Hæmorrhage and Shock
Blood transfusion is pre-eminently the best form of treatment that is known for the condition of acute anæmia following hæmorrhage to whatever cause it may be due. Its good effects were seen by a number of operators in many hundreds of exsanguinated patients during the latter part of the war, and its value was then established upon a secure foundation. It was unusual during the war to meet with patients who were in danger of their lives from loss of blood alone without the additional factor of traumatic shock, but such cases did occur, and they are also to be met with in civil practice, as, for instance, in attempted suicide by throat cutting, in gastric ulcer with severe hæmatemesis, and in secondary hæmorrhage after operation. The more typical condition following war wounds, hæmorrhage with shock, will be faithfully reproduced in the victims of train or street accidents, in patients who have undergone certain severe operations, and in women suffering from post-partum hæmorrhage or a ruptured ectopic gestation.
The signs and symptoms of acute anæmia will be familiar to most readers. It is characterized by a peculiar greyness of the skin, by extreme pallor of the mucous membranes, by a cold perspiration, by a thready and rapid pulse which may exceed 140 beats to the minute, and by extreme restlessness. The “amaurosis” of the text-books is seldom met with, but in the last stages the patient becomes semi-unconscious, the restlessness tends to disappear, the muscles relax, and the respiration takes on a peculiar sighing character, which is described as “air hunger,” and probably indicates exhaustion of the respiratory centre. Meanwhile, if instruments are at hand, additional signs may be recognized. The most important of these is a fall in blood pressure. It has been stated that a systolic pressure below 70 mm. of mercury is scarcely compatible with life, but this is not in accordance with experience. It was common during the war to meet with blood pressures below 45 mm., so low in fact that they could not be measured with the ordinary apparatus that was available, but many patients whose lives had reached even so low an ebb as this were quickly restored by the administration of blood, provided that the exsanguinated state had not lasted for too long a time. If the medullary centres are damaged beyond recovery by inadequate oxygenation lasting for several hours, then no treatment is of any avail. But provided that it be given before this length of time has elapsed, a blood transfusion may succeed in saving life at any stage of the condition. Its efficacy is indeed only limited by the actual cessation of the patient’s heart beats. I have successfully treated a patient who before transfusion could only be described as moribund. He was almost unconscious, absolutely blanched, and his radial pulse imperceptible; his jaw was relaxed and his breathing had become a series of fish-like gasps, such as are only associated with imminent dissolution. His heart would certainly have ceased beating within a few minutes, yet his condition improved so rapidly after transfusion that an hour later it was possible, with the help of a second transfusion, to amputate his leg above the knee. This patient ultimately recovered, having been as near death as it is possible to be and yet remain alive.
The results of a blood transfusion upon a patient suffering from acute anæmia are, indeed, amongst the most dramatic effects to be obtained in the whole range of surgery. Within a few minutes of its commencement the whole aspect of the patient alters. His respiration becomes deep and regular, his restlessness disappears, colour returns to his face, his pulse rate falls, and he begins to take an intelligent interest in his surroundings. These changes taking place within a period of fifteen minutes may well strike an onlooker as little short of miraculous. Shortly afterwards the patient may fall into a natural sleep, a sure sign that the normal circulation has been restored to the exhausted central nervous system.
In considering how much blood should ordinarily be given in the treatment of acute anæmia, experience is a safer guide than any theoretical considerations. Nevertheless, it is worth while to inquire briefly into the experimental and theoretical basis upon which the treatment of acute anæmia rests. It is difficult to estimate accurately the total quantity of blood in the body of an adult, but it has been variously stated by physiologists to be from a twentieth to a tenth part of the body weight, or, in liquid measure, from 3 to 6 litres (approximately 5 to 10 pints). This has been estimated in several ways, the results of which show some discrepancy. A figure approaching the higher one was obtained long ago by the direct method of washing out the blood from the bodies of executed criminals. Recently it has been claimed by Haldane that these determinations were inaccurate; by means of his carbon monoxide method, with the details of which we are not concerned here, he has estimated that the blood volume is but one-twentieth of the body weight, or in very stout persons is even as low as one-thirtieth. Still more recently Haldane’s estimation has been challenged in its turn by observers who have injected a dye into the circulation and have then determined its degree of concentration in the blood by means of colorimetric comparisons. It is evident that if the dilution which occurs when a known quantity of dye is injected can be accurately estimated, then the total volume of circulating fluid can be calculated. This method could not be used until a non-toxic, non-diffusable dye had been discovered, but it was found in 1915 that “vital red” fulfilled these requirements (143). The results obtained in this way show that those originally given by the direct method were substantially correct. The blood volume was found to vary from 1/13 to 1/10·5 of the body weight; on the average it amounted to 5,350 cc., or 85 cc. per kilogram of body weight. These observations have been in their turn criticized (114), but only to the extent of reducing the amount by 1/10. It may therefore be assumed that, according to the most recent work, the blood volume is from 5 to 6 litres, or, approximately, 8 to 10 pints.
