Effect of Disodium Cromoglycate on Ventilation and Gas Exchange During Exercise in Asthmatic Children With a Postexertion FEVi Fall Less Than 15 Percent: Exercise Testing
Spirometric measurements were performed at rest and at 5, 8, 11, and 15 min after the run. They included forced vital capacity (FVC), (FEVi), and forced expiratory flow between 25 and 75 percent of the expired vital capacity (FEF25-75%) measured by a 10-L bell spirometer (Biomedin, Padova, Italy). For this purpose, each child performed at least three forced expirations from full inspiration in the standing position, and the best was accepted. In test B, the spirometric values taken at rest 30 min after inhalation of DSCG were used as the baseline. In both tests, as values of postexercise FEVi and FEF25-75%, we chose the lowest values among those recorded at different times after the exercise. The maximal reduction in FEVi and FEF25-75%> the percent postexercise fall of these two parameters with respect to baseline, was calculated. Exercise-induced asthma was excluded according to the criterion of a less than 15 percent FEV i fall. The predicted values were those of Polgar and Promadhat. anti allergy
The children were connected via a fitted mask and a corrugated tube to a spirometer and a gas analyzer (Biomedin), which was calibrated with standard gases before each test. They breathed through a 40-ml dead space low resistance three-way valve at the mouth and a second emptying valve at the spirometer, as described in detail previously. After a resting period of 3 min, the subjects ran to exhaustion at a speed of 6.5 km • h, while the inclination of the treadmill was increased by 2 percent every minute. They were periodically incited throughout the test. The observation of at least two of the three following criteria was necessary to consider that the subjects had performed a maximal exercise test: (1) reaching of heart rate (HR) value close to the theoretical maximal HR; (2) stability of oxygen consumption (V02) in spite of the increase of work load; and (3) the inability of the subject to maintain the treadmill speed despite a vigorous encouragement.