Acute Care of the Electrocuted Patient
Case
A 30-year-old male without significant past medical history presented as a code blue after high voltage electrocution. The patient was working as a technician servicing high tension wires when he had a witnessed electrocution. Bystander CPR was initiated immediately; EMS arrived shortly thereafter and found the patient pulseless and asystolic. ACLS was initiated and a laryngeal mask airway (LMA) was placed. On arrival in the emergency department, the patient was pulseless, asystolic, and without signs of significant blunt trauma on primary and secondary surveys. ACLS was continued, he was intubated, and after several rounds of compressions, in addition to epinephrine, calcium, and bicarbonate, he was noted to be in pulseless ventricular tachycardia. Defibrillation was performed, and return of spontaneous circulation (ROSC) was achieved, but his neurologic exam remained unchanged. The patient briefly required norepinephrine for hemodynamic support after ROSC, but quickly developed hypertension and increased airway pressure. A chest x-ray showed findings consistent with acute respiratory distress syndrome (ARDS), a bedside ultrasound (FAST) was negative for intra-abdominal free fluid, and a CT scan did not show acute findings. The patient was admitted to the intensive care unit for further management.
Discussion
Throwback to Physics Class
All of the physics you need to know about electricity is represented below by Ohm’s law. Before you have too many flashbacks to high school and college, bear with me.
I=V/R
Electricity is the flow of electrons from high to low concentration. The volume/number of electrons that flow between these two concentrations per second is the current (I), in amperes. The magnitude of potential difference between the high and low concentrations is the voltage (V). Finally, the hindrance of electron flow through material is the resistance (R).[1]
While each of these variables plays an important role in the clinical effects of electrocution, the current (I) is primarily what dictates the degree of injury.[2] However, in the real world, it is often very difficult to know what the exact current was in an electrocution, since resistance is variable depending on the situation. Instead, voltage is the controlled variable in most situations (e.g., US wall sockets are 120 V) and is directly proportional to current; therefore, it is often the surrogate used in electrocution. Hence, why we say “high-voltage electrocution” rather than “high-current electrocution.”
Most of the damage done to tissues by electrocution is the resultant heat generated as it passes through them. Although I promised earlier that I would only have you remember one equation, I will share Joule’s law below to illustrate an important concept:
Heat=I2 x R x t
As shown, the heat, and therefore clinical tissue damage, increases as current, tissue resistance, and amount of time (t) exposed. So, a brief high-voltage electrocution can do significant damage, but so can a relatively low-voltage electrocution if it goes on long enough. This brings the last piece of electrophysics into play; DC vs AC current.
In DC (Direct Current), all of the electrons flow in a one-way gradient from high to low voltage, like a one-way road. This is the type of electricity emitted from batteries, railway tracks, cars, and lightning. DC electrocution tends to induce a single forceful muscle contraction which can throw a victim with significant force. Imagine the scene from Jurassic Park where Tim is electrocuted and thrown off the fence. Consequently, victims of DC cardioversion are at higher risk of blunt trauma.
In AC (Alternating Current), the direction of flow of electrons alternates on a cyclical basis, like a metronome. This stimulates muscles in a rhythmic fashion, and can induce tetanus. Most AC electrocutions start at the hand, and can induce tetanus such that the victim becomes locked in position and has a prolonged electrocution. As mentioned earlier the longer the electrocution, the more heat generated, the more tissue damage.[3]
Types of Electrical Injuries
Electricity can cause injury in several ways:
True electrocution: Current passes through the body tissues, inducing direct tissue injury as detailed above. There may be entry/exit burns, but they do not reliably predict where current passed. The burns often grossly underestimate the amount of tissue that was burned.
Flash/arc burns: Current passes over the skin causing external burns, but no current passes through the tissues.
Flame burn: Current lights clothing on fire, and that fire burns the victim.
Lightning injury: Very brief (1/1000th of a second), incredibly high voltage (10 million volts). The voltage is so high that the air temperature around the lightning bolt briefly reaches 54,000°F. This extreme heat burst can cause a blast wind, inducing barotrauma and throwing a victim, similar to a bomb.[4]
Blunt trauma associated with falls/being thrown.
Fracture/dislocation caused by powerful muscle contraction induced by electrocution
Tissue Effects
Cardiac: Arrhythmia is a frequent cause of death in electrocution. While any type of electrocution can cause any type of arrhythmia, DC/lightning tends to induce asystole, while AC tends to cause ventricular fibrillation. Most malignant arrhythmias occur very shortly following the event. Other non-life threatening arrhythmias can occur within a few hours of the event, most of which self-resolve.
Pulmonary: Temporary respiratory paralysis can occur following electrocution, and should be evident on initial evaluation. In addition, pneumothorax due to associated blunt trauma or lightning blast wind may be noted.
