Asthma (Gr.) is a disease characterised by the occurrence of paroxysms, in which the breathing, previously natural, becomes difficult, and is accompanied by wheezing and a distressing sense of tightness in the chest. Asthma frequently appears at first after some inflammatory affection of the respiratory mucous membrane, but often without any such cause. It may begin at any age, but most often before ten. It is often clearly hereditary, affecting several members of the same family; and it may occur in families with a tendency to nervous diseases—e.g. epilepsy. The paroxysms are often preceded by premonitory symptoms—in some by great drowsiness; in others by extreme wakefulness and unusual mental activity and buoyancy of spirits; in at least one case by an attack of ophthalmia. The difficulty of breathing may become permanent in a lesser degree, with severer paroxysms at intervals.
The spasms may occur at any hour, but least often in the forenoon, most commonly between two and four in the morning. The causes inducing an attack vary greatly. In some, asthma only occurs with bronchitis, or with disorder of the stomach; in some it is brought on by particular odours, or articles of food; in many, locality exerts most influence—e.g. they may suffer little in a smoky town, much in the country; or the reverse.
The asthmatic paroxysm is thus described by Dr Salter, the standard authority on this common but terrible disease: 'The patient goes to bed and sleeps two or three hours, becomes distressed in his breathing, and begins to wheeze, so as to waken those in adjoining rooms. He awakes, changes his position, falls asleep again and again, and the miserable fight between asthma and sleep may go on, till the increased suffering does not allow the patient longer to forget himself for a moment; he becomes wide awake, sits up in bed, throws himself forward, plants his elbows on his knees, and with fixed head and elevated shoulders, labours for breath like a dying man.' If the spasm is protracted, the oxygenation of his blood is imperfectly performed, owing to the scanty supply of air, and his extremities get cold and blue, but at the same time the violent muscular efforts at respiration—in which all the extraordinary muscles of Respiration (q.v.) are called into action—cover him with sweat. The pulse is always small. The chest enlarges during the paroxysm, but in it there is almost perfect stagnation of air. Alarming, however, as the attacks are, even to an onlooker, they are almost never fatal.
The symptoms of asthma are probably produced by spasmodic contraction of the muscular fibres surrounding the smaller bronchial tubes (see RESPIRATION); but they may be caused, at least in some cases, by temporary swelling of the bronchial mucous membrane, analogons to Nettle-rash (q.v.) on the skin.
During the occurrence of a paroxysm, the patient's clothes should be loosened, and he should be placed in such a position as will best assist him in his effort to breathe; to this his own sensations will generally guide him. The number of remedies recommended and sometimes useful during the attack, is itself a testimony to their uncertainty. A few of the most valuable are antimony or ipecacuanha in emetic doses; ether or very strong coffee; nitroglycerine in small doses; chloroform, transient in its effects, and to be used with caution; inhalations of oxygen; tobacco, stramonium, or lobelia smoked in the usual way, with inhalation of the smoke; blotting-paper impregnated with saltpetre and burnt.
A sufferer from asthma must avoid all causes which he finds apt to induce an attack; must attend carefully to his general health, and especially his digestive system; and may obtain much benefit from tonic and anti-spasmodic medicines. The selection of a suitable locality for residence procures for many sufferers relief or immunity. When asthma begins very early in life, it often passes off at or before maturity.