The treatment depends on the cause. If ir ritating vapour has set up a spasmodic con dition, breathing of steam is useful as well as hot applications to the throat. In many cases inhaling the vapour of ether or chloroform acts like magic ; but it must be superintended by some competent person. In hysterical and nervous cases dashing cold water over the chest causes the spasm to relax.
Asthma (Greek, asthma, panting) is an affec tion due to a spasm of the small bronchial tubes, causing great difficulty of breathing. The bron chial tubes have a middle coat of muscular fibres (p. 343). If they contract they will diminish the extent of passage in the tube. In the walls of the smallest bronchial tubes there are no plates of gristle to keep the tubes open ; thus contraction of the muscular fibres will readily narrow them, and, if it be excessive, close them altogether, so that air can no longer pass along the affected tubes till the spasm is relaxed. The amount of contraction is regulated by the ner vous system, so that some irritable condition of the nerves supplying the bronchial tubes may occasion tonic contraction of the bronchial tubes, an attack of asthma.
Causes.—True asthma is thus a nervous disealie ; but the nervous irritation giving rise to an attack may be produced by many causes. It is a disease not unfrequently handed down from parent to child, showing itself perhaps in infancy, and most commonly at least before the tenth year. But it may begin at any period of life. The immediate cause of an attack may be the inhalation of irritating vapour or dust. It is a peculiar disease in this respect that the cir cumstances exciting an attack vary with each individual who is subject to it. Thus the smell of new-mown hay brings on a spasm in one, in others the smell of some particular flower, or some particular animal, cat, dog, hare, rabbit, &c., or of some particular drug, for example, ipecacuanha powder. Some asthmatics suffer in one kind of atmosphere, others in an atmosphere of a totally different kind. Each person has to determine for himself what is not hurtful to him. Some asthmatics can live in one place for only one period of the year, and must remove elsewhere for other periods. One of the com
monest causes of asthma is obstruction of one or both nostrils either by chronic catarrhal swelling or by hypertrophy of bone or mucous membrane. The removal of the obstruction fre quently causes the attacks to cease. Stomach affections, specially dilated stomach, are also very frequent causes; of course no treatment which omits to take these things into account is likely to afford permanent cure. A loaded condition of the bowels, states of the heart, liver, and kidneys, may all occasion asthmatic attacks.
Symptoms.---An attack may come on sud denly, or may be preceded by drowsiness and a sense of tightness and constriction in the chest. A peculiar itching of the chin, not relieved by scratching, is in some eases a forerunner of the attack. It commonly comes on at a particular hour, and generally in the, middle of the night. The chief symptom is intense difficulty of breath ing, which compels the patient to rise from his bed and place himself in the position that will enable him to expand his chest to the utmost for the entrance of air. He throws off clothing, and raises his shoulders ; if there is anything above him convenient for the purpose he grasps it with his hands, thus fixing his shoulders in an elevated position and enabling his muscles to act from a fixed point in expanding the chest. Every attitude indicates a struggle for breath. His face expresses great anxiety; his eyes are prominent, his skin pale or bluish, and perspiration breaks out over his body. The breathing is attended with great 'wheez ing.
The spasm may last for only a few minutes or for several hours. It may be present in a mild form for some time. When it passes off, cough comes on, and with the cough a small amount of mucus is frequently discharged, but not in sufficient quantity to account for the difficulty of breathing. It usually recurs at more or less regular intervals or seasons. An asthmatic individual may live to a good age. The disease sometimes disappears in adult life when it has appeared in infancy, but it is usually life-long. Repeated attacks are apt to occasion changes in the lungs, and changes con nected with the heart.