RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED TRIAL OF INTRAVENOUS KETAMINE IN ACUTE ASTHMA

Study objective: To evaluate the efficacy of IV ketamine in the manage ment of acute, severe asthma. Methods: This prospective, randomized, d ouble-blind, placebo-controlled clinical trial at an urban teaching ho spital emergency department involved 53 consecutive patients aged 18 t o 65 with a clinical diagnosis of acute asthmatic exacerbation and a p eak expiratory flow of less than 40% of the predicted value after thre e albuterol nebulizer treatments. All patients received oxy gen, conti nuous nebulized albuterol, and methylprednisolone sodium succinate (So lu-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 h ours or a placebo bolus and infusion for 3 hours. Because of the occur rence of dysphoric reactions, the bolus dose was lowered to .1 mg/kg a fter the first 9 patients; the infusion dose was kept the same. Result s: The first nine patients were eliminated from analysis. Repeated ANO VA testing on the remaining 44 patients determined significant improve ments 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=.000 1), and 1-second forced expiratory volume (F=9.076, P=.0001). However, no difference could be detected over time between treatment groups (p ower, 80%). Patients receiving ketamine gave the treatment a rating of 4.3 on a scale of 1 to 5, whereas those receiving placebo scored thei r treatment 3.7 (P=.0285). The hospital admission rate was not differe nt between treatment groups (P=.1088). Conclusion: IV ketamine at a do se low enough to avoid dysphoric reactions demonstrated no increased b ronchodilatory effect compared with standard therapy in treating exace rbations of asthma in the ED. Although there was a slight increase in satisfaction in the ketamine group, no clinical benefit in terms of ho spital admission rate was noted.