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Primary Surgery Vol.2 – Trauma |  |
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Primary Surgery Vol.2 – Trauma | |
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A patient in hypovolaemic shock is intensely pale with cold extremities. The first signs to suggest that insufficient blood is reaching his brain are drowsiness and withdrawal from his environment, although he can be deceptively alert and euphoric. As shock deepens he becomes agitated, delirious, and finally comatose. His pulse is rapid, and his blood pressure low. When you pinch one of his nails, its bed empties of blood and takes a long time to fill up. His breathing is fast and rapid. He is thirsty and acidotic, and he passes little urine.
He has two main ways of compensating for the blood he loses: (1) He immediately constricts the vessels in his skin and gut. About 75% of the blood is in the veins, so venous constriction is particularly effective. (2) Later, he slowly absorbs the extracellular fluid from his tissues, with the result that his skin loses its elasticity, and his eyes sink into their sockets. Although this maintains his blood volume, it dilutes his remaining red cells, so that his haemoglobin falls and he becomes anaemic over several days.
Both these mechanisms have their limits. A normal adult’s blood volume is 80 ml/kg or about 5.5 litres. Whether he goes into shock, or not, depends on how much blood he loses. If he loses 10% of it (500 ml) he is unlikely to show signs of shock, but if he loses 20% of it (a litre) he almost certainly will. Provided he loses less than a third of his blood volume (2 litres), he can usually maintain his blood pressure above 100 mm. If he loses half of it (about 3 litres) for more than a few minutes, he dies. So a shocked adult needs a transfusion of at least a litre, and if he is severely shocked he may need 3 litres. If he continues to bleed, he may need much more. A child has a smaller blood volume, so that a given loss is proportionately more serious in him.
When you try to decide how shocked a patient is, remember that: (1) His condition is never static. From moment to moment he will be getting better or worse. (2) Shock usually develops slowly over several hours, although it can develop rapidly. (3) A single sign may not be reliable, so use several. (4) His symptoms may be out of proportion to the volume of blood he has lost. A small loss may occasionally cause severe shock and vice versa. (5) A falling blood pressure is an unreliable sign, and occurs late. For example, the blood pressure of a child or young adult may not fall at all, until it finally falls catastrophically, when he has lost a third or more of his blood volume. Try to restore the blood volume before this happens. A rising pulse rate is an earlier and more reliable sign than a falling blood pressure. But even the pulse may not rise until late, particularly if the patient is old. A good pulse volume, a warm pink skin (if he is Caucasian), well filled veins, and a good urine output, are better signs of an adequate blood volume than a normal blood pressure. If a patient’s systolic blood pressure falls below 100 mm after an injury, he needs an infusion. If it falls below 80 mm he needs it urgently.
![\includegraphics[scale=0.27]{/home/kumasi/Desktop/primsurg-tex/vol-2/ch-53/fig/53-1.eps}](images/img-0020.png)
Electrolyte solutions are useful replacements for lost blood. If a patient can only maintain his cardiac output, he can meet the oxygen demands of his tissues even if his haemoglobin falls as low as 8 g/dl. He is only likely to need a blood transfusion if: (1) He has lost 1000 ml of blood or more. Or, (2) his haemoglobin later falls below 10 g.
If an adult is in severe hypovolaemic shock, give him a large volume (2–3 litres) of an electrolyte solution fast, preferably Ringer’s lactate, but if necessary 0.9% saline, or glucose saline. Then assess his needs by evaluating his clinical response. Unfortunately, these solutions will leave his circulation in an hour or two. Colloids like dextran stay in it longer; you can give him dextran 70 in 0.9% saline to replace up to 30% of his blood volume, or up to about 2 litres if he is an adult. Giving more may damage his kidneys.
If possible, try to stop him bleeding, then restore his blood volume, and then operate on him. If he is bleeding externally, this it should not be difficult (55.1). If he is bleeding internally, resuscitate him as best you can, and then operate. He will probably need a laparotomy. He will not die from anaemia while you do this, but he may die from hypovolaemia. His blood pressure should be over 80 mm before surgery starts. Ideally, it should have remained over 100 mm for at least 20 minutes. But, if he does not respond to resuscitation, an immediate laparotomy is his only hope. For example, if he has ruptured his spleen, try to get your hand on his splenic pedicle as soon as you can—bold action may save his life. You are like a person who is trying to fill a bath without first putting in the plug. Somehow, you will have to put in the plug.
Restoring a patient’s blood pressure is not a sufficient aim in itself. A good pulse volume, warm extremities, and a systolic pressure of only 70 mm, are better than a normal systolic pressure, cold extremities, and a rapid pulse. The surest way to know if you have given a patient enough fluid is to put a catheter in his bladder, and to monitor his urine output.
The common mistake is to underestimate the volume of blood that a patient has lost, and so to give him too little fluid too slowly. You are unlikely to give a young healthy person too much fluid before you realize that his circulation is normal. But in an old hypertensive or cardiac patient, be more cautious. You can precipitate cardiac failure before you have corrected his hypovolaemia. Ideally, such a patient needs a CVP monitor (A 19.2).
