The principles and practice of modern surgery

The maintenance of the normal pressure of the blood is a material factor in the welfare of surgical cases. Deviations in the direction of lowered pressure constitute the most important features of shock and collapse. Prevention of loss of blood is but one of several complex indications in prophylaxis and after-treatment.

Blood pressure is maintained in large part by the vasomotor system of nerves, whose prime centre is in the gray matter of the fourth ventricle, with subsidiary centres in the spinal cord and great ganglia. Stimulation of these centres causes contraction of the peripheral arterioles and increases intravascular pressure. If, however, it be long-continued or excessive, these centres become exhausted, vasomotor paralysis results, the arterioles dilate, and pressure is lowered.

Three factors coöperate to maintain this pressure:

• 1. Regular and normal rhythmic heart action;
• 2. Normal vascular contractility;
• 3. Normal quantity of suitable fluid in the vascular system.

Departure from the normal in any one of these factors causes perceptible disturbance, but when in all three of them it may prove fatal. Whether this be caused by emotion, accidental injury, or deliberate operation is of slight concern, as the effect is essentially the same.

The pulse will usually tell its own story to the experienced observer, but scientific accuracy in measuring blood pressure can only be obtained by certain instruments of precision, such as the tonometer or the sphygmomanometer, consisting of an air-containing armlet which encircles the arm, a bulb by which the pressure of air can be regulated, and the whole connected with a manometric gauge and mercury tube. These instruments can be procured of the dealers, and their employment during an operation gives the operator a continuous record of the blood pressure, by which he may judge at any moment of the degree of shock.

The normal blood pressure in healthy adults is 130 to 140 Mm. of mercury in the tube. In children it ranges from 90 to 110 Mm. Females have an average lower pressure of 10 Mm.

Excitement or slight stimuli will send the pressure up thirty or forty points. It is also higher than the above average in arteriosclerosis. In uremia it is always high. In cases of intracranial tension it is also high, as the brain alone of all the organs of the body has no complete vasomotor apparatus of its own; when it needs more blood this has to be contributed from the general supply. When pressed upon by a clot, depressed bone, or foreign body it becomes anemic, and on effort to furnish the needed blood from other parts the vascular tonus is increased. Cushing has shown the value of these estimations in cases of head injury, for the rise of blood pressure may be regarded as an indication for operation. In typhoid fever a sudden rise of pressure is associated with perforation, or perhaps with the peritonitis which is its immediate result. On the other hand, in this disease a sudden fall of pressure is an indication of hemorrhage.

The course of events in surgical shock is about as follows: Injury to afferent sensory nerves acts as a vasomotor stimulus after it reaches the centre in the fourth ventricle; a reflex impulse is then sent out which produces arterial contraction and raises the blood pressure. When the abdomen is concerned the opening and handling of its contents produce the same result through the splanchnic centres. If, however, the stimulus is excessive, too often repeated, or too prolonged the vasomotor grip is lost, the arterioles dilate, and the blood pressure is reduced. A severe injury to any part of the body may produce this effect without the preliminary rise. The popular impression that a patient “bleeds to death into his own veins” has this to justify itself, that the arterial tonus is lost and the blood is pumped through the arterioles to accumulate in the capillaries and veins, especially the abdominal, thus overloading the right side of the heart and giving it a disproportionate amount of work.

Accompanying these circulatory disturbances are others, secondary and unavoidable, as of respiration, which becomes rapid and enfeebled in proportion to the degree of shock.

Any factor which tends to weaken the heart’s force favors both phenomena. So important is the respiratory action that patients die from cessation of respiration rather than from impairment of the circulation. This shows the importance of maintaining artificial respiration in cases of severe shock.

Cushing and Crile have studied the subject exhaustively in animals. They have shown that certain injuries are likely to be followed by well-marked reduction of blood pressure; for example, those of the brain, the interior of the larynx, the abdomen and testicle, are often followed by a marked reduction of pressure without any preliminary rise. In other words, vasomotor paralysis is sometimes an almost instantaneous effect of certain injuries. When most of the blood is collected in the venous system and the central nervous system fails, because of lack of blood supply, to respond to those normal stimuli which are essential to heart action and respiration, the heart weakness or heart failure is due, not alone to failure of its innervation, but to its reduced output and its diminished content of blood on the left side.

