Causation of Shock

Formerly shock was classified as (a) primary shock, and (b) secondary shock.

The differentiation was unsatisfactory, and shock began to be qualified by the circumstances under which it had arisen, and wound shock was the term applied to shock arising as the result of wound trauma. The causation of wound shock was then held to be largely due to loss of blood volume, by loss of blood from the wound. (A survey had shown that 80 per cent of deaths on the battlefield were due to bleeding from a main vessel.) Later, attention was drawn to the marked loss of blood serum into the damaged tissues and also the loss of serum from the surface of extensive burns as a cause of loss of blood volume. All agreed that loss of blood volume constituted the most important cause of wound shock.

Lieutenant-Colonel W. C. Wilson, RAMC, Medical Research Section, MEF, in his investigation at Alamein could find no evidence that injuries of any special nature or part caused any extra degree of shock. The effect of histamine in the production of shock had been known for a long time and it was thought that some such substance might be responsible for the occurrence of severe shock in wounds complicated by gross injury to muscle. Research, however, had shown no histamine in these cases, but something of that nature probably accounted for the failure of resuscitation noted.

Chloroform and spinal anaesthesia were both deleterious.

Signs of Shock

Lieutenant-Colonel Wilson described the typical case as' a talkative, even garrulous, man with ashen grey face, beads of sweat on the brow, and tiny pupils narrowed by morphia, making restless fidgety movements, keeping an apprehensive eye on the bearers lest his wound be jarred, asking constantly for drinks, and vomiting without warning a few minutes after each drink.' There was a serious loss of vitality, with weakness, pallor, low body temperature, sweating, low blood pressure, rapid thready pulse, vomiting and intense thirst.

Lieutenant-Colonel Grant, in charge of the Research Shock Unit of the Medical Research Council, described different syndromes recognisable as: (a) vasovagal collapse, with bradycardia, hypotension, and vasoconstriction; (b) post-traumatic hypotension with normal or slow pulse, hypotension, and vasoconstriction; and (c) oligaemic hypotension with tachycardia, hypotension, and either vasoconstriction or vasodilatation.

He explained that superficial vasoconstriction was shown by a thin pulse, small veins, cold extremities, pale face. These signs were present in cold hypotension, and the patient looked ill. Cold hypotension was common before operation, and presented the ordinary picture of shock and low blood pressure. There was an page 109 associated low blood volume, for which plasma was indicated. After operation the condition probably indicated low blood volume, and if recovery did not take place in three or four hours transfusion was indicated. Blood loss was often greater than was realised, and even if adequate fluid had been given before operation a good deal soon left the circulation. Also, before operation the circulation might be restored, but not the blood volume.

Warm hypotension was common before operation and very common afterwards. In warm hypotension there was a wide pulse and warm extremities. The face might even be flushed and the patient look well, and the condition was often not recognised. It was associated with warm surroundings and after-effects of ether anaesthesia, but these after-effects generally cleared up quickly. It was frequently associated with large muscle injuries. Treatment of this condition was not stabilised. Transfusion gave some relief.

In both conditions there was a reduction of urine which was rectified by raising the blood pressure.

Grant also observed that:

Reactions to Blood Loss

Vasoconstriction was the normal reaction to blood loss and was effective for moderate bleeding in which it could often sustain the blood pressure. When the bleeding was more marked and the blood pressure fell, diminished tissue circulation with anoxaemia occurred, leading to irreversible changes including increased capillary permeability. This caused plasma loss in the tissues and pulmonary oedema.

Estimation of Severity

Although some observers relied more on one particular sign than another, it was generally agreed that no one sign was sufficient in itself and that a general evaluation was essential, taking into account the extent of the damage and the general vitality of the patient. The pulse and blood pressure were relied on to supply most of the information. A rapid pulse of poor tension was a serious sign, the volume being of more importance than the rate. A rate over 140 was serious.

