The last 4 h of that period in both groups was devoted for the study protocol.
More patients in the BPV group reached the predetermined primary end points at 4 h of treatment (12 patients; 80%), as compared to the control group, where only 3 patients (20%) reached the primary end points (p < 0.004). With regard to the secondary end point, the rate of hospitalization, an intention-to-treat analysis was performed, comparing 17 patients in the BPV group with 16 patients in the control group (including the 3 patients withdrawn earlier from the study). Three of 17 patients (17.6%) in the BPV group required hospitalization as compared to 10 of 16 patients (62.5%) in the control group (p = 0.0134).
A subgroup analysis of patients who were hospitalized (Table 5) shows that on hospital admission their FEV1, FVC, PEFR, and indexes of smaller airway obstruction (data not shown) were similar. Their hospital stay, however, slightly differed and lasted 4 days in the BPV group as compared to 2.55 days in the control group (Table 5). There was no variance for independent sample t test analysis; therefore, p value could not be calculated for this parameter. During a follow-up of 1 month after discharge from the emergency department, only one patient in each group was readmitted to the emergency department. Both were discharged after a short treatment in the emergency department and were not hospitalized.
Discussion
This study shows that the use of noninvasive ventilatory support in the form of BPV in selected patients with a severe attack of asthma can alleviate the attack faster, improve lung function test results more completely—namely FEV1, FVC, and PEFR—and prevent hospitalizations.
Table 2—Treatment in the Emergency Department*
| Parameters | BPV Group | Control Group | p Value |
| IV methylprednisolone f | 15 | 12 | NS |
| IV hydrocortisone, mg{ | 186.66 ± 124.6 | 156.66 ± 137.4 | NS |
| Nebulizations with ipratropium and salbutamol,§ No. | 11 | 9 | NS |
| Inspiratory positive airway pressure] | | 13.06 ± 0.45 | 1 | |
| Expiratory positive airway pressure] | 4.06 ± 0.45 | 1 |
Although the use of noninvasive ventilation in treating respiratory failure in cardiogenic pulmonary edema and COPD has been shown to be effective, its role in asthma has not been established.
Prior reports indicate that noninvasive ventilatory support may have a role in asthma as well. CPAP has been shown to avert bronchoconstriction in asthma induced by methacholine or histamine, and reduce dyspnea in acute asthmatic attacks. Patients with severe asthma attacks probably have intrinsic PEEP causing an increased work of breathing. The application of externally applied PEEP to offset this effect might be of value in an asthmatic attack.
