Anaesthesia, 1975, Volume 30, pages 791-802
Thoughts on immediate care Anaesthetists are being increasingly called upon to give immediate treatment for various life-threatening conditions in casualty departments and elsewhere. This feature of short papers by inoited experts is designed to describe the proper management of patients who require immediate care before the opinion of specialists in a particular field can be obtained.
Immediate care of burns A . W. D I A M O N D , R . W . P I G G O T T
AND
P. L. G. T O W N S E N D
This paper is intended to present an approach to the early care of burns coming to the district general hospital of a town some distance from a regional burn unit and requiring admission. Whatever the aetiology coagulative necrosis of the body covering is the common feature, the depth of burn being a function of time and energy applied. In the common thermal burn 45°C is the threshold temperature above which a normal circulation may not be able to dissipate heat fast enough to prevent irreversible damage.
Classification From many classifications of burn depth, it is practical to recognise three degrees: 1. Erythema or reversible damage. 2. Partial thickness skin loss. Such burns will heal from surviving epithelial elements in the deeper layers of the dermis within a reasonable time. These partial thickness burns will give a positive response to a firm pinprick testing. 3. Full thickness skin loss. These burns are entirely anaesthetic to pinprick. Most burns are mixed thickness loss, expectant treatment is pursued till the more superficial parts are healed and the remainder grafted after desloughing. It should be noted that for all practical purposes electrical, molten metal and hot press burns will always be full thickness loss and, being usually of limited area, are most suitable for primary or delayed primary excision and graft. The colour of a burn indicates the temperature of the burning agent and not the depth of the burn. Infection increases the depth of loss, as indeed does desiccation of the surface.
First aid
Respiratory management The immediate problems arising are asphyxia and poisoning. A fire in a confined A. W. Diamond, FFARCS, Consultant Anaesthetist, R. W. Pigott, FRCS, Consultant Plastic Surgeon and P. L. G. Townsend, FRCS, Senior Registrar in Plastic Surgery, Frenchay Hospital, Bristol.
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space will consume the available oxygen, or smoke may displace the air resulting in asphyxia. When carbon compounds are burned in the absence of an adequate supply of oxygen, the rescuer should be prepared to encounter carbon monoxide poisoning. Combustion of modern plastics, particularly those used in the furniture industry, may release higher oxides of nitrogen which are acutely poisonous as well as being responsible for delayed pulmonary problems. In view of these dangers a rescuer must decide first, whether he will be able to reach and extricate any casualties without himself being overwhelmed by asphyxia or acute poisoning. If suitable breathing equipment is available he should use it but if not he should assess the circumstances and the period of time that he will have to spend in a contaminated atmosphere with care, lest he achieve nothing more than adding to a subsequent adequately equipped rescuer’s problems. Patients rescued from heavily contaminated atmospheres are likely to be unconscious; immediate medical care should therefore aim at providing an effectively high concentration of oxygen, positive pressure ventilation, and endotracheal intubation in order to administer adequate respiratory resuscitation during transport to hospital.
Skin management It is vital to minimise the time of application of the burning agent but all that can be done has usually been done before medical help arrives. Cooling must be applied in the first half-minute to have any effect on depth, though it can be very soothing. Dilution of chemicals will almost invariably have been done but it will be necessary to use small scattered injections of calcium gluconate 10% subcutaneously for hydrofluoric acid burns, repeating them till pain is alleviated. In the case of phosphorous burns 1% copper sulphate solution is used to identify black phosphorous particles and remove them and until this can be done the part must be kept under water to prevent ignition of the phosphorous. It is not essential to remove tar, but this can be accomplished with ‘strapping remover’ where blistering has not occurred. Freshly laundered linen is an acceptable dressing for transport purposes. Lotions, creams, etc. are of psychological value only and may even impede diagnosis. Few burns go to operating theatre on the day of injury and analgesics and small quantities of fluids may be given. Larger quantities usually induce vomiting in the first 2 days after moderately severe burning. Assessment in the accident department
Airway burns Gases have a low specific heat and the upper part of the airway is an efficient heat exchanger; furthermore, if the inhaled gases retain enough heat to damage the lower trachea and bronchi, it is likely that the adjacent great vessels and mediastinal tissues will have been damaged to such an extent that, together with the almost inevitable external extensive burns, the patient’s immediate survival is unlikely. Thus, in survivors, heat damage is unusual below the upper trachea. The effects of this damage are: in the nose loss of warming, humidification, and filtration of inspired air; in the pharynx, oedema that may lead to airway obstruction; in the larynx, a similar danger of oedema and obstruction, associated with a failure of speech, swallowing and
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coughing; in the upper trachea, damage to the mucous membrane, resulting in a failure of mucous transport and secretion retention. Subsequently sloughing of the mucous membrane of a large part of the upper airway may produce acute airway obstruction. These problems are normally progressive for up to 48 hours following the burn injury. Burn damage to the upper airway should be suspected when the face is burned, when the patient’s clothes have caught fire or when there is extensive burning of the trunk. Examination will reveal a whitened and oedematous mucous membrane in the mouth and pharynx, nasal obstruction, and deficient phonation and coughing. If the larynx and upper trachea are damaged secretion retention develops rapidly and cannot be cleared by the patient. Initially the management may be expectant, but the airway should be bypassed at the first sign of obstruction or laryngeal or tracheal damage. Damage to the nasal mucous membrane requires the administration of warmed, humidified and filtered air, as the failure of the normal nasal humidifying mechanism may aggravate problems resulting from lesser degrees of damage lower in the airway.
Hypovolaemic shock It is rare for shock to have developed by the time a patient reaches the accident department, with the exception of elderly patients found unconscious, so that there is ample time for thorough examination. The fundamental immediate decision is the advisability of fluid replacement and for this a diagnosis of depth of burn is irrelevant.
History The initial examination will be concentrated therefore on obtaining a detailed history. This should include the age, weight and/or height, the state of heafth of the patient prior to the burn, the precise mechanism of burning and the time of burning as well as the nature of the first aid care which has been given-including the drugs which have been administered and whether drinks have been given and whether or not urine has been passed.
Exam ination The following points are of the utmost importance in the physical examination of the patient; the presence of intra-oral burns, respiratory obstruction or cyanosis, the degree of hypovolaemic shock, the area of the burn, whether there is a tourniquet effect on the extremities, neck, chest or abdomen and whether there are any eye burns (fluorescein eye stain should be used if there is any doubt).
Management As soon as the information is obtained by the history and examination, decisions can be taken with regard to the type and route of the administration of analgesics, the hospital admission, dressings, the advisability of using antibiotics, the type and extent of nursing, physiotherapy and social care which will be required, whether respiratory
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burn management is necessary and the treatment which is likely to be required in the shock phase. The possible need for immediate or subsequent transfer to a specialist burns unit should also be considered without delay.
Analgesia By the time of admission to hospital pain is not infrequently in almost inverse proportion to severity of burn. Full thickness loss areas are of course pain free. Superficial scalds can be extremely painful. Non-addicting drugs such as pentazocine (Fortral) should be used, as powerful analgesia may be required for many weeks. A tranquiliser such as diazepam may be a desirable supplement, as severe burns cause extreme anxiety and fear. Inhalational agents such as premixed 50% nitrous oxide and 50% oxygen (Entonox) and methoxyflurane may be used to alleviate the intense pain caused by movement and nursing procedures and, when these are inadequate, they may be potentiated by intravenous analgesics or neuroleptanalgesia. If only unconsciousness is required, ketamine has considerable advantages for procedures carried out in the patient’s bed.
