Normal breathing requires no conscious effort to expand the chest and the respiratory movements are automatic in sleep as during waking hours. In dyspnoea the effort is noisy, requires force, and the muscles other than those ordinarily used for respiration are called into action. The trouble may be due to a foreign body in the air passages, their compression, disease of the respiratory organs, heart or kidneys, some general disease, such as asthma, diabetic coma, etc., or narcotic poisoning.

In children the obstruction in the nose is due to the introduction of coins, pebbles, seeds, etc. if the object is small it may produce no symptoms, but it sets up septic inflammation, and there is a risk of its being drawn into the lings. If it is close to the nostril and not too large it can be removed with a small scoop or forceps. It is possible to remove it by syringing or douching through the other nostril. The child is made to sit in a chair and asked to breathe through the mouth, the nozzle of the syringe or the irrigator is introduced into the opposite nostril and a solution of common salt (one teaspoonful to a print of water) allowed running with moderate force.

The stream travels to the back of the nasal cavity and is directed from behind. If the foreign body is lodged in the throat or the larynx it may be possible to remove it with a pair of forceps or scoop it out with the forefinger. Care should be taken not to push it down. Holding the child with the head down and stroking the chest or the back may dislodge the body if it is smooth or round. Chronic nasal obstruction is children are due to adenoids. In old persons the obstruction is often due to a badly fitting tooth-plate being displaced and drawn into the larynx while shouting, laughing or coughing; usually it lodges in the larynx and can be easily removed. Small objects might pass down and cause fatal choking or septic pneumonia.

Dyspnoea is a very distressing symptom in heart disease. And in bad cases the patient is unable to breathe in the recumbent position and has to sit up in bed. It occurs in kidney disease when its excretory function begins to fail and uremia sets in, and unless it is soon restored, a fatal termination is certain. In diabetes, when coma supervenes, the breathing becomes deep and labored without any obstruction, the breathing becomes deep and labored without any obstruction, and the breath has a peculiar fruity odor. In hysteria, the patient sometimes complains of difficulty of breathing and a choking feeling as if a ball were rising in the throat. This subsides without any trouble if the patient is left alone.