In the early stages of chronic obstructive pulmonary disease (COPD), patients appear to be symptomless and may not present to a physician until the condition is quite advanced, often only after an acute exacerbation. There are a number of reasons for this. Unlike asthma, there may be no sudden episodes of acute chest tightness, dyspnea, or wheeze that might catch the patient's attention. At first, all that may be noticed is increasing breathlessness during leisure activities and recreational pursuits.