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ukmla 2026

Electrocution

Injury from passage of electrical current through the body — severity depends on voltage, current type (AC vs DC), pathway, duration, and tissue resistance. Cardiac arrhythmias are the primary cause of immediate death

Review date
reviewed 2026-04-05
Reading time
4 min read
Author
Dr Kola Tytler MBBS CertHE MBA MSt MRCGP
Emergency Medicinerareacute
On this page
Condition details
Emergency Medicine
rare
4 min read
reviewed 2026-04-05
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About This Page

This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.

Key points

  • Low voltage (<1000 V — domestic): cardiac arrhythmias (VF) are the main immediate risk. AC more dangerous than DC
  • High voltage (≥1000 V — industrial/power lines): extensive deep tissue injury, burns, blast injury, compartment syndrome, rhabdomyolysis
  • Cardiac monitoring: all patients with LOC, ECG abnormalities, or high-voltage injury need ≥24 h cardiac monitoring
  • Entry and exit wounds may appear small but mask extensive deep tissue damage (current follows path of least resistance — nerves, blood vessels)
  • Check CK: rhabdomyolysis common → aggressive IV fluid hydration to prevent myoglobinuric AKI
  • Lightning strike: current flows over body surface (flashover) — cardiac arrest (asystole) is common but often reversible with immediate CPR

Overview

Electrical injuries result from the passage of electric current through the body, causing thermal injury, electroporation of cell membranes, and direct tissue damage. The severity depends on voltage, current type (AC is more dangerous than DC due to tetanic muscle contraction preventing release), current pathway through the body (transthoracic = highest cardiac risk), duration of contact, and tissue resistance (dry skin has high resistance; wet skin dramatically reduces it). Low-voltage (<1000 V) injuries from domestic mains (230 V AC in UK) primarily cause cardiac arrhythmias. High-voltage (≥1000 V) injuries cause deep tissue destruction along current pathways, with entry and exit wound burns that underestimate the extent of internal damage. Lightning strikes cause a brief, massive DC current — cardiac arrest from asystole is the primary cause of death but is often reversible if CPR is initiated immediately.

Epidemiology

Electrical injuries account for approximately 1,000 ED attendances per year in the UK. Approximately 30 deaths per year from electrocution (excluding lightning). Most domestic injuries occur in children (putting objects in sockets, biting cables). Occupational injuries predominate in adults (electricians, construction workers). Lightning strikes kill approximately 1–3 people per year in the UK. The case fatality rate for high-voltage injury is approximately 3–15%, and for lightning strike approximately 10–30%.

Clinical Features

Symptoms
History of electrical contact or lightning strike
Tetanic muscle contraction (unable to release grip — AC current)
Loss of consciousness, cardiac arrest
Burns at entry and exit points
Muscle pain (rhabdomyolysis), dark urine (myoglobinuria)
Numbness, weakness, paraesthesiae (nerve injury)
Signs
Entry wound: charred, depressed, painless. Exit wound: may be larger, "blown out" appearance
Cardiac arrhythmias: VF (AC), asystole (DC/lightning), AF, ST changes
Compartment syndrome (deep tissue swelling)
Flash burns (arcing), flame burns (clothing ignition), contact burns
Lichtenberg figures (fern-like skin pattern) — pathognomonic for lightning strike
Tympanic membrane rupture (blast effect from lightning)
Falls and secondary trauma (thrown by the current or falling from height)

Investigations

First-line
ECGArrhythmia assessment: VF, VT, AF, ST changes, QT prolongation. All patients with LOC, abnormal ECG, or high-voltage need cardiac monitoring
Bloods: CK, U&Es, FBCCK markedly elevated in rhabdomyolysis (often >10,000). Monitor renal function — myoglobinuric AKI
TroponinIf chest pain, ECG changes, or high-voltage — assess for myocardial injury
Urine myoglobinDark/cola-coloured urine — positive dipstick for blood but no RBCs on microscopy = myoglobinuria
Second-line
Cardiac monitoring (continuous)≥24 h if: LOC, ECG abnormality, high-voltage injury, transthoracic current pathway
CT/imagingAs indicated for secondary trauma (falls from height, blast injuries), C-spine if lightning
Specialist
Compartment pressure measurementIf concern for compartment syndrome — high-voltage injury causes deep tissue oedema
Ophthalmology reviewCataracts can develop acutely or months after electrical injury

Management

Resuscitation Council UK 2025 — Special Circumstances; NICE CKS
1
Scene safety and immediate management
  • SCENE SAFETY FIRST: disconnect power source before approaching. Do NOT touch patient if still in contact with live current. Use non-conducting material if needed
  • High-voltage (power lines): stay ≥18 m away until power company confirms isolation
  • If cardiac arrest: standard ALS algorithm. Lightning-strike arrest (asystole) may respond well to prolonged CPR
  • In multiple lightning casualties: triage "reversed" — prioritise apparently dead patients (cardiac arrest may be reversible) over those showing signs of life
2
Hospital management
  • ABCDE approach. Treat associated trauma (falls, blast injury)
  • Continuous cardiac monitoring ≥24 h if: LOC, ECG abnormality, high-voltage, transthoracic pathway
  • IV fluid resuscitation: target urine output >1 mL/kg/h if rhabdomyolysis (protect kidneys from myoglobin)
  • Burns management: entry/exit wound care. May need escharotomy/fasciotomy
  • Monitor CK and renal function serially — rhabdomyolysis may worsen over 48–72 h
  • Tetanus prophylaxis
  • ECG normal + low-voltage + no LOC + no symptoms → safe for discharge after ED assessment and observation

Complications

  • Cardiac arrest: VF (AC current) or asystole (DC/lightning). Primary cause of immediate death
  • Rhabdomyolysis and AKI: Deep muscle necrosis → myoglobin release → renal tubular injury
  • Compartment syndrome: Deep tissue oedema from current damage — fasciotomy may be needed
  • Cataracts: Can develop acutely or months later — ophthalmology follow-up
  • Delayed arrhythmias: Can occur up to 24 h — hence cardiac monitoring period
  • Neurological: Peripheral neuropathy, spinal cord injury, chronic pain syndromes
UKMLA Exam Tips
  • 1AC is more dangerous than DC — causes tetanic contraction preventing release from source, and VF
  • 2Entry/exit wound burns: small externally but extensive internal damage. "Iceberg" of injury
  • 3Lightning strike: Lichtenberg figures (fern-like pattern) = pathognomonic. Reverse triage: prioritise "dead" victims (arrest may be reversible)
  • 4Cardiac monitoring ≥24 h if: LOC, ECG changes, high voltage. Low-voltage + normal ECG + no LOC = can discharge
  • 5CK for rhabdomyolysis. Aggressive fluids (target UO >1 mL/kg/h) to prevent myoglobinuric AKI
  • 6Scene safety: do NOT touch patient still in contact with electricity. Disconnect power first

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Verified Sources & References

Resuscitation Council UK 2025 — Special Circumstances
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