Objective: To investigate whether nebulized racemic epinephrine or albuterol improves respiratory distress in infants with acute bronchiolitis.
Design: A randomized, placebo-controlled, double-blind study.
Setting: A university hospital providing primary hospital care for all pediatric patients in a defined area.
Patients: One hundred consecutive infants younger than 24 months treated in the hospital for acute bronchiolitis.
Intervention: The patients received two inhalations at 30-minute intervals: racemic epinephrine followed by physiologic saline (REP group; n = 24), albuterol followed by physiologic saline (AP group; n = 27), physiologic saline followed by racemic epinephrine (PRE group; n = 24), and physiologic saline followed by albuterol (PA group; n = 25). All patients received intramuscular epinephrine 60 minutes after the beginning of the study.
Main outcome measures: Oxygen saturation, respiratory rate, and two clinical scores were used: one based on wheezing and retractions (Respiratory Distress Assessment Instrument) and the other based on changes in wheezing, retractions, and respiratory rate (Respiratory Assessment Change Score).
Main results: During the study, there were no significant differences among the four groups in clinical scores, oxygen saturations, and respiratory rates. Mean Respiratory Distress Assessment Instrument scores improved significantly within the REP, PRE, and AP groups 15 minutes after the first inhalation. In only the REP group, which received racemic epinephrine, the confidence limits did not overlap. A comparison of paired data of each patient revealed that the difference in Respiratory Assessment Change Score was significant between racemic epinephrine and physiologic saline, but not between albuterol and physiologic saline. Intramuscular epinephrine significantly improved Respiratory Distress Assessment Index scores in those groups treated earlier with racemic epinephrine (REP and PRE groups). No significant adverse effects were seen in any group or at any phase of the study.
Conclusions: Elimination of hypoxia by supplemental oxygen and moistening of inspired air relieve the symptoms of acute bronchiolitis. Nebulized racemic epinephrine and albuterol are safe and useful in the treatment of acute bronchiolitis. Improvements in symptom scores at 15 minutes favor the use of racemic epinephrine. As the action of epinephrine is short, the effect can be increased by repeated inhalations.