It is a still more difficult matter for obvious reasons to estimate how much blood a man can lose and yet remain alive. This will depend partly on the power of physiological accommodation possessed by the individual in his vaso-motor system and tissue fluids and partly on the rapidity with which the bleeding takes place. Clinical observations have shown that after a moderate hæmorrhage, such as the withdrawal of 800 cc. of blood from a donor, the blood volume may be restored to normal within an hour. If, on the other hand, the hæmorrhage is excessive, a condition results in which the normal process of rapid restoration of volume fails, and the circulation remains in a dangerously depleted condition. The heart attempts to keep the blood pressure at an adequate level by an increase in its rate, but it is in effect attempting to circulate a small volume of fluid in a vascular system which has become too big for it. Imperfect oxygenation of the medullary and cerebral centres with exhaustion of the heart results, and this is accompanied by all the symptoms of anæmia which have been already described.
If the initial hæmorrhage be very rapid, death may result almost at once, since the physiological processes may have no time to act. On the other hand, a rapid hæmorrhage may under certain circumstances save the patient’s life, for the immediate syncope which results produces so great a fall in the blood pressure that hæmorrhage almost ceases and a clot may form in the lumen of the divided vessel. If the hæmorrhage be more gradual, the physiological compensation may at first be adequate to maintain the blood volume, but finally a point is reached at which this process fails and the patient then passes into the condition of acute anæmia.
The actual amount of blood therefore that must be lost to be fatal will vary according to circumstances. Experience shows that hæmorrhage may take place into the peritoneal or pleural cavities to the extent of two litres or even more, and it may be stated as a rough guess that 2·5 litres, that is to say, even as much as almost half the total blood volume, may be lost without immediate death resulting. This degree of depletion could not, however, be endured for long. A series of clinical observations made by Keith by the vital-red method upon the blood volume in soldiers suffering from the combined effects of hæmorrhage and wound shock showed that in the most serious cases the volume was below 65 per cent. of the normal, frequently even between 50 and 60 per cent. Serious symptoms followed a reduction to between 65 and 75 per cent. In patients without distressing symptoms the volume was never below 75 per cent. of the normal. There is direct evidence, therefore, that those patients who are most in need of treatment, such as a transfusion of blood, will probably have lost from 25 to 50 per cent. of their blood volume, that is to say, 1·5 to 3 litres in amount, and will need from 750 cc. to 1·5 litres to restore them to, or near to, the 75 per cent. level at which the compensatory processes can begin to regain their power.
It is thus possible to arrive at a theoretical basis on which an idea can be formed of the amount of blood that should be given in acute anæmia. Practical experience is in agreement with the theory, and it will now be easier to understand how it is that in treating acute anæmia no attempt need be made to replace the whole amount of blood that has been lost, or indeed anything approaching it. In an extreme case 2 to 3 litres of blood will have been lost and 1 litre or more will be needed to restore the blood volume to approximately 75 per cent. of the normal. A case of this sort, however, is fortunately not often to be met. One has already been described on [page 21]; this patient received altogether nearly 1,600 cc. of blood in two transfusions, and 1,000 cc. of normal saline were given in addition.
In most cases of severe hæmorrhage the patient has probably not lost more than 1,400 to 1,800 cc. of blood, and 600 to 800 cc. will be enough to restore the balance of the circulation. This is in practice the amount of blood that is commonly administered, and it is well within the limits of what a single blood donor can afford to lose. If a more definite standard be required, it may be laid down that in a single transfusion for acute anæmia 750 cc. of blood should be given. If, in an exceptional case, more than this is needed, a second transfusion should be performed with a similar amount taken from another donor. Sometimes it may happen that a patient already in extremis from loss of blood, needs a severe operation; in such a case a second transfusion may be given with great advantage at the conclusion of the operation. The first transfusion will restore the patient sufficiently to render the performance of an operation possible; the second will combat the additional shock and hæmorrhage which it has caused.
