Inhalation anti-asthma therapy with spacers: technical aspects.

Inhalation is the method of choice for delivering therapeutic agents to the lung. The advent of metered-dose inhalers (MDIs) has made inhalation easier, less expensive and more efficient. However, 20-50% of patients are unable to use MDIs correctly. The main problems are: 1) impact of aerosol particles in the mouth (responsible for side-effects); 2) poor co-ordination between firing the MDI and breathing; 3) and too fast an inspiration. Various spacer devices have been designed to overcome these problems. These are: large volume devices, which reduce the oral impact and select the respirable particles; devices equipped with a one-way valve that reduces co-ordination problems; indication of too rapid an inspiration by a high-flow mark. The introduction of these devices has resulted in an improved bronchial/oral deposition rate and a reduced incidence of side-effects. Training and education of patients is fundamental in ensuring the correct use of inhalers.