Admission The decision to admit will depend on both medical and social factors such as distance, home nursing and availability, as well as site and size of the burn. Should it be decided to admit a major burn, which may be defined as one of twice the minimal transfusable area, it is essential to ascertain that the receiving officer is free to start an infusion before shock develops.
The burn wound and dressings Blisters almost never remain as intact sterile dressings, it is, therefore, best to remove them immediately lest they become culture media. Early removal is surprisingly pain free. Escharotomy. Any circumferential full thickness burn causes venous obstruction, which may progress to circulatory arrest and distal ischaemic necrosis. If in doubt it is best to divide the eschar longitudinally down to the normal tissue and into the normal skin proximal and, if possible, distal to the burn. Haemostasis will be required. Dressings will usually be required for outpatient burns and for burns to be admitted to open wards but a side ward is usually preferable for burns involving the trunk as dressings of the neck, shoulders, body and groins are difficult to perform and maintain effectively. A semi-open method is often adopted allowing the exposed surface to dry off under a bed cradle to form a coagulum and placing the under surface on sterile sheets over plastic sheeting. Large sheets of melolin smeared with an antibacterial cream such as silver sulphadiazine (Flamazine) and changed once or twice daily reduces the chance of colonisation with pyocyaneus in the warm moist under surface. Whatever cream is used it is advisable to change it every few days to decrease the chance of resistance. (Other effective antibacterial agents include nitrofurazone 0.2%, Povidone-iodine 10% or the simple, cheap and very effective solution of hypochlorite 0.25% with Paraffin 50%/50%.) It is vital to keep hands moving prior to surgery. This is best accomplished by enclosing the hand in a polythene bag; this should be about 25 x 50 cm for an adult. An
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antibacterial agent may be applied but it is not essential as a routine. Serum collects in large quantities in the first few days and can be emptied away. Patients and relatives dislike the appearance but a covering mitten may be fabricated. The treatment is quick, simple and cheap, encourages epithelial growth, minimizes loss by dessiccation and gives the patient a measure of independence to hold a newspaper and feed himself. Long bags can be used for forearm or lower leg burns fixed at the upper end with conventional gauze and crepe dressings. In cases of eye burns the opinion of an ophthalmologist should be obtained immediately.
Antibiotics Antibiotics should in general be reserved for invasive bacterial illness. Heavy growths of multiple and resistant organisms will often be obtained without evidence of local cellulitis or pyrexia, bacteraemia or septicaemia; they should be treated by antibacterial agents only. A good case has been made for prophylactic penicillin so that whatever the bacterial population the greatest evil of B Haemolytic Strep Group A will not be suffered; but even penicillin induces morbidity. Colonisation decreases rapidly once dead tissue has been separated.
Nursing, physical and social care A very heavy physical intellectual and emotional load is imposed by a major burn on the nursing staff. If a major burn is to be nursed outside an Intensive Care Unit and extra nurses cannot be allocated, it is essential to reduce the work load of the other beds in the ward; as a rule of thumb two beds of a twenty-bed ward should be officially ‘closed’ (preferably physically removed) for every multiple of 15% deep burn. It is also essential that a very clear chain of command is established so that contradictory instructions are not given. A treatment planning meeting at least once daily by the entire team responsible is advisable following which it is useful practice to rewrite the entire treatment chart including not only the intravenous but the oral fluids as well as the drugs. A fluid balance chart with a separate column for colloid fluids is advisable. A clear instruction given to the nursing staff that fluids are only to be charted when these have actually entered the patient prevents double entries. It has been found helpful for the House Officer to keep up a large daily chart on the wall similar to those which one often used in ITUs; this is used to record the temperature, pulse and respiration, crystalloid and colloid intake, separately blood gases and central venous pressure (CVP) and blood pressure when they are indicated. Daily total urine sodium, potassium and urea estimations will often disclose a trend towards the sick-cell syndrome (vide infra) before clinical signs appear; when these results are correlated with twiceweekly serum values and muscle protein loss may be calculated from the serum and urine urea values. Care of tracheostomy, CVP and intravenous lines, nasogastric tube and urethral catheter and the specific management of the burn wound (involving dressings that can take a team of two or three nurses and doctors one or two hours per day per patient) demand great energy, enthusiasm, understanding and even courage. An
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experienced burns ward nurse, who often senses clinical deterioration before the less continuously involved medical staff, is invaluable. Physical and occupational therapy and social welfare. Few burns have involved locomotor systems and every effort must be made to encourage the patient to move, to stand out of bed each day, to do things for himself, as well as the more formal breathing and leg exercises. Distraction from the horrors of the days and weeks of healing is most important and the occupational therapist can contribute considerably to the burns team. Social welfare problems can also be considerable and early settling of anxieties about these are a great help to morale. Respiratory burn management A burn injury may result in severe and multiple respiratory problems; as it is likely that many of these will be progressive in nature it is important that their presence should be suspected at an early stage before the signs and effects of advanced damage and respiratory insufficiency become apparent. Patients who have sustained extensive burns to the respiratory tract invariably become heavily infected. This greatly increases the danger of infection of a tracheostomy wound from adjacent burn, with the subsequent hazards of arterial erosion and mediastinitis. Nasal intubation with a plastic endotracheal tube should be used if at all possible and, when the trachea is intubated in the presence of an upper airway burn, humidification is of paramount importance. Mucosal damage, haemoptysis, and pulmonary damage following the inhalation of irritant products of combustion unite in these circumstances to produce a viscid secretion that may result in rapid lethal obstruction in an endotracheal or tracheostomy tube, even in the presence of normally adequate airway care. When the secretion is particularly difficult to remove by suction it may be essential to instil sterile water or saline to liquefy it to allow adequate airway toilet. Airway obstruction should be treated by immediate extubation followed by re-intubation with a fresh tube. Pulmonary damage. Lung damage is the result of inhalation of acid or alkali fumes or the toxic and irritant products of combustion. Inhalation results in bronchospasm, pulmonary oedema, the development of adult respiratory distress syndrome, and methaemoglobinaemia which may be associated with a high level of carbon monoxide haemoglobin. Both of these, by preventing oxygen transport, and by shifting the dissociation curve to the left, preventing oxygen delivery and exacerbate the hypoxia resulting in pulmonary damage. Circulatory problems, associated with the fluid and protein loss from the burn will also reduce cardiac output producing a further reduction in arterial oxygen tension and available oxygen. Hypoxaemia may complicate a burn, even in the absence of an airway burn and this is particularly likely if a patient has been in a house or industrial fire or has inhaled large amounts of smoke. A sample of arterial blood should be taken for blood gas estimation as early as possible; this investigation should be repeated every 12 hours until it is clear that there is no progressive pulmonary lesion. Early administration of adequate controlled concentrations of oxygen, well humidified where there are nasal and upper airways burns will minimise the hypoxaemia and its profound effect on the prognosis of a severely burned patient. If an inspired oxygen concentration of 50% fails to produce an adequate oxygen
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tension, intermittent positive pressure ventilation with positive end expiratory pressure (PEEP) may correct the situation. Circumferential burns of the thorax and upper abdomen. As the eschar hardens and contracts in the hours following the burn, circumferential involvement of the lower thorax and upper abdomen may restrict ventilation. Escharotomy should be undertaken if the eschar is causing the patient obvious respiratory distress, if the vital capacity is approaching the tidal volume, or where neither of these factors can be assessed, when the respiratory rate or carbon dioxide tension rises. Respiratory problems associated with burn injuries may be severe, complex and fatal. Upper airway damage and hypoxaemia are of particular importance. Early bypassing of the damaged upper airway, associated with a very high standard of airway care, and vigorous, controlled management of hypoxaemia may be lifesaving to the burned patient.