Lieutenant-Colonel Wilson stated that the pulse rate was found to show enormous variation. A rapid weak pulse was invariable in a desperately ill man. A rapid pulse, and especially a rapid page 110 pulse of low volume, was a more constant indication of danger than a fall in blood pressure, but examination of the pulse alone was not sufficient for a proper assessment of the general condition.

The blood pressure could be readily assessed and changes noted, and thus its observance was particularly valuable. Any pressure under 100 was generally a cardinal sign of wound shock with blood loss, and a blood pressure of 80 was held by Wilson to be the crucial level, anything under that being extremely serious and demanding urgent treatment by replacement of blood loss. Cyanosis was a very serious sign. A rapid pulse and cold, pale extremities were sometimes seen when the blood pressure was satisfactory, indicating vasoconstriction. Low blood pressure, pallor, and a rapid pulse were the usual signs that demanded blood transfusion.

Warmth

In the First World War the warming of the patient was considered to be of considerable importance in combating shock. In the Second World War, however, it was soon realised that it was dangerous to warm the patient unduly, especially in the early period before full resuscitation. The body's first reaction to the loss of body fluid brought about by the blood loss from wounds was vasoconstriction of the superficial blood vessels. This enabled the lowered quantity of blood to suffice temporarily for the preservation of the vital centres. If warmth were applied to the body vasodilatation of the superficial vessels would ensue, with corresponding loss to the vital centres and increase of shock. This was clearly pointed out by Lieutenant-Colonels Wilson and Grant. The latter carried out experiments in the chilling of patients to prevent and combat shock, but this was never adopted in the treatment of casualties. Care was taken, however, only to use simple measures such as covering with blankets till adequate restoration of blood volume by blood transfusion had been brought about. The use of oil stoves and primuses under the stretcher had been responsible for overheating with increase in shock. It had also led at times to serious burns. Major Staveley, NZMC, in 1944 stated that he had seen no deterioration of the circulation which he could attribute to warming, but at that time care was taken to transfuse early and the danger of warming had been brought home to all. The use of stoves under the stretcher was discontinued in the latter period of the war.

Variations according to Wound Conditions

Variation according to the Site of the Wound

Quantity of Blood to be Given

There was much difference of opinion over this. Lieutenant-Colonel Wilson, as a result of his researches at Alamein, considered that early rapid adequate blood transfusion was the prime necessity in the treatment of wound shock, and that a volume at least equal to the loss should be given and any extra loss at operation made good.

Major Stewart, NZMC, and Captain Powles, NZMC, gave as much as seven to eight pints in a couple of hours when bleeding had been very severe. They gave blood till the colour appeared normal, and found that three to four pints of blood were generally required.

Lieutenant-Colonel Grant considered the average transfusion should be about three pints, but that in severe bleeding much larger quantities should be given. The Canadian research unit stressed the need for rapid transfusion in severe cases and also the necessity for blood post-operatively. Captain Milne, an FTU officer in the North-West European front, strongly urged the giving of much larger quantities of blood and considered that insufficient blood had been given during the war. He normally gave 5 pints before operation and in severe cases up to double that amount.

Great variation was needed according to the type of injury.

Results of Treatment by Blood

These, in the presence of real blood loss, were generally excellent. There was not a discordant voice throughout the war on this point.

Temperature of Blood when Given

Some difference of opinion was expressed on this point. It was asserted that cold blood was deleterious. A War Office memorandum of July 1941 recommended warming to 40 degrees C, and not allowing it to go below 4 degrees C., and the Canadian research unit recommended heating to room temperature. Milne, on the other hand, thought warming of the blood unnecessary. It would seem there was no definite data to support either point of view.

Rate of Administration

At the beginning of the war it was held advisable to give blood slowly because of the danger of incompatability. This soon proved to be wrong because of the consequent inability to relieve the shock in cases of severe bleeding. It was then considered that the first blood should be given as rapidly as possible and positive pressure utilised; up to 3 pints could be given rapidly without trouble (2 pints in half an hour), and some field transfusion officers gave more. After the first 4 pints blood was given more slowly unless serious bleeding was still taking place. In secondary anaemia blood was always given slowly and in much smaller quantities at a time.

