Noninvasive ventilation in acute asthma

Noninvasive ventilation (NIV) has well-recognized benefits in acute exacerbation of chronic obstructive pulmonary disease and pulmonary edema. Its utilization in acute asthma, however, remains controversial. In this review, we describe the physiological basis to justify NIV use in acute asthma and contribute a critical appraisal of the available literature relating to this practice. A discussion of some of the more pertinent, clinically relevant practicalities is also provided. Original research articles were identified using the electronic PubMed database. Randomized controlled trials of NIV in the setting of acute asthma were selected. Retrospective observational studies were also included if they were considered to contribute to the literature review. The use of NIV in the acute asthma setting has been shown to be associated with improvements in important physiological variables including measures of airflow and respiratory rate, and lends support to further study in this field. Improvements in airflow may be a direct effect of applied positive airway pressure or an indirect effect secondary to better dispersal of aerosolized medication. Reductions observed in respiratory rate and dyspnea are likely influenced by the amount of pressure support provided. Evidence suggestive of any improvement in mortality, intubation rate, or hospital/intensive care unit length of stay, however, is lacking. Studies to date have been hampered by small numbers and a lack of demonstrable meaningful clinical outcomes. Data relating to mortality, endotracheal intubation rates, and hospital length of stay/admission should be sought in future large clinical trials.