ABSTRACT

International guidelines on acute asthma management endorse inhaled bronchodilator therapy, supplemental oxygen, and systemic corticosteroids (1-3). Beta-agonists are the recommended initial bronchodilator, and the severity of the attack determines whether they are delivered by nebulizer or by an MDI with spacer. Response to initial therapy should determine both the subsequent dose and the frequency of administration of betaagonist therapy. Two recent studies in acute severe asthma (4,5) suggest a greater improvement over 2 hours when inhaled beta-agonists are administered continuously than when administered intermittently. While the majority of patients respond to this treatment approach, the degree of response, the amount of bronchodilator therapy consumed previously during the attack, and the severity of attack will determine whether other bronchodilators are likely to be efficacious and whether the inhaled or intravenous approach should be employed. Intravenous theophyllines have generally lost favor, since they infrequently add to the effect of inhaled bronchodilating therapy and since they have such a narrow therapeutic index (6). Toxicity may be induced particularly in the critically ill due to acute changes in hepatic metabolism and drug handling (6). Intravenous betaagonist therapy has been shown to augment inhaled beta-agonist therapy in very severe attacks, particularly when patients are having difficulty in tolerating nebulized therapy (7). However, unless the attack of asthma is particularly severe and the patient is intolerant of, or unable to be administered, inhaled therapy, then intravenous beta-agonist therapy contributes to improvement in neither lung function nor therapeutic effect (8-10), and causes more side effects.