Background and objective: Although non-invasive ventilation (NIV) has been shown to be effective in a wide variety of respiratory diseases, its role in severe asthma attacks remains uncertain. The aim of this study was to clarify the effectiveness of NIV in patients experiencing severe attacks of asthma.
Methods: A retrospective cohort study was performed, comparing the periods November 1999-October 2003 (pre-introduction of NIV) and November 2004-October 2008 (post-introduction of NIV). The data and clinical outcomes for patients who experienced severe attacks of asthma, and who fulfilled the inclusion criteria, were retrieved and compared.
Results: Fifty events (48 patients) from the pre-NIV period and 57 events (54 patients) from the post-NIV period, which required hospitalization, were included in the analysis. Nine of the 50 pre-NIV events (mean PaO(2)/fraction of inspired O(2) (FiO(2)) 241 +/- 161; PaCO(2) 79 +/- 40) were treated primarily by endotracheal intubation (ETI), while 17 of the 57 post-NIV events (PaO(2)/FiO(2) 197 +/- 132, P = 0.39; PaCO(2) 77 +/- 30, P = 0.95) were treated primarily by NIV. The rate of ETI decreased in the post-NIV period (2/57 (3.5%) vs 9/50 (18%), P = 0.01). NIV was started earlier than mechanical ventilation (MV) with ETI (mean time interval between arrival and start of MV 171.7 +/- 217.9 min vs 38.5 +/- 113.8 min for NIV, P < 0.05). In the post-NIV cohort, there was a trend towards a reduction in the duration of MV with ETI or NIV (36.9 +/- 38.4 h vs 20.3 +/- 35.8 h, P = 0.09), and hospital stay was shortened (12.6 +/- 4.2 vs 8.4 +/- 2.8 days, P < 0.01). No deaths occurred during this period as a consequence of asthma attacks.
Conclusions: The need for ETI in patients with severe attacks of asthma was decreased after introduction of NIV. The ready availability of NIV enabled the rapid commencement of MV and may decrease the need for ETI. NIV is an acceptable and useful method of stabilizing patients experiencing severe attacks of asthma.