Chapter 33. Noninvasive Ventilation

• Many patients with ventilatory failure can be successfully managed with noninvasive positive pressure ventilation (NIPPV).
• NIPPV improves gas exchange, reduces the work of breathing, and relieves dyspnea.
• Patients most likely to benefit include those with acute hypercapnic exacerbations of chronic obstructive pulmonary disease (COPD) or hypercapnic forms of acute cardiogenic pulmonary edema.
• In selected patients with acute hypoxemic nonhypercapnic respiratory failure, NIPPV may obviate the need for endotracheal intubation. Selection may require exclusion of patients with hemodynamic instability, central neurologic dysfunction, or an inability to protect the upper airway.
• In severely hypoxemic patients, undiscerning use of NIPPV may inappropriately delay intubation. In these patients, the decision to switch to endotracheal intubation should be made early.
• The use of NIPPV to treat postextubation respiratory distress has not been found to be superior to conventional management.
• The first hour on NIPPV is crucial in predicting the outcome and requires that experienced physicians, nurses, or respiratory therapists spend considerable time at the bedside.
• A favorable response to NIPPV is usually apparent within the first hour. Absence of improvements in dyspnea, respiratory rate, and gas exchange within 1 hour strongly suggests a need for endotracheal intubation.
• Typical settings in a patient with COPD include pressure support of 10 cm H2O above a positive end-expiratory pressure (PEEP) of 5 cm H2O.
• In appropriately selected patients, NIPPV produces better outcomes than does endotracheal mechanical ventilation.

Noninvasive positive pressure ventilation (NIPPV) has emerged as a valuable tool in the treatment of acute respiratory failure (ARF). NIPPV can substantially reduce the need for endotracheal intubation (ETI) and mechanical ventilation (MV). In selected patients, the benefits of NIPPV include decreased rates of adverse events associated with MV, shorter time spent in the ICU and hospital, and lower mortality rates. Patients with hypercapnic forms of ARF are most likely to benefit, but NIPPV may also improve outcomes of carefully selected patients with hypoxemic respiratory failure. This chapter reviews the evidence supporting NIPPV use in patients with ARF.

When MV was first developed for widespread clinical use during the poliomyelitis epidemic, attention focused on replacing the failing respiratory muscles by a perithoracic pump. This led to the development of the “iron lung,” the first form of noninvasive ventilation, which saved many lives.1,2 However, the device was cumbersome and impeded patient care. In addition, the iron lung proved of limited efficacy in the treatment of parenchymal lung disease. Thus delivery of mechanical assistance through an endotracheal tube that provided access to the lower airway was considered a significant advance, and positive pressure ventilation became the standard for MV.

Soon after the introduction of endotracheal MV, many complications of positive pressure ventilation were identified.3,4 These complications were found to be common and generated concern about the invasiveness of MV. ETI itself has been implicated in a large number of complications. Of these, some are directly related to the procedure, such ...