Paediatric respiratory reviews
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Among ventilated children, the incidence of acute lung injury (ALI) was 9%; of that latter group 80% developed the acute respiratory distress syndrome (ARDS). The population-based prevalence of pediatric ARDS was 5.5 cases/100.000 inhabitants. Underlying diseases in children were septic shock (34%), respiratory syncytial virus infections (16%), bacterial pneumonia (15%), near-drowning 9%, and others. ⋯ Lung protective mechanical ventilation with optimal lung recruitment is the mainstay of supportive therapy. New therapeutic modalities refer to corticosteroid and surfactant treatment. Well-designed follow up studies are needed.
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Severe acute respiratory syndrome (SARS) and avian influenza are two important newly emerged infections with pandemic potential. Both infections have crossed the species barrier to infect humans. SARS originated from southern China and spread to many countries in early 2003. ⋯ Current evidence suggests that the human-to-human transmission of avian influenza is rather inefficient, but mutation might occur in the future resulting in improved transmission and possibly a pandemic in humans. As with the outbreak of SARS, the development of sensitive and accurate early diagnostic tests is extremely important for successful control of the outbreak at source. The availability of isolation facilities, the stockpiling of antiviral agents and effective and safe vaccination will be extremely important in minimising the damage of a new influenza pandemic.
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This review examines specific mucoactive agents from three classes: expectorants, which add water to the airway; ion-transport modifiers, which promote ion and water transport across the epithelium of the airway; and mucokinetics, which improve cough-mediated clearance by increasing airflow or reducing sputum adhesivity. The agents are isotonic and hypertonic saline, mannitol, denufosol and beta-agonists. Our understanding of these agents has recently improved through pre-clinical research, clinical trials and, in particular, extensive research into the nature of the liquid lining the surface of the airway, both in health and in cystic fibrosis (CF). For each agent, recent research is reviewed, highlighting the evidence for possible mechanisms of action and for clinical efficacy in CF, as well as the implications for the optimal clinical application of the agent.
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Mucus accumulation in the lower airways is a key feature of cystic fibrosis (CF) lung disease. The major component of mucus in CF is not mucin derived from mucus producing cells but rather pus that includes viscous material such as polymerized DNA derived from degraded neutrophils. This has important implications for mucolytic therapy aiming to improve mucus clearance from the airways, since degradation of mucin may not be a suitable treatment strategy. ⋯ Dornase alfa has been shown to reduce pulmonary exacerbations and improve lung function and is currently the only mucolytic agent with proven efficacy in CF. Newer agents targeting other components of CF mucus, such as filamentous actin, are currently in development. Ultimately, drugs that are mucokinetic, which preserve viscoelasticity, rather than mucolytic may prove to be beneficial for CF lung disease in the future.
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The biophysical properties of airway secretions are largely determined by the polymeric components. In normal airway mucus, the gel-forming mucins, MUC5AC and MUC5B, are responsible not only for the viscoelastic properties essential for clearance and protecting the airway epithelium from invaders and water evaporation. ⋯ Sputum viscoelastic and surface properties determine how well secretions can be cleared by cilia or cough. In this mini-Symposium on Airway Clearance in Cystic Fibrosis, the physiology of CF secretion structure and rheology is discussed in the context of medications and physical maneuvers for enhancing sputum clearance.