This section is from the book "A Text-Book Of Pharmacology, Therapeutics And Materia Medica", by T. Lauder Brunton. Also available from Amazon: A text-book of pharmacology, therapeutics and materia medica.
Chloroform 1 fl. oz., rectified spirit 19 fl. oz., B.P.; purified chloroform 10, alcohol 90, U.S.P.
Dose. - 20 to 60 min.
B.P. Tinctura Chloroformi Composita. Compound Tincture of Chloroform.
Chloroform 2 fl. oz., rectified spirit 8 fl. oz., compound tincture of cardamoms 10 fl. oz.
Dose. - 0 to 60 minims.
Uses. - The liniment is used as a stimulant and local anaesthetic. Spirit of chloroform, chloroform mixture, and compound tincture are used as carminatives and sedatives. Chloroform water as a vehicle and carminative.
Action of Chloroform. - When mixed with albumen, chloroform produces a precipitate, but renders the supernatant albumen more easily filtered than before. It is a powerful solvent of protagon, which forms the essential ingredient both of the nerve-centres, of the nerves themselves, and of the red blood-corpuscles, and some authors have considered that to. this solvent property the action of chloroform as an anaesthetic was, in gome measure at least, due. This, however, is at present hypothetical. It appears to lessen the oxidising power of the blood, although not to a very great extent, for the diminution of this power is hardly perceptible in the blood of animals poisoned by chloroform, although distinct in blood which has been mixed with it. When applied to the skin, it evaporates rapidly, and produces a feeling of cold. When its evaporation is prevented, it passes through the epidermis, and acts as an irritant on the skin, producing rubefaction, and leaving behind a painful burning spot, or even vesication. It greatly assists the absorption of organic alkaloids by the skin, so that a number of them will pass through the epidermis and be absorbed with considerable ease when mixed with chloroform, although they would not pass through at all if applied as an alcoholic solution. In the mouth it has an exceedingly sweet taste, and stimulates the secretion of saliva. When swallowed in large quantities, it acts first as an irritant, producing gastro-enteritis, and afterwards, from its absorption, will cause anaesthesia and coma, so that the vomiting, pain at the epigastrium, and purging, which are first observed, gradually pass off, and are succeeded by stupor, coma, and abolition of reflex sensibility, which may either end in death, or may pass off, while the irritation of the intestines and stomach may con-tinue for some time afterwards. In small doses it probably stimulates the secretion of gastric juice and the movements of the stomach (cf. p. 367), and both increases and co-ordinates more perfectly the movements of the stomach and intestines, so that it causes expulsion of flatulence and relieves griping.
After absorption into the blood, either from the stomach or; from the lungs, it acts on the nervous system in somewhat the same way as alcohol, paralysing the nerve-centres in much the same order. Its action, however, is more rapid than that of alcohol, and it does not appear to produce the stimulation with-out derangement of the mental faculties which marks the first stage of the action of alcohol. Chloroform appears to derange the mental faculties from the very first. The effect of chloroform may generally be divided into three stages : (1) of imperfect consciousness, (2) of excitement, and (3) of anaesthesia; or perhaps one might divide it more exactly into four stages (p. 206), and add a fourth stage, that of paralysis. Its first effect is to produce a feeling of warmth over the surface, with affection of the optic and auditory nerves, noises being heard in the ears, and a sensation of light experienced in the eyes. There is also a feeling of oppression at the chest, and sometimes a choking sensation, occasionally accompanied by cough. The choking and pough are more especially felt if the vapour is administered in too concentrated a form, and not unfrequently the patient will put up his hand to try and take away the cloth containing the chloroform. External impressions are now slightly felt, sounds are faintly heard, questions are slowly and imperfectly answered, and any sensation of pain which may be present becomes greatly diminished or entirely disappears. In children and weak persons this stage may pass into that of complete anaesthesia, but in most cases it is succeeded by the stage of excitement. The patient is no longer conscious of what is going on around him, but he may, according to his temperament, sing, shout, or struggle violently. The violent struggles are more especially noticed in men of irritable temperament, who have been accustomed to the use of alcoholic stimulants. In them the excitement is greater, and more chloroform is required in order to produce the stage of complete anaesthesia. During the violent struggles, the efforts of the patient may induce him to hold his breath until suffocation seems impending; the face becomes livid, the eyes prominent, and the jugulars distended. The struggling is usually less in women than in men, and is less in patients exhausted by previous illness. In women, hysterical sobbing or crying may occur; occasionally indications of venereal excitement have been observed, and even a complete venereal orgasm. When the chloroform is pushed, this stage soon subsides, and the patient passes into the state of complete anaesthesia. The limbs become flaccid; when the hand is taken up it falls like that of a corpse; painful stimuli produce neither reflex action nor any indication of sensation. The last reflex actions to disappear are those from the conjunctiva, the anus, and the vagina. When touching the conjunctiva no longer causes reflex contraction of the eyelid, anaesthesia may be regarded as complete, and surgical operations may be commenced. During the administration of chloroform the respiration is generally first rendered somewhat slow, then quicker, and lastly steady, unless the anaesthetic be pushed too far, when it again becomes slower and weaker, and finally ceases altogether. The pulse is usually affected in a similar manner. The reason of this appears to be that the chloroform vapour, as it descends the respiratory passages, successively irritates those parts with which it comes immediately in contact: (1) the nasal mucous membrane, (2) the larynx, and (3) the lungs. It causes, through the nerves of the nose and larynx (p. 242), reflex slowing of the respiration and reflex slowing of the pulse. As these nerves gradually become paralysed by the action of the drug, its stimulating effect on the branches of the vagus distributed to the lung becomes manifest in accelerated respiration, usually accompanied by a quickened pulse. Next, as the drug continues to act, it paralyses those nerves also, and the respiratory centre, being now no longer affected by any reflex irritation, continues to keep up the respiratory movements with a somewhat slow and steady rhythm. If the drug be now pushed still further, the respiratory centre itself becomes paralysed, the respirations become still slower and feebler, and finally cease altogether. These alterations in the respiratory rhythm during the administration of chloroform may sometimes be more or less interfered with by the effect upon the respiratory centre of blood which has become venous in consequence of the altered respiratory movements. The action of the heart is also modified by chloroform, the pulse usually becoming somewhat slower just at first; then accelerated during the whole period of excitement; and afterwards steady, at or below its normal rate. The blood-pressure is usually lowered, and if the chloroform vapour be strong the pressure may fall very considerably, and may even be reduced to zero. The fall of blood-pressure is probably due in great measure to the dilatation of the vessels, but it may also be partly owing to enfeebled action of the heart, even at the beginning of the anaesthesia. When the chloroform has been pushed so far as greatly to lower the blood-pressure, the fall is caused, to a great extent, by the weakening of the heart. The dilatation of the vessels is not due to paralysis of the vaso-motor nerves, for these, when irritated directly, will still cause the artery to contract during chloroform-narcosis. It appears to be due to paralysis of the vaso-motor centre. The reflex power of this centre is first diminished, and then abolished, by chloroform, so that irritation of a sensory nerve during imperfect chloroform-narcosis, causes only a slight rise of blood-pressure, and in perfect narcosis no rise at all.