This review discusses published evidence on the use of metered dose inhaler (MDI)/spacer combinations and nebulizers for delivering β₂ adrenoeeptor agonists (β₂ agonists) in stable and acute severe childhood asthma. Although nebulizers have been the mainstay of inhalation therapy in childhood asthma for many years, these devices are cumbersome, bulky, time-consuming, and expensive to use. As a result, over the past decade the emphasis of inhalation therapy in children has shifted from nebulizers to metered-dose inhalers (MDI) in combination with spacer devices.

MDI/spacer combinations have been shown to be a practical and effective way of delivering medications for inhalation in children with asthma, irrespective of their age. Lung deposition increases with age, being low in young children. This underscores the need for administering relatively high nominal dosages of medication when using an MDI/spacer in young children; the most practical approach is to use the same dose, irrespective of the child’s age or weight.

In children with both stable chronic asthma and acute severe asthma, numerous studies have shown that β₂ agonists can be delivered by MDI/spacer at least as effectively and safely as by nebulizer. Although nebulizers may still play a role in status asthmaticus (because they allow combined administration of β₂ agonists, anticho-linergic agents, and oxygen in a single procedure), the vast majority of children of all ages with acute severe asthma can be managed effectively and safely by β₂ agonists delivered via MDI/spacer. This cost-effective and practical approach should, therefore, be preferred.