Conditions causing Failure of Resuscitation by Blood Transfusion

If the giving of 3–4 pints of blood failed to restore the circulation and so combat shock, other factors were present such as excessive haemorrhage requiring a larger transfusion; continued haemorrhage; transfusion given too slowly; massive muscle injury; cerebral shock; blast injuries; fat embolism; unsuspected abdominal or chest injury; toxaemia from sepsis, abdominal injury, or gas gangrene.

Estimation of Condition of Patients Fit for Operation

The patient was considered ready for operation when his general condition and also his pulse and blood pressure were considered satisfactory. The estimation of the general condition depended on the knowledge and judgment of the transfusion officer and the surgeon. It depended on many things, the colour and warmth of the patient and his alertness. The estimation of the pulse depended on both the volume and the rate, the volume being especially important. A blood pressure of 110–120 systolic was generally aimed at before operation, but a level of 100 systolic was considered quite satisfactory, and patients were operated on frequently with still lower blood pressures when operation was essential to their chance of recovery. Wilson gave 80 mm. as the danger level below which operation was extremely hazardous. Accurate and repeated observations of the blood pressure, pulse rate and volume, skin circulation and colour were necessary. Once the patient's condition was deemed satisfactory and the optimum level had been reached, operation was undertaken at once. Any delay led to a deterioration of the patient's condition and further resuscitation to the same level was generally impossible.

Post-operative Resuscitation

It was realised more and more as the war progressed that severe cases, especially abdominals, needed the same attention after operation as before operation and generally needed further blood replacement as well as glucose salines. Experienced workers urged the provision of a field transfusion officer especially for post-operative resuscitation. Grant drew attention at the Rome conference to the importance of post-operation care and urged careful supervision and further transfusion.

Transportation

The effect of shifting the patient was found to be of marked influence on shock. This referred to all cases, but particularly to those with abdominal wounds after operation when any movement page 115 in the first week was fraught with danger. It also affected the more serious chest cases and patients with burns. The excellent splinting of fractures as a rule prevented serious disturbance in these cases.

Resuscitation during Travel

The giving of transfusions of serum or blood during evacuation by ambulance was developed in the Western Desert and was continued in Italy. Special clamps were invented to fix on to the stretchers, and the needles were held more securely in the arm by means of plaster bandages. The results of this treatment were considered very valuable.

Particular Values of Blood and Plasma

Blood was considered preferable for:

Plasma was considered preferable for (a) burns, (b) blast, (c) sometimes in abdomens in the absence of any serious blood loss, and (d) protein deficiencies during convalescence.

It was considered advisable to combine blood and plasma so as to minimise any dangers from large dosage of whole blood. Plasma was also of great value in the forward areas where refrigeration was impracticable.

Blood that otherwise would have been wasted could be converted into serum or plasma and stocks could also be laid down in the intervals between the active periods of warfare.

Value of Crystalloids

In the 1914–18 War intravenous salines and gum arabic were used as a preventive of shock. It was appreciated, however, that salines did not have any lasting effect on blood volume, and in the latter part of the war some blood was given. Crystalloids, however, were valuable in combating dehydration and in stimulating renal action, as well as in supplying any deficiency in chlorides. They were especially valuable in the post-operative treatment of abdominal cases when fluid could not be given by the mouth, particularly when gastric suction was still further depleting the body fluids. Isotonic saline was the ideal fluid when page 116 chlorides were required, and isotonic glucose solutions made an ideal non-toxic and useful metabolic base.

