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

Comparison of Outpatient Nebulized vs Metered Dose Inhaler Terbutaline in Chronic Airflow ObstructionNebulized bronchodilator therapy is frequently prescribed for home use in patients with severe chronic airflow obstruction even though many of them do not have asthma and can use a hand-held device appropriately. A belief shared by many of these patients (and some physicians) is that nebulized therapy confers benefits over and above those achieved by MDI bronchodilators. Notably, patients often remark that nebulizer therapy eases sputum expectoration and provides greater relief of dyspnea. It would seem likely, however, that the impression of improved clinical response to nebulized bronchodilator medications is a reflection of the dose of bronchodilator drugs delivered to the lung rather than the mode of delivery.

Such a conclusion is supported by recent studies- which have examined the acute bronchodilator responses achieved with wet and dry modes of bronchodilator delivery and found that the MDI achieves equivalent bronchodilatation to NEB, provided adequate doses are used. These studies examined only the acute response to each delivery system and did not assess patients after a period of days or weeks on each form of treatment to determine whether any benefits other than acute bronchodilatation were achieved. The aim of this study was to examine a group of patients with severe chronic airflow obstruction comparing short-term and long-term responses to bronchodilator drugs using equipotent doses of MDI and nebulized terbutaline.
Material and Methods
Patient Selection

Nineteen outpatients with stable chronic airflow obstruction were selected. All patients had a FEVt level of less than 2.2 L and a FEV|/VC ratio of less than 54 percent. Nine patients were using regular beta-agonists administered by either MDI or NEB. Eleven patients were taking theophylline, ten of whom had serum theophylline levels within the therapeutic range at the start of the study. Theophylline and corticosteroids were continued. All patients were competent in their use of the MDI.
Nine patients had asthma, defined by a history of variable dyspnea and wheeze and improvement in FEV, by greater than 15 percent after therapy with 200 micrograms of inhaled salbutamol (MDI). Ten patients had poorly reversible airflow obstruction. This group lacked typical asthmatic symptoms and FEV, improved by less than 15 percent after 200 micrograms of inhaled salbutamol (although five of ten achieved a greater than 15 percent FEV, increase after 250 micrograms of terbutaline, the standard “unit dose” given in the outpatient phase of the study).