When people get so short of breath that the very effort of breathing is difficult and when breathing is harsh and labored, anyone can tell that something is wrong. Since respiration is necessary to life difficult breathing creates serious anxiety. Usually people breathe eighteen to twenty times a minute, and regularly. The breathing is effortless and without any special sensation. If breathing becomes irregular or if a severe effort has to be made to get enough breath, pain may appear.
Anyone can get short of breath after severe work or exhaustive exercise. Shortness of breath occurs more often in fat people than in thin ones, in old people than in young ones, and in women than in men. The response of the heart and the breathing to a measured physical effort may be used as an indication of physical fitness.
When shortness of breath is not accompanied by extra effort, the trouble may be more mental than physical. Anyone can imitate shortness of breath. Allergic conditions and asthma which narrow the bronchial tubes bring on “wheezing.” Damage to the diaphragm, the lining of the chest cavity or the lungs may bring about trouble in breathing. In pneumonia when a portion of the lung is inflamed and congested, the breathing is labored. Severe anemia, which lessens the supply of blood able to carry oxygen, may result in quickened breathing to get the necessary oxygen to the tissues.
The most important causes of shortness of breath are diseases of the heart and lung, and disorders which in any way prevent air from getting into the lungs. As with every other part of the body, damage to the nervous system can also be reflected in serious difficulties with breathing.