Neurologic: Both central and peripheral damage is possible. Paralysis, anesthesia, dysautonomia, coma, fixed, dilated pupils and/or anisocoria are possible. These can be nebulous, but major points are that the scary findings above may make a patient appear dead, but in fact are the result of neurologic electrocution and may be temporary.
Renal: Rhabdomyolysis (from muscular electrocution), and hypovolemia (from third spacing).
Skin: All kinds of burns. Most importantly, external burns grossly underestimate the amount of internally burned tissue.
Musculoskeletal: Bone has very high resistance, so it tends to heat up significantly in electrocution, in effect “cooking” nearby tissue. This can lead to rhabdomyolysis and compartment syndrome. In addition, associated blunt trauma or muscle spasm can cause fractures/dislocations. Always assume C-spine injury in severely electrocuted patients.
Other: Visceral injury other than those described above is uncommon but has been reported.
Management
Mild electrocution (<1000V)
Examples include a brief electric shock, stun gun.
Workup: EKG often performed, other workup such as troponin/CK unnecessary unless there is a clinical concern.
Disposition
If the patient appears well and the physical exam is unrevealing, they are highly unlikely to experience any clinically significant effects and likely can be discharged.[5] Some suggest observation with telemetry, especially for those at higher risk of arrhythmia (cardiac disease or active sympathomimetic intoxication).
If there are mild symptoms/burns, but the patient appears well, monitor for 4-6 hours. If workup is reassuring and the patient remains stable, discharge.
Severe electrocution (>1000V)
Examples include high tension wire, industrial accidents.
If the patient is awake and talking, this is a very reassuring start, but careful evaluation is needed.
Strongly consider a broad workup and admission for observation.
Coding patient
Pursue in usual ACLS fashion.
Keep the possibility of trauma in mind (e.g., tension pneumothorax).
Immobilize C spine
Remember that a patient with fixed/dilated pupils, no respiratory effort, and no spontaneous movement in this scenario may only have temporary neurologic stunning. Terminating these resuscitations can be difficult and must be done using your clinical judgement.
Pursue resuscitation longer than usual, as these patients can have ROSC with good outcomes despite being initially asystolic.[6]
Take-Aways
Electrocuted patients are at risk of any combination of severe blunt trauma, burn, and cardiac, and neurologic injuries, so they should be treated simultaneously with ACLS and ATLS protocols, depending on the individual case.
Reverse field triage in disaster situations; if they’re alive and talking, they will likely remain so. Victims who are pulseless and apneic have a significant chance at survival with good neurologic status if early BLS/ACLS/ATLS is initiated.
Always assume C-spine injuries in electrocuted patients, even if no clear history of blunt trauma.
External findings often underestimate internal injuries in electrocuted patients
Major causes of acute cardiopulmonary arrest in electrocuted patients:
Cardiac (VT, VF, and asystole): Treat per ACLS, consider longer than “typical” resuscitation despite asystole, given the higher likelihood of recovery in these patients.
Pulmonary (diaphragmatic paralysis, PTX): Intubate and rule-out pneumothorax.
Hemorrhage (if associated blunt trauma): Treat as per ATLS.
Hyperkalemia (from rhabdomyolysis): Treat as per ACLS with Ca and bicarbonate.
Patients may appear clinically “dead” (e.g., fixed/dilated pupils, anisocoria, no respiratory effort, no movement), but do not halt resuscitation early on, as it can be the result of temporary nervous system injury!
References
Suckling, E. E., Kashy, E., McGrayne, S. B., & Robinson, F. N. H. (2020, February 3). Electricity. Retrieved from https://www.britannica.com/science/electricity
Dalziel, CF, The Threshold of Perception Currents,Trans Am Inst Electrical Engineering. 1954; 73:990.
Jain, S., & Bandi, V. (1999). ELECTRICAL AND LIGHTNING INJURIES. Critical Care Clinics, 15(2), 319–331. https://doi.org/10.1016/s0749-0704(05)70057-9
Jain, S., & Bandi, V. (1999). ELECTRICAL AND LIGHTNING INJURIES. Critical Care Clinics, 15(2), 319–331. https://doi.org/10.1016/s0749-0704(05)70057-9
Jain, S., & Bandi, V. (1999). ELECTRICAL AND LIGHTNING INJURIES. Critical Care Clinics, 15(2), 319–331. https://doi.org/10.1016/s0749-0704(05)70057-9
Spies, C., & Trohman, R. G. (2006). Narrative Review: Electrocution and Life-Threatening Electrical Injuries. Annals of Internal Medicine, 145(7), 531. https://doi.org/10.7326/0003-4819-145-7-200610030-00011