What signs indicate high impedance during electrotherapy?

• A. Consistent current and no symptoms
• B. Device buzzing but no impedance alert
• C. Flickering or unstable current, sudden loss of sensation or performance, patient reports unusual warmth or burning, device displays impedance alert
• D. Uniform heating with no fluctuation

Answer: (C)

High impedance means the path from the device to the patient is resisting current flow, so the equipment struggles to deliver the set parameters. When impedance is high, you’ll often see the output flicker or become unstable as the device tries to maintain current. The patient may report a sudden change in sensation or a drop in effective stimulation, indicating the current isn’t consistently reaching the target tissues. Unusual warmth or a burning sensation at the electrode site can also occur due to uneven or intermittent current flow, a symptom the device may flag with an impedance alert. This combination of unstable output, altered sensation, patient warmth or burning, and a visible impedance alert is characteristic of high impedance. By contrast, a consistent current with no symptoms suggests good contact and normal impedance; a buzzing device without an impedance alert points to another issue rather than high impedance; and uniform heating with no fluctuation implies stable, adequate contact.