The use of glucose salines as a preventive of anuria was stressed in the latter part of the Second World War. It was held by most observers that anuria was associated with profound and prolonged shock, especially in abdominal cases. Many considered that anoxaemia of the kidney resulted because of diminished renal circulation during the profound shock, possibly increased by the shunting of the renal circulation to buttress up the general circulation. Whitby considered renal ischaemia associated with exsanguination was one important factor in causation and therefore counselled early and adequate restoration of the circulation. Air Commodore Keynes stated that the RAF considered renal ischaemia was the most important factor in anuria. It seemed rational to try and increase the fluid content of the blood by salines as soon as possible, as well as to give the requisite blood and plasma, so that kidney functions might early be stimulated. Certain it was that when anuria developed, treatment was unavailing, so any possible preventive measure was called for. In the treatment of anuria fluid had to be restricted as the kidneys were unable to excrete, and the fluid administered merely embarrassed the circulation and led to oedema.

The quantity of crystalloid required in abdominal cases having gastric suction was evaluated, and special attention was given to the amount of chloride that was required in these cases. Lieutenant-Colonel Grant advised a routine of 2 pints of plasma or normal saline daily, plus 1 pint for every pint of gastric contents withdrawn by suction. More saline (up to 4 pints) might be needed in tropical climates or if the urine did not contain chlorides. The remainder of the fluids given should be 5 per cent glucose or other non-saline fluids. A total of 8 pints of glucose and saline fluids was generally given daily to these cases.

The urine output was a valuable indication of dehydration and an output of between 2 and 3 pints was aimed at. Normal fluid loss from the body from the lungs, skin, and urine was about 3 pints. With lack of fluid the urine output became insufficient for adequate excretion, and uraemia resulted. A normal man deprived of all water would die within nine days. Dehydration was a major factor in rendering a casualty seriously ill, giving a clinical picture similar to that of secondary shock. Dry mouth and scanty urine, low blood pressure, feeble pulse, and cyanosis occurred. The chloride content of the urine was also an indication of value.

Oxygen was of value in cyanosed cases, especially in chest injuries. The BLB mask was utilised.

Reactions after Blood Transfusion

At the Base severe reactions did arise and called for careful matching and the use of fresh blood. Renal changes from incompatability proved to be rare, as was also the finding of haemoglobin in the tubules.

Changes in Stored Blood

The necessity to draw off blood before an offensive rendered it inevitable that some blood waste should take place. With refrigeration and careful handling it was proved that blood would normally last for fourteen days. Haemolysis gradually took place, but was little marked before that time. The changes could be seen in the blood. They consisted in the loss of the clear-cut margin between the corpuscles and the plasma layer, with the gradual discoloration of the plasma and the change of colour from orange to purple red. Infection was very uncommon in stored blood. It did, however, sometimes occur with marked alteration in the blood colour. Blood not showing any marked changes was often used when occasion demanded at a later period than fourteen days, but, despite no serious reaction, the blood had much less effect in relieving the shock.

Plasma and Serum

In serious abdominal cases 1 pint of serum was given daily along with glucose salines.

Salines and Glucose Salines

These solutions had long been of common use in surgical and medical conditions and were freely availed of during the First World War. They were prepared at the Base Transfusion Units and transported to the forward areas. They were used mostly for abdominal cases during the first week whilst gastric suction was being employed. They acted by relieving dehydration and supplying chlorides. Eight pints a day was normally required when no fluid was being taken by the mouth.

The Problem of Shock as seen at the End of the War

Even at the end of the war the problem of shock and its treatment remained to a large extent unsolved. The most important factor was the early death of the badly shocked patients, the large majority dying in the first twenty-four to forty-eight hours. The transfusion of blood had proved our most effective treatment. When much blood had been lost large transfusions had been essential to success.

In some of our cases very large amounts were given. If many more of the cases dying in the first twenty-four hours were to be saved, then Milne might be right and more blood should have been given, but one cannot but feel that the severity of the injury alone, quite apart from blood loss, would still make the majority of these deaths inevitable under war conditions. There was need for more research and for controlled survey of clinical treatment, page 120 and especially for correlation between the two. Concentration of study must be made on the first twenty-four hours following injury.