Why is verifying impedance within an acceptable range important before stimulation?

• A. It helps ensure safe and effective current delivery.
• B. It has no impact on safety.
• C. It only affects battery life.
• D. It changes electrode color.

Answer: (A)

Impedance at the electrode-skin interface determines how much current actually reaches the tissue, so checking it before stimulation ensures the device delivers what is intended in a safe way. If impedance is too high, the target current may not be achieved, meaning the treatment could be ineffective and the device may have to run longer or fail to reach therapeutic levels, sometimes causing uneven stimulation or increased discomfort as the system tries to compensate. If impedance is too low, the current could exceed safe levels for the skin, raising the risk of burns or irritation, and the device’s safety protections may trigger or behave unpredictably. Verifying impedance also helps confirm good electrode contact—issues like dry skin, insufficient gel, air gaps, or misplacement are identified and corrected before stimulation begins. In short, knowing the impedance range guarantees that current delivery is both safe for the patient and effective for the intended therapy.