The more highly the injured part is endowed with sensory nerves the more marked is the shock; a crush of the hand, for example, is attended with a more intense degree of shock than a correspondingly severe crush of the foot; and injuries of such specially innervated parts as the testis, the urethra, the face, or the spinal cord, are associated with severe degrees, as are also those of parts innervated from the sympathetic system, such as the abdominal or thoracic viscera. It is to be borne in mind that a state of general anæsthesia does not prevent injurious impulses reaching the brain and causing shock during an operation. If the main nerves of the part are “blocked” by injection of a local anæsthetic, however, the central nervous system is protected from these impulses.
While the aged frequently manifest but few signs of shock, they have a correspondingly feeble power of recovery; and while many young children suffer little, even after severe operations, others with much less cause succumb to shock.
When the injured person's mind is absorbed with other matters than his own condition,—as, for example, during the heat of a battle or in the excitement of a railway accident or a conflagration,—even severe injuries may be unattended by pain or shock at the time, although when the period of excitement is over, the severity of the shock is all the greater. The same thing is observed in persons injured while under the influence of alcohol.
Clinical Features.—The patient is in a state of prostration. He is roused from his condition of indifference with difficulty, but answers questions intelligently, if only in a whisper. The face is pale, beads of sweat stand out on the brow, the features are drawn, the eyes sunken, and the cheeks hollow. The lips and ears are pallid; the skin of the body of a greyish colour, cold, and clammy. The pulse is rapid, fluttering, and often all but imperceptible at the wrist; the respiration is irregular, shallow, and sighing; and the temperature may fall to 96° F. or even lower. The mouth is parched, and the patient complains of thirst. There is little sensibility to pain.
Except in very severe cases, shock tends towards recovery within a few hours, the reaction, as it is called, being often ushered in by vomiting. The colour improves; the pulse becomes full and bounding; the respiration deeper and more regular; the temperature rises to 100° F. or higher; and the patient begins to take notice of his surroundings. The condition of neurasthenia which sometimes follows an operation may be associated with the degenerative changes in nerve cells described by Crile.
In certain cases the symptoms of traumatic shock blend with those resulting from toxin absorption, and it is difficult to estimate the relative importance of the two factors in the causation of the condition. The conditions formerly known as “delayed shock” and “prostration with excitement” are now generally recognised to be due to toxæmia.
Question of Operating during Shock.—Most authorities agree that operations should only be undertaken during profound shock when they are imperatively demanded for the arrest of hæmorrhage, the prevention of infection of serous cavities, or for the relief of pain which is producing or intensifying the condition.
Prevention of Operation Shock.—In the preparation of a patient for operation, drastic purgation and prolonged fasting must be avoided, and about half an hour before a severe operation a pint of saline solution should be slowly introduced into the rectum; this is repeated, if necessary, during the operation, and at its conclusion. The operating-room must be warm—not less than 70° F.—and the patient should be wrapped in cotton wool and blankets, and surrounded by hot-bottles. All lotions used must be warm (100° F.); and the operation should be completed as speedily and as bloodlessly as possible. The element of fear may to some extent be eliminated by the preliminary administration of such drugs as scopolamin or morphin, and with a view to preventing the passage of exciting afferent impulses, Crile advocates “blocking” of the nerves by the injection of a 1 per cent. solution of novocaine into their substance on the proximal side of the field of operation. To prevent after-pain in abdominal wounds he recommends injecting the edges with quinine and urea hydrochlorate before suturing, the resulting anæsthesia lasting for twenty-four to forty-eight hours. To these preventive measures the term anoci-association has been applied. In selecting an anæsthetic, it may be borne in mind that chloroform lowers the blood pressure more than ether does, and that with spinal anæsthesia there is no lowering of the blood pressure.
Treatment.—A patient suffering from shock should be placed in the recumbent position, with the foot of the bed raised to facilitate the return circulation in the large veins, and so to increase the flow of blood to the brain. His bed should be placed near a large fire, and the patient himself surrounded by cotton wool and blankets and hot-bottles. If he has lost much blood, the limbs should be wrapped in cotton wool and firmly bandaged from below upwards, to conserve as much of the circulating blood as possible in the trunk and head. If the shock is moderate in degree, as soon as the patient has been put to bed, about a pint of saline solution should be introduced into the rectum, and 10 to 15 minims of adrenalin chloride (1 in 1000) may with advantage be added to the fluid. The injection should be repeated every two hours until the circulation is sufficiently restored. In severe cases, especially when associated with hæmorrhage, transfusion of whole blood from a compatible donor, is the most efficient means (Op. Surg., p. 37). Cardiac stimulants such as strychnin, digitalin, or strophanthin are contra-indicated in shock, as they merely exhaust the already impaired vaso-motor centre.
Artificial respiration may be useful in tiding a patient over the critical period of shock, especially at the end of a severe operation.