EFFECT OF DISODIUM-CROMOGLYCATE ON VENTILATION AND GAS-EXCHANGE DURING EXERCISE IN ASTHMATIC-CHILDREN WITH A POSTEXERTION FEV(1) FALL LESS-THAN-15-PERCENT

The purpose of this study is to evaluate the effect of disodium cromog lycate (DSCG) on gas exchange and ventilation during incremental exerc ise in asthmatic children with an FEV(1) fall less than 15 percent fro m the baseline after the exercise. Seventeen children (aged 8 to 14 ye ars) with a history of mild to moderate asthma but no clinical and spi rometric evidence of exercise-induced asthma (EIA) underwent two maxim al exercise tests in a randomized order: test A without premedication and test B after inhalation of DSCG, 40 mg. To evaluate the effect of DSCG on normal airways, nine healthy children performed the same exerc ise protocol. Pulmonary function was normal at rest and after treadmil l exercise test (the mean postexercise fall in FEV(1) was 5.9 percent in test A and 1.5 percent in test B). Gas exchange, minute ventilation (VE) and heart rate (HR) were monitored during running in both tests. In the asthmatic subjects, there were no differences in oxygen uptake (V-O2), carbon dioxide output (V-CO2), and V-E at rest between the tw o tests. During exercise, V-E, V-O2, V-CO2, and energy cost (EC [O-2 m l.kg(-1) m(-1)]) of running in the asthmatic subjects were significant ly lower in test B than in test A (analysis of variance, p<0.01) for c omparable work rates. Maximal minute ventilation (V-Emax) was signific antly higher in test A (46.9 +/- 14.6[+/-SD] L.min(-1)) than in test B (43.2 +/- 14 L.min(-1); p<0.05). We found no significant effect of DS CG on gas exchange and ventilation during exercise in the healthy chil dren (V-Emax 47.8 +/- 25 and 48.4 +/- 25 L min(-1) in test A and B, re spectively). In conclusion, premedication with DSCG appears to decreas e the ventilatory cost of exercise in asthmatic children who do not pr esent a substantial fall in FEV(1) after an exercise test without pret reatment.