It has already been stated that it was uncommon during the war to meet with patients who were suffering from anæmia uncomplicated by traumatic shock. It was in fact the condition of shock which tended to dominate the clinical picture, and it was towards the elucidation of the facts concerning shock, its causation, prevention, and treatment, that the investigations co-ordinated by the Medical Research Committee were mainly directed. These investigations were carried out both in the laboratory and in the military hospitals, and considerable additions were made to the knowledge of the condition. It is necessary to give some account of the conclusions which were reached in order that the rôle of blood transfusion in the treatment of shock may be fully understood.
Hæmorrhage and shock cannot be dissociated, and this is not only because they so frequently occur together in the same patient, but also because the manifestations of the two conditions are essentially the same. In shock, as in hæmorrhage, are found the same pallor of the face and mucous membranes, the same fall of blood pressure and rapid pulse, the same perspiration, restlessness, and shallow respiration. The symptoms following a severe hæmorrhage have sometimes been referred to as constituting a “shock-like condition.” As will be seen, however, it is more accurate to describe the symptoms of shock as closely resembling those of hæmorrhage, and to regard both conditions as a manifestation of deficient fluid content in the circulation.
Numerous theories have been advanced to account for the symptoms seen in shock. Until recent years it was customary to suppose the vaso-motor centres had failed, being overcome by exhaustion consequent upon excessive stimulation by a greatly increased number of afferent impulses from the periphery of the body. It was suggested that as a result there was a general dilatation of the vascular system, especially in the abdominal veins, and therefore a general impairment of the circulation. Various hypotheses were, in addition, formulated, to account for the vaso-motor failure. These included the ideas of deficient carbon dioxide in the blood, exhaustion of the adrenal secretion, and exhaustion of nerve-cells in the higher centres. All these theories found their supporters and much experimental evidence was brought forward, but none was susceptible of final proof. The whole theory of vaso-dilatation and the idea that the patient “bleeds into his own abdominal veins” were eventually disposed of by observation of the clinical facts. Many extensive abdominal operations have been performed upon shocked patients, but the accumulation of blood in the splanchnic area has never been demonstrated. It has, on the other hand, been found that in the limbs the arteries and arterioles are strongly contracted. It is also by no means unusual to meet with the condition known as venospasm; the veins are collapsed and their walls contracted, so that it becomes necessary to use a considerable positive pressure before any fluid can be induced to flow into them. It has, in addition, been shown that the vaso-motor system is still active, and the heart, although beating rapidly, still responds to reflex stimulation and to increase of intracranial tension.
It becomes necessary, therefore, to find some other explanation of the low blood pressure which is the essential feature of shock. Of especial value in this connexion are the investigations by Keith, already mentioned, into the changes in blood volume found in soldiers suffering from shock and hæmorrhage. In very few of these cases were the symptoms due to shock alone, but usually the loss of blood volume was much greater than could be accounted for by the amount of hæmorrhage which had taken place. Here, therefore, was evidence strongly suggesting that the symptoms of shock are due to actual loss of circulating fluid, and the problem now resolved itself into a search for this fluid which has ceased to be part of the effective blood volume. Enough has already been said to show that there is no evidence that the larger vessels, whether arteries or veins, are acting as reservoirs in which the blood is stagnating. It therefore only remains to consider whether the capillary system is capable, under abnormal conditions, of holding so large a proportion of the blood as has been shown by Keith to have left the circulation. For a discussion of this problem the reader may be referred to W. B. Cannon’s summary of the arguments (45), from which it becomes clear that the capillary system may be regarded as a potential reservoir large enough to contain the lost blood in shock. The question is, however, further complicated by the fact that the capillary blood in shock differs from the circulating blood in containing an abnormal concentration of corpuscles. Extensive observations made on wounded soldiers have shown that the number of red blood cells may rise even to 8,000,000 per cmm. in the capillary blood, while the number in the venous blood remains at 5,500,000 or less. This concentration of the red cells is gradual and progressive, and will by itself account for a large part of the loss of volume, since normally the bulk of the blood is made up of corpuscles and plasma in approximately equal parts. The stagnation is, moreover, accentuated by the increased viscosity of the blood resulting from the concentration, and by the chilling of the surface of the body, which is always a feature of the state of shock. A vicious circle is thus established, and the symptoms of shock become severe as the capillary stagnation becomes more pronounced.
