FREE RST Artifact Recognition and Troubleshooting Questions and Answers

Question 1

During a polysomnogram on a patient with a history of obstructive sleep apnea, the technologist notes very low-amplitude, slow, undulating waves across multiple EEG and EOG channels. The patient appears to be perspiring heavily. What is the most likely artifact, and what is the best initial troubleshooting step?

Accepted Answer

Sweat artifact; decrease the room temperature and use a fan if possible.

Answer

Heavy perspiration can cause slow, rolling artifacts on the recording due to changes in skin conductivity. The primary intervention is to cool the patient and the room to reduce sweating, which addresses the root cause of the artifact.

Question 2

A technologist observes a thick, uniform, fast frequency line in all AC-coupled channels (EEG, EOG, EMG). Which of the following is the most probable cause and first corrective action?

Accepted Answer

60 Hz interference; check the integrity and placement of the common ground electrode.

Answer

A thick, consistent, high-frequency line across all or most AC channels is the classic presentation of 60 Hz electrical interference. When this artifact is generalized across many channels, the issue often lies with the common ground or reference electrodes, or a nearby piece of electrical equipment. The first step is to check the ground electrode connection.

Question 3

While monitoring a study, the signal from the nasal pressure transducer becomes flat, while the oronasal thermistor and respiratory effort belts continue to show clear respiratory cycles. What is the most appropriate immediate action for the technologist to take?

Accepted Answer

Check the cannula for displacement or blockages and re-seat it if necessary.

Answer

When a single respiratory sensor fails but others show continued breathing, the issue is almost always localized to that specific sensor or its interface. A flat line on the nasal pressure channel, while other respiratory signals are normal, strongly suggests the cannula is either dislodged from the patient's nares or the tubing is kinked or blocked. The technologist should physically check and correct this first.

Question 4

A patient is observed bruxing (teeth grinding) during sleep. Which of the following artifacts would be most prominent in the polysomnogram during this activity?

Accepted Answer

High-amplitude, high-frequency activity in the chin EMG and temporal EEG channels.

Answer

Bruxism involves the contraction of the masseter and temporalis muscles. This generates significant electromyographic (EMG) artifact, which appears as high-frequency, high-amplitude signals. This artifact is most prominent in the chin EMG channels but also frequently contaminates nearby EEG electrodes, particularly those in the temporal regions (T3/T4).

Question 5

During a recording, a single, sharp, high-voltage vertical deflection appears in C3-M2 and F3-M2, but not in any other channels. This is most likely an example of:

Accepted Answer

An electrode pop artifact.

Answer

An 'electrode pop' is a sharp, spike-like deflection that is typically isolated to a single electrode due to a sudden change in impedance, often from a loose connection. Because it appears in channels that share a common electrode (in this case, likely M2 if C3 and F3 are referenced to it, or if the pop is from a common reference), but not in channels without that electrode, it points to a technical, non-physiological artifact related to that specific electrode.

RST - Registered Sleep Technologist Practice Test

RST - Registered Sleep Technologist Practice Test

FREE RST Artifact Recognition and Troubleshooting Questions and Answers