Respiratory care
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Noninvasive ventilation is an effective treatment for a significant proportion of patients with acute respiratory failure. The success of noninvasive ventilation, however, depends on several factors, a major one being the selection of the proper interface. The choice and application of the interface in patients with acute respiratory failure is a considerable challenge for any treatment team. This review discusses the different types of interfaces that can be used in patients with acute respiratory failure, the differences between nasal, oro-nasal, and total face masks and the helmet, as well as the effect of interface type on treatment success and upper airway patency, mask fitting, problems related to the interface, and the relationship between ventilator type and interface choice.
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This review describes the current understanding of the lungs' response to deforming stress under conditions of both normal physiology and acute lung injury. Several limiting assumptions are needed to infer lung parenchymal stress and strain from airway pressure, volume, and flow data from mechanically ventilated patients with injured lungs. These assumptions include the effects of the chest wall on lung-surface pressure, its topographical distribution, and the effects of non-uniform tissue properties on local parenchymal stresses. ⋯ Understanding both the assumptions of lung mechanics and the scope of injury mechanisms operating during ARDS is necessary to interpret the results of clinical trials that inform prevailing ventilator-management guidelines. The implications issuing from these 3 topics inform a safer approach to setting and adjusting the ventilator to minimize the risk of ventilator-induced lung injury. This is enumerated in a 5-step approach that can be used to guide ventilator management of unstable patients with severe lung injury.