Ribavirin effect on pulmonary function in young infants with respiratory syncytial virus bronchiolitis.

To assess the effect of ribavirin on pulmonary function in infants with respiratory syncytial virus bronchiolitis, we performed a randomized (nonmatched), double blinded, placebo-controlled study of 19 infants with RSV bronchiolitis. Infants with underlying respiratory, cardiac or immunologic disease were excluded. Patients were given ribavirin (10) or placebo (9) via an aerosol generator for 18 hours/day for 3 days. Pulmonary function (dynamic compliance, total lung resistance) was calculated using a pneumotachographic method on Days 1, 2 and 7. Differences between groups on clinical criteria were not found. Approximately one-half of each group showed increased compliance and decreased lung resistance after 24 to 48 hours of therapy. By Day 7 compliance had increased 30% in the placebo group and 210% in the ribavirin-treated infants (P = 0.05). Significant differences in the rate of change of lung resistance were not seen by Day 7. We conclude that previously noted improvements in the early course of respiratory syncytial virus bronchiolitis treated with ribavirin do not appear to be a result of measurable changes in pulmonary function. However, paradoxical increases in airway resistance were not found in patients treated with ribavirin.