EFFECT OF SALBUTAMOL ON SPECIFIC AIRWAY-RESISTANCE IN INFANTS WITH A HISTORY OF WHEEZING

The purpose of this study was to assess the effectiveness of nebulized salbutamol in infants with a history of wheezing. Eighty-eight children aged 3-24 months with a history of wheezing were studied, in seven groups: I (n = 15) and I/A (n = 17) with elevated specific airway resistance (SRaw); II (n = 17) with normal SRaw; III (n = 23), III/A (n = 17), and IV (n = 18) with normal SRaw exposed to carbachol bronchial challenge (CBC); and V (n = 13) serving as control. Infants for groups I/A and III/A were selected to match by age and by baseline and post-carbachol SRaw values, respectively. Baseline airway resistance and thoracic gas volume (TGV) were measured plethysmographically. Specific airway resistance was selected as an index of bronchial function. Thereafter every child in groups I, I/A and II inhaled 200-mu-g of salbutamol by tidal breathing, and the children in groups III, III/A, and IV were exposed to CBC. Following positive reaction to carbachol, children of groups III and III/A inhaled salbutamol (200 mu-g, tidal breathing), and those of group IV received no drug. Controls from group V with normal SRaw received placebo (phosphate-buffered saline). Plethysmography was repeated in all children at 5 minute intervals. Following salbutamol SRaw was reduced in children with elevated and normal SRaw. In contrast, children not receiving salbutamol had unchanged SRaw value. The response to salbutamol measured by SRaw, Raw, and TGV was not significantly different in the spontaneously obstructed infants compared to those who received carbachol. In conclusion, infants with a history of wheezing do respond to inhaled salbutamol.