Chest
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Neurally adjusted ventilatory assist (NAVA) delivers airway pressure (Paw) in proportion to neural inspiratory drive as reflected by electrical activity of the diaphragm (EAdi). Changing positive end-expiratory pressure (PEEP) impacts respiratory muscle load and function and, hence, EAdi. We aimed to evaluate how PEEP affects the breathing pattern and neuroventilatory efficiency during NAVA. ⋯ During NAVAal, increasing PEEP reduces respiratory drive. Patients adapt their neuroventilatory efficiency such that the individual ventilatory pattern is preserved over a wide range of PEEP levels. Monitoring Vt/EAdi during PEEP changes allows identification of a PEEP level at which tidal breathing occurs at minimal EAdi cost.
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Purinergic signaling is involved in asthma pathogenesis. Not only adenosine but also adenosine triphosphate (ATP) might play a role, but human evidence is scarce. ATP can be measured in exhaled breath condensate (EBC), a noninvasive airway sample suggested as being suitable for patient monitoring. We determined EBC ATP concentration in asthma, investigated its relation to disease parameters, and calculated airway ATP level. ⋯ EBC ATP concentration does not seem to be useful for asthma monitoring. The relation between EBC mediator concentration and EBC conductivity highlights the importance of further standardization of EBC methodology and the need for more studies to understand airway droplet formation.
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Emphysematous change as assessed by CT imaging has been reported to correlate with COPD prognostic factors such as FEV(1) and diffusing capacity of the lung for carbon monoxide (Dlco). However, few studies have assessed the relationship between CT scan assessment and COPD mortality from mild to severe stages of the disease. In this study, we analyzed this relationship in patients with various stages of COPD. ⋯ Emphysematous change as assessed by CT scan predicts respiratory mortality in outpatients with various stages of COPD.