57 research outputs found

    Neurally adjusted ventilatory assist in patients with critical illness-associated polyneuromyopathy

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    Purpose: Diaphragmatic electrical activity (EAdi), reflecting respiratory drive, and its feedback control might be impaired in critical illness-associated polyneuromyopathy (CIPM). We aimed to evaluate whether titration and prolonged application of neurally adjusted ventilatory assist (NAVA), which delivers pressure (P aw) in proportion to EAdi, is feasible in CIPM patients. Methods: Peripheral and phrenic nerve electrophysiology studies were performed in 15 patients with clinically suspected CIPM and in 14 healthy volunteers. In patients, an adequate NAVA level (NAVAal) was titrated daily and was implemented for a maximum of 72h. Changes in tidal volume (V t) generation per unit of EAdi (V t/EAdi) were assessed daily during standardized tests of neuro-ventilatory efficiency (NVET). Results: In patients (median [range], 66 [44-80]years), peripheral electrophysiology studies confirmed CIPM. Phrenic nerve latency (PNL) was prolonged and diaphragm compound muscle action potential (CMAP) was reduced compared with healthy volunteers (p<0.05 for both). NAVAal could be titrated in all but two patients. During implementation of NAVAal for 61 (37-64)h, the EAdi amplitude was 9.0 (4.4-15.2)ÎŒV, and the V t was 6.5 (3.7-14.3)ml/kg predicted body weight. V t, respiratory rate, EAdi, PaCO2, and hemodynamic parameters remained unchanged, while PaO2/FiO2 increased from 238 (121-337) to 282 (150-440)mmHg (p=0.007) during NAVAal. V t/EAdi changed by −10 (−46; +31)% during the first NVET and by −0.1 (−26; +77)% during the last NVET (p=0.048). Conclusion: In most patients with CIPM, EAdi and its feedback control are sufficiently preserved to titrate and implement NAVA for up to 3days. Whether monitoring neuro-ventilatory efficiency helps inform the weaning process warrants further evaluatio

    Effects of Neurally Adjusted Ventilatory Assist (NAVA) levels in non-invasive ventilated patients: titrating NAVA levels with electric diaphragmatic activity and tidal volume matching

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    BACKGROUND: Neurally adjusted ventilatory assist (NAVA) delivers pressure in proportion to diaphragm electrical activity (Eadi). However, each patient responds differently to NAVA levels. This study aims to examine the matching between tidal volume (Vt) and patients' inspiratory demand (Eadi), and to investigate patient-specific response to various NAVA levels in non-invasively ventilated patients. METHODS: 12 patients were ventilated non-invasively with NAVA using three different NAVA levels. NAVA100 was set according to the manufacturer's recommendation to have similar peak airway pressure as during pressure support. NAVA level was then adjusted ±50% (NAVA50, NAVA150). Airway pressure, flow and Eadi were recorded for 15 minutes at each NAVA level. The matching of Vt and integral of Eadi (ʃEadi) were assessed at the different NAVA levels. A metric, Range90, was defined as the 5-95% range of Vt/ʃEadi ratio to assess matching for each NAVA level. Smaller Range90 values indicated better matching of supply to demand. RESULTS: Patients ventilated at NAVA50 had the lowest Range90 with median 25.6 uVs/ml [Interquartile range (IQR): 15.4-70.4], suggesting that, globally, NAVA50 provided better matching between ʃEadi and Vt than NAVA100 and NAVA150. However, on a per-patient basis, 4 patients had the lowest Range90 values in NAVA100, 1 patient at NAVA150 and 7 patients at NAVA50. Robust coefficient of variation for ʃEadi and Vt were not different between NAVA levels. CONCLUSIONS: The patient-specific matching between ʃEadi and Vt was variable, indicating that to obtain the best possible matching, NAVA level setting should be patient specific. The Range90 concept presented to evaluate Vt/ʃEadi is a physiologic metric that could help in individual titration of NAVA level.Peer reviewe

    The effectiveness and safety of neurally adjusted ventilatory assist iviechanical ventilation compared to pressure support ventilation in optimizing patient venfilator synchrony in critically ill patients: a systematic review and meta-analysis

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    Background: Patient ventilator dyssynchrony is a physical characteristic of suboptimal interaction between patient and ventilator. Some primary clinical studies using neurally adjusted ventilatory assist compared to pressure support suggest it improves patient ventilator synchrony and reduces hospital mortality. With conflicting study outcomes, a systematic review of the effectiveness and safety of neutrally adjusted ventilatory assist is warranted. Objectives: This systematic review aimed to evaluate the effectiveness of neutrally adjusted ventilatory assist (NAVA) compared to pressure support ventilation (PSV) in optimizing patient ventilator synchrony in critically ill adult patients in intensive care unit (ICU). Methods: Seven databases ; the Cochrane Central Register of Controlled Trials, MEDLINE (PubMed), EMBASE, SCOPUS, ClinicalTrials.gov, Web of Science and CINAHL were searched using the following terms: neurally adjusted ventilatory assist, NAVA, neural trigger, interactive ventilatory support, respiration, artificial, mechanical ventilation, patient ventilator asynchrony, synchrony, asynchrony, dyssynchrony. The last search was conducted in April 2018. This review included studies that evaluated the use of NAVA compared with PSV in adult patients who required invasively mechanical ventilation. Outcomes of interest included the frequency of patient ventilator dyssynchrony (PVD) and mortality from all causes. The methodological quality of included studies was assessed, and the data were extracted by using standard forms. Standardized mean differences (SMDs) were calculated for continuous data and risk ratios for dichotomous data, both with 95% CIs. Results: A total of 1,078 articles were identified, for which 210 full text articles were reviewed. In total 17 studies met inclusion criteria. The outcome data were available for approximately 90% of participant (n=398). Neurally adjusted ventilatory assist significantly reduced the AI% by nearly one half of standard deviation; SMD 0.401, 95% CI 0.223 to 0.57, p value 0.000 and I2 0.00% (fixed effect model; two RCTs,128 participants). It was maintained in crossover study group ; SMD 0.304, 95% CI: 0.079 to 0.528, p value 0.008 and I2 75.85% (random effects model, 13 crossover studies, 347 participants). The reduction of the AI% estimated effect size was found to be larger in a sedated group; SMD 0.413, 95% CI: 0.125 to 0.702, p value 0.005 and I2 71.24% than a non-sedated group; SMD 0.225, 95% CI: - 0.208 to 0.659, p value 0.308 and I2 86.76% (random effects model, 10 studies, 248 participants). In addition, a higher reduction of AI% effect size was found in a treatment duration longer than an hour group; SMD 0.413, 95% CI:0.044 to 0.782, p value 0.028 and I2 0.00% than a shorter than an hour group; SMD 0.287, 95% CI:0.069 to 0.505, p value 0.010 and I2 77.62% ( random effects model, 13 studies,301 participants). Similarly, in a 20- minute and longer PVD event-measurement time group found that NAVA reduced AI% more than in a shorter than 20-minute PVD event -measurement time group; SMD 0.389, 95% CI: 0.109 to 0.668, p value 0.006 and I2 0.00% and SMD 0.267, 95% CI: 0.024 to 0.510, p value 0.031 and I2 82.18%, respectively ( random effects model, 13 studies, 301 participants). Neurally adjusted ventilatory assist was associated with a reduction of the risk of AI>10%; OR 0.688,95% CI:0.514 to 0.921, p value 0.012 and I2 21.93%). It significantly reduced the NeuroSync index; SMD 0.745, 95% CI:0.316 to 1.175, p value 0.001 and I2 0.00% (fixed effect model, two studies, 24 participants). In addition, patients in the NAVA group had a lower patient ventilator asynchrony % than in the PSV group in both two levels of assistance; NAVA-low and NAVA-high (Mean ± SD) 7±2% and 7±2%; PSV-low and PSV-high 18±13% and 23±12%, respectively. Patient ventilated with NAVA had a lower ICU mortality compared to the PSV; OR 0.610, 95% CI:0.263 to 1.418, p value 0.251 and I2 0.00% (fixed effect model, two RCTs, 153 participants). Conclusion: Neurally adjusted ventilatory assist is associated with a reduction of PVD frequency compared with PSV. However, effect on lowering the ICU mortality rate is uncertain.Thesis (MClinSc) -- University of Adelaide, The Joanna Briggs Institute, 201

