First Things First (assess & treat for the following)

• Mechanical Ventilation (MV): Several methods to provide ventilatory assistance are available, particularly for patients who have been intubated or have a tracheostomy tube (see Modes of Mechanical Ventilation for more detail). These methods are considered invasive. Over the past 2 decades, development and application of non-invasive methods has increased significantly. As with invasive MV, non-invasive MV can be delivered using methods that provide ventilation through the generation of both negative and positive intra-thoracic pressure.
  
  • Non-invasive Negative-Pressure Ventilation: Examples include the iron lung, cuirass wrap, and pneumowrap. Use of these modes is currently minimal and will not be reviewed further herein.
  • Non-invasive Positive-Pressure Ventilation (NPPV): Two principal methods are available and are delivered through a variety of oral/nasal masks:
  • Continuous positive airway pressure: CPAP is the delivery of PEEP to non-intubated patients. Its principal benefits are to maintain upper airway patency and alveolar recruitment. Since CPAP does not directly assist the patient’s spontaneous inspiratory effort, it is typically not considered a mode of ventilation.
    • Bilevel positive airway pressure: BiPAP combines the delivery of CPAP with pressure support ventilation (PSV), which directly assists the spontaneous inspiratory effort. In BiPAP, two levels of pressure must be selected by the operator: ePAP (CPAP) and iPAP (PSV).
• Respiratory Failure: Failure of the lungs can be failure of ventilation (hypercarbic) or oxygenation (hypoxic) or both. Please refer to Modes of Mechanical Ventilation for details regarding key physiologic principles in respiratory failure that also apply to the effective delivery of NPPV. NPPV has proven efficacy in both acute and chronic forms of respiratory failure, and these will be discussed separately, with an emphasis on acute forms. However, the etiologies of respiratory failure for which NPPV has been proven to be effective are more limited than for invasive ventilation, and application of NPPV to patients with certain forms of respiratory failure may worsen outcomes. Efficacy of NPPV is often measured by the ability to prevent the need for endotracheal intubation and invasive ventilation.