TOPIC 18. ELECTRICAL INJURY AND CHEMICAL INJURY
A. Electrical injury
1. Mechanism and determinants of severity
Electrical injury occurs when current passes through the body or when an electrical arc/flash causes burns. Injury severity depends on voltage, current type (AC/DC), current pathway, duration of contact, tissue resistance and environmental conditions. Wet skin lowers resistance and increases current flow.
- Current may cause thermal injury, direct cellular/electroporation effects, muscle tetany and cardiac or respiratory disturbance.
- Alternating current can cause sustained muscle contraction (tetany), prolonging contact; direct current may cause a single intense contraction and throw the victim.
- Deep tissues, vessels, nerves and muscle may be severely injured despite limited skin burns.
- Current passing through the chest may trigger arrhythmia; passage through the head may cause neurological injury.
2. Clinical manifestations
Local: entry and exit burns, deep muscle necrosis, pain, swelling, fractures or dislocations from tetany/falls.
Cardiovascular: ventricular fibrillation, asystole, other arrhythmias, myocardial injury and cardiac arrest.
Respiratory: respiratory arrest due to respiratory muscle tetany or central nervous system injury.
Neurological: loss of consciousness, seizures, confusion, peripheral nerve injury and delayed neurological symptoms.
Renal/systemic: rhabdomyolysis, myoglobinuria, hyperkalaemia, metabolic acidosis and acute kidney injury.
Associated trauma: falls, blast effects, fractures and spinal injury.
3. Management
Scene safety: do not touch the victim until the electrical source is isolated. Call emergency services and use trained rescue procedures.
Primary survey: assess responsiveness, airway, breathing and circulation; begin CPR/AED if indicated once safe.
Cardiac assessment: obtain ECG and monitor according to voltage, symptoms, loss of consciousness, chest pathway, abnormal ECG and local protocol.
Burn/trauma assessment: examine entry/exit sites, assess limb perfusion and neurological function, and evaluate for fractures or compartment syndrome.
Investigations: electrolytes, renal function, CK, urinalysis for myoglobin and other tests based on severity.
Fluid therapy: treat shock and rhabdomyolysis with appropriate IV fluids and urine-output monitoring; manage hyperkalaemia and other metabolic complications.
Wound care: burn management, analgesia, tetanus prophylaxis and surgical debridement when required. Consider specialist burn/trauma referral.
4. Complications
- Immediate cardiac arrest or dysrhythmia, respiratory arrest and deep burns.
- Compartment syndrome, rhabdomyolysis and acute kidney injury.
- Neurological sequelae, cataracts after some high-voltage exposures, chronic pain and psychological effects.
B. Chemical injury
1. Mechanism
Chemical injury occurs when a corrosive or toxic substance contacts skin, eyes, mucosa or is inhaled/ingested. Acids typically cause coagulative necrosis, while alkalis cause liquefactive necrosis and may penetrate deeply. Actual tissue damage depends on concentration, amount, duration, temperature and site.