A second factor which may also play its part in the loss of blood volume in the general circulation is the exudation of some of the plasma into the surrounding tissue spaces. As the stagnation increases, oxygenation decreases, and the walls and the capillaries become more permeable, so that some fluid is probably lost in this way. This permeability may also be accentuated by the increased hydrogen-ion concentration in the blood, which often accompanies shock, but it seems to be clear that this is a secondary phenomenon resulting from imperfect oxygenation in the tissues, and it will therefore not be regarded as one of the factors responsible for shock. Further fluid is lost by the copious perspiration commonly seen in shock. There seems, therefore, to be a conspiracy between a whole set of different factors all tending to deprive the patient of his circulating fluid. The net result is a condition so closely resembling hæmorrhage that it may be impossible to distinguish the two, this difficulty being increased by the fact that they so often occur together.
In the foregoing account of the production of shock the fate of the lost blood has been discussed, but nothing has been said of the factors initiating the capillary stagnation. This is a subject which is of great interest and some obscurity, and is of evident importance in considering how shock may be avoided. The present treatise, however, is primarily concerned with the treatment of shock when already established, and it is therefore not proposed to follow out the other question in detail. An injury may be followed immediately by a condition of “primary wound shock,” in which the patient becomes suddenly pale and pulseless. This is a physiological reaction, which may be transient, and it is to be distinguished from the much more serious condition of “secondary wound shock” which appears some time later. It is this secondary shock alone which has been under consideration in the preceding pages. The chief importance of the primary shock lies in the fact that it may initiate the conditions which predispose to secondary shock, so that under certain circumstances the one may become merged in the other. These predisposing conditions are increased evaporation from the skin, a general fall in the temperature of the body, mental anxiety, and the continued stimulation of the higher centres by afferent impulses as is manifested by pain. The condition of secondary wound shock was shown in a striking degree, during the earlier years of the war, by the men suffering from fracture of the femur. In the later part of the war warmth was supplied more systematically than before to the seriously wounded, and all fractured femurs were treated at an early stage with Thomas’s splints. Two of the factors predisposing to shock, namely cold and pain, were in this way to some extent eliminated, and it was very striking how much better than before was the general condition of the patients on arrival at the hospitals.
Nevertheless, the elimination of these factors, which is a simpler matter in civil life than it was under conditions of war, will not avert all shock in a large proportion of cases. It is necessary, therefore, to find some additional factor which will initiate shock in addition to the predisposing causes. It is thought that this may have been identified in a substance of obscure nature which is derived from the damaged tissues themselves, and which, circulating in the blood, is able directly to affect the capillary system. Just as the shock following severe burns is believed to be due to the circulation of a toxic substance formed by the burning of the skin and other tissues, so the shock following severe trauma is believed to be of toxic origin, the toxin being derived from damaged tissues, muscle being particularly active in this respect. The condition may, therefore, be one of “traumatic toxæmia,” in which there is a general loss of capillary tone throughout the body, so that “the blood percolates into the network of channels as into a sponge.” The circulating blood is thus rapidly depleted, and the symptoms of shock become established. The investigation of this source of shock was carried out chiefly by Dale, Bayliss and Cannon (65), who were able to reproduce the condition of shock in animals by the injection into their circulation of a substance obtained from damaged muscles. To this substance the name histamine was given. It would be a mistake, however, to suppose that because a substance producing shock experimentally has been obtained from muscles, that therefore this is the identical substance which is responsible for every case of traumatic toxæmia. Extreme shock may be produced when but little damage has been done to muscles. Probably damage to any tissue of the body if extensive enough will produce a substance or substances which will give rise to the symptoms, and it may be a long time before these are isolated and identified. That the last word on the production of shock is still far from being uttered is shown by the fact that profound shock may be induced without doing any appreciable damage to tissue, namely, by handling and exposing the abdominal viscera.
It may be this traumatic toxæmia which will account for many cases of post-operative shock, but it has been shown that some anæsthetics, such as chloroform or ether, will of themselves greatly accentuate shock initiated by other causes.
It has already been mentioned that the increased hydrogen-ion concentration in the blood, which results from imperfect oxygenation in the tissues, is not itself a cause of shock, but it will aggravate shock due to other factors. A discussion of this will be found in the paper by W. B. Cannon already referred to.
