Electrical Burns April 2012 Singh M

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 burns 1 They can be classified into 3 groups: –1) Low voltage <1000V Examples: Home electrical supply, car batteries, surgical diathermy 2 –2) High voltage >1000V Examples: Industrial supplies, power lines –3) Lightning High voltage and current, short duration

Pathophysiology Joule’s First Law: –Q=I 2 RT 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 transection 3

Lightning Lightning Burns: –Can cause injury by: Direct strike Ground splash Side splash –Typically, current flows superficially, causing partial thickness burns 2 –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 ml/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; Emergency Management of Severe Burns Course Manual. Australia and New Zealand Burn Asociation; Stone, C. Plastic Surgery Facts. New York: Cambridge University Press; 2006