Nebulized or intravenous beta 2 adrenoceptor agonist therapy in acute asthma?

Nebulized salbutamol has been known to be an effective treatment of asthma for almost two decades [1] and nebulized bronchodilator therapy has now become firstline treatment of severe acute asthma in the Emergency Departments of most British hospitals [2]. This treatment was recommended as the most effective in 1972 [3J. but after the advent of intravenous salbutamol and terbutaline the choice of administering these drugs in severe acute asthma by aerosol or by the intravenous route was considered to be contentious [4), because of conflicting results of clinical trials in which the efficacy of these two routes of administration had been compared. In mild asthma it has been reported that salbutamol was more effective when inhaled than when given intravenously [5], but in the report of a study of 10 patients with severe acute asthma it was concluded that sympathomimetics should be given intravenously if the response to nebulized therapy was poor [6]. Unfortunately, in this study all 10 patients were given aerosol before intravenous salbutamol instead of being allocated at random to the two forms of treatment, and the validity of the conclusions is, therefore, open to question. Recently it was concluded that intravenous salbutamol is more effective than nebulized salbutamol in severe acute asthma, but may have unacceptable cardiovascular effects [7]. However, the design of this study has been harshly criticized on a number of counts, including patient selection and the doses of salbutamol chosen for intravenous and aerosol administration [8]. Evidence for superiority of the intravenous route of administration of be~ adrenoreceptor agonists is sparse and based mainly upon poorly designed studies. The case for nebulized salbutamol is much stronger. In a doubleblind, parallel group study of 16 patients with severe asthma, nebulized salbutamol was considered to be superior to intravenous treatment because it produced fewer unwanted cardiovascular effects, but efficacy of the two routes of administration was similar [9]. The same conclusion was reached after a double-blind, crossover study of 22 episodes of life-threatening asthma in which all patients received intravenous and nebulized salbutamol, the treatment order being randomized [10]. The multicentre study organized by the Swedish Society of Chest Medicine [11] provides definitive evidence of the superiority of the inhaled route of salbu-