The present state of knowledge concerning the causation of shock having been thus briefly reviewed, the question of the treatment of the condition may be discussed. In this connexion the value of blood transfusion will be considered. It will have become clear that essentially the condition to be combated in treating shock is one of lowered blood pressure following upon a diminution of the volume of blood in the circulation. All the factors which have been mentioned in considering the causation of shock must be combated. Warmth must be supplied, morphia administered, fractures efficiently immobilized, damaged tissues excised: but clearly all these measures are prophylactic rather than curative. None of them will remove a state of profound shock once established, for they will not of themselves restore the blood volume depleted by capillary stasis. It is necessary, therefore, to attack this condition directly. It may with justice be compared to a state of acute anæmia following hæmorrhage, but with this difference, that the blood is still present in the body and will return to the circulation when the capillary stasis has been abolished and the circulating balance has been restored. The possibility of recovery from shock depends upon how long the condition has existed. After a certain time the toxæmia, whether the primary traumatic toxæmia or the secondary increase in hydrogen-ion concentration, appears to have a damaging effect upon the capillary walls, so that an increased loss of fluid takes place into the tissues and this cannot be remedied. It is essential, therefore, to use the means which will most rapidly restore the circulation and bring about a rise in blood pressure which will be permanent. It is reasonable to infer that the most hopeful means of bringing this about is by a blood transfusion, which will actually replace the blood temporarily lost. This is the physiological remedy, and its value has been proved by the results obtained in many cases of my own as well as in those recorded by others. The efficiency of the treatment is accentuated by the fact that so large a proportion of cases of shock are associated with, and aggravated by, some degree of hæmorrhage. Apart from this, Keith’s observations have shown that the diminution of blood volume in shock is comparable with that which attends severe hæmorrhage. The state of shock in fact so closely resembles hæmorrhage that most of the same remarks concerning blood volume and the amounts that should be given by transfusion may be applied, and it is unnecessary to repeat them here. It must be remembered, however, that in pure shock the amount of hæmoglobin in the body is not reduced though there is less in the circulation. It is restored to the circulation when the capillary stagnation is overcome. This will be referred to again later on.
During the war the value of blood transfusion in shock was amply demonstrated. In civilian practice I have found it to be of value when given after operations such as removal of the rectum, whether by the perineal or abdomino-perineal route, amputation of the leg through the hip joint, or removal of a sarcoma from the nasopharynx. Transfusion should be given towards the close of the operation before the evidences of shock have reached their maximum. The depletion of the blood volume is then actually remedied as it takes place, and transfusion becomes almost as much a prophylactic measure as warmth and the administration of morphia.
It is probable that the mortality following very severe operations such as those mentioned above would be considerably reduced if blood transfusion were to be given as a routine measure. Reference has already been made to the bad effect of the ordinary anæsthetics, and the best effects are obtained by a blood transfusion in conjunction with gas and oxygen or with spinal anæsthesia. It is necessary, however, to draw attention to the fact that a blood transfusion if given to a patient under the influence of a spinal anæsthetic must not be performed until the operation is very nearly completed, for it will very often produce a much more rapid return of sensation than would otherwise occur.
In advocating the use of blood transfusion to combat the effects of shock and hæmorrhage, it would be misleading to imply that this is necessarily the only treatment that is available. Something must be said of the substitutes for blood that have been used, and in particular the value of gum acacia must be considered. In the days before the war it was customary to treat post-operative shock or hæmorrhage with large quantities of normal salt solution given intravenously or subcutaneously. During the earlier part of the war also this was used, and there can be no doubt that for the less severe cases this treatment is often beneficial. Occasionally even the lives of patients who were desperately ill have been saved by it; I have seen a saline infusion cause the recovery of a man who had a dozen perforations of the small intestine and who had, in addition, lost several pints of blood intraperitoneally from a wound of a large mesenteric vessel. Such cases are, however, exceptional. In the presence of severe shock or hæmorrhage a saline infusion may cause an immediate rise in blood pressure, but the fluid exudes so rapidly into the tissues that the effect is usually very transient. This fact is universally admitted to be true and need not be further emphasized. Saline solution administered by the rectum is likely to have a more lasting effect, but the process of absorption is slow, and the patient may be dead before it has had time to act. The same applies to water given by the mouth. A patient suffering from severe shock is unable to tolerate more than a very small quantity of fluid in his stomach without vomiting. Some success was attained by Oswald Robertson in treating cases of hæmorrhage by the method of “forced fluids,” large quantities being given by the mouth and by the rectum (245). In many serious cases, however, this treatment is inapplicable, and it is clear that transfusion is more rapid and more certain in its effect. Isotonic saline having been found ineffectual, it was suggested that a hypertonic solution (2 per cent. sodium chloride) might be of more value. This was tested clinically and in the laboratory, and was found to have no advantage over the isotonic solution (11).