Shock phase resuscitation Physiological and metabolic efects in burns. Unlike many other forms of traumatic shock the full effects of reduction in circulating volume in burnt patients may not be apparent for several hours. Immediately after the burn there is an increase in capillary permeability with loss of plasma both from the burnt surfaces and into the surrounding tissues for some distance away. Serum albumin and other lower molecular weight serum proteins are lost into the interstitial extracellular space increasing the osmotic pressure resulting in the expansion of this space. The compensatory response to the burn stress is a massive outpouring of hormones for example corticotrophin (ACTH), Catecholamines, antidiuretic hormone ADH, renin, insulin and glucagon.’ Catecholamines levels in burns, notably noradrenaline, have been found to be proportional to the extent and depth of the burn and, in severe, mainly full thickness burns, levels up to twenty-six times mean normal level are reached. Maximal levels occur 3-4 days after the burn. The alpha effects of catecholamines are best demonstrated by noradrenaline which mainly produces alpha receptor activity; these are vasoconstriction of skin and splanchic vessels, a rise in blood pressure with reflex slowing of the heart, dilatation of the pupil and relaxation of the bowel. Hypertension has been noted in adults and burnt children and, in the latter, an associated higher mortality has been reported. Prolonged vasoconstriction may lead to intravascular coagulation and cell death and in the bowel ischaemic and mucosal breakdown. Fifty percent of untreated and 25% of treated fatal burns have superficial anoxic breakdown haemorrhages at post mortem which have often been unsuspected in life. The classical Curling’s ulcer in the duodenum is very rare. Liver function has been shown to be impaired in most burns and there is experimental evidence to indicate damage to the reticuloendothelial system and, consequent to this, failure to remove toxic products absorbed from the bowel; this may be a contributory factor in ‘Burn toxaemia’. The effect on renal function is particularly important, the high level catecholamines produce shunting of the circulation and reduction of renal plasma flow following vasoconstriction of the arterioles ; this produces a reduction in glomerular filtration rate with reduced flow and there is a more efficient extraction of sodium from the
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loops of Henle which tends to produce an oliguria of low concentration. The ischaemic kidney produces renin from the juxtaglomerular apparatus surrounding the renal afferent arterioles entering the glomerulae ; this releases large quantities of aldosterone via angiotensinogen-angiotensin which accentuates the retention of sodium and with it water. In addition, the increased level of ACTH stimulates the output of aldosterone as well as the glucocorticoids. This two-pronged stimulation of aldosterone contributes towards the reversal of the Na/K ratio in the urine often found in burnt patients. If the patient is very oedematous with reversed urine Na/K ratio an zldosterone antagonist (for example aldactone A) has been found to be very beneficial. Insulin and glucagon. Catecholamines affect metabolism partly by direct stimulation of the islets of Langerhans. Glucagon is increased markedly, in relationship to catecholamine output. Insulin is either decreased or if increased not in proportion to the Insulin/Glucagon ratio. This is aggravated by the adrenaline induced glycogenolysis in liver and muscle producing in many severely burned non-diabetic patients hyperglycaemia and glycosuria, so called pseudo diabetes. Clinical management. Healthy adults compensate for serum lost by burns of up to 15% of their surface area. Children compensate less well and a figure of 10% surface area involvement is taken as the threshold for replacement. First degree burns or erythema are not counted when assessing requirements for intravenous transfusion. Estimates of body surface involved can be made in adults from the rule of nines and, in infants, whose body proportions are different, from the rule of tens (Fig. 1); in children the minimum affected area for transfusion and distribution of surface area moves with age to the adult pattern.
Fig. 1. The rule of 10s for infants and 9s for adults emphasises the considerable size of the infants’ head and relatively minute development of the legs. Progressive change through childhood, and considerable variation from the normal in adults make these crude approximations. Functioning kidneys compensate for a good deal of error.
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The amount of fluid required can be estimated by a number of formulae; a common one is that of Muir & Barclay’ Body weight (grammes) x area of burn (1%) 2
Intravenous fluid to be given in each period of which there are six 4,4,4,6,6,12 hours
={
This compensates for the finding that in the first 12 hours there is a massive outpouring of fluid from the circulation with the result that the amount of fluids required in resuscitation are seldom equalled by other clinical situations. Within the last period fluid is starting to be reabsorbed back into the circulation and a diuresis will be seen. This formula is only a guide which must be monitored by the clinical state of the patient. Fluid requirements should be estimated from the time of burning if the patient is seen within a few hours, however, those seen 12 hours or more after the burn may well be compensated, so care must be taken in giving such large quantities of fluid intravenously. The nature of the fluid to be given intravenously is debatable though plasma has been most widely used as it seems logical to replace what is lost from the circulation by similar fluid. As human plasma protein fraction (HPPF) is now supplied instead of whole plasma, it should be remembered that HPPF is almost entirely albumen and almost no globulin or fibrinogen which means that in the 48 hour resuscitation of a major burn which involves the equivalent of an exchange transfusion, serious depletion of these constituents will occur. It is therefore advisable to give one unit of fresh frozen plasma for every two of HPPF. It is very important to institute a reliable intravenous infusion and a cut-down may be indicated especially in children; this should be placed preferably in the upper limb to reduce the possibility of deep vein thrombosis. In an extensive burn, a suitable vein may often be found underneath an anaesthetic burn eschar. Subclavia or internal jugular punctures can also be useful. The patient will require a fluid intake at a rate of 50ml/kg/24 hours as well as a plasma expander. Oral fluids should be limited to small amounts of clear cold fluids given frequently because of the reduced bowel mobility and poor absorption which is part of the stress reaction. If vomiting occurs, an equivalent volume should be given intravenously as 5% dextrose and Hartman’s or normal saline to replace water and electrolytes. The clinical state of the patient is all important, the presence or absence of shock may be assessed by pulse rate, blood pressure, refilling of subungual capillary bed after compression, filling of peripheral veins, urine output and content, restlessness and sweating, nausea and vomiting, skin temperature, skin colour. Special monitoring techniques must also be considered. Central venous pressure measurement has proved most useful where there is a rapid loss of circulating volume, particularly whole blood, as occurs for example in multiple fractures, but in burns, where the loss is mainly in the plasma fraction and is more insidious, the high peripheral resistance resulting from massive output of catecholamines causes a reflex slowing of the heart with reduced cardiac output in an attempt to maintain the blood pressure at normal levels. This will tend to produce in severe burns an inability of the heart to keep up with venous return and a consequent elevation of central venous pressure despite reduced circulating volume. Interpretation requires simultaneous measurements of arterial pressure which tends to be
