Shortness of breath — known medically as dyspnea — is often described as an intense tightening in the chest, air hunger, difficulty breathing, breathlessness or a feeling of suffocation.According to Dr. Steven Wahls, the most common causes of dyspnea are asthma, heart failure, chronic obstructive pulmonary disease (COPD), interstitial lung disease, pneumonia, and psychogenic problems that are usually linked to anxiety. If shortness of breath starts suddenly, it is called an acute case of dyspnea.