Sympathomimetics in acute severe asthma: inhaled or parenteral, nebulizer or spacer?

It is accepted today that all patients with acute asthma should be treated with a sympathomimetic, irrespective of previous therapy. This short review addresses the question of the optimal mode of administration of these drugs in acute severe asthma. Inhaled sympathomimetics are as effective as subcutaneous adrenaline, or intravenous salbutamol or terbutaline, and, as they produce fewer side-effects, are recommended as the best mode of administration. However, self-medication with a ready to use subcutaneous preparation may be indicated in those patients prone to very abrupt attacks. The conventional mode of inhalation therapy in acute asthma is nebulization, but equally effective bronchodilatation may be obtained with metered-dose inhalers combined with valved spacers. Tachypnoeic patients unable to perform a conventional inhalation manoeuvre can use one-way valve inhalation devices with repeated tidal breaths. Finally, sequential or even continuous inhalation techniques have recently been advocated, particularly in patients with impending respiratory failure.