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difficult or impossible due to leathery eschar on all four limbs in the very patients where the assessment would be most valuable. If one adds to this the problem of positioning the tip of the catheter in an extremely burnt patient, the possibility of producing pulmonary collapse, mediastinitis, the real danger of introducing infection direct into the central circulation and the difficulty of interpreting the information from CVP measurement, it has been found of little clinical use in burns except in the rare condition of irreversible shock which is described later. Jugular venous pressure (JVP) measurement by clinical assessment is worth noting on an occasional basis especially in children in whom there is a very real danger of overloading the circulation. Haematocrit estimation can be used as an index of plasma deficit but variations in normal persons according to age, sex and weight must be taken into account. This is a particularly valuable guide to effectiveness of treatment in superficial burns, if, from a careful history, the patient can be assumed to have had no pre-existing abnormality. In deeper burns it is still useful but interpretation is more complicated. There is variable local destruction of red cells and increased red cells fragility which reduces their half life. In severe burns with delayed or inadequate treatment, prolonged peripheral vasoconstriction results, and the capillaries eventually dilate as a result of metabolic acidosis; this produces an expansion of the vascular space and in the late stages of shock disseminated intravascular coagulation occurs with subsequent haemolysis. Clumped red cells have been noted to be trapped in the vast capillary network of the lungs in burnt patients. It is probable that this may occur to a variable degree even in apparently well-treated burns, with a loss of effective circulating red cells by agglutination and trapping in the dilated capillary bed. The haematocrit is obviously of limited value if a blood transfusion is given; for this reason it is better to defer giving blood transfusion until the acute phase is over. The problems of multiple blood transfusions are well known but the maintenance of a really good peripheral circulation is fundamental to healing the burn wound and these hazards must be accepted. Blood volume measurement by tagging radioactive albumin is obviously inaccurate because of loss from the circulation; chromium tagged red cell method if available is a more accurate method of estimating circulating volume, but is laborious and impractical for routine use. Urine volume and spec$c gravity. The measurement of a specific gravity of the urine may be of assistance but the presence of glucose, mannitol, protein or dextran in the urine will affect the result and when present the result should be ignored. The measurement of the amount of urine and content is important so patients should be catheterised. If oliguria occurs despite aggressive fluid replacement a bolus of 100-200 ml of 20% mannitol can be given to promote a diuresis. If this fails dialysis may be required. Clinically, in a proportion of severely burnt patients, despite apparently adequate transfusion there remains a poor peripheral circulation with oliguria; the condition of so-called irreversible shock. Haemaglobinuria and reduction in urine osmolarity are often present in these cases. These are bad prognostic signs of impending renal failure, associated renal tubular dysfunction and inability to concentrate urine. In these patients an alpha blocker should be considered: this is one clinical situation where central venous pressure and arterial pressure monitoring are essential. The patient should be placed in a flat or Trendelenberg position: an alpha blocker, e.g. phenoxybenzamine in a dose of 1 mg per kg diluted in 250 ml of 0.9% saline is given over 2 to 4 hours; it is discontinued when the slow administration has produced
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an effective alpha blockade as shown by warm extremities and increased urine output. If the blood pressure changes this provides a reliable method of estimating the adequacy of previous intravascular volume replacement. If there is little or no change in blood pressure this has been adequate; if it falls below a mean blood pressure of 70 mmHg tissue perfusion is unlikely to be adequate and further colloid fluid is required quickly.
Calorie requirement Burn patients are undergoing hypercatabolism in which the Basal Metabolic Rate (BMR) is increased up to +loo% with calorie requirements 3000-6000 per day, gluconeogenesis is activated with high levels of free fatty acids; there is accelerated hepatic ureagenesis with negative introgen balance. To prevent this, extra calorie requirements can be provided by high calorie products for example Vivonex HC by slow nasogastric drip, Carnation Instant Breakfast by mouth, or less easily by various intravenous fat and amino acid preparations. Better utilisation of glucose can be achieved by adding extra insulin; the insulin resistance which develops in some major burns can lead to the development of the sick cell syndrome with failure of the sodium pump to maintain the potassium level in the cells and drive sodium out; there is consequently an increase in interstitial and urine potassium. It has been advocated that 50 ml of a 50% glucose solution with added potassium chloride (40 mEq litre) and insulin 120 units/litre should be given hourly as a bolus; if a clinitest demonstrates 4% or more glucose in the urine further insulin should be given. By this method the peripheral utilisation of glucose is increased, potassium pours back into the cells and there is a diminution of protein catabolism with decreased urea formation. Environmental temperature is all important especially where extensive burns are exposed, in a warm (32"C), dry (relative humidity 30%) environment the negative nitrogen balance and BMR is reduced. Large areas of skin loss reduce the body's ability to retain heat.
Transfer to a specialist burn unit The decision on whether and when to transfer the patient to a specialist burns unit will depend on many factors. It should be remembered that few patients need the care of an intensive therapy unit more than major burn cases but, on the other hand, few patients are less welcome in a general ITU since for all practical purposes all major burns will be colonised with bacteria. Intensive levels of nursing care will not normally be available outside an ITU and the need for intensive nursing care will continue for weeks in some cases. In considering what a burns unit may achieve one should consider the expected mortality. A practical rule of thumb is to add the patient's age and area of full thickness skin loss. If the result exceeds 100, survival is unlikely in the extreme and patients should not usually be referred away to a burn unit but kept near to the support of the family. A burns unit may hope to minimize mortality to these figures and perhaps of greater importance expect to minimize morbidity by greater familiarity with the practical problems of closing large areas of skin loss and combating catabolism and infection.
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Burns of the eye and extensive deep loss of face and hands pose particular problems which will usually require treatment in an Eye Hospital or Burns Unit. Timing. If it is decided that a burn is too big a problem to retain in the District General Hospital during resuscitation the timing of transfer should be considered. The availability of staff is crucial to this decision. If the patient is to be safely transferred to a Burns Unit, staff from the original admitting hospital must be available and competent to ensure the patency of the patient’s airway and the adequacy of transfusion during the journey however prolonged it may be. Failure to maintain the airway or to continue transfusion may be fatal if the journey is protracted. On the other hand, if the patient is admitted to the original hospital medical and nursing staff must be available to deal with dangerous situations which may develop in the subsequent phase of hypovolaemic shock ; these may include such procedures as endotracheal intubation, and escharotomy in addition to the time-consuming commitment of resuscitation. Discussion of clinical details meticulously obtained with the Registrar or Consultant of the Regional Burns Unit may clarify the priorities. Estimated delay in provision of transport and travelling time should be obtained from senior personnel of the ambulance service and may be critical to the decision. Provided that adequate resuscitation continues, burned patients travel well in the shock phase and Burns Units will usually prefer to take patients immediately. In some cases it may be easier to provide intensive cover for a matter of hours of an ambulance journey rather than for the days during the shock phase.
Summary The assessment, first aid treatment and immediate care of severely burned patients in the Accident and Emergency Department have been reviewed and the factors which influence the decision to transfer a case to a specialist Burns Unit have been discussed.
References 1. SEVITT, S. (1974) Reactions to Injury in Burns. Heinemann, London. 2. MUIR,I.F.K. & BARCLAY, J.L. (1962) Burns and their Treatment. Lloyd-Luke, London.