When the association of increased hydrogen-ion concentration with shock was demonstrated, it was at first supposed to be one of the factors producing the condition. It was therefore natural that the effect of a solution of sodium bicarbonate (4 per cent.) should be tried. The effect upon certain cases suffering from extreme “acidosis” and air hunger was very striking, but in general the alkaline solution was no more effective than the ordinary isotonic saline. I soon abandoned its use for intravenous infusion, but it was of service in serious cases when given by the rectum.
During the war the necessity for the conservation of time—and of blood—was evident. The search for a satisfactory substitute for blood was therefore prosecuted with great energy, most of the research being done by, or under the direction of, Professor W. M. Bayliss. The object of the research was to discover a non-toxic solution which possessed the same “viscosity” as the blood, and the same osmotic pressure due to contained colloid. It was believed that such a solution would not tend to exude so rapidly into the tissues and would therefore augment the blood volume more effectively than the fluids previously used. After many experiments it was claimed in 1916 that a blood substitute had been found in a 6 per cent. solution of gum acacia with ·9 per cent. sodium chloride. It was even stated on the evidence of laboratory experiments that the gum solution was as effective as blood in the treatment of shock and hæmorrhage. It was therefore used very extensively among the wounded, and favourable reports upon its value were made by various workers. It is difficult, however, to control the results in giving treatment of this kind. If a patient dies after being given a gum infusion, no one can state definitely that he would have lived had he been given a blood transfusion instead. If a patient lived after having a blood transfusion, it would be equally rash to state that he would have died had he been given gum. Nevertheless, after giving the gum solution a number of trials, I formed the opinion that the results were inferior to those obtained with blood. Patients did not recover whom from previous experience with blood transfusion I should have expected to do so. I accordingly continued to use blood in preference to gum whenever it was available, although justice must be done to those who so strongly advocated gum by saying that there can be no doubt that it is very much more effective than other solutions previously used. The same opinion was formed by many other surgeons, although it was natural to feel a bias in favour of gum which could be given with much greater economy of time and effort than blood. Up to the present time I have seen no reason for altering this opinion, and should always prefer to treat hæmorrhage and shock with a blood transfusion if possible.
Recently the relative values of a number of intravenous infusions for shock have been put to an extensive experimental test by F. C. Mann. The shock was produced by handling the abdominal contents, and the effect on the blood pressure of the various fluids was mechanically registered. The conclusion was reached that far the best results were obtained by a transfusion of blood or blood serum, the effect of these being more permanent than that of any other substance used. The use of gum acacia was found to give results which were “variable and sometimes disastrous,” but this may have been due to some extent to errors in the technique of preparing the solution.
This draws attention to a possible objection to the use of gum, namely, that some samples of the solution have been found to be actually toxic; but it is said that this can be avoided if proper care be exercised in its preparation. Full instructions for this are given in a paper by S. V. Telfer.
Into the discussion of the relative merits of blood and gum solutions may be profitably introduced the further question as to which is the more valuable constituent of transfused blood, the corpuscles or the plasma. It has been seen that the essential factor in producing the symptoms of shock and hæmorrhage is a reduction of blood volume, and treatment is therefore directed in the first place towards the restoration of this volume, with a fluid of the same viscosity and osmotic pressure as blood. This might be done with plasma or, some may say, equally well with gum. From the point of view only of volume, the corpuscles and plasma are of equal value, since each forms approximately half the total volume of a given quantity of blood. There is, however, another aspect to be considered. One of the results of loss of blood volume is imperfect oxygenation in the tissues. When the volume is increased by the addition of plasma or gum, the corpuscles in the circulation are diluted, and this by itself would tend further to impair oxygenation. The dilution is, however, compensated for by the improvement in circulation which in its turn improves the supply of oxygen to the tissues, and it is still further counteracted by the restoration to the circulation of the blood corpuscles which were stagnating in the capillary system. It seems clear that these successive processes will be accelerated by the use of a fluid which itself contains corpuscles, and this may afford a theoretical explanation of the clinical observation that blood is more effective than gum. Its use will tend to establish more quickly the “virtuous circle” following increased volume, and so undo the “vicious circle” due to insufficient volume. It has been questioned whether the corpuscles of transfused blood really do play an active part in the economy of their new host, or whether their new environment may not quickly render them effete. This has been answered by the exceedingly interesting and ingenious series of experiments carried out by Winifred Ashby. She has transfused blood of a known group (see Chapter IV) into an individual of a different, but compatible group, and then shown that it is possible by selective agglutination with a suitable serum to demonstrate the presence in the blood of the two kinds of corpuscles side by side. In this way she has shown that transfused corpuscles are still present in the circulation and of normal appearance thirty days after they were introduced.
