Based on the results reported herein, the “standard” two inhalations of metaproterenol by MDI-spacer (MDI-InspirEase) are not equivalent to the “standard” 15 mg of HHN metaproterenol. However, analysis of the above-cited studies provides a strong basis that additional MDI inhalations can produce therapeutic equivalence even in acutely ill patients. Further studies should be done using a wide range of dosages of (3-agonist delivered by MDI-spacer to determine the optimal dose of medication in acutely ill patients with exacerbations of obstructive airways disease. The economic advantages of MDI-spacer over HHN for administration of inhaled bronchodilators have already been documented. It is possible that teaching hospitalized patients the use of the MDI-spacer may reduce hospital costs and at the same time foster improved quality of care by permitting patients to administer and control their own therapy.
It is clear that the conventional method of treatment of acute bronchospasm with metaproterenol delivered by HHN produces a greater therapeutic effect than metaproterenol delivered by MDI, even with a spacer attached. It is likely that this reflects the fact that recommended dose of MDI is too low and should be increased.