This section is from the book "Materia Medica And Therapeutics: An Introduction to the National Treatment of Disease", by John Mitchell Bruce. Also available from Amazon: The pharmacology and therapeutics of the materia medica.
2. Defective vomiting may be said to occur when only attempts at retching ensue on the presence of direct or indirect stimulation of the centre. In the vast majority of cases, however, we have to deal with conditions in which, whilst vomiting is urgently demanded, no attempt at vomiting is made by nature, the substances which require to be expelled from the stomach being of a non-irritant or even sedative nature, such as narcotic poisons. This introduces us, further, to the use of emetics for other purposes than simple evacuation of the stomach. Vomiting may be desired for the sake of obtaining one or more of the associated effects on other viscera. In certain inflammatory diseases of the larynx and bronchi, such as croup and bronchitis, which are attended by the production of thick or solid products, or whooping cough, which is characterised by defective or disordered expulsive power, an emetic will be indicated to empty the respiratory passages and restore the free entrance of air. Similarly, rigidity of the cervix uteri in the first stage of labour is believed by some obstetricians to call for emetics which shall relax the uterine sphincter.
Vomiting usually ceases with the removal of its cause, but it may persist indefinitely, until the therapeutist steps in.
Whilst it is in itself a natural provision for relief, there is a limit to its beneficial effect. Protracted vomiting appears to increase the irritability of the mucous membrane and nerves of the stomach, and thus to tend to go from bad to worse; and the same is the case with the vomiting centre, which may become so sensitive as a consequence of sickness that the slightest change of posture brings on the symptom afresh. There is urgent need for treatment in such cases.
The therapeutical relations of vomiting, rationally considered, are obvious. Excessive vomiting has to be arrested; vomiting may have to be assisted when it is ineffectual, or excited when entirely absent; and the action of emetics may be taken advantage of for other purposes than to empty the stomach.
Excessive Vomiting. The study of the physiology and pathology of vomiting serves to impress upon the student the absolute necessity for diagnosis, or investigation of the cause of disorder, before rational therapeutics can be carried out, and the thoroughly unscientific and unsatisfactory character of the practice which applies treatment to symptoms without ascertaining the pathological condition on which they depend. How extremely irrational it would be to attempt to relieve by the same means the vomiting caused by indigestible food at the commencement of acute indigestion, and the vomiting due to the swelling which persists in the second stage. At the former period, vomiting is relieved by temporarily encouraging it by a good emetic; at the second period, the very opposite set of measures-gastric sedatives-must be employed.
The first step to be taken manifestly is to attempt to remove the originating cause of the reflex act. If the stomach contain irritant food, it must be quickly neutralised, as we saw in the last chapter; if a poison, some antidote must immediately be administered; or either of the two may be removed from the stomach by facilitating and completing vomiting, or by means of the pump. Once emptied, the stomach must be quieted by the gastric sedatives studied in the last chapter. If the cause be discovered in any of the other abdominal organs, the same plan of removal, if possible, must be pursued. Vomiting originating in injury or disease of the brain will call for the special treatment proper in such cases, and the free use of nervous sedatives, such as the Bromides of Potassium and Ammonium. If the vomiting centre is being irritated by some intrinsic poison such as urea, or an extrinsic poison such as antimony, the excretion of the morbid substance by the kidneys, skin, or bowels, must be hastened, or its effects antagonised by stimulants.
If, on the other hand, disturbance of the circulation in the centre be the cause of the vomiting, we must restore the normal supply of blood by keeping the patient in the recumbent posture and insuring bodily rest, and stimulate the circulation by Alcohol and food, if they can be retained in the stomach. Nitro-glycerine, Nitrite of Amyl, and Chloral appear to have been given with some success under these circumstances.
When the cause cannot be removed we must reduce the irritability of the centre by Opium or similar drugs.
2. Defective Vomiting: Use of Emetics.-The adoption of vomiting as a therapeutic measure, and the selection of an emetic from the list just given, are matters of the greatest practical importance. The student must not think that in inducing vomiting we are effecting a simple mechanical act of evacuation; he must appreciate the extent and degree of physiological disturbance which we are setting up. If the patient be very weak, the therapeutist may be alarmed to find that his emetics or unsuccessful attempts at emesis are followed by intense circulatory depression, faintness, and even threatening dissolution. The condition of the patient must be carefully, if quickly, ascertained; and if vomiting be considered a justifiable and proper method of treatment, a selection must be made of one or other emetic, according to the patient's strength and other circumstances. Fortunately, in most cases of acute poisoning, where vomiting is urgently indicated, the patient is able to bear the shock, and Sulphate of Zinc, twenty grains in two ounces water, Sulphate of Copper, two to five grains in an ounce of water, or a table-spoonful of Mustard in a cupful of hot water, should be given without delay. Where blocking of the respiratory passages by the products of croup or bronchitis calls for an emetic, great judgment is required to estimate the patient's strength and to select a proper emetic, if any. Vinum Ipecacuanhas, in doses of 1 fl.dr. for children, or 1/2 fl.oz. for adults, is the best, because it is also an expectorant. Antimony is decidedly more depressing, in doses of 1 to 2 gr. of Tartarated Antimony, or 1/2 fl.oz. of Vinum Antimoniale for an adult. Carbonate of Ammonia is a suitable emetic in these cases, being a stimulant to the heart and respiration. In acute dyspepsia the mildest emetics are indicated, including tepid water, Salt and water, warm nauseous infusions such as Chamomile; and may be freely given. Apomorphia is at once the most certain and generally applicable, whilst the least employed of emetics, because rarely at hand. 1/16 gr. may be given sub-cutaneously, or a dose of 1/8 gr. by the mouth. It is frequently necessary to follow an emetic by a stimulant, such as alcohol.