Crile has shown that the more abundant the blood supply to a given part the more it contributes to production of shock; hence, the value of cocainizing the interior of the larynx and the nerve trunks.

Aside from emotional causes—which are sometimes inseparable from even surgical cases—the principal agencies in the production of surgical shock and collapse are those which make a sudden and deep impression through the medium of the sensory nerves upon the central nervous system or the large sympathetic ganglia; ultimately upon the latter in all serious cases. Loss of blood, then, need not play a very important role.

Weakened, anemic, or neurotic patients are predisposed by virtue of these conditions, and also the young and aged. Fright combined with injury increases the degree of the effect. Crile has shown that trifling lesions of the interior of the larynx will cause symptoms which do not occur in animals if the superior laryngeal nerves be divided or if the parts be cocainized.

The upper portions of the abdomen are more sensitive in this respect than are the lower, testicles particularly. The skin is more impressible than the muscles or tissues beneath, save the nerve trunks, which are very sensitive; the bones and large joints slightly so. After shock has been once produced further injury causes a disproportionate lowering of blood pressure.

So-called “concussion of the brain” is essentially a condition of shock following injury to this particular part of the body. (See Head Injuries.)

Shock and hemorrhage are often closely associated, and loss of blood is doubtless a powerful factor in the production of the former, especially in those already reduced or whose blood contains a lowered percentage of hemoglobin. There are, therefore, great advantages in entrusting an assistant with the duty of watching blood pressure during serious operations.

The terms shock and collapse are nearly interchangeable, but, by common consent, the latter is usually the name given to conditions that are more sudden and overwhelming. Shock may be of all degrees—from temporary faintness, from which the patient recovers within a few moments, up to a condition of vital depression which terminates fatally, there being no reaction in spite of all efforts to produce it.

Symptoms.

—These vary to a considerable extent according as the patient is or is not under a general anesthetic. The description of types and symptoms includes an expressionless face, pallor of the skin and mucous membranes, with corresponding coldness of the same, i. e., reduction of surface circulation and heat; dilated pupils, reacting slowly to light; irregularity of the heart’s action, with a weak, irregular, thready, or almost imperceptible pulse; irregular respiration, i. e., irregular both in rate and depth; mental inactivity and apathy; loss of voluntary muscle movement; impairment of superficial sensibility; reduction of body temperature; and nausea or actual vomiting. These at least constitute the symptoms and form the apathetic or torpid type of shock.

In the so-called erethistic type (Travers) the patients are restless and excited, uncontrollable, with irregular pulse and breathing, often with dilated pupils.

In a third type, described by Travers as the delayed, the symptoms are as above detailed, but do not appear until some hours after the cause which has produced them, which may be a concealed (internal) hemorrhage. The delayed type is also seen in those who escape serious accident with a minimum of physical harm.

As shock becomes more pronounced, mental depression deepens into coma, or mental excitement subsides into it; the surface becomes colder and bathed with perspiration, and death follows. These symptoms are those generally noted, whether following injury to the head and denoting so-called concussion of the brain, loss of blood, wound of the abdomen with injury to the viscera, blows upon the testicles, gunshot wounds or other accidents which are causes of shock. They follow also after perforation of the bowel, as in typhoid fever or appendicitis; depression following the receipt of bad news, or fright, etc.; in other words, the physical condition is practically the same no matter what the exciting cause.

Diagnosis.

—Shock is mainly to be diagnosticated from fat embolism; concealed hemorrhage as well as pulmonary edema and suppression of urine are to be suspected. It is unquestionable that many patients have died of fat embolism in whom the actual cause of death has not been ascertained, yet has been ascribed to shock. (See Fat Embolism, Chapter II.)

Treatment.

