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

To evaluate the efficacy of IV ketamine in the management of acute, severe asthma.

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 oxygen, 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.

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=.001), respiratory rate (F=8.11, P=.0001). and 1-second forced expiratory volume (F=9.076, P=.001). 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).

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.