RPSGT Technology & Tools 5 — Questions and Answers
Question 1: Which artifact is characterized by a 60 Hz sinusoidal pattern superimposed on PSG channels and is MOST commonly caused by:
- Patient movement near recording equipment
- Alternating current (AC) electrical interference from nearby devices (Correct answer)
- Cardiac electrical artifact contaminating EEG
- High electrode impedance at the mastoid reference
Correct answer: Alternating current (AC) electrical interference from nearby devices
60 Hz artifact (50 Hz outside North America) is caused by AC electrical interference from power lines, fluorescent lights, or nearby electrical devices.
Question 2: During PSG, a technologist observes rhythmic, saw-tooth appearing artifact in the ECG channel that correlates with the patient's respiratory rate. This is MOST likely:
- Atrial flutter with a 2:1 block
- Respiratory baseline wander from electrode movement (Correct answer)
- Sinus arrhythmia causing rate variation
- Premature ventricular contractions during apneas
Correct answer: Respiratory baseline wander from electrode movement
Respiratory baseline wander in the ECG channel is caused by chest movement altering electrode-skin impedance rhythmically at the breathing rate.
Question 3: CPAP heated humidification is used primarily to:
- Reduce the pressure required to eliminate apneas
- Prevent nasal dryness and improve CPAP adherence (Correct answer)
- Improve the accuracy of leak detection algorithms
- Reduce condensation in the CPAP circuit
Correct answer: Prevent nasal dryness and improve CPAP adherence
Heated humidification adds warmth and moisture to the delivered air, reducing mucosal drying and irritation which are major causes of CPAP non-adherence.
Question 4: A full-face mask (oronasal mask) is typically indicated over a nasal mask when a patient:
- Has a high AHI requiring higher CPAP pressures
- Is a confirmed mouth breather or has significant mouth leak (Correct answer)
- Experiences aerophagia at lower pressures
- Has central rather than obstructive sleep apnea
Correct answer: Is a confirmed mouth breather or has significant mouth leak
Mouth breathing or significant mouth air leak with nasal masks causes pressure loss and therapy ineffectiveness, making an oronasal mask the appropriate interface.
Question 5: Which signal processing technique is used by APAP devices to distinguish true apneas from mask leak artifacts?
- Frequency analysis of the flow signal for snoring vibrations
- Cross-referencing flow signal with pressure fluctuations and snore microphone
- Proprietary algorithms analyzing flow signal shape, amplitude, and timing patterns (Correct answer)
- Comparing SpO2 trends to flow cessation timing
Correct answer: Proprietary algorithms analyzing flow signal shape, amplitude, and timing patterns
APAP devices use proprietary algorithms that analyze flow signal morphology, amplitude, timing, and response patterns to differentiate true respiratory events from leaks.
Question 6: The oxygen desaturation index (ODI) as measured during PSG typically counts events where SpO2 drops by at least:
- 2% from baseline
- 3% from baseline
- 4% from baseline (Correct answer)
- 5% from baseline
Correct answer: 4% from baseline
The most widely used definition of ODI counts SpO2 drops ≥4% from the preceding baseline, though some protocols use 3%.
Question 7: Which PSG channel configuration is recommended by AASM for detecting bruxism during sleep?
- Single submental EMG channel with high sensitivity
- Bilateral masseter EMG electrodes with high-pass filter at 10 Hz
- Bilateral masseter EMG electrodes in addition to the standard submental EMG (Correct answer)
- EEG derivation over the temporal region to detect muscle artifact
Correct answer: Bilateral masseter EMG electrodes in addition to the standard submental EMG
AASM recommends adding bilateral masseter EMG electrodes supplementing standard submental EMG to improve bruxism detection sensitivity and specificity.
RPSGT Technology & Tools 5
Which artifact is characterized by a 60 Hz sinusoidal pattern superimposed on PