Dyspnea is always serious, especially if it gets worse with time.
      The word dyspnea or shortness of breath comes to us from the compound Greek word ‘duspnoia’ where ‘dus’ means difficult and ‘pnoē’ means breathing.  It is one of the most ominous medical signs because it can feel like choking and is often accompanied by a sense of dread.  Although not all the causes of dyspnea are dangerous, the fear that accompanies it can elicit great alarm and urgency in both doctor and patient.  The common denominator is oxygen hunger or the lack of enough oxygen to the body, muscles, and brain.  Dyspnea may not be noticed initially except with exertion but as it progresses, it becomes noticeable even at rest and that makes it much more serious.  The common causes of dyspnea are twelve:
      1. Lung diseases such as infections, asthma, emphysema, and bronchitis are invariably accompanied by cough, which points to the lungs as the potential source.  Giving oxygen, relieving the airway spasm, clearing the mucus, and treating the infection provide relief in most cases.
      2. Conditions that cause fluid to accumulate around the lungs, pleural effusion and pleurisy, cause dyspnea by restricting respirations.  Here, giving oxygen may not help but draining the fluid does.
      3. Blood clots that travel to the lungs block the lungs’ blood flow and prevent the blood from becoming oxygenated.  These pulmonary emboli commonly occur after surgery or trauma and are not visible on chest x-rays.  Oxygen may not help much because the blood flow through the lungs is restricted but thinning the blood and clearing the clots is life saving.
      4. Diseases that reduce heart pumping or cardiac output and cause heart failure—such as bad valves, clogged arteries, sick heart muscle, or abnormal heart rhythms—decrease blood supply to the body and brain, which reduces the available oxygen and causes the feeling of dyspnea.
      5. Diseases of muscles, which cause the muscles to weaken and shrink or atrophy, make it harder for the involved muscles to pull oxygen out of the circulating blood.  When these muscles are exercised, as in walking or moving, their inability to extract enough oxygen to satisfy their needs results in the feeling of dyspnea.
      6. Deconditioned states, where after major surgery or a prolonged illness our bodies grow out of shape or atrophy, causing our heart and skeletal muscles to have similar trouble extracting enough oxygen out of our circulating blood.  Consequently, dyspnea results from the slightest activity but it may be reduced or eliminated with gradual reconditioning.
      7. Overweight, especially when accompanied by deconditioning, overloads the heart and body muscles.  This imbalance causes easy exhaustion and dyspnea just like one feels while carrying a heavy load or while running uphill.
      8. Smoking and smoke inhalation, even in the absence of lung disease, reduce the oxygen carrying capacity of the hemoglobin by blocking it with carbon monoxide.  This reduces the effectiveness of the oxygen delivery to tissues and leads to dyspnea at the slightest exertion.
      9. Pulmonary hypertension, or high lung blood pressure, is a consequence of many diseases such as lung infections, lung blood clots, and autoimmune diseases.  The increase in lung blood pressure makes it harder for the blood to pass through the lungs.  This decreases the amount of oxygenated blood reaching the tissues, thus causing dyspnea.        
      10. High altitude dyspnea occurs in those who are not acclimatized or conditioned to mountain living and is caused by the low oxygen concentration in the thin mountain air.  In extreme cases it can lead to lung swelling or edema, which requires rapid mountain descent for resolution.
      11. Anxiety and panic states, when triggered by an adrenalin rush, lead to dyspnea in spite of adequate tissue oxygenation.  That dyspnea is caused by the rapid heartbeats and the rapid respirations, both consequences of the high adrenaline, which causes a feeling of alarm with accompanying dyspnea.
      12. Esophageal acid burn caused by acid reflux may trigger a reflex that gives us the false feeling of dyspnea.  This pseudo-dyspnea is mostly present at rest and causes us to take in frequent but unsatisfying, deep sighs.  Unlike true dyspnea, esophageal pseudo-dyspnea disappears with exercise, reappears with rest, and responds to antacids such as Malox and to acid suppressants such as Pepsid and Prilosec.  I discovered this entity by coincidence when I suffered from it a few years ago.  Having learned to recognize it, I now see and treat it frequently in my medical practice.  I do not know if it has ever been described in the published medical literature.
      As a general rule, any dyspnea that worsens with time constitutes an emergency and should be brought to medical attention without delay.