Thoughts on immediate care Anaesthetists are being increasingly called upon to give immediate treatment for various life-threatening conditions in casualty departments and elsewhere. This feature of short papers by inoited experts is designed to describe the proper management of patients who require immediate care before the opinion of specialists in a particular field can be obtained.
Immediate care of burns A . W. D I A M O N D , R . W . P I G G O T T
AND
P. L. G. T O W N S E N D
This paper is intended to present an approach to the early care of burns coming to the district general hospital of a town some distance from a regional burn unit and requiring admission. Whatever the aetiology coagulative necrosis of the body covering is the common feature, the depth of burn being a function of time and energy applied. In the common thermal burn 45°C is the threshold temperature above which a normal circulation may not be able to dissipate heat fast enough to prevent irreversible damage.
Classification From many classifications of burn depth, it is practical to recognise three degrees: 1. Erythema or reversible damage. 2. Partial thickness skin loss. Such burns will heal from surviving epithelial elements in the deeper layers of the dermis within a reasonable time. These partial thickness burns will give a positive response to a firm pinprick testing. 3. Full thickness skin loss. These burns are entirely anaesthetic to pinprick. Most burns are mixed thickness loss, expectant treatment is pursued till the more superficial parts are healed and the remainder grafted after desloughing. It should be noted that for all practical purposes electrical, molten metal and hot press burns will always be full thickness loss and, being usually of limited area, are most suitable for primary or delayed primary excision and graft. The colour of a burn indicates the temperature of the burning agent and not the depth of the burn. Infection increases the depth of loss, as indeed does desiccation of the surface.
First aid
Respiratory management The immediate problems arising are asphyxia and poisoning. A fire in a confined A. W. Diamond, FFARCS, Consultant Anaesthetist, R. W. Pigott, FRCS, Consultant Plastic Surgeon and P. L. G. Townsend, FRCS, Senior Registrar in Plastic Surgery, Frenchay Hospital, Bristol.
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space will consume the available oxygen, or smoke may displace the air resulting in asphyxia. When carbon compounds are burned in the absence of an adequate supply of oxygen, the rescuer should be prepared to encounter carbon monoxide poisoning. Combustion of modern plastics, particularly those used in the furniture industry, may release higher oxides of nitrogen which are acutely poisonous as well as being responsible for delayed pulmonary problems. In view of these dangers a rescuer must decide first, whether he will be able to reach and extricate any casualties without himself being overwhelmed by asphyxia or acute poisoning. If suitable breathing equipment is available he should use it but if not he should assess the circumstances and the period of time that he will have to spend in a contaminated atmosphere with care, lest he achieve nothing more than adding to a subsequent adequately equipped rescuer’s problems. Patients rescued from heavily contaminated atmospheres are likely to be unconscious; immediate medical care should therefore aim at providing an effectively high concentration of oxygen, positive pressure ventilation, and endotracheal intubation in order to administer adequate respiratory resuscitation during transport to hospital.
Skin management It is vital to minimise the time of application of the burning agent but all that can be done has usually been done before medical help arrives. Cooling must be applied in the first half-minute to have any effect on depth, though it can be very soothing. Dilution of chemicals will almost invariably have been done but it will be necessary to use small scattered injections of calcium gluconate 10% subcutaneously for hydrofluoric acid burns, repeating them till pain is alleviated. In the case of phosphorous burns 1% copper sulphate solution is used to identify black phosphorous particles and remove them and until this can be done the part must be kept under water to prevent ignition of the phosphorous. It is not essential to remove tar, but this can be accomplished with ‘strapping remover’ where blistering has not occurred. Freshly laundered linen is an acceptable dressing for transport purposes. Lotions, creams, etc. are of psychological value only and may even impede diagnosis. Few burns go to operating theatre on the day of injury and analgesics and small quantities of fluids may be given. Larger quantities usually induce vomiting in the first 2 days after moderately severe burning. Assessment in the accident department
Airway burns Gases have a low specific heat and the upper part of the airway is an efficient heat exchanger; furthermore, if the inhaled gases retain enough heat to damage the lower trachea and bronchi, it is likely that the adjacent great vessels and mediastinal tissues will have been damaged to such an extent that, together with the almost inevitable external extensive burns, the patient’s immediate survival is unlikely. Thus, in survivors, heat damage is unusual below the upper trachea. The effects of this damage are: in the nose loss of warming, humidification, and filtration of inspired air; in the pharynx, oedema that may lead to airway obstruction; in the larynx, a similar danger of oedema and obstruction, associated with a failure of speech, swallowing and
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coughing; in the upper trachea, damage to the mucous membrane, resulting in a failure of mucous transport and secretion retention. Subsequently sloughing of the mucous membrane of a large part of the upper airway may produce acute airway obstruction. These problems are normally progressive for up to 48 hours following the burn injury. Burn damage to the upper airway should be suspected when the face is burned, when the patient’s clothes have caught fire or when there is extensive burning of the trunk. Examination will reveal a whitened and oedematous mucous membrane in the mouth and pharynx, nasal obstruction, and deficient phonation and coughing. If the larynx and upper trachea are damaged secretion retention develops rapidly and cannot be cleared by the patient. Initially the management may be expectant, but the airway should be bypassed at the first sign of obstruction or laryngeal or tracheal damage. Damage to the nasal mucous membrane requires the administration of warmed, humidified and filtered air, as the failure of the normal nasal humidifying mechanism may aggravate problems resulting from lesser degrees of damage lower in the airway.
Hypovolaemic shock It is rare for shock to have developed by the time a patient reaches the accident department, with the exception of elderly patients found unconscious, so that there is ample time for thorough examination. The fundamental immediate decision is the advisability of fluid replacement and for this a diagnosis of depth of burn is irrelevant.
History The initial examination will be concentrated therefore on obtaining a detailed history. This should include the age, weight and/or height, the state of heafth of the patient prior to the burn, the precise mechanism of burning and the time of burning as well as the nature of the first aid care which has been given-including the drugs which have been administered and whether drinks have been given and whether or not urine has been passed.
Exam ination The following points are of the utmost importance in the physical examination of the patient; the presence of intra-oral burns, respiratory obstruction or cyanosis, the degree of hypovolaemic shock, the area of the burn, whether there is a tourniquet effect on the extremities, neck, chest or abdomen and whether there are any eye burns (fluorescein eye stain should be used if there is any doubt).
Management As soon as the information is obtained by the history and examination, decisions can be taken with regard to the type and route of the administration of analgesics, the hospital admission, dressings, the advisability of using antibiotics, the type and extent of nursing, physiotherapy and social care which will be required, whether respiratory
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burn management is necessary and the treatment which is likely to be required in the shock phase. The possible need for immediate or subsequent transfer to a specialist burns unit should also be considered without delay.
Analgesia By the time of admission to hospital pain is not infrequently in almost inverse proportion to severity of burn. Full thickness loss areas are of course pain free. Superficial scalds can be extremely painful. Non-addicting drugs such as pentazocine (Fortral) should be used, as powerful analgesia may be required for many weeks. A tranquiliser such as diazepam may be a desirable supplement, as severe burns cause extreme anxiety and fear. Inhalational agents such as premixed 50% nitrous oxide and 50% oxygen (Entonox) and methoxyflurane may be used to alleviate the intense pain caused by movement and nursing procedures and, when these are inadequate, they may be potentiated by intravenous analgesics or neuroleptanalgesia. If only unconsciousness is required, ketamine has considerable advantages for procedures carried out in the patient’s bed.