    Monitoring and regulation of supported breathing in Intensive Care

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    This thesis describes several chapters related to monitoring and regulation of breathing. The main goal is to provide better insight in the interaction between spontaneous breathing and mechanical ventilatory support. In chapter 2 we investigated the effect of metabolic alkalosis on the ventilatory response. To analyze whether speckle tracking ultrasound can be used to noninvasively quantify diaphragm contractility, in chapter 3 this technique is used in healthy subjects undergoing a randomized stepwise threshold loading protocol. Chapters 4, 5 and 6 of this thesis focus on the interaction between the two parallel systems involved in providing adequate ventilation: the patient and more specific its upper airway, and the ventilator. We studied this interaction in patients with an acute exacerbation of COPD during noninvasive ventilation

    Mechanical ventilation in critically ill children:From intuition to evidence based

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    Mechanical ventilation in critically ill children:From intuition to evidence based

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    Towards respiratory muscle-protective mechanical ventilation in the critically ill: technology to monitor and assist physiology

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    Inadequate delivery of ventilatory assist and unphysiological respiratory drive may severely worsen respiratory muscle function in mechanically ventilated critically ill patients. Diaphragm weakness in these patients is exceedingly common (>60% of patients) and associated with poor clinical outcomes, including difficult ventilator liberation, increased risks of intensive care unit (ICU) and hospital readmission, and mortality. The underlying mechanisms of diaphragm dysfunction were extensively discussed in this thesis. Pathways primarily include the development of diaphragm disuse atrophy due to muscle inactivity or low respiratory drive (strong clinical evidence), and diaphragm injury as a result of excessive breathing effort due to insufficient ventilator assist or excessive respiratory drive (moderate evidence, mostly from experimental work). Excessive breathing effort may also worsen lung injury through pathways that include high lung stress and strain, pendelluft, increased lung perfusion, and patient-ventilator dyssynchrony. Relatively little attention has been paid to the effects of critical illness and mechanical ventilation on the expiratory muscles; however, dysfunction of these muscles has been linked to inadequate central airway clearance and extubation failure. The motivation for performing the work presented in this thesis was the hypothesis that maintaining physiological levels of respiratory muscle activity under mechanical ventilation could prevent or attenuate the development respiratory muscle weakness, and hence, improve patient outcomes. This strategy, integrated with lung-protective ventilation, was recently proposed by international experts from different professional societies (this thesis), and is referred to as a combined lung and diaphragm-protective ventilation approach. Today, an important barrier for implementing and evaluating such an approach is the lack of feasible, reliable and well-understood modalities to assess breathing effort at the bedside, as well as strategies for assisting and restoring respiratory muscle function during mechanical ventilation. Furthermore, monitoring breathing effort is crucial to identify potential relationships between patient management and detrimental respiratory (muscle) function that can be targeted to improve clinical outcomes. In this thesis we identified and improved monitoring modalities for the diaphragm (Part I), we investigated the impact of mechanical ventilation on the respiratory pump, especially the diaphragm (Part II), and we evaluated a novel strategy for maintaining expiratory muscle activity under mechanical ventilation (Part III)

    Substrats neurophysiologiques des interactions patient- ventilateur et des sensations respiratoires correspondantes

