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Noninvasive ventilation (NIV) refers to the provision of mechanical ventilation without the need for an invasive artificial airway. Many different approaches to assisting ventilation noninvasively have been used in the past, including negative-pressure ventilators, pneumobelts, and rocking beds (see Chapters 16 and 17).1 By virtue of its effectiveness and convenience compared with other noninvasive approaches, however, noninvasive positive-pressure ventilation (NIPPV) using a mask (or interface) that conducts gas from a positive-pressure ventilator into the nose or mouth has become the predominant means of administering NIV throughout the world. NIPPV has long been used to treat chronic respiratory failure caused by chest wall deformities, slowly progressive neuromuscular disorders, or central hypoventilation.2 In more recent years, NIPPV has been increasingly used to treat patients with various forms of acute respiratory failure.3 For the purposes of this discussion, NIPPV refers to active ventilator assistance achieved by the noninvasive provision of a mechanical positive-pressure breath during inhalation, and continuous positive airway pressure (CPAP) refers to the provision of a nonfluctuating positive-pressure. This chapter discusses the rationale for use, evidence for efficacy of noninvasive positive-pressure techniques in both acute and chronic settings, selection of appropriate patients, techniques for administration, and pitfalls and complications.
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NIV has become an integral component of ventilator support in both acute and chronic settings because it avoids the complications of invasive ventilation. Invasive mechanical ventilation is highly effective and reliable in supporting alveolar ventilation, but endotracheal intubation carries well-known risks of complications that have been described elsewhere in detail (see Chapter 39).4,5 These complications have been lumped into three main categories: complications related to insertion of the tube and mechanical ventilation, those caused by loss of airway defense mechanisms, and those that occur after removal of the endotracheal tube.4
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In the first category, aspiration of gastric contents; trauma to the teeth, hypopharynx, esophagus, larynx, and trachea; arrhythmias; hypotension; and barotrauma may occur during placement of a translaryngeal tube.6,7 Tracheostomy tube placement incurs risks of hemorrhage, stomal infection, intubation of a false lumen, mediastinitis, and acute injury to the trachea and surrounding structures, including tracheal rupture,8 and esophageal and vascular injury.6 In the second category, endotracheal tubes serve as a source of continual irritation, interfere with airway ciliary function, and require frequent suctioning that contributes to airway injury, patient discomfort, and mucus hypersecretion. They also provide a direct channel to the lower airways for microorganisms and other foreign materials, leading to biofilm formation, chronic bacterial colonization, and ongoing inflammation. As a consequence, health care–acquired pneumonias are seen in up to 20% of mechanically ventilated intensive care unit (ICU) patients (see Chapter 46),9 and sinusitis is seen in 5% to 25% of nasally intubated patients, related to blockade of the sinus ostia and accumulation of infected secretions in the paranasal sinuses (see Chapter 47).10 In the third category, hoarseness, ...