Admission The decision to admit will depend on both medical and social factors such as distance, home nursing and availability, as well as site and size of the burn. Should it be decided to admit a major burn, which may be defined as one of twice the minimal transfusable area, it is essential to ascertain that the receiving officer is free to start an infusion before shock develops.
The burn wound and dressings Blisters almost never remain as intact sterile dressings, it is, therefore, best to remove them immediately lest they become culture media. Early removal is surprisingly pain free. Escharotomy. Any circumferential full thickness burn causes venous obstruction, which may progress to circulatory arrest and distal ischaemic necrosis. If in doubt it is best to divide the eschar longitudinally down to the normal tissue and into the normal skin proximal and, if possible, distal to the burn. Haemostasis will be required. Dressings will usually be required for outpatient burns and for burns to be admitted to open wards but a side ward is usually preferable for burns involving the trunk as dressings of the neck, shoulders, body and groins are difficult to perform and maintain effectively. A semi-open method is often adopted allowing the exposed surface to dry off under a bed cradle to form a coagulum and placing the under surface on sterile sheets over plastic sheeting. Large sheets of melolin smeared with an antibacterial cream such as silver sulphadiazine (Flamazine) and changed once or twice daily reduces the chance of colonisation with pyocyaneus in the warm moist under surface. Whatever cream is used it is advisable to change it every few days to decrease the chance of resistance. (Other effective antibacterial agents include nitrofurazone 0.2%, Povidone-iodine 10% or the simple, cheap and very effective solution of hypochlorite 0.25% with Paraffin 50%/50%.) It is vital to keep hands moving prior to surgery. This is best accomplished by enclosing the hand in a polythene bag; this should be about 25 x 50 cm for an adult. An
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antibacterial agent may be applied but it is not essential as a routine. Serum collects in large quantities in the first few days and can be emptied away. Patients and relatives dislike the appearance but a covering mitten may be fabricated. The treatment is quick, simple and cheap, encourages epithelial growth, minimizes loss by dessiccation and gives the patient a measure of independence to hold a newspaper and feed himself. Long bags can be used for forearm or lower leg burns fixed at the upper end with conventional gauze and crepe dressings. In cases of eye burns the opinion of an ophthalmologist should be obtained immediately.
Antibiotics Antibiotics should in general be reserved for invasive bacterial illness. Heavy growths of multiple and resistant organisms will often be obtained without evidence of local cellulitis or pyrexia, bacteraemia or septicaemia; they should be treated by antibacterial agents only. A good case has been made for prophylactic penicillin so that whatever the bacterial population the greatest evil of B Haemolytic Strep Group A will not be suffered; but even penicillin induces morbidity. Colonisation decreases rapidly once dead tissue has been separated.
Nursing, physical and social care A very heavy physical intellectual and emotional load is imposed by a major burn on the nursing staff. If a major burn is to be nursed outside an Intensive Care Unit and extra nurses cannot be allocated, it is essential to reduce the work load of the other beds in the ward; as a rule of thumb two beds of a twenty-bed ward should be officially ‘closed’ (preferably physically removed) for every multiple of 15% deep burn. It is also essential that a very clear chain of command is established so that contradictory instructions are not given. A treatment planning meeting at least once daily by the entire team responsible is advisable following which it is useful practice to rewrite the entire treatment chart including not only the intravenous but the oral fluids as well as the drugs. A fluid balance chart with a separate column for colloid fluids is advisable. A clear instruction given to the nursing staff that fluids are only to be charted when these have actually entered the patient prevents double entries. It has been found helpful for the House Officer to keep up a large daily chart on the wall similar to those which one often used in ITUs; this is used to record the temperature, pulse and respiration, crystalloid and colloid intake, separately blood gases and central venous pressure (CVP) and blood pressure when they are indicated. Daily total urine sodium, potassium and urea estimations will often disclose a trend towards the sick-cell syndrome (vide infra) before clinical signs appear; when these results are correlated with twiceweekly serum values and muscle protein loss may be calculated from the serum and urine urea values. Care of tracheostomy, CVP and intravenous lines, nasogastric tube and urethral catheter and the specific management of the burn wound (involving dressings that can take a team of two or three nurses and doctors one or two hours per day per patient) demand great energy, enthusiasm, understanding and even courage. An
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experienced burns ward nurse, who often senses clinical deterioration before the less continuously involved medical staff, is invaluable. Physical and occupational therapy and social welfare. Few burns have involved locomotor systems and every effort must be made to encourage the patient to move, to stand out of bed each day, to do things for himself, as well as the more formal breathing and leg exercises. Distraction from the horrors of the days and weeks of healing is most important and the occupational therapist can contribute considerably to the burns team. Social welfare problems can also be considerable and early settling of anxieties about these are a great help to morale. Respiratory burn management A burn injury may result in severe and multiple respiratory problems; as it is likely that many of these will be progressive in nature it is important that their presence should be suspected at an early stage before the signs and effects of advanced damage and respiratory insufficiency become apparent. Patients who have sustained extensive burns to the respiratory tract invariably become heavily infected. This greatly increases the danger of infection of a tracheostomy wound from adjacent burn, with the subsequent hazards of arterial erosion and mediastinitis. Nasal intubation with a plastic endotracheal tube should be used if at all possible and, when the trachea is intubated in the presence of an upper airway burn, humidification is of paramount importance. Mucosal damage, haemoptysis, and pulmonary damage following the inhalation of irritant products of combustion unite in these circumstances to produce a viscid secretion that may result in rapid lethal obstruction in an endotracheal or tracheostomy tube, even in the presence of normally adequate airway care. When the secretion is particularly difficult to remove by suction it may be essential to instil sterile water or saline to liquefy it to allow adequate airway toilet. Airway obstruction should be treated by immediate extubation followed by re-intubation with a fresh tube. Pulmonary damage. Lung damage is the result of inhalation of acid or alkali fumes or the toxic and irritant products of combustion. Inhalation results in bronchospasm, pulmonary oedema, the development of adult respiratory distress syndrome, and methaemoglobinaemia which may be associated with a high level of carbon monoxide haemoglobin. Both of these, by preventing oxygen transport, and by shifting the dissociation curve to the left, preventing oxygen delivery and exacerbate the hypoxia resulting in pulmonary damage. Circulatory problems, associated with the fluid and protein loss from the burn will also reduce cardiac output producing a further reduction in arterial oxygen tension and available oxygen. Hypoxaemia may complicate a burn, even in the absence of an airway burn and this is particularly likely if a patient has been in a house or industrial fire or has inhaled large amounts of smoke. A sample of arterial blood should be taken for blood gas estimation as early as possible; this investigation should be repeated every 12 hours until it is clear that there is no progressive pulmonary lesion. Early administration of adequate controlled concentrations of oxygen, well humidified where there are nasal and upper airways burns will minimise the hypoxaemia and its profound effect on the prognosis of a severely burned patient. If an inspired oxygen concentration of 50% fails to produce an adequate oxygen
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tension, intermittent positive pressure ventilation with positive end expiratory pressure (PEEP) may correct the situation. Circumferential burns of the thorax and upper abdomen. As the eschar hardens and contracts in the hours following the burn, circumferential involvement of the lower thorax and upper abdomen may restrict ventilation. Escharotomy should be undertaken if the eschar is causing the patient obvious respiratory distress, if the vital capacity is approaching the tidal volume, or where neither of these factors can be assessed, when the respiratory rate or carbon dioxide tension rises. Respiratory problems associated with burn injuries may be severe, complex and fatal. Upper airway damage and hypoxaemia are of particular importance. Early bypassing of the damaged upper airway, associated with a very high standard of airway care, and vigorous, controlled management of hypoxaemia may be lifesaving to the burned patient.
