This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol2", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
Symptoms. The vomiting does not immediately follow the administration of the emetic. At first, no unusual sensation is experienced, except that which may be occasioned by the disagreeable taste of the medicine. But, in a period varying from five to thirty minutes, an uneasiness is usually experienced in the epigastrium, soon followed by the sensation denominated nausea, with a peculiar attendant state of system; vermicular motions are not unfrequently felt in the stomach; and these phenomena increase in intensity until vomiting, at length, takes place. Sometimes the stomach discharges its contents at one effort; but more frequently the emetic action is repeated, and occasionally several times, before the organ becomes quiescent.
From the commencement of the feeling of nausea, to the return of the system to its original condition, a series of phenomena occur, which it is very necessary to understand, in order to appreciate the full therapeutic influence of emetics. During the nausea, the face is pale; the skin cool, moist, and relaxed; the pulse feeble, often frequent and irregular; the saliva flows copiously; and feelings are usually experienced of gastric uneasiness, languor, and universal weakness, which are sometimes in the highest degree distressing, so much so as, if long continued, to render the patient utterly prostrate in mind and body, and indifferent to all things around him, even to life itself. It is very seldom, however, that the nauseating influence is felt in this degree; and sometimes it is scarcely experienced at all; vomiting coming on promptly, and with little antecedent sensation of any kind. Emetics differ extremely in the degree to which they produce nausea. Thus, the sulphates of copper and zinc cause very little; tobacco and lobelia, a great deal, and often prolonged.
During the act of vomiting, another set of symptoms appear. Instead of the sensation of nausea, there is a feeling of constriction in the epigastrium, not unfrequently amounting to spasmodic pain. The face is flushed, the jugular veins are swollen, the temples feel as if distended, there is a general sense of fulness of the head, and sometimes pain, the pulse becomes full and often slow; there is obvious congestion of the brain, resulting from an impeded return of blood from the head. A copious sweat often breaks out, particularly about the face, neck, and upper part of the body. Occasionally, though rarely, an involuntary discharge takes place of the contents of the bladder or rectum. The matter vomited varies, being at first the previous contents of the stomach; but afterwards, if the act be repeated, different liquid secretions, mucus, pancreatic liquor, or bile; and sometimes there is a slight intermixture of blood, derived probably from the rupture of a small vessel in the pharynx or oesophagus, caused by its over-distension.
Upon the subsidence of the vomiting, the system falls again into a state of general relaxation, but not, in this stage, attended with nausea. The depression now existing is a result of the immediately antecedent state of violent muscular action. The skin is moist, and relaxed; the pulse, soft and rather feeble; and feelings of languor and weakness are experienced, which often end in drowsiness, or even sound sleep. The drowsiness is so obvious a phenomenon, that, in experiments upon lower animals, substances which have produced an emetic effect have sometimes been erroneously considered as possessing narcotic properties, in consequence of the apparent stupor which has followed vomiting. It is nothing more than the rest of the brain, after the commotion into which it has been thrown.
Not unfrequently, after the system has suffered a short continuance of vol. ii.-29 depression, it reacts; and something like gentle febrile phenomena are produced; but, in most instances, there is a gradual return to the former state, with whatever difference, in regard to any previously abnormal condition, the action of the emetic may have occasioned.
Unpleasant and even dangerous results sometimes attend or follow the emetic action. The great distension of the blood-vessels of the brain has caused apoplectic phenomena, probably from effusion of blood. I have never witnessed an instance of this kind; but my preceptor, the late Dr. Jos Parrish, used to relate to his pupils the case of a young man under his care, who, in the act of vomiting, was attacked with apoplexy, which proved fatal. The pulmonary congestion has led also occasionally to bleeding from the lungs; and the uterus is said to have suffered in the same way. Hernia, rupture of the abdominal walls, rupture of the stomach itself, prolapsus uteri, and abortion, are other evil effects which have sometimes been ascribed to the straining produced by emetics. A case has recently been reported, in which portions of the chordae tendineae of the mitral valve, in a patient affected with chronic disease of the heart, were torn from their connection by the act of violent vomiting.* The prostration into which the system is thrown by the nausea, or in which it is left after the violence of the muscular action, is sometimes alarming, and has proved fatal in some cases of great debility. Another source of danger has been pointed out. in the stasis of blood attendant on the extreme circulatory prostration of the state of protracted nausea, or secondary depression, amounting sometimes almost or quite to syncope, it is asserted that coagulation of the fibrin has taken place in the heart or elsewhere; and the clots being carried into the arteries have arrested circulation, and given rise to mortification of remote parts. Thus, cases are recorded in which gangrene of the feet, hands, and even of the nose and ears, has followed the prolonged prostration or partial syncope of vomiting. But cases of the kind above mentioned are very rare. I must confess that I cannot recall an instance of serious injury having occurred from the operation of an emetic, under my own personal observation.