Many patients have difficulty employing the proper technique for using MDIs. Spacer/reservoir systems circumvent some of these difficulties. With proper use of MDIs, a much smaller dose of drug than that administered by nebulizer is equipotent for bronchodilation. However, patients with acute exacerbations of COPD are frequently tachypneic, and this makes optimal use of MDIs difficult. For this reason, many physicians have used nebulizers to deliver sympathomimetic medication in this setting. We hypothesized that the use of a spacer might make an MDI use more practical in these tachypneic patients. This study compared the efficacy of nebulizer and MDI-spacer systems in the delivery of albuterol in acutely ill hospitalized patients with severe COPD. review

We found that both methods of delivery increased the FEV, and FVC and decreased the Borg dyspnea score. While the increases in the FEV, and FVC were greater for the nebulizer and the decreases in the Borg score were greater for the MDI-spacer system, these differences were not statistically significant. No significant effects on heart rate or blood pressure were found.
This study did not compare the efficacy of an MDI vs the MDI-spacer system; therefore, we cannot conclude that the use of the spacer improved the effectiveness of the MDI device. Some studies in patients whose condition is stable have suggested that if the MDI technique is suboptimal, spacers do increase the bronchodilation from a given MDI dose. The study of Moss et al published in preliminary form found that nebulizer delivery of metaproterenol (15 mg) improved the FEV, and FVC more than MDI administration without a spacer device (three puffs; 1.95 mg) in patients hospitalized with an acute exacerbation of chronic airflow limitation. Thus, it is possible that the spacer did make MDI use more effective in our patients. Alternatively, perhaps difficulties in proper MDI use could be overcome by simply increasing the dose (ie, four to six puffs, etc).