It is therefore justifiable to make the inference that transfused corpuscles can for some little time carry out their normal function. If it be true that their presence is an advantage in the treatment of deficient blood volume, it may also be conjectured that their presence is likely to be of greater importance in treating hæmorrhage than it is in the treatment of pure shock, for in the latter condition all the original corpuscles are still present in the body, while in the former they are not.
I should sum up the discussion of the relative merits of blood and gum by saying that on the grounds of experiment and clinical experience I believe blood to be the more efficient of the two, particularly in the most serious cases. Every patient who needs it should therefore have the advantages conferred by blood transfusion if it can be done. If it cannot, then gum and saline is much the most satisfactory substitute that is at present known.
Some of the concluding remarks in the foregoing pages will have suggested that the use of gum infusion may be considered of more value in treating pure shock than in treating hæmorrhage. For this reason, apart from other diagnostic considerations, it may be of importance to be able to distinguish clinically between shock and hæmorrhage. Attention has already been drawn to the fact that the symptoms and appearance seen in a patient suffering from severe shock very closely resemble those seen in hæmorrhage. It may, in fact, be impossible to say from purely clinical evidence whether a patient is suffering from shock, or hæmorrhage, or both. A case which recently came under my own observation well illustrates this point. A very stout, elderly man had fallen down a lift-shaft and was brought into St. Bartholomew’s Hospital soon after the accident. He appeared to have fallen on his feet, and the lower ends of both tibiæ had been driven through the inner sides of his soles, but there were no other signs of injury. His general condition on arrival at hospital was fairly good, but all the usual measures were taken to minimize shock. An hour or two later he had passed into a condition of extreme collapse, and exhibited all the symptoms which have already been described. Not much hæmorrhage had taken place from the wounds in his feet, and the question arose as to whether his present condition was due to internal hæmorrhage from visceral injury, or whether it was due chiefly to shock. His abdomen contained so much fat that no evidence could be obtained from an examination of it, and it was in fact impossible to arrive at any conclusion. There could, however, be no question of performing any operation, and the patient made no response to other treatment. At the autopsy it was found that there were fractures of the ribs, spinal column, and symphysis pubis in addition to the injuries to the legs. There was very little hæmorrhage in connexion with any of the fractures, and it appeared that death was to be attributed almost entirely to shock. This was perhaps a somewhat unusual case, in which no help could be derived from an examination of the patient, but similar difficulties will sometimes be met.
It might be expected that a criterion would be supplied by an examination of the blood. The results from this, however, have proved to be disappointing. The facts have been investigated by Cannon and others (47) and may be summarized as follows. The number of red corpuscles in the blood from the capillaries of the ear or finger has been found to be invariably raised in patients suffering from shock. A blood count may show an increase up to seven million red cells per cmm. or even more. The blood in the venous circulation, however, of the same patient is more dilute, the count being less by one to two million red cells. When the shock is complicated by hæmorrhage, the blood count in the venous system will again be lower than that in the capillaries, but in both the counts will be less than if there were no hæmorrhage. The differences are, however, not so great or so constant that any principle can be laid down by which the two conditions may be distinguished. In patients in whom hæmorrhage is the outstanding feature the blood counts will be still lower, but the capillary and venous difference will still be present. It was found that in hæmorrhage the hæmoglobin percentage, and therefore the colour index, tended to be lower than in shock, but this was most obvious when the hæmorrhage had been very severe, and in such cases the diagnosis is usually clear from other evidences. The clinical difficulty lies in the distinction between cases of pure shock and of shock complicated by considerable hæmorrhage. It seems that little help is to be derived from an examination of the blood. This difficulty in diagnosis can only influence treatment in the direction of giving blood rather than gum-saline, though the latter would probably be effective for many of the cases of shock if they could be distinguished.
The effects of transfusion for hæmorrhage and shock are to be judged best by the clinical results. The abnormal distribution of the corpuscles is altered by the treatment with a consequent redistribution in the circulation. No constant changes, therefore, in the blood count follow transfusion, and no exact mathematical effect can be demonstrated. It has been shown by Huck that sometimes the immediate rise in the blood count is greater than can be accounted for by the amount of blood given. This is often followed by a fall, which is succeeded in its turn by a second rise. These results are to be explained by alterations in the amount of destruction and formation of red cells going on in the body. That is to say, they are biological rather than mechanical, and are at present but imperfectly understood.
