How to assess the dyspnea of a presenting patient?

Determine time course, if acute (<days) [could be caused by airway (bronchospasm), parenchyma (pleural edema, respiratory tract infection), pleura (pneumothorax) and vascular (emboli)] If subacute (days till 3 weeks) [airway (exacerbation), parenchyma (infectious, Wegne's, pneumonia, cyrptogenic), neuromuscular (Guillain-Barre, myasthenia), pleura (pleural disease or effusion)] If Chronic (>3 weeks) [airway (asthma and COPD), parenchyma (multiple disease with slow progression causing fibrosis)]