—The treatment of shock consists essentially in measures directed toward raising the lowered blood pressure. At the outset reaction should not be established too quickly, lest it be succeeded by overaction, with attendant disasters in the shape of secondary hemorrhage, etc. Patients should not be expected to swallow nor act as they would under other circumstances. They should not drink strong liquors, for the irritating fluid may escape into the larynx and induce coughing, which might prove fatal. The same is true of inhalations of strong volatile stimulants, like ammonia. These measures, therefore, should all be resorted to with great care and discretion. Warm, stimulating drinks, if they can be swallowed, are useful; and whisky, brandy, etc., should be given dilute and warm rather than strong and cold. External heat is advisable, and can be supplied by immersing the patient in a bath-tub of warm water, care being taken to keep the face out of the water. When this is not at hand, bottles and other receptacles for warm water may be used, but with caution, since too much heat has been the cause of serious burns.

Numerous drugs have been recommended in the treatment of shock. There are but two or three which are worthy of confidence. Crile, of Cleveland, subjected a large number of animals to tests in regard to the effect of various drugs in influencing blood pressure. He found, for example, that alcohol apparently produces more depression, and in deep shock is dangerous. Nitroglycerin and amyl nitrite seem to increase shock and lower pressure. Digitalis may produce a temporary rise in pressure, but in considerable doses impairs or arrests respiration, and it seemed to him that cases of severe shock treated with it did not live as long as the control animals. Strychnine has been one of the main reliances in these conditions. Crile found that if enough were given to cause increased excitability of the spinal cord it raised the blood pressure, while small doses had little or no effect. Pressure was raised by doses large enough to produce convulsions; repeated smaller doses had little effect, tending rather to increase shock.

These were the experimental results in the treatment of shock, and are to be distinguished from what may be done with the same drugs in the way of fortification and preparation as against shock. Thus strychnine always exalts susceptibility of the cord of the medulla and digitalis may temporarily supplement its use; together they may help to sustain pressure or to fortify as against depressing agencies. They are like whip or spur to a jaded horse.

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]

It must not be forgotten that indiscriminate resort to intravenous infusion may do great harm. It is a minor procedure which requires skill. When the lungs are congested from the irritating effect of ether, and the right heart is embarrassed, a too sudden flushing with saline solution may further embarrass it or even check its activity. So with a patient in the Trendelenburg posture, the intestines are crowded up against the diaphragm and its natural downward play impeded, though the brain is better supplied with blood in this than in any other position.

Much may be done in the way of prevention when shock can be foreseen. This includes the general fortification of the patient by overcoming any auto-intoxication which may have been previously noticed, by improving elimination, and by stimulating the heart’s action with strychnine, digitalis, cactus, etc. Atropine is especially a stimulant to the respiratory centres.

Once the operation is begun, and remembering that the depressing influences which tend to reduce blood pressure are transmitted through the afferent nerves, we may take advantage of Crile’s suggestions and temporarily paralyze them, by exposing them and injecting directly into the nerve trunks two or three drops of 1 per cent. cocaine solution. This should be done before division of the main trunks and at a point above the line of section. It is possible during an amputation, by taking a little extra time and pains, to “block off,” as it is called, the nerves in this way and prevent their conveying any depressing sensation. At other times, as in operations on the mouth, and especially the larynx, cocaine solution may be used locally, as by the spray, and the same effect produced. Cocaine seems to be a protoplasmatic poison which inhibits nerve action.

In the description of the treatment of shock there has been little reference made to the result of loss of blood as such. In cases where this has already occurred, or cannot be prevented, it should be atoned for by the infusion of saline solution, either by intravenous introduction or by hypodermoclysis, i. e., its injection into the loose connective tissues in various parts of the body. While a special apparatus has been devised for this purpose, a sterile fountain syringe with an ordinary aspirator needle will be found to be sufficient for nearly all purposes.

The erethistic, or extremely restless type of shock, may be profitably treated by small doses of morphine given subcutaneously.

The question of immediate operation or delay should be carefully considered. Shock is often alleviated by prompt removal of mutilated limbs or parts whose fragments, while still connected with the trunk, seem rather to perpetuate the condition, especially if the principal nerve trunks are cocainized. In serious cases intravenous infusion should be practised.

After commencing with the anesthetic, while scrubbing and cleansing the field of operation it is advisable to scrub an arm where it may be necessary to expose a vein, or the skin at several points, where a needle may be entered, so that there may be no delay for this purpose should infusion or hypodermoclysis be suddenly required.