While the initial assessment is being made, what key information should be sought?

Describe the important points of your initial assessment and calculate his initial intravenous fluid requirements.

The patient was intubated and ventilated and a urinary catheter inserted in preparation for transport. His blood pressure was 125/80 mmHg with a pulse rate of 130/min. His clothes were removed to allow an accurate assessment to be made of the extent and severity of his injuries. The photographs show the burned areas of his buttocks, left knee and right foot (Figures 10.1–10.3). There was a 6 cm burn on the scalp with a similar appearance to those on his buttocks. His back had four similar burns. The changes to the left foot resembled those seen on the right foot. Five similar-sized burns were present on the upper limbs. Blood samples were collected for haemoglobin estimation, cross-matching, serum electrolytes and creatinine kinase.

Figure 10.1

Figure 10.2

Figure 10.3

Describe his burns.

What emergency surgical interventions are required here? Describe the difference between escharotomy and fasciotomy.

Comment on the appearance of the urine, the likely cause, and state what measures need to be taken.

What is meant by ‘fourth degree’ burns?

What is meant by a ‘free flap’?

What are the important early complications that must be considered in the management of this patient?

A.1 Since the patient arrived intubated and ventilated, no direct history is available. In any trauma case it is important to interview witnesses, ambulance officers, members of the retrieval team, etc. to obtain as much information as possible about the incident leading up to the injury and what has happened in the time between the injury and arrival at the hospital. The following information is important:

Some information may have to wait until family arrive, or may necessitate a phone call to the patient’s family doctor, such as:

A.2 The initial assessment (primary survey) must assess:

A secondary survey can now be performed looking for joint disruptions or dislocations, bony fractures and to fully assess the burn size, burn sites and burn depth. The standard techniques for assessing burn size (Wallace rule of nines, Lund and Brouder charts, etc.), while good at assessing cutaneous injuries, tend to underestimate fluid requirements since electrical conduction causes deep tissue injury which cannot be measured with any accuracy. However, skin injury calculation can at least provide a ‘starting’ volume for fluid resuscitation using an approved formula. The modified Parkland formula suggests that the fluid volume (in Hartmann’s solution) needed in the first 24 hours can be calculated by multiplying the patient’s weight in kilograms by the percentage of the total body surface area which has been burnt by 3 or 4 mL. In this case it would be prudent to err on the 4 mL factor, to account in part for the underestimation mentioned above. Thus, with the 25% TBSA cutaneous burn in this 80 kg patient, the fluid requirement in the first 24 hours is 4 × 25 × 80 = 8000 mL, half (4000 mL) to be given in the first 8 hours after injury and the second half over the next 16 hours. All formulae are merely guidelines to be increased or decreased according to the patient’s physical response picked up by monitoring (particularly urine output).

A.3 The burns occupy around 25% of the patient’s total body surface area and are, as usual, heterogenous in depth. The estimation is not easy from the photographs because the burns on the trunk, head and upper limbs were caused by arcing at multiple sites separated by uninjured skin. The burns to the skin of the toes of both feet are ‘fourth degree’ (involving non-skin deep tissue such as vessels, tendons, bones, ligaments and joints). The burn over the lateral left knee is similarly fourth degree since deep tissue disruption to the knee joint capsule is evident). These injuries are devastating and are the commonest reason for amputation in burns practice. More proximally on the feet, the burns are white and dry – these are full thickness (although venous thrombosis is visible below the burn). The burns over the shins and anterior ankles are deep dermal. The only superficial/mid-dermal burns (which could be treated conservatively) are over the anterior thighs. The left buttock, hip, flank and scapular burns are deep full thickness (involving subcutaneous fat), as are the scalp burns.

A.4 Escharotomy is division or ‘opening’ of circumferential full-thickness burns of the limbs or trunk. An escharotomy does not extend through the subcutaneous fat. An escharotomy is performed through incisions running down the midaxial lines but avoiding important superficial structures (ulnar nerve at elbow, common peroneal nerve as it winds around the neck of the fibula, etc.). Fasciotomy is division of the muscular fascia of all affected compartments in a limb injured by severe crush or, in this case, electrical conduction. Skin incisions are designed to afford best exposure of the muscular fascia. The clinical findings mandate fasciotomy release of the left calf muscular compartments and those of the left forearm. Radical debridement of severely disrupted and non-viable tissue of both feet was also performed early (within a few hours). Close and frequent operative review of tissues obviously having conducted large current is necessary. The electrical injury has damaged the left foot to such an extent that the patient is likely to require a left below-knee amputation.

A.5 The urine has a maroon colour which is almost certainly due to the presence of haemochromogens – most likely to be myoglobin, although haemoglobin usually accompanies it. These large proteins are released by damaged muscle and vessels and can result in sluggish blood flow (especially where hypovolaemia is allowed to co-exist). The main problem is the challenge they pose to the kidneys leading to acute renal failure. Intravenous fluid administration should be increased to raise the urine output up to 2 mL/kg/hour rather than the 1 mL/kg/hour normally optimal in adult burn patients during resuscitation; 25 g of mannitol (an osmotic diuretic) can be administered immediately intravenously followed by the addition of 12.5 g to each litre of administered fluid. Finally, intravenous administration of bicarbonate (2 vials stat) alkalinizes the urine, making the pigments more water-soluble and facilitating their excretion. With these manoeuvres, the urine colour lightens from black/dark purple through purple, plum, maroon, dark red/brown, rose, pink, orange and dark yellow on its way to a normal straw colour.

A.6 ‘Fourth degree’ burns involve tissues deep to the subcutaneous fat such as deep vessels (including large arteries), tendons, bones, ligaments and joints. They are devastating and the commonest cause of amputation in burns practice.

A.7 A ‘free flap’ is a composite piece of tissue, which can be made up of skin, fat, fascia, tendon/muscle and bone (in any combination depending on the origin and the defect to be repaired), which is raised with the arterial inflow and venous drainage intact. The vascular pedicle is then divided (usually as far from the flap as possible, giving the greatest pedicle length possible), separating the tissue from its donor site. The artery and vein(s) within the vascular pedicle are then anastomosed to vessels at the recipient site (the defect to be repaired) and the flap inset to fill the defect. The tissue is thus technically a flap because it has an immediate blood supply but a ‘free’ flap because the blood supply has to be established by surgical anastomosis. In this case a composite piece of tissue was raised from tissue planned to be discarded as part of the right below-knee amputation, its blood supply was the peroneal artery which was anastomosed into the vastus medialis artery so the flap could repair the left knee defect.

A.8 The immediate complications of an electrical injury include cardiac arrhythmias (which can cause instant death), skin burns and compression fractures. Important early complications include hypovolaemia secondary to inaccurate assessment of burn size (failing to account for the hidden internal injury), vascular compromise, nerve destruction (muscular paralysis/loss of sensation), muscle breakdown and myoglobinuria leading to acute renal failure, other injuries (including compression fractures of the vertebrae), compartment syndrome and sepsis secondary to inadequate debridement of necrotic tissue.