Anaesthesia is dangerous if a patient is severely shocked (16.7), because he is only maintaining his blood pressure by severe vasconstriction; a general anaesthetic abolishes this, so does subarachnoid (spinal) anaesthesia in the lower half of the body. If he is desperately ill, local infiltration anaesthesia may be best (A 5.4, A 6.7).
GRADING SHOCK Skin(4,0)(1,0)100 (-23,0)(-4,0)100 Degree of Blood Pulse Temperature Colour Circulation Thirst Urine Mental Shock Pressure Quality Output state None Normal Normal Normal Normal Normal Normal Normal Normal Slight To 20 per cent Normal Cool Pale Definite Normal Normal Clear and distressed decrease slowing Moderate Decreased 20 Definite Cool Pale Definite Definite Reduced Clear and some per cent to 40 decrease in slowing apathy unless per cent volume stimulated Severe Decreased 40 Weak to Cold Ashen to Very Severe Oliguria Apathetic to per cent to non imperceptible cyanotic sluggish comatose; little recordable mottling distress except thirst
This extends Section 51.3 on the care of a severely injured patient. You have diagnosed shock, and have already inserted an intravenous line.
These things make hypovolaemic shock worse, so try to avoid them: (1) Rough handling. (2) Prolonged or rough operating, including (a) the repeated vigorous manipulation of fractures, (b) the prolonged handling of gut through too small an incision, (c) too many operations on the day of the injury. (3) Ignoring intra–operative bleeding by failing to use warm packs, or to tie or clamp bleeding vessels. (4) Associated dehydration due to severe vomiting, diarrhoea, or sweating. (5) Warming a patient with hot water bottles or shock cradles. Warmth may overcome the vasoconstriction that he needs to maintain his circulation, so don’t let a shocked patient get too warm. Instead, put a blanket over him to prevent him losing heat and actually getting cold.
so that if a patient has one of them and is shocked, suspect that it is not the cause of his shock and that he has some other injury also, probably an abdominal one. Injuries which do not by themselves cause shock include: (1) Any minor injury. (2) Head injuries. (3) Maxillofacial injuries.
Raise the patient’s legs at right angles to his body. The blood in them will give him an autotransfusion and increase the venous return to his heart. Don’t tilt him with his head down because: (1) It is uncomfortable. (2) It causes cererebral congestion, and (3) it impairs the movement of his diaphragm.
Don’t rely on one sign only, use as many as you can. Apply the rules Fig. 53-2. Measure his blood pressure, and the rate and quality of his pulse; assess the colour of his skin; ask him if he is thirsty, assess his mental state. Later, his urine volume will be the best guide.
Feel the warmth and wetness of his forehead and hands. Are his hands or his nose cold? If his feet are cold, how far up his legs does the coldness go? If he is cold below the knee, he has lost 30% of his blood volume.
How full are his peripheral veins? Judge this from two signs: (1) Empty any convenient superficial vein by pressing it between two of your fingers. Remove your distal finger, and see how fast the empty vein fills up. (2) Look at the veins on the dorsum of his ankle. If they are invisible through a white skin, he is likely to be in hypovolaemic shock. This sign is less valuable in a dark one.
What is the capillary pressure in his nail beds? Press the blood out of one of them. How quickly does it fill up?
What is the pressure of his interstitial fluid? Look for: (1) sunken eyes, (2) loss of skin elasticity, (3) lowered eyeball tension, and (4) in severe cases, a Hippocratic facies. These are late signs.
If his respiration is shallow and rapid (air hunger), he is severely shocked.
If possible, and if you are sufficiently skilled, insert a central venous line (A 19.2) and measure his central venous pressure (CVP). This will be useful for monitoring treatment.
CAUTION! (1) A falling blood pressure is a late sign of increasing shock. (2) Don’t give him vasopressor drugs.
A patient’s history will be of some help. On the floor or on his clothes 100 ml of blood covers about a thousand square centimetres, or one square foot. A litre covers about a square metre (or square yard).
The volume of your fist is about 500 ml (one unit of blood or fluid). For each mass of soft tissue swelling equal to this, he needs a unit of replacement fluid. Fractures cause approximately the following blood loss. Upper limb fractures 1 unit. Tibia and fibula 2 units. Femur 1.5 units. Pelvis or multiple fractured ribs 2 to 6 units. For each rib fracture you can see on the X–ray, estimate 100 ml. If a fracture is open, add another 0.5 to 1 unit. A patient’s abdomen or thorax can hold 3 litres of blood or more. If he has multiple injuries he can thus lose much blood.
CAUTION! (1) Lost blood need not reach the surface. (2) The loss of only a few hundred millilitres may be fatal in a small child, as in Fig. 53-1.
Perhaps the patient has a fractured forearm and a fractured femur with an average sized haematoma, yet a litre of blood does not resuscitate him. He probably lost more blood externally at the site of the accident, or he has lost it into his abdomen or chest.
