COLD-AIR INHALATION AND EXERCISE-INDUCED BRONCHOCONSTRICTION IN RELATIONSHIP TO METACHOLINE BRONCHIAL RESPONSIVENESS - DIFFERENT PATTERNS IN ASTHMATIC-CHILDREN AND CHILDREN WITH OTHER CHRONIC LUNG-DISEASES

Cold air inhalation and exercise-induced bronchoconstriction (EIB) hav e both been used as measures of bronchial responsiveness, Both stimuli are often combined in the Nordic climate. The main objective of the p resent study was to investigate the climatic influence of cold tempera tures upon exercise-induced asthma. The secondary aims were: ia) to as sess metacholine bronchial hyper-responsiveness and EIB in children wi th bronchial asthma (n=32; mean age 10.8 years) compared to children w ith other chronic lung diseases (CLD) (n=26, mean age 10.1 years); and (b) to assess the influence of cold air inhalation upon EIB in the tw o groups of children. Methods used were: (a) the metacholine concentra tion causing a reduction in FEV1 of 20% (PC20-M), (b) maximum FEV1 fal l (Delta FEV1) after submaximal treadmill run (EIB test); and (c) Delt a FEV, after submaximal treadmill run while inhaling cold (-20 degrees C) dry air (CA-EIB test). Geometric mean PC20-M did not differ signif icantly between the asthma children (1.28 mg ml(-1)) and the CLD child ren (2.90 mg ml(-1)). In the asthma children, mean Delta FEV1 after EI B test was 12.8% vs 21.8% after adding cold air (P<0.0001), compared t o 5.2 and 7.4%, respectively (P=0.03, in the CLD group. Maximum sensit ivity and specificity for the EIB test were 69.8% at a fall in FEV1 of 6.8%; for the CA-EIB test, 72% at a fall in FEV1 of 10.2%; and for me tacholine provocation. 56% at a PC20-M of 1.5 mg ml(-1). In conclusion , children with bronchial asthma are substantially more sensitive to c old air than children with CLD, and EIB is markedly increased by cold air inhalation in asthmatic children, maintaining the specificity of t he EIB test and increasing the sensitivity, The low sensitivity of the EIB test is probably influenced by the use of inhaled steroids, Metac holine inhalation test has less specificity and sensitivity in discrim inating asthma from other chronic lung diseases.