Certified Respiratory Therapist Practice Exam

If a 12-lead ECG shows a noisy signal, what action can help improve the signal quality?

1. Reducing paper speed

2. Calibrating the machine

3. Turning off filtering of extraneous electrical activity

4. Applying more gel on electrodes

The correct answer is: Turning off filtering of extraneous electrical activity

Improving the signal quality of a noisy 12-lead ECG can often be achieved by addressing the presence of extraneous electrical activity that interferes with the clear representation of the heart's electrical signals. By turning off filtering of this noise, the machine allows for a more accurate depiction of the underlying cardiac signals, as the filter typically serves to eliminate high-frequency noise but can also inadvertently filter out relevant information in certain cases. In situations where noise is excessive, adjustments such as applying more gel on electrodes or calibrating the machine may not yield the desired clarity, as they address different aspects of signal transmission. For instance, more gel might enhance contact, but if a significant amount of electrical noise persists, the chief concern remains unaddressed. Similarly, reducing paper speed may alter the time representation of the graph but wouldn't remedy the signal quality affected by noise. Thus, adjusting the filtering settings allows for a more direct and effective resolution of the issue at hand.