (68%) patients and successful for 12 (9%) patients. In multivariate analysis, a tidal volume ≥ 7.8 ml/kg of ideal body weight was associated with an increased likelihood of adequate NIV initiation (hazard ratio: 5.765 [95% CI:1.824–18.223], p = 0.006]. Improvement in daytime partial arterial carbon dioxide pressure (PaCO2) was not correlated to improvement in HRQL or sleep quality. Severe to very severe NIV-related side effects occurred in 114 (47%) patients and were associated with higher daytime PaCO2 (6.35 ± 1.08 vs. 5.92 ± 0.79 kPa, p < 0.001).Conclusion: Successful home NIV initiation is rarely achieved in real life. HRQL and NIV tolerance should be assessed to improve patient-centred outcomes

Detection of Simulated Pediatric Breathing by CPAP/Noninvasive Ventilation Devices

International audienceBACKGROUND: Home CPAP and noninvasive ventilation (NIV) are increasingly used in children. An appropriate choice of the CPAP/NIV device, according to the manufacturer recommendations, should guarantee accurate data collection software. However, not all devices display accurate patient data. We hypothesized that the detection of patient breathing may be expressed as a minimal tidal volume (VTmin ) rather than a minimal weight. The aim of the study was to estimate the VTmin detected by home ventilators when set on CPAP. METHODS: Twelve level I-III devices were analyzed using a bench test. Pediatric profiles were simulated with increasing VT values to determine the VTmin that the ventilator may detect. The duration of CPAP use and the presence/absence of waveform tracings on the built-in software were also gathered. RESULTS: VTmin varied according to the device, ranging from 16-84 mL, independent of level category. The duration of CPAP use was underestimated in all level I devices, which were either not able to display any waveform or only intermittently, until VTmin was reached. The duration of CPAP use was overestimated for the level II and III devices, with the display of different waveforms according to the device as soon as the device was switched on. CONCLUSIONS: Based on the VTmin detected, some level I and II devices may be suitable for infants. A careful testing of the device should be done at CPAP initiation, with a review of data generated from ventilator software. Copyrigh

Responses of Bilevel Ventilators to Unintentional Leak: A Bench Study

International audienceBackground: The impact of leaks has mainly been assessed in bench models using continuous leak patterns which did not reflect real-life leakage. We aimed to assess the impact of the pattern and intensity of unintentional leakage (UL) using several respiratory models. Methods: An active artificial lung (ASL 5000) was connected to three bilevel-ventilators set in pressure mode; the experiments were carried out with three lung mechanics (COPD, OHS and NMD) with and without upper airway obstruction. Triggering delay, work of breathing, pressure rise time, inspiratory pressure, tidal volume, cycling delay and the asynchrony index were measured at 0, 6, 24 and 36 L/min of UL. We generated continuous and inspiratory UL. Results: Compared to 0 L/min of UL, triggering delays were significantly higher with 36 L/min of UL (+27 ms) and pressure rise times were longer (+71 ms). Cycling delays increased from −4 [−250–169] ms to 150 [−173–207] ms at, respectively 0 L/min and 36 L/min of UL and work of breathing increased from 0.15 [0.12–0.29] J/L to 0.19 [0.16–0.36] J/L. Inspiratory leakage pattern significantly increased triggering delays (+35 ms) and cycling delays (+263 ms) but decreased delivered pressure (−0.94 cmH2O) compared to continuous leakage pattern. Simulated upper airway obstruction significantly increased triggering delay (+199 ms), cycling delays (+371 ms), and decreased tidal volume (−407 mL) and pressure rise times (−56 ms). Conclusions: The pattern of leakage impacted more the device performances than the magnitude of the leakage per se. Flow limitation negatively reduced all ventilator performances

Se requieren altos índices de flujo de O2 para alcanzar una FiO2 aceptable en los pacientes con covid-19 tratados con CPAP: un estudio experimental basado en la clínica

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