Morphine alone, or in combination with ether as a general anesthetic, reduces susceptibility to shock, and appears to be an equalizer of pressure and a tranquillizer of an excited heart. Nitroglycerin and the nitrites usually fail to raise or even sustain pressure. Saline infusion and adrenalin are the reliable and efficient means to be used in combating shock and collapse; they always raise blood pressure, and the latter is the most powerful of all known vasomotor constrictors. Adrenalin always produces rise of blood pressure, even after cocainization of the medulla and cord or destruction of the medulla, division of the splanchnics, or arrest of the heart by powerful electrical currents (2300 volts, alternating). Even after death by decapitation and an interval of fifteen minutes, adrenalin salt solution thrown into the veins causes a rise of blood pressure. If this be combined with artificial respiration and rhythmic pressure over the heart, resuscitation is possible in most extreme cases. In one case, reported by Crile, a human heart which had stopped beating for nine minutes was made to resume its pulsation for thirty-two minutes. From all this it will appear that the heart stimulants, so called, have a very limited applicability.
Crile further experimented by raising the atmospheric pressure surrounding the animal, and found that blood pressure was somewhat exalted. The reverse was also found to be true. When he so arranged his experiment that an animal inhaled air under increased pressure he found the tendency was rather to impairment of heart action, blocking the circulation and reducing pressure. Changing the experiment and causing the animal to breathe air at normal pressure while the body was under increased atmospheric pressure, blood pressure was notably raised, but respiration became labored and the heart’s action impaired. After death the heart and the pulmonary vessels were found engorged.
This has its practical interest because it concerns not alone the general treatment of shock, but the management of those cases where the thorax must be opened, as in the surgery of the heart, the lungs, the esophagus, etc., and the mechanical devices recently suggested for maintaining differences of atmospheric pressure, and preventing a traumatic collapse of the lungs.
These experiments also suggested the so-called “pneumatic suit” devised by Dr. Crile, which is in effect a double-layered garment of rubber cloth. The patient is enveloped in the suit, which can be inflated with an ordinary bicycle pump, so that pressure is made upon the surface of the body, and at the same time evenly distributed. By such pressure accumulation of blood in the venous reservoirs is prevented, and the emptying of the arteries, especially those in the brain, is prevented. This is a more perfect and ideal application of the idea underlying the practice of bandaging the extremities or raising them, in extreme conditions of shock; the former requires an elaborate and expensive outfit, while for the latter purpose cotton bandages or rubber may suffice. The latter, however, must be used with great caution lest pressure be overdone. When the bandages are removed they should be taken off slowly, and from one limb at a time, lest the change be too abrupt.
Two other expedients are of the greatest value in conditions of this kind; the first is artificial respiration. This cannot be carried out, as is done on experimental animals, in a well-furnished laboratory, by opening the trachea and making connection with a pump; it must be effected by the usual methods, coupled with the aid afforded by the improved Fell apparatus. If oxygen can be administered at the same time it will enhance the effect.
The second expedient is rhythmic pressure made over the lower part of the thorax, or beneath the ribs, by which is produced a stimulus to contraction of the heart. This may be made slowly at first, but may approximate a rate corresponding to a slow pulse.
The temptation is to use the adrenalin solution too strong or in too large doses. It may be administered in doses of 4 or 5 minims in a small syringeful of salt solution, but when the symptoms are profound and the case urgent, 300 to 500 Cc. of sterilized salt solution, containing the same amount, should be injected beneath the skin into the subcutaneous cellular tissue about the shoulder-blade, the buttock, behind the breast, or into a convenient vein. Much larger amounts, even up to 1000 Cc., may be used, but the adrenalin should never be mixed until just before using it, as it is quickly oxidized and changed, and should be used in the freshest possible condition. With salt solution containing 1 to 50,000 of adrenalin and continuously administered, Crile has kept a decapitated dog alive for over ten hours—that is, the heart continued its action. One may agree with him, then, in the statement that “control of blood pressure is the control of life itself.”
Mathews, after a careful study of the osmotic behavior of blood plasma and saline solutions, has shown that the ordinary salt solution, which has been usually made in proportion of 6 to 1000, is not the best which can be used for purposes of saline infusion. Many observers have added potassium and calcium salts to such a mixture, the latter, especially, because of its property of increasing the coagulability of the blood.
The following mixture meets the indications for what may be called the “balanced” physiological solution: Sodium chloride 0.9, potassium chloride 0.03, calcium chloride 0.02, water 100.[6]
[6] To the fluid for hypodermoclysis (salt solution) there may be added a proportion of grape sugar, by which much is gained of true nutritive value, which may be enhanced by the addition of pure pepsin peptone free from albumose. Thus if every four hours there be injected beneath the skin 100 Cc. of water containing 2 grams each of grape sugar and table salt to 4 grams of pepsin peptone, the necessity for further nourishment may be almost obviated, at least for a period of two or three days at a time; as for instance when intense nausea of severe peritonitis prevents the ingestion of anything possessing food value. Credé recommends for the same purpose a preparation containing soluble albumin in the strength of 95 per cent., with traces of iron and salt. This preparation is called by him kalodol, and much resembles blood albumin, which is why it is so easily assimilated. According to Credé, four injections of kalodol a day will suffice for ordinary needs.