A prospective randomized controlled trial on the efficacy of noninvasive ventilation in severe acute asthma

Noninvasive ventilation (NIV) is an emerging modality in the management of patients with acute respiratory failure. However, its role in severe acute asthma is not well defined.

Evaluate the efficacy of NIV in severe acute asthma.

Patients with severe acute asthma were randomized to receive either standard medical therapy or NIV in addition to medical therapy. The primary outcomes were improvement in forced expiratory volume in the first second (FEV1), intensive care unit (ICU) stay, and hospital stay. The secondary outcomes were rate of improvement in respiratory rate, blood pH, ratio of PaO2 to fraction of inspired oxygen (F(I)O2), PaCO2, requirement for inhaled medications, and failure of primary therapy.

Fifty-three patients with severe acute asthma (42 females and 11 males, mean +/- SD age 44 +/- 15 y, FEV1 < 30% of predicted) were randomized to NIV (n = 28) or standard medical therapy (n = 25). The baseline variables were similar in the 2 groups except for the mean duration of asthma, which was shorter in the standard-medical-therapy group. The median inspiratory and expiratory airway pressures applied were 12 cm H2O and 5 cm H2O, respectively. There was a significant improvement in respiratory rate, FEV1, and PaO2/F(I)O2 (but not pH or PaCO2) in both the groups, but no significant difference between the 2 groups. The number of patients who had a > or = 50% improvement in FEV1 at 1, 2, and 4 hours was nonsignificantly greater in the NIV arm. ICU and hospital stay was significantly shorter in the NIV group. The mean dose of inhaled bronchodilator was significantly less in the NIV group. There were 4 instances of standard-medical-therapy failure, and all those patients improved with NIV. Two patients in the NIV arm required invasive ventilation. There was no mortality in either of the arms.

In patients with severe acute asthma, the addition of NIV to standard medical therapy probably accelerates the improvement in lung function, decreases the inhaled bronchodilator requirement, and shortens the ICU and hospital stay, but a larger study is required to settle this issue.