TY - JOUR T1 - Bronchial responsiveness and lung function in infants with lower respiratory tract illness over the first six months of life. JF - Archives of Disease in Childhood JO - Arch Dis Child SP - 1454 LP - 1458 DO - 10.1136/adc.67.12.1454 VL - 67 IS - 12 AU - J R Clarke AU - A Reese AU - M Silverman Y1 - 1992/12/01 UR - http://adc.bmj.com/content/67/12/1454.abstract N2 - The aim of this study was to determine whether increased bronchial responsiveness to histamine is associated with lower respiratory tract illness (one or more episodes of wheeze or cough, or both) in infancy. Fifty four normal newborn infants who had at least one atopic parent were recruited. At a median age of 6.5 months, 45 infants, 23 with a history of lower respiratory tract illness, and 22 without, underwent pulmonary function testing during a symptom free period. The maximum flow at functional residual capacity (VmaxFRC) was calculated from partial forced expiratory flow volume curves using the squeeze technique. Bronchial responsiveness to increasing doses of histamine was assessed by determining the provoking concentration which caused a 30% decrease in VmaxFRC (PC30). The length adjusted VmaxFRC was lower for symptomatic infants before the challenge (median 125 ml/s; 95% confidence intervals (CI) 85 to 164 ml/s) compared with control infants (median 215 ml/s; 95% CI 159 to 298 ml/s). There was no significant difference in PC30 between symptomatic infants (median 10.3 g/l; 95% CI 2.8 to 23.8 g/l) and control infants (median 16.5 g/l; 95% CI 2.4 to 27.9 g/l). Bronchial responsiveness to histamine can be shown in most infants early in life and is independent of lower respiratory tract symptoms including wheezing. ER -