Shock phase resuscitation Physiological and metabolic efects in burns. Unlike many other forms of traumatic shock the full effects of reduction in circulating volume in burnt patients may not be apparent for several hours. Immediately after the burn there is an increase in capillary permeability with loss of plasma both from the burnt surfaces and into the surrounding tissues for some distance away. Serum albumin and other lower molecular weight serum proteins are lost into the interstitial extracellular space increasing the osmotic pressure resulting in the expansion of this space. The compensatory response to the burn stress is a massive outpouring of hormones for example corticotrophin (ACTH), Catecholamines, antidiuretic hormone ADH, renin, insulin and glucagon.’ Catecholamines levels in burns, notably noradrenaline, have been found to be proportional to the extent and depth of the burn and, in severe, mainly full thickness burns, levels up to twenty-six times mean normal level are reached. Maximal levels occur 3-4 days after the burn. The alpha effects of catecholamines are best demonstrated by noradrenaline which mainly produces alpha receptor activity; these are vasoconstriction of skin and splanchic vessels, a rise in blood pressure with reflex slowing of the heart, dilatation of the pupil and relaxation of the bowel. Hypertension has been noted in adults and burnt children and, in the latter, an associated higher mortality has been reported. Prolonged vasoconstriction may lead to intravascular coagulation and cell death and in the bowel ischaemic and mucosal breakdown. Fifty percent of untreated and 25% of treated fatal burns have superficial anoxic breakdown haemorrhages at post mortem which have often been unsuspected in life. The classical Curling’s ulcer in the duodenum is very rare. Liver function has been shown to be impaired in most burns and there is experimental evidence to indicate damage to the reticuloendothelial system and, consequent to this, failure to remove toxic products absorbed from the bowel; this may be a contributory factor in ‘Burn toxaemia’. The effect on renal function is particularly important, the high level catecholamines produce shunting of the circulation and reduction of renal plasma flow following vasoconstriction of the arterioles ; this produces a reduction in glomerular filtration rate with reduced flow and there is a more efficient extraction of sodium from the
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loops of Henle which tends to produce an oliguria of low concentration. The ischaemic kidney produces renin from the juxtaglomerular apparatus surrounding the renal afferent arterioles entering the glomerulae ; this releases large quantities of aldosterone via angiotensinogen-angiotensin which accentuates the retention of sodium and with it water. In addition, the increased level of ACTH stimulates the output of aldosterone as well as the glucocorticoids. This two-pronged stimulation of aldosterone contributes towards the reversal of the Na/K ratio in the urine often found in burnt patients. If the patient is very oedematous with reversed urine Na/K ratio an zldosterone antagonist (for example aldactone A) has been found to be very beneficial. Insulin and glucagon. Catecholamines affect metabolism partly by direct stimulation of the islets of Langerhans. Glucagon is increased markedly, in relationship to catecholamine output. Insulin is either decreased or if increased not in proportion to the Insulin/Glucagon ratio. This is aggravated by the adrenaline induced glycogenolysis in liver and muscle producing in many severely burned non-diabetic patients hyperglycaemia and glycosuria, so called pseudo diabetes. Clinical management. Healthy adults compensate for serum lost by burns of up to 15% of their surface area. Children compensate less well and a figure of 10% surface area involvement is taken as the threshold for replacement. First degree burns or erythema are not counted when assessing requirements for intravenous transfusion. Estimates of body surface involved can be made in adults from the rule of nines and, in infants, whose body proportions are different, from the rule of tens (Fig. 1); in children the minimum affected area for transfusion and distribution of surface area moves with age to the adult pattern.
Fig. 1. The rule of 10s for infants and 9s for adults emphasises the considerable size of the infants’ head and relatively minute development of the legs. Progressive change through childhood, and considerable variation from the normal in adults make these crude approximations. Functioning kidneys compensate for a good deal of error.
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The amount of fluid required can be estimated by a number of formulae; a common one is that of Muir & Barclay’ Body weight (grammes) x area of burn (1%) 2
Intravenous fluid to be given in each period of which there are six 4,4,4,6,6,12 hours
={
This compensates for the finding that in the first 12 hours there is a massive outpouring of fluid from the circulation with the result that the amount of fluids required in resuscitation are seldom equalled by other clinical situations. Within the last period fluid is starting to be reabsorbed back into the circulation and a diuresis will be seen. This formula is only a guide which must be monitored by the clinical state of the patient. Fluid requirements should be estimated from the time of burning if the patient is seen within a few hours, however, those seen 12 hours or more after the burn may well be compensated, so care must be taken in giving such large quantities of fluid intravenously. The nature of the fluid to be given intravenously is debatable though plasma has been most widely used as it seems logical to replace what is lost from the circulation by similar fluid. As human plasma protein fraction (HPPF) is now supplied instead of whole plasma, it should be remembered that HPPF is almost entirely albumen and almost no globulin or fibrinogen which means that in the 48 hour resuscitation of a major burn which involves the equivalent of an exchange transfusion, serious depletion of these constituents will occur. It is therefore advisable to give one unit of fresh frozen plasma for every two of HPPF. It is very important to institute a reliable intravenous infusion and a cut-down may be indicated especially in children; this should be placed preferably in the upper limb to reduce the possibility of deep vein thrombosis. In an extensive burn, a suitable vein may often be found underneath an anaesthetic burn eschar. Subclavia or internal jugular punctures can also be useful. The patient will require a fluid intake at a rate of 50ml/kg/24 hours as well as a plasma expander. Oral fluids should be limited to small amounts of clear cold fluids given frequently because of the reduced bowel mobility and poor absorption which is part of the stress reaction. If vomiting occurs, an equivalent volume should be given intravenously as 5% dextrose and Hartman’s or normal saline to replace water and electrolytes. The clinical state of the patient is all important, the presence or absence of shock may be assessed by pulse rate, blood pressure, refilling of subungual capillary bed after compression, filling of peripheral veins, urine output and content, restlessness and sweating, nausea and vomiting, skin temperature, skin colour. Special monitoring techniques must also be considered. Central venous pressure measurement has proved most useful where there is a rapid loss of circulating volume, particularly whole blood, as occurs for example in multiple fractures, but in burns, where the loss is mainly in the plasma fraction and is more insidious, the high peripheral resistance resulting from massive output of catecholamines causes a reflex slowing of the heart with reduced cardiac output in an attempt to maintain the blood pressure at normal levels. This will tend to produce in severe burns an inability of the heart to keep up with venous return and a consequent elevation of central venous pressure despite reduced circulating volume. Interpretation requires simultaneous measurements of arterial pressure which tends to be
