Hello thanks for asking from HCM for your doubts I can understand your concern. Bronchial asthma is an immunologically medicated illness. Though the disease remain mild in most of individuals but severe asthma attacks some times result in landing in emergency visits to hospitals. You have severe asthma attack and was hospitalised with oxygen so in my opinion to prevent such situations in future proper treatment should be given to you. For asthma medicines like beta agonists as Salbutamol, Albuterol, Salmetrol etc are used. Aminophylline, Theophylline etc can be used in emergency situations. For more severe cases some times steroids are given. Apart from this try to keep precautions to prevent attacks. Avoid exertion in dust, cold like situations. Try to improve your exercise tolerance gradually. Visit a doctor for prescription and evaluation. Thanks, Hope this helps. Good Luck