Electrocution

Electrocution - Watts Up?

Electric current passage. Ohm's Law: $V=IR$; Joule's Law: $Q=I^2Rt$.

• Severity Factors (📌 DR. VACT):
  • Duration (t), Resistance (R) (skin: dry/wet)
  • Voltage (V), Amperage (I)
  • Current type (AC/DC), Tissue path
• AC vs DC:
  • AC: More dangerous (3-5x), tetany ("can't let-go").
  • DC: Single convulsion, throws victim.
• Critical AC (50Hz) Levels:
  • Perception: ~1 mA
  • Let-go: ~10-25 mA
  • VF: ~50-100 mA
  • Asystole: >4 A

⭐ AC is more dangerous than DC, causing tetany and having a lower threshold for Ventricular Fibrillation (VF).

Electrocution - System Overload

• Cardiovascular System:
  • Arrhythmias: Ventricular Fibrillation (VF) with AC (50-100 mA), Asystole with DC.
  • Myocardial necrosis, coronary artery spasm, hypertension.
• Respiratory System:
  • Tetany of respiratory muscles (e.g., diaphragm).
  • Central respiratory arrest (medullary depression).
  • Pulmonary edema, ARDS.
• Nervous System:
  • Loss of consciousness, seizures, amnesia.
  • Peripheral neuropathy (motor/sensory deficits).
  • Spinal cord injuries (e.g., transverse myelitis).
• Musculoskeletal System:
  • Fractures/dislocations (violent muscle contractions, falls).
  • Rhabdomyolysis → myoglobinuria.
  • Compartment syndrome.
• Renal System:
  • Acute Kidney Injury (AKI) due to myoglobinuria, direct effects.
• Vascular System:
  • Endothelial damage, thrombosis, aneurysm formation, delayed hemorrhage.

⭐ AC current (50-100 mA for VF) is more dangerous than DC of equivalent voltage, readily inducing tetanic muscle contraction and increasing risk of the "lock-on" phenomenon.

Electrocution - Spark of Evidence

• Death from electric current. Severity factors: Current (Amps) - Ohm's Law $I = V/R$, while AC is generally more dangerous than DC due to sustained muscle contraction and ventricular fibrillation risk, the danger depends on voltage, amperage, frequency, duration, and body pathway.
• External Findings:
  • Joule Burn (Electric Mark): Entry/Exit. Dry, firm, depressed, central pallor, hyperemic rim. Often painless.
    • Spark burns: Arcing near entry.
    • Metallization: Conductor metal deposited.
  • Lichtenberg figures (ferning): Rare, transient electrical injury sign; not pathognomonic for electrocution.
• Internal Findings:
  • Often non-specific: Visceral congestion, petechiae.
  • HPE: Streaming of nuclei, endothelial pearls (non-specific findings).
• Cause of Death: Ventricular fibrillation (AC), respiratory arrest, medullary paralysis (DC).

⭐ The most critical factor determining electrocution severity is the current (amperage), not the voltage.

Electrocution - Bolt & Blame

• Severity Factors: Voltage, Current (Amperage), Resistance (Skin: Dry >40kΩ, Wet ~1kΩ), Type (AC/DC), Path, Duration. 📌 VCR-TPD.
• Amperage is the more critical factor in determining harm extent, including death risk. Higher amperage causes greater injury for same exposure duration.
• AC 3 to 5 times more dangerous than DC (causes tetany, "no-let-go" effect due to prolonged muscle contraction).
• Joule Burn (Electric Mark): Entry - dry, firm, depressed, pale centre, hyperemic border. Exit - often larger, everted.
• Common COD: Ventricular Fibrillation (VF), respiratory arrest.

Lightning vs. High Voltage (HV) Electrocution

Medico-Legal Investigation

High‑Yield Points - ⚡ Biggest Takeaways

• Joule burn (electric mark): Characteristic lesion when present; dry, firm, depressed, avascular - but absence doesn't rule out electrocution.
• AC more dangerous than DC: causes tetany, ↑ risk of Ventricular Fibrillation.
• Skin resistance is key; wet skin drastically ↓ resistance, ↑ current flow.
• Current pathway through heart/brain is critical for lethality.
• Primary COD: Ventricular Fibrillation; also respiratory paralysis.
• Amperage, not voltage, is the crucial factor for tissue damage.
• Internal autopsy findings often non-specific; comprehensive scene investigation and history vital per BNSS procedures.