Comparison of Outpatient Nebulized vs Metered Dose Inhaler Terbutaline in Chronic Airflow Obstruction: Conclusion

The above-mentioned studies demonstrate that the majority of nebulizers are less efficient than MDI at delivering bronchodilators, but that this lack of efficiency is more than compensated for by the striking excess of dose usually prescribed for the nebulizer (20-25 times the usual maintenance MDI dose). The results of the acute response study demonstrated no significant difference between metered-dose inhaler and nebulizer in the degree of bronchodilatation and improvement in 6-min walking distance. The findings of the outpatient study also demonstrated no difference between the two modes of delivery in FEVi, 6MWD, symptom scores, and extra beta-agonist use. The statistically significant improvement in VC after both treatment fortnights was small and unlikely to be clinically relevant. The 4-5 percent improvement in 6-min walking distance also reached statistical significance, but was not reflected in the patients’ perception of their exertional breathlessness.

Unlike the study of Jenkins et al where all patients had poorly reversible airflow obstruction, our study included nine asthmatic patients. In these patients there were again no differences between the NEB and MDI treatment fortnights. The conclusions drawn from the study therefore apply equally to this subset of patients. It should be emphasized that this study refers only to patients whose clinical condition is stable and we can draw no conclusions about the use of nebulized bronchodilators during acute exacerbations of asthma.
We conclude from these observations that in patients with stable airflow obstruction and adequate MDI technique there is no justification for the preferred use of nebulizers to administer bronchodilators. The metered-dose inhaler provides equivalent therapy with greater efficiency. In patients who are unable to use metered-dose inhalers effectively, simple 750 ml valved spacer devices deal with the problems of incoordination, may improve the efficiency of lung deposition, and are as efficient as nebulizers in the treatment of airflow obstruction in acute asthma. Many patients require greater than the normally prescribed MDI dose of bronchodilator to achieve maximal bronchodilatation and adequate doses of bronchodilator should be established by individual dose-response studies.