1 Brunton and Cash, Central.f, die med. Wissensch., 1886, p. 241.

Action on Mammals. - Opium causes partial abolition of voluntary movement, sometimes preceded by. a certain amount of increased excitability, followed by sleep. Sometimes the spinal cord shows signs of increased excitability with diminished conducting power, evidenced by convulsions with a tendency to paralysis of the hinder limbs.

Action on Man. - In man the action of opium is chiefly upon the brain, producing sleep. When taken in small doses of 1/4 gr. to 1 gr. there is, first, a stage of excitement of the circulation, as evidenced by the pulse being fuller and quicker, and by the surface of the skin being warm and flushed. During this stage the individual has the power of directing his energies to any particular object, and the action of the drug causes him to do well whatever he wishes to do. Thus, if he wishes to sleep, and surrounding circumstances be favourable, an agreeable languor followed by quiet sleep comes on. He can be easily aroused from this sleep; and after a few hours the effect passes off, leaving, however, slight headache and languor, with dryness of mouth and slight nausea. If, on the other hand, he wishes to work, he can do this with increased energy; or, if he desires to exert the mind, he will find his imagination more vivid, his thoughts more brilliant, and his power of expression greater (Christison). The after-effects are the same as after sleep.

With moderate doses of 1 gr. to 2 grs. the stage of excitement is short and is followed by deep sleep, from which the person can still be aroused. The after-effects are severe headache, with nausea, furred tongue, and loss of appetite. During the stage of sleep the brain is anaemic, both the arteries and veins being empty (vide p. 197).

With large doses, of 3 grs. or more, the first stage is very short. Sleep rapidly follows, becomes deeper and deeper, and passes into coma, from which the patient can no longer be aroused. The arms and limbs are limp; the face is generally pale, with a bluish tinge at times; the eyes are sunken, the pupils very much contracted, almost to the size of a pin's point; respiration slow and stertorous. The pulse during sleep and coma is slow and full; as coma proceeds it becomes feebler. Finally death by asphyxia occurs, the respiration ceasing before the heart. It may occasionally be preceded by convulsions, though this is rare.

Post mortem the ordinary appearances of death by asphyxia are found, viz. congestion of the brain and lungs, etc.; the ventricles of the brain contain serous fluid, the veins of the brain and spinal cord are distended with dark blood, and there may be slight extravasation of blood in some of the tissues.

Diagnosis between Opium-poisoning, Intoxication, and Apoplexy. - One should obtain the history of the case where it is possible, as this may enable one to diagnose not only between opium-poisoning, intoxication, and apoplexy, but between these and other forms of coma, e.g. post-epileptic and uraemic coma. The former is recognised by the history of convulsions, and the latter by the presence of albumen in the urine, with sometimes oedema of the legs. When the history cannot be obtained - for instance, in cases where the patient is found lying unconscious - the diagnosis is sometimes extremely difficult.

Notice first the odour of breath; the smell guides one in opium-poisoning. The smell of alcohol does not assist one much, as it may be taken with opium; and in apoplexy brandy is frequently given by the person who first finds the unconscious patient.

Secondly, the pupil, which is very much contracted in opium, but dilated in alcoholic, poisoning, and often unequally contracted in apoplexy. It must be borne in mind that in apoplexy of the pons varolii, the pupils may be equally and extremely contracted, just as in opium-poisoning. In apoplexy the arms on being raised and then relaxed fall unequally on the two sides, one being more rigid or flaccid than the other. The rectal temperature is often an important sign, as in apoplexy there is an initial fall with a subsequent rise in the majority of cases. In no case should the individual be treated roughly or exposed to the slightest chance of a chill, but, on the contrary, he must be kept warm; and if it appears to be a case of poisoning by alcohol or opium, and not apoplexy, the stomach should be washed out and strong coffee injected.

Treatment in Opium Poisoning. - Evacuate the stomach as soon as possible by administering 20 grs. of zinc sulphate in a little water; if this acts, then give some strong coffee. Sometimes the zinc will not produce vomiting on account of the insensibility of the stomach and vomiting centre, due to the action of the opium. If such be the case, employ the stomach-pump, wash out the stomach with warm water, and inject coffee. Keep the patient awake by walking him about the room, tapping on the forehead with the finger-nails, or flicking him with a wet towel. Apply mustard-leaves to various parts of the body, or use a galvanic battery. Cold affusion is a good adjunct; but the alternate use of hot and cold water is better both as a stimulant and as preventing the risk of chilling the patient. Lastly, give a subcutaneous injection of 4 minims of liquor atropinae sulphatis, B.P. every ten minutes, until symptoms of recovery show themselves or the pulse is quickened or the pupil dilated.

Precautions. - Do not allow the patient to become cold while trying to rouse him, and take care not to chill him when applying cold affusions, as death may result from syncope after recovery from the comatose condition. The average length of insensibility is twelve hours, and if this period be passed, recovery is nearly certain, but sometimes the symptoms may reappear, and death from asphyxia or syncope occur.

Treatment of the Symptoms after an Ordinary Dose.Strong coffee with or without brandy, or lemon-juice and water, should be administered. The patient should be kept in bed.