Randomized, double-blind, placebo-controlled trial of intravenous ketamine in acute asthma

Study objective: To evaluate the efficacy of IV ketamine in the management of acute, severe asthma. Methods: This prospective, randomized, double-blind, placebo-controlled clinical trial at an urban teaching hospital emergency department involved 53 consecutive patients aged 18 to 65 with a clinical diagnosis of acute asthmatic exacerbation and a peak expiratory flow of less than 40% of the predicted value after three albuterol nebulizer treatments. All patients received oxy gen, continuous nebulized albuterol, and methylprednisolone sodium succinate (Solu-Medrol). Patients then received either ketamine hydrochloride in a bolus of .2 mg/kg followed by IV infusion of .5 mg/kg per hour for 3 hours or a placebo bolus and infusion for 3 hours. Because of the occurrence of dysphoric reactions, the bolus dose was lowered to .1 mg/kg after the first 9 patients; the infusion dose was kept the same. Results: The first nine patients were eliminated from analysis. Repeated ANOVA testing on the remaining 44 patients determined significant improvements over time within each treatment group in peak flow (F=3.637, P=.004), Borg score (F=22.959, P=.0001), respiratory rate (F=8.11, P=.0001), and 1-second forced expiratory volume (F=9.076, P=.0001). However, no difference could be detected over time between treatment groups (power, 80%). Patients receiving ketamine gave the treatment a rating of 4.3 on a scale of 1 to 5, whereas those receiving placebo scored their treatment 3.7 (P=.0285). The hospital admission rate was not different between treatment groups (P=.1088). Conclusion: IV ketamine at a dose low enough to avoid dysphoric reactions demonstrated no increased bronchodilatory effect compared with standard therapy in treating exacerbations of asthma in the ED. Although there was a slight increase in satisfaction in the ketamine group, no clinical benefit in terms of hospital admission rate was noted.