Electrical Injury

Shocked
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Diagnosis and reasoning

This patient has experienced both electrical as well as physical trauma following a fall. Nonetheless, his initial evaluation should follow advanced trauma life support (ATLS) guidelines. The ABCDEs of the primary survey reveal an already protected airway; mild tachycardia; severe obtundation; and sluggish but reactive pupils. The secondary survey shows a burn over the sternum, as well as two burns over the bilateral medial malleoli. Given the mechanism of injury, the former most likely corresponds to the electrical entry point, and the latter to the exit points. An abrasion of the occipital scalp is also apparent, suggesting that he fell backward off the ladder. Given the earlier episode of ventricular fibrillation, a full 12-lead ECG should be obtained. This reveals ST-segment elevations in the leads V5-V6. Follow up bedside imaging shows apical hypokinesia, suggesting at ischemia of that region. Note that this is close to the entry point of the current. Soft tissue injury leading to rhabdomyolysis is another important complication of electrical injury and can occur even when the external skin injuries are seemingly innocuous. Here, this is suggested by the urinalysis that is dipstick positive for blood, but without red cells on microscopy - and confirmed by the markedly elevated creatine phosphokinase (CPK) levels. Computed tomography (CT) imaging of the brain is also essential, given the neurological impairment and evidence of direct trauma to the head. However, this shows no abnormalities. He needs management in an intensive care (ICU) setting. Intravenous (IV) fluid therapy is an important element of his treatment and should be geared at maintaining a urine output of at least 0.5 to 1 cc/kg. This will help prevent acute kidney injury (AKI). Note that the cardiac ischemia is most likely due to either direct electrical injury and/or hypotension during the episode of ventricular fibrillation. Thrombolytics are unlikely to be helpful, and in fact, may potentially cause harm. While his wounds require proper debridement and antiseptic dressings, there is no justification for IV antibiotic therapy currently.


Discussion

Electrical injury occurs when the body comes into contact with a source of significant electricity, whether man-made or natural (e.g. lightning). In the United States, this accounts for over 5,000 emergency admissions and 1,000 deaths per year. The majority of adult victims are male, with most exposures occurring at the workplace. In the case of children, most electrical injuries occur at home. It is important to appreciate that electrical injury can be caused by both alternating current (AC) and direct current (DC). Among other differences, AC often causes tetanic contractions, potentially increasing the duration of exposure. DC tends to push the victim away from the source. Electricity can cause injury via several different mechanisms. These direct effects while passing through the body; burns due to the conversion of electrical to thermal energy; and mechanical trauma following tetany and falls. Skin burns are often the most obvious injury. Low-voltage exposure causes small, well-defined burns at the points of entry and exit. Higher voltages cause severe burns that appear depressed, yellow, and charred, with necrosis. Bone, tendons, and fat provide the highest resistance to electrical current and bear the brunt of thermal injury. It is quite possible for these tissues to be severely damaged in patients whose skin appears relatively unharmed. Cardiac injury may occur due to direct effects of the current; ischemia following hypotension caused by arrhythmias or coronary artery spasm; and, autonomic dysfunction following catecholamine release. Arrhythmias are also common and may terminate in asystole and cardiac arrest. There is evidence that AC injuries are more often associated with ventricular fibrillation, while DC injuries are more likely to cause asystole. Tetanic contraction of the thoracic and diaphragmatic musculature can culminate in respiratory failure. Injury to the musculoskeletal tissue may give rise to rhabdomyolysis and compartment syndrome. Acute kidney injury (AKI) may occur secondary to rhabdomyolysis or as a consequence of ischemia. Hearing loss may result from rupture of the tympanic membrane, effects of the current on the cochlea, or hemorrhage. Nervous system involvement is usually transient, but delayed neuropathy may occur. Spinal cord injury can result in quadriplegia or paraplegia. Key investigations include ECGs to detect arrhythmias and cardiac ischemia; baseline renal function assessment; and, serum myoglobin levels. In persons with high voltage injuries, serial creatine kinase assays are of use to evaluate muscle injury and recovery. Magnetic resonance imaging (MRI) with gadolinium and technetium-99 pyrophosphate scintigraphy can be used to localize areas of muscle necrosis, especially if surgical exploration is being considered. Cutaneous burns should treated similar to burns due to other etiologies. Admission to a burns center should be considered if the patient has suffered a high voltage injury. Neurovascular function should be evaluated sequentially as the onset of compartment syndrome may be delayed. Surgical exploration may be indicated to confirm or exclude myonecrosis. Escharotomy, fasciotomy, or amputation may eventually be required. Affected limbs should be elevated and positioned to minimize the risk of developing edema and compartment syndrome. Visceral injury is a rare complication, but where suspected may necessitate laparotomy or laparoscopy for diagnosis and treatment. Pancreatectomy, splenectomy, and partial or total colectomies may be indicated. Note also that these patients often present with additional traumatic injuries resulting from falls and tetany. These should be evaluated and treated as necessary.


Take home messages

  1. Burns are the most prominent feature of electrical injury. However, severe internal soft tissue injury may occur even where the skin is mostly untouched.
  2. Cardiac injury, arrhythmias, and acute kidney injury due to rhabdomyolysis are less obvious but even more lethal complications.
  3. These patients often also have non-electrical injuries secondary to trauma from falls and tetany.
  4. The basic management should follow standard ATLS guidelines, followed by specific workup and treatment for the common complications.

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  1. GHAVAMI YASER, MOBAYEN MOHAMMAD REZA, VAGHARDOOST REZA. Electrical Burn Injury: A Five-Year Survey of 682 Patients. Trauma Mon [online] 2014 November [viewed 10 September 2017] Available from: doi:10.5812/traumamon.18748
  2. MARQUES EG, JúNIOR GA, NETO BF, FREITAS RA, YAEGASHI LB, ALMEIDA CE, JúNIOR JA. Visceral injury in electrical shock trauma: proposed guideline for the management of abdominal electrocution and literature review Int J Burns Trauma [online] 2014 Feb 22, 4(1):1-6 [viewed 10 September 2017] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3945822