Determinants of bronchial responsiveness at school age in prematurely bornchildren

The bronchial challenge test using isocapnic hyperventilation of cold air ( IHCA) was used to evaluate bronchial responsiveness in 63 offspring of mult iple pregnancies when they were 8-15 years old. At birth, 27 (43%) children had had intrauterine growth retardation (IUGR, birth weight <-2 SD, or bir th weight difference between twin pairs >1.3 SD). The median birth weight w as 2,050 g (range, 800-3,150), and the median gestational age was 35 weeks (range, 28-38). None of the children had asthma or suffered from asthma-lik e symptoms. In the interpretation of the IHCA test, a fall of 9% or more in the forced expiratory volume in 1 sec (FEV,) was considered as abnormal, a nd these children were classified as "cold air responders." The number of responders was 16 (25%); their baseline FEV1/forced vital cap acity ratio (FEV1/FVC) and forced expiratory flow between 25-75% FVC (FEF25 -75), but not FEV, were significantly lower than the corresponding values i n nonresponders. No differences were found in perinatal or neonatal factors between responders or nonresponders. Eight (30%) of the 27 IUGR and 8 (22% ) of the 36 appropriate for gestational age (AGA) children were IHCA respon ders. In particular, IUGR was not correlated with maximal FEV, falls follow ing the IHCA test. Respiratory infections after the neonatal period were eq ually common in IUGR and AGA children; but infections were associated with subsequent IHCA responsiveness. Adenoidectomy, tonsillectomy, and/or myring otomy had been performed significantly more often in the responders than in the nonresponders. At least one of the above invasive procedures had been performed in 20 (32%) of the children; this group was termed the "ENT tear, nose, throat) surgery group." Fifty-six percent of the responders, but onl y 26% of the nonresponders, belonged to the ENT surgery group (P = 0.02). We conclude that intrauterine growth retardation or prematurity is not asso ciated with abnormal cold air responsiveness in the IHCA test. (C) 1999 Wil ey-Liss, Inc.