If he has a fast pulse and a low blood pressure with only a small wound, suspect that he has some serious internal injury, or, if a day or two has passed since the accident, some massive infection or gas gangrene.
This follows on from Section 51.3. You have taken blood for cross matching, and set up at least one good intravenous line, by the methods in A 15.2. If the patient is bleeding externally, you have controlled it (55.1). He is receiving oxygen. His management during (A 4.4) and after the operation (A 4.5), or when burns (58.4) or dehydration (A 15.3) are causing his shock, are described elsewhere.
Insert an indwelling catheter and attach it to a urine bag. Or, collect his urine in a 250 ml plastic measuring cylinder. If you suspect a urethral injury, insert the catheter suprapubically (68.1). An adequate urine output will be the most useful indication that you have treated his hypovolaemic shock adequately. Examine the first urine from this catheter. Look especially for blood, and if possible culture it.
![\includegraphics[scale=0.44]{/home/kumasi/Desktop/primsurg-tex/vol-2/ch-53/fig/53-3.eps}](images/img-0021.png)
If, later, no urine appears in the bag, make sure: (1) that the catheter is not kinked, and (2) that the inlet spigot has been removed from the bag.
If the catheter only produces a little urine and some blood, suspect that he has a bladder or urethral injury (68.1).
A severely shocked patient must have an effective intravenous line (A 15.2), if necessary, from two drops. If possible, replace the volume of blood you calculate he has lost. In very severe hypovolaemia give him a litre in 5 minutes. If he is shocked enough to have air hunger and a blood pressure less than 60 mm, he will need 2 or 3 litres.
If he is reasonably young, transfuse him at the most rapid convenient rate until the signs of shock go.
If he is old, or hypertensive, or has vascular or coronary disease, give him repeated rapid transfusions of about 100 ml, watching his jugular venous pressure carefully between each transfusion. Do this until there are signs that his cardiac output is normal. A change in his JVP or CVP is more important than its absolute value. Listen to the bases of his lungs for crepitations.
If you are fortunate enough to be able to give more than 4 units, warm them. The only safe way to do this is to fit two drips sets together and lead the cooled tubes through a water bath at 37°C measured with a thermometer. Too much cold blood may cause ventricular fibrilation. After you have given 12 units of blood, give him 5 ml of a 10% solution of calcium chloride, or 10 ml of a 10% solution of calcium gluconate for every 3 or 4 units of blood you transfuse.
Start this (A 15.5).
(1) Monitor his skin temperature. If you have transfused him adequately, his skin will become warm, dry, and pink (of he is Caucasion), instead of being cold, damp and white. His nail beds now fill up again after you have emptied them and his nose becomes warm. These signs may sometimes be delayed, even if transfusion is satisfactory. (2) A normal blood pressure is a good sign, but perfusion can be inadequate, even if it is normal. (3) An adult’s urine flow should be at least 20 ml/hour, and preferably 30 to 60 ml (1 ml/kg hour). If you have transfused him adequately, it should reach this value very soon after the injury.
CAUTION! Watch for: (1) A rose on his jugular venous pressure. (2) Basal crepitations.
when he is oligaemic, you can give him fluid safely and rapidly until it rises 12 cm of water.
If his CVP is over 15 cm, you are overtransfusing him, or he has a failing heart.
If his CVP rises, but his blood pressure and peripheral circulation do not improve, give him isoprenaline 0.5 to 10 micrograms/minute by intravenous infusion.
If a patient is severely shocked he will be acidotic. So give an adult 100 mmol of sodium bicarbonate, and another 50 mmol an hour or two later if necessary (A 15.1).
Shock from a fractured femur or a bleeding limb responds rapidly. If a patient’s shock does not respond, suspect an abdominal or thoracic injury.
For the care of hypovolaemia during and after the operation, see ’Primary Anaesthesia’ 5.4 and 5.5.
If you are in DOUBT AS TO THE CAUSE OF A PATIENT’S SHOCK, and he is fit enough, prop him up with his legs horizontal and his trunk at 45°. His neck veins should not be visibly distended. If they are, his jugular venous pressure is raised. He probably has some medical condition, or a bruised heart, or cardiac tamponade, or overtransfusion. If you can see an upper level on the blood on his neck veins, estimate how many centimetres it is above his sternal angle.
If his BLOOD PRESSURE FAILS TO RISE: (1) You have probably failed to give him enough fluid. (2) He may have been on shock too long. (3) He may have acute adrenocorticosteroid lack due to previous steroid therapy. Thos will weaken the response of his adrenal cortex to stress. Or, he may have some other cause of adrenocortical insuffiency.
If his VENOUS PRESSURE AND HIS PULSE RATE RISE, he has BASAL CREPITATIONS, PERIORBITAL OEDEMA AND A HEADACHE, you have given him too much fluid. The more usual mistake is to give him too little. Slow down the infusion, give an adult 40 to 80 mg of frusemide intravenously. If his kidneys are working normally, he will then have a massive diuresis. If necessary repeat the frusemide after 6 hours.
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Primary Surgery Vol.2 – Trauma | |
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