A randomized, single-blind, cross-over, prospective study was conducted in seventy critically ill adult patients with acute air flow obstruction. Patients were randomized to nebulized albuterol alternating with levalbuterol every 4 to 6 hours. Group A received albuterol 2.5 mg alternating with levalbuterol 0.63 mg. Group B received albuterol 2.5 mg alternating with levalbuterol 1.25 mg. All patients received nebulized ipratropium bromide 500 micrograms with each treatment. Heart rate and cardiac rhythm were continuously recorded before and 15 minutes after finishing each treatment. Any new rhythm abnormalities between treatments were also recorded.
