Histamine-induced versus exercise-induced asthma in young adults

ABSTRACT

The objective of the study was to measure the prevalence of exercise induced asthma among young medical students of Rawalpindi Medical College, Rawalpindi and to compare airway responses to histamine and exercise challenge. Ninety-eight medical students from Rawalpindi Medical College, Rawalpindi were selected after obtaining written consent. They were asked to fill up questionnaire before taking history and doing their physical examination. Each subject was put on exercise by cycle ergometer to such an extent that 80-90% of maximum predicted heart rate was obtained and then same exercise was continued for 6-8 minutes or till symptoms of asthma developed. Before and after exercise challenge, lung functions were measured by using vitalograph compact spirometer and percentage fall in these results was calculated. In another 40 medical students, histamine inhalation challenge was given by increasing dilutions of histamine acid phosphate with the help of Boreal Nebulizer and airway responses were measured with the help of a spirometer. The overall prevalence of exercise and histamine induced asthma in young medical students was found to be 39% and 92% respectively. The comparison between percentage fall of forced expiratory volume [FEV[1]] in first second and peak expiratory flow rate [PEFR] after exercise and after histamine was significant. The present study revealed that overall exercise induced asthma was more common in our subjects as compared to other studies. Moreover, it was also seen that histamine challenge is a more sensitive test as compared to exercise challenge test for detecting latent asthma.