In the foregoing discussion hæmorrhage and shock have been considered in a general way. Something must now be said of the particular conditions for which transfusion may be given. Concerning traumatic hæmorrhage and shock there is little to be added, for these conditions present the general features of the problem in its least complicated form. No clear-cut rule can be laid down as to the point at which transfusion becomes necessary. The blood pressure is perhaps the best single indication, and if this has fallen below 80 mm. (systolic), then a transfusion is certainly indicated. Apart from this, the patient’s general condition is the safest guide. As soon as it becomes evident that his life is in danger, a transfusion should be given. Better save a few lives by many transfusions than lose them by reserving transfusion for those who are actually moribund.
Secondary hæmorrhage following an operation is fundamentally similar to primary hæmorrhage, but may present a few additional points. In recent years by far the largest number of transfusions for secondary hæmorrhage have been given for bleeding from septic amputation stumps. In many cases of this sort it is no easy matter to stop the bleeding by ligaturing a bleeding vessel; sometimes it is impossible. Nevertheless, transfusion should not be withheld owing to a risk of increased hæmorrhage supposed to follow a rise in blood pressure. Usually the patient is debilitated by prolonged suppuration, and often his blood is deficient in its power of coagulation. It has been found that a transfusion, in addition to replacing some of the blood that has been lost, tends to improve the patient’s resistance to micro-organisms, and to shorten the coagulation time of the blood. Recurrence of the hæmorrhage is therefore discouraged on the whole, and in many cases a series of transfusions for recurrent hæmorrhages has saved a patient’s life when the prognosis had seemed to be almost hopeless.
Post-operative hæmorrhage associated with chronic jaundice is another condition which demands special consideration; this will be dealt with later under the heading of hæmorrhagic diseases.
The proper treatment of severe hæmorrhage from a gastric or duodenal ulcer has always puzzled physicians and surgeons alike. It is probably true that patients very seldom die as the result of a single rapid hæmorrhage, even if severe. There can, however, be no doubt that death due actually to acute anæmia may follow repeated or prolonged hæmorrhage. Hitherto treatment has been conducted mainly on medical lines. Opinion is now, however, tending to favour earlier and more frequent surgical interference, and this can be made a less dangerous procedure by giving a preliminary blood transfusion to improve the patient’s general condition. When the patient’s life is threatened by hæmorrhage repeated or prolonged, transfusion is undoubtedly the best means of saving him. Here again the fear of restarting the hæmorrhage by raising the blood pressure has acted as a deterrent, so that transfusion is apt to be withheld until too late. Nevertheless, it is clear from the numerous cases recorded in the literature that this fear is groundless (130, 215, etc.). The effect of a transfusion on the coagulating power of the patient’s blood more than compensates for the risk attending a rise in blood pressure. Now only is lost blood replaced, but also the clot plugging the damaged vessel is made more secure. The patient is tided over the immediate danger to his life, and surgical treatment is made possible. This view will doubtless meet with much adverse criticism, but its justice will eventually be recognized.
As in the early days of transfusion, so at the present time, a considerable proportion of the patients that need transfusion will be met with in the course of obstetrical practice. It has often been remarked how much blood can be lost by a woman following the delivery of her child without any serious result; nevertheless, many deaths are occasioned every year by post-partum hæmorrhage, placenta prævia, and rupture of an ectopic gestation. Sometimes the bleeding is so rapid that there is no margin of time available for a transfusion unless all the facilities be immediately at hand. Short of this, transfusion is the ideal treatment, and the problem is a simple one, the relief of acute anæmia being the only object in view. One interesting modification of the procedure has been recently recommended by German writers, namely, the reinfusion of the patient’s own blood. This is applicable only when the hæmorrhage has taken place into the peritoneal cavity, and is therefore limited to the treatment of a ruptured liver or spleen, a ruptured uterus, or a tubal abortion. With a ruptured uterus the sterility of the blood is not assured, and this condition were better not included. For the other conditions Lichtenstein recommends that the blood should be ladled out of the peritoneal cavity into Ringer’s solution and then strained to remove clots. The resulting fluid is infused into a vein. Judging from my own experience of intraperitoneal hæmorrhage, not much blood would actually be recovered in this way, since usually so much of it has clotted. In any case, the whole procedure is to be looked upon with suspicion owing to the unknown and probably profound changes that have taken place in partially clotted blood. Eberle records that in one case reinfusion was followed by hæmolysis, and among twenty-one cases reported by Schweitzer in 1921, one death was attributed to the reinfusion, which, as in Eberle’s case, was followed by hæmoglobinuria. Transfusion has also been used for the toxæmias of pregnancy, but this will be dealt with under another heading.