Pulmonary Function and Exercise Challenge Test in Thai Children: 10 Years Post Respiratory Syncytial Virus Infection
PAISAL LERDLUEDEEPORN, M.D.*, AROONWAN PREUTTHIPAN, M.D.** SUBHAREE SUWANJUTHA, M.D.**,
Affiliation : * Allergy Unit, Division of Pediatrics, Queen Sirikit National Institute of Child Health, Children's Hospital, Department of Medical Services, Ministry of Public Health, ** Division of Pediatric Pulmonology and Critical Care, Department of Pediatrics, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand.
Objective : To report the occurrence of asthma, pulmonary function and exercise challenge
test abnormalities found in Thai children, who 10 years earlier had lower respiratory tract infection
caused by respiratory syncytial virus (RSV -LRI).
Patients and Methods : 37 children, with RSV-LRI admitted at Ramathibodi Hospital
during January 1986 through December 1987, were contacted, of whom 13 patients responded and
completed history-review-questionnaires. Pulmonary function measurements at pre- and post-
exercise and testing for bronchodilator response were performed.
Results : The occurrence of physician-diagnosed asthma in the patients with and without
family history of allergic diseases was 75 per cent and 40 per cent, respectively. Of II patients
who performed spirometry, 45 per cent had concave flow-volume curves, 36 per cent showed
decreased ratio of forced expiratory flow in the first second (FEV 1) to forced vital caracity
(FVC) and 27 per cent showed either decreased forced expiratory flow between 25-75 per cent
of FVC (FEF25-75%) or peak expiratory flow rate (PEFR). Of 8 patients who completed exercise
challenge tests, 87.5 per cent showed markedly decreased PEFR at post exercise challenge tests
and 37.5 per cent had markedly decreased FEV 1. 62.5 per cent and 25 per cent showed markedly
increased PEFR and FEV, respectively, after inhalation of bronchodilators.
Conclusion : This study suggests that the occurrence of asthma in children, who had
previous RSV-LRI, is relatively high compared with that reported in general Thai children.
Baseline pulmonary function tests showed evidence of airway obstruction as demonstrated by
concave-shaped flow-volume curves, decreased FEV 1/FVC ratio, FEF25-75% and PEFR. The
presence of bronchial hyperreactivity to exercise challenge test and positive response to bron-
chodilators confirms the evidence of exercise-induced bronchospasm in children with history
of RSV-LRI.
Keywords : Pulmonary Function, Exercise Test, RSV
