Which statement accurately describes electrical injuries from alternating current (AC) and direct current (DC)?

Which statement accurately describes electrical injuries from alternating current (AC) and direct current (DC)?

• A. AC causes tetany and fibrillation; DC causes instant muscle contraction and asystole
• B. DC causes tetany and fibrillation; AC causes instant muscle contraction and asystole
• C. AC and DC have identical effects
• D. Only DC causes fibrillation

Answer: (A)

Electrical injuries from different waveforms affect nerves and the heart in distinct ways. Alternating current, especially at household frequencies, repeatedly depolarizes nerves and cardiac tissue with every cycle. That rapid, ongoing stimulation produces sustained muscle contractions (tetany) and is highly likely to disrupt the heart’s rhythm into ventricular fibrillation, a chaotic and life-threatening rhythm. Direct current delivers one strong impulse, causing an immediate, powerful muscle contraction at the moment of contact. This can fling a person away from the source and break contact, but if the current passes through the chest, it can briefly arrest the heart’s activity, leading to asystole rather than a fibrillating rhythm. In short, AC tends to cause tetany and fibrillation, while DC tends to cause an instantaneous strong contraction with potential brief cardiac arrest. The exact outcome also depends on voltage, duration, pathway through the body, and skin/ tissue impedance.

Electrical injuries from different waveforms affect nerves and the heart in distinct ways. Alternating current, especially at household frequencies, repeatedly depolarizes nerves and cardiac tissue with every cycle. That rapid, ongoing stimulation produces sustained muscle contractions (tetany) and is highly likely to disrupt the heart’s rhythm into ventricular fibrillation, a chaotic and life-threatening rhythm.

Direct current delivers one strong impulse, causing an immediate, powerful muscle contraction at the moment of contact. This can fling a person away from the source and break contact, but if the current passes through the chest, it can briefly arrest the heart’s activity, leading to asystole rather than a fibrillating rhythm.

In short, AC tends to cause tetany and fibrillation, while DC tends to cause an instantaneous strong contraction with potential brief cardiac arrest. The exact outcome also depends on voltage, duration, pathway through the body, and skin/ tissue impedance.