A pilot prospective, randomized, placebo-controlled trial of bilevel positive airway pressure in acute asthmatic attack. Reversal of bronchial obstruction with bi-level positive airway pressure and nebulization in patients with acute asthma.
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.
                A prospective, randomized, placebo-controlled study.
                An emergency department at a university hospital.
                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.
                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).
                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. Jet nebulization (JN) and non-invasive mechanical ventilation (NIMV) through bi-level pressure is commonly used in emergency and intensive care of patients experiencing an acute exacerbation of asthma. However, a scientific basis for effect of JN coupled with NIMV is unclear. Objective. To evaluate the effect of jet nebulization administered during spontaneous breathing with that of nebulization with NIV at two levels of inspiratory and expiratory pressures resistance in patients experiencing an acute asthmatic episode. Methods. A prospective, randomized controlled study of 36 patients with severe asthma (forced expiratory volume in 1 second [FEV(1)] less than 60% of predicted) selected with a sample of patients who presented to the emergency department. Subjects were randomized into three groups: control group (nebulization with the use of an unpressured mask), experimental group 1 (nebulization and non-invasive positive pressure with inspiratory positive airway pressure [IPAP] = 15 cm H(2)O, and expiratory positive airway pressure [EPAP] = 5 cm H(2)O), and experimental group 2 (nebulization and non-invasive positive pressure with IPAP = 15 cm H(2)O and EPAP = 10 cm H(2)O). Bronchodilators were administered with JN for all groups. Dependent measures were recorded before and after 30 minutes of each intervention and included respiratory rate (RR), heart rate (HR), oxygen saturation (SpO(2)), peak expiratory flow (PEF), forced expiratory volume in 1 second (FEV(1)), forced vital capacity (FVC), and forced expiratory flow between 25 and 75% (FEF(25-75)). Results. The group E2 showed an increase of the peak expiratory flow (PEF), forced vital capacity (FVC), FEV(1) (p < 0.03) and F(25-75%) (p < 0.000) when compared before and 30 minutes after JN+NIMV. In group E1 the PFE (p < 0.000) reached a significant increase after JN+ NIMV. RR decreased before and after treatment in group E1 only (p = 0.04). Conclusion. Nebulization coupled with NIV in patients with acute asthma has the potential to reduce bronchial obstruction and symptoms secondary to augmented PEF compared with nebulization during spontaneous breathing. In reversing bronchial obstruction, this combination appears to be more efficacious when a low pressure delta is used in combination with a high positive pressure at the end of expiration.
This review of studies has highlighted the paucity of data that exist to support the use of NPPV in patients in status asthmaticus. As such this course of treatment remains controversial despite its continued use in current clinical practice. Larger, prospective randomised controlled trials of rigorous methodological design are needed to determine the role of NPPV in patients with asthma.