Study objective: Noninvasive ventilation has been shown to be effective in patients with acute respiratory failure due to pulmonary edema and exacerbations of COPD. Its role in an acute asthmatic attack, however, is uncertain. The purpose of this pilot study was to compare conventional asthma treatment with nasal bilevel pressure ventilation (BPV) [BiPAP; Respironics; Murrysville, PA] plus conventional treatment in patients with a severe asthmatic attack admitted to the emergency department.
Design: A prospective, randomized, placebo-controlled study.
Setting: An emergency department at a university hospital.
Patients: Thirty patients with a severe asthma attack were recruited from a larger group of 124 asthmatic patients seen in the emergency department. Fifteen patients were randomly assigned to BPV plus conventional therapy and 15 patients to conventional therapy alone. The two groups had similar clinical characteristics on hospital admission. Mean (+/- SD) FEV(1) on recruitment was 37.3 +/- 10.7% in the BPV group and 33.8 +/- 10.2% in the control group (p = not significant).
Interventions and measurements: BPV with predetermined inspiratory and expiratory pressures was applied for 3 h in the BPV group; in the control group, a similar sham device with subtherapeutic pressures was applied for 3 h. Bedside lung function test results and vital signs were obtained at baseline, and during and at the completion of the study protocol.
Results: The use of BPV significantly improved lung function test results. Eighty percents of the patients in the BPV group reached the predetermined primary end points (an increase of at least 50% in FEV(1) as compared to baseline), vs 20% of control patients (p < 0.004). Mean rise in FEV(1) was 53.5 +/- 23.4% in the BPV group and 28.5 +/- 22.6% in the conventional treatment group (p = 0.006). The intention-to-treat analysis of the secondary end point rate of hospitalization included 33 patients. Hospitalization was required for 3 of 17 patients (17.6%) in the BPV group, as compared with 10 of 16 patients (62.5%) in the control group (p = 0.0134).
Conclusion: In selected patients with a severe asthma attack, the addition of BPV to conventional treatment can improve lung function, alleviate the attack faster, and significantly reduce the need for hospitalization.