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    Ventilatory support must be tailored to the load capacity balance of the respiratory system to avoid patient-ventilator dysharmony as it may lead to patient-ventilator asynchronies and dyspnea. Minimizing this dysharmony is crucial. Neurally Ventilatory Assist Ventilation (NAVA) and Proportional Assist Ventilation (PAV) modes may improve patient-ventilator interaction. We showed in this work that PAV and NAVA both prevents overdistension, restores breath by breath variability of the breathing pattern and improves neuromechanical coupling and patient- ventilator asynchrony in fairly similar ways compared to pressure support ventilation. In addition the use of NAVA with non-invasive ventilation may also improve patient-ventilator interaction. We also demonstrated that dyspnea is a frequent issue in mechanically ventilated ICU patients and it can be difficult to assess when the patient is unable to report it. Surface electromyograms of extradiaphragmatic inspiratory muscles provides a simple, reliable and non-invasive indicator of respiratory muscle loading/unloading in mechanically ventilated patients. Because this EMG activity is strongly correlated to the intensity of dyspnea, it could be used as a surrogate of respiratory sensations in mechanically ventilated patients, and might, therefore, provide a monitoring tool in patients in whom detection and quantification of dyspnea is complex if not impossible. These data provide a better understanding of patient-ventilator dysharmony. Further studies are needed to evaluate the possible clinical benefits of NAVA and PAV on clinical outcomes and the impact of an early detection of dyspnea in mechanical ventilation.En ventilation assistée, l’inadéquation entre l’activité des muscles respiratoires du patient et l’assistance délivrée par le ventilateur se traduit par la survenue d’une dysharmonie patient-ventilateur potentiellement associée avec la survenue d’asynchronies patient-ventilateur et d’une dyspnée. Minimiser cette dysharmonie est un objectif majeur de la ventilation assistée. Le Neuro Asservissement de la Ventilation Assistée (NAVA) et la Ventilation Assistée Proportionnelle (PAV) sont deux nouveaux modes qui pourraient améliorer l’harmonie patient-ventilateur. Nous avons montré que, de façon similaire, le NAVA et la PAV diminuent le nombre d’asynchronie patient-ventilateur, préviennent la surdistension pulmonaire, restaurent la variabilité cycle à cycle du comportement ventilatoire et améliorent l’équilibre charge-capacité et le couplage neuromécanique. De plus, l’utilisation du mode NAVA en ventilation non invasive pourrait également permettre d’améliorer la synchronisation patient-ventilateur. Nous avons également montré aux cours de différents travaux sur la dyspnée en ventilation mécanique que celle ci était fréquente mais néanmoins difficile à identifier, en particulier chez les patients non communicants. L’EMG de surface des muscles inspiratoires extra-diaphragmatiques pourrait constituer un outil simple et objectif pouvant permettre au clinicien de diagnostiquer une dyspnée en ventilation mécanique et optimiser les réglages du ventilateur dans le but de minimiser la dysharmonie patient-ventilateur. Ces données permettent de progresser vers une meilleure connaissance de la dysharmonie patient- ventilateur. L’impact clinique de l’utilisation des modes proportionnels et d’une détection précoce de la dyspnée doit maintenant être évalué par des essais cliniques

    Clinical review: Liberation from mechanical ventilation

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    Mechanical ventilation is the defining event of intensive care unit (ICU) management. Although it is a life saving intervention in patients with acute respiratory failure and other disease entities, a major goal of critical care clinicians should be to liberate patients from mechanical ventilation as early as possible to avoid the multitude of complications and risks associated with prolonged unnecessary mechanical ventilation, including ventilator induced lung injury, ventilator associated pneumonia, increased length of ICU and hospital stay, and increased cost of care delivery. This review highlights the recent developments in assessing and testing for readiness of liberation from mechanical ventilation, the etiology of weaning failure, the value of weaning protocols, and a simple practical approach for liberation from mechanical ventilation
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