Electrical Burns

Electrical Burns April 2012 Singh M www.setpras.org

Learning Objectives • Understand the classification of electrical injuries • Understand the pathophysiology of an electrical injury • Know how to initially assess and manage patients with electrical burns • Know how to manage wounds and complications that may result from an electrical injury

Introduction • Electrical burns have an incidence of around 3% of all burns1 • They can be classified into 3 groups: • 1) Low voltage • <1000V • Examples: Home electrical supply, car batteries, surgical diathermy2 • 2) High voltage • >1000V • Examples: Industrial supplies, power lines • 3) Lightning • High voltage and current, short duration

Pathophysiology • Joule’s First Law: • Q=I2RT • Q = heat produced, I = current, R = resistance, T = time • Therefore most heat generated when high current, high resistance and prolonged time • Different tissues have different resistances: • Blood<Muscle<Nerves<Skin<Bone • Lowest resistance to Highest • Therefore different patterns of injury between different body tissues

Low Voltage • Low Voltage Burns: • Causes local tissue necrosis • Mimic thermal burn injuries • No deep tissue injury • Household 50Hz AC supply can cause muscle spasm/tetany • This is sometimes why patients cannot release their grasp of an electrical source • May cause cardiac arrest

High Voltage • High Voltage Burns: • Causes both local tissue and deep tissue injury • Generally has an entrance and exit point (must be looked for on patients). These and other contact areas are likely to be full thickness defects • Deep muscle injury may be severe with little overlying skin injury • This can lead to excessive muscle necrosis, rhabdomyolysis and compartment syndrome, secondary to muscle swelling • Must be observant for signs of this as patients may need urgent fasciotomies • May also suffer bowel perforation or spinal cord transection3

Lightning • Lightning Burns: • Can cause injury by: • Direct strike • Ground splash • Side splash • Typically, current flows superficially, causing partial thickness burns2 • May have exit wounds on feet • Cardiorespiratory arrest is common. Usually reversible, therefore prolonged resuscitation worthwhile • Lichtenberg flowers are pathognomonic • May cause cardiac dysrhythmias, tympanic membrane perforations and corneal damage

Management • Initial management must be: ABCDE approach • Include protection of C-spine, many patient have suffered concurrent trauma • Full primary and secondary survey with resuscitation • Catheterise – to monitor for urine discolouration (haemochromogenuria) and urine output • Aim for urine output in an adult of 50-75ml/hr, if pigments in urine, increase to 75-100ml/hr

Management • May require aggressive fluid resuscitation due to underlying muscle injury • Mannitol may be used where difficulty maintaining urine output • ECG monitoring for cardiac damage/dysrhythmias • Must assess limbs for signs of compartment syndrome or vascular compromise – May need fasciotomy • Cutaneous injuries should be managed as for thermal burns

Conclusions • 3 types of electrical injuries • Electrical burns may produce cutaneous wounds similar to thermal burns or deep compartment damage, that may be difficult to detect • Patients should be assessed and managed as for trauma • Cardiac and urine output monitoring are both useful adjuncts • Mortality ranges from 8-14%1

References • 1. Giele H, Cassell O. Oxford Handbook of Plastic and Reconstructive Surgery. Oxford: Oxford University Press; 2008 • 2. Emergency Management of Severe Burns Course Manual. Australia and New Zealand Burn Asociation;2006 • 3. Stone, C. Plastic Surgery Facts. New York: Cambridge University Press; 2006

Electrical Burns