Respiratory physiology & neurobiology
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Respir Physiol Neurobiol · Nov 2013
ReviewMechanical ventilation, diaphragm weakness and weaning: a rehabilitation perspective.
Most patients are easily liberated from mechanical ventilation (MV) following resolution of respiratory failure and a successful trial of spontaneous breathing, but about 25% of patients experience difficult weaning. MV use leads to cellular changes and weakness, which has been linked to weaning difficulties and has been labeled ventilator induced diaphragm dysfunction (VIDD). Aggravating factors in human studies with prolonged weaning include malnutrition, chronic electrolyte abnormalities, hyperglycemia, excessive resistive and elastic loads, corticosteroids, muscle relaxant exposure, sepsis and compromised cardiac function. ⋯ Molecular and functional studies on the effects of MV on the human diaphragm have largely confirmed the animal results and identified potential treatment strategies. Only recently potential VIDD treatments have been tested in humans, including pharmacologic interventions and diaphragm "training". A limited number of human studies have found that specific diaphragm training can increase respiratory muscle strength in FTW patients and facilitate weaning, but larger, multicenter trials are needed.
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Respir Physiol Neurobiol · Jan 2018
Effect of airway remodeling and hyperresponsiveness on complexity of breathing pattern in rat.
The complexity of respiratory dynamics is decreased, in association with disease severity, in patients with asthma. However, the pathophysiological basis of decreased complexity of breathing pattern in asthma is not clear. In the present study, we investigated the effect of airway remodeling and hyperresponsiveness induced by repeated bronchoconstriction (using methacholine) on breathing pattern in rats with or without allergen-induced sensitization. ⋯ However, these airway alterations had no significant effect on the complexity of breathing pattern in non-sensitized rats. Our results indicate that mechanical respiratory alterations cannot per se attenuate the complexity of respiratory dynamics, unless there is an underlying inflammation. We suggest further studies on underlying mechanisms of breathing variability with focus on respiratory control alterations due to airway inflammation.
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Respir Physiol Neurobiol · Feb 2014
Airflow obstruction and left ventricular filling pressure in suspected chronic obstructive pulmonary disease.
Left ventricular (LV) filling impairment is present in patients with chronic obstructive pulmonary disease (COPD). Airflow obstruction is related to reduced LV end-diastolic volume, stroke volume, and cardiac output. The ratio of peak early diastolic filling velocity of the mitral inflow to peak early diastolic velocity of the mitral annulus (E/e'), an echocardiographic parameter, can be applied as a surrogate marker of LV filling pressures. ⋯ Multivariate linear regression analysis showed that the FEV1/FVC ratio (β=0.01; 95% confidence interval, 0.001-0.019; p=0.036) independently predicted the log transformed E/e' ratio. An increase of FEV1/FVC ratio (in percentage) by 1 unit was associated with an increase of the E/e' ratio multiplied by 1.01. Airflow obstruction inversely predicts LV filling pressure in suspected COPD cases.
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Respir Physiol Neurobiol · May 2014
Comparative Study Clinical TrialPhysiological comparison of breathing patterns with neurally adjusted ventilatory assist (NAVA) and pressure-support ventilation to improve NAVA settings.
Neurally adjusted ventilator assist (NAVA) assists spontaneous breathing in proportion to diaphragmatic electrical activity (EAdi). Here, we evaluate the effects of various levels of NAVA and PSV on the breathing pattern and, thereby, on [Formula: see text] homeostasis in 10 healthy volunteers. For each ventilation mode, four levels of support (delivered pressure 0 i.e. baseline, 5, 8, and 10cmH2O) were tested in random order. ⋯ Diaphragmatic activity can decrease during NAVA without any change in VT and [Formula: see text]. This suggests that NAVA adjustment cannot be based solely on VT and [Formula: see text] criteria. Registered by Frédéric Lofaso and Nicolas Terzi on ClinicalTrials.gov, #NCT01614873.
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Respir Physiol Neurobiol · Nov 2015
Mechanical consequences of allergic induced remodeling on mice airway resistance and compressibility.
The effect of remodeling on airway function is uncertain. It may affect airway compressibility during forced expirations differently than airflow resistance, providing a tool for its assessment. The aim of the current study was to compare the effects of acute and chronic antigen challenge on methacholine-induced bronchoconstriction assessed from resistance and maximal tidal expiratory flow. ⋯ Acute and chronic allergen challenge induced airway hyperresponsiveness (AHR) to methacholine. However the relationship between maximal tidal expiratory flow and resistance during methacholine challenge was different between the two conditions, suggesting that the determinants of AHR are not identical following acute and chronic allergen exposure. We conclude that the contrast of changes in maximal tidal expiratory flow and respiratory resistance during methacholine-induced bronchoconstriction may allow the detection of the mechanical consequences of airway remodeling.