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difficult or impossible due to leathery eschar on all four limbs in the very patients where the assessment would be most valuable. If one adds to this the problem of positioning the tip of the catheter in an extremely burnt patient, the possibility of producing pulmonary collapse, mediastinitis, the real danger of introducing infection direct into the central circulation and the difficulty of interpreting the information from CVP measurement, it has been found of little clinical use in burns except in the rare condition of irreversible shock which is described later. Jugular venous pressure (JVP) measurement by clinical assessment is worth noting on an occasional basis especially in children in whom there is a very real danger of overloading the circulation. Haematocrit estimation can be used as an index of plasma deficit but variations in normal persons according to age, sex and weight must be taken into account. This is a particularly valuable guide to effectiveness of treatment in superficial burns, if, from a careful history, the patient can be assumed to have had no pre-existing abnormality. In deeper burns it is still useful but interpretation is more complicated. There is variable local destruction of red cells and increased red cells fragility which reduces their half life. In severe burns with delayed or inadequate treatment, prolonged peripheral vasoconstriction results, and the capillaries eventually dilate as a result of metabolic acidosis; this produces an expansion of the vascular space and in the late stages of shock disseminated intravascular coagulation occurs with subsequent haemolysis. Clumped red cells have been noted to be trapped in the vast capillary network of the lungs in burnt patients. It is probable that this may occur to a variable degree even in apparently well-treated burns, with a loss of effective circulating red cells by agglutination and trapping in the dilated capillary bed. The haematocrit is obviously of limited value if a blood transfusion is given; for this reason it is better to defer giving blood transfusion until the acute phase is over. The problems of multiple blood transfusions are well known but the maintenance of a really good peripheral circulation is fundamental to healing the burn wound and these hazards must be accepted. Blood volume measurement by tagging radioactive albumin is obviously inaccurate because of loss from the circulation; chromium tagged red cell method if available is a more accurate method of estimating circulating volume, but is laborious and impractical for routine use. Urine volume and spec$c gravity. The measurement of a specific gravity of the urine may be of assistance but the presence of glucose, mannitol, protein or dextran in the urine will affect the result and when present the result should be ignored. The measurement of the amount of urine and content is important so patients should be catheterised. If oliguria occurs despite aggressive fluid replacement a bolus of 100-200 ml of 20% mannitol can be given to promote a diuresis. If this fails dialysis may be required. Clinically, in a proportion of severely burnt patients, despite apparently adequate transfusion there remains a poor peripheral circulation with oliguria; the condition of so-called irreversible shock. Haemaglobinuria and reduction in urine osmolarity are often present in these cases. These are bad prognostic signs of impending renal failure, associated renal tubular dysfunction and inability to concentrate urine. In these patients an alpha blocker should be considered: this is one clinical situation where central venous pressure and arterial pressure monitoring are essential. The patient should be placed in a flat or Trendelenberg position: an alpha blocker, e.g. phenoxybenzamine in a dose of 1 mg per kg diluted in 250 ml of 0.9% saline is given over 2 to 4 hours; it is discontinued when the slow administration has produced
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an effective alpha blockade as shown by warm extremities and increased urine output. If the blood pressure changes this provides a reliable method of estimating the adequacy of previous intravascular volume replacement. If there is little or no change in blood pressure this has been adequate; if it falls below a mean blood pressure of 70 mmHg tissue perfusion is unlikely to be adequate and further colloid fluid is required quickly.
Calorie requirement Burn patients are undergoing hypercatabolism in which the Basal Metabolic Rate (BMR) is increased up to +loo% with calorie requirements 3000-6000 per day, gluconeogenesis is activated with high levels of free fatty acids; there is accelerated hepatic ureagenesis with negative introgen balance. To prevent this, extra calorie requirements can be provided by high calorie products for example Vivonex HC by slow nasogastric drip, Carnation Instant Breakfast by mouth, or less easily by various intravenous fat and amino acid preparations. Better utilisation of glucose can be achieved by adding extra insulin; the insulin resistance which develops in some major burns can lead to the development of the sick cell syndrome with failure of the sodium pump to maintain the potassium level in the cells and drive sodium out; there is consequently an increase in interstitial and urine potassium. It has been advocated that 50 ml of a 50% glucose solution with added potassium chloride (40 mEq litre) and insulin 120 units/litre should be given hourly as a bolus; if a clinitest demonstrates 4% or more glucose in the urine further insulin should be given. By this method the peripheral utilisation of glucose is increased, potassium pours back into the cells and there is a diminution of protein catabolism with decreased urea formation. Environmental temperature is all important especially where extensive burns are exposed, in a warm (32"C), dry (relative humidity 30%) environment the negative nitrogen balance and BMR is reduced. Large areas of skin loss reduce the body's ability to retain heat.
Transfer to a specialist burn unit The decision on whether and when to transfer the patient to a specialist burns unit will depend on many factors. It should be remembered that few patients need the care of an intensive therapy unit more than major burn cases but, on the other hand, few patients are less welcome in a general ITU since for all practical purposes all major burns will be colonised with bacteria. Intensive levels of nursing care will not normally be available outside an ITU and the need for intensive nursing care will continue for weeks in some cases. In considering what a burns unit may achieve one should consider the expected mortality. A practical rule of thumb is to add the patient's age and area of full thickness skin loss. If the result exceeds 100, survival is unlikely in the extreme and patients should not usually be referred away to a burn unit but kept near to the support of the family. A burns unit may hope to minimize mortality to these figures and perhaps of greater importance expect to minimize morbidity by greater familiarity with the practical problems of closing large areas of skin loss and combating catabolism and infection.
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Burns of the eye and extensive deep loss of face and hands pose particular problems which will usually require treatment in an Eye Hospital or Burns Unit. Timing. If it is decided that a burn is too big a problem to retain in the District General Hospital during resuscitation the timing of transfer should be considered. The availability of staff is crucial to this decision. If the patient is to be safely transferred to a Burns Unit, staff from the original admitting hospital must be available and competent to ensure the patency of the patient’s airway and the adequacy of transfusion during the journey however prolonged it may be. Failure to maintain the airway or to continue transfusion may be fatal if the journey is protracted. On the other hand, if the patient is admitted to the original hospital medical and nursing staff must be available to deal with dangerous situations which may develop in the subsequent phase of hypovolaemic shock ; these may include such procedures as endotracheal intubation, and escharotomy in addition to the time-consuming commitment of resuscitation. Discussion of clinical details meticulously obtained with the Registrar or Consultant of the Regional Burns Unit may clarify the priorities. Estimated delay in provision of transport and travelling time should be obtained from senior personnel of the ambulance service and may be critical to the decision. Provided that adequate resuscitation continues, burned patients travel well in the shock phase and Burns Units will usually prefer to take patients immediately. In some cases it may be easier to provide intensive cover for a matter of hours of an ambulance journey rather than for the days during the shock phase.
Summary The assessment, first aid treatment and immediate care of severely burned patients in the Accident and Emergency Department have been reviewed and the factors which influence the decision to transfer a case to a specialist Burns Unit have been discussed.
References 1. SEVITT, S. (1974) Reactions to Injury in Burns. Heinemann, London. 2. MUIR,I.F.K. & BARCLAY, J.L. (1962) Burns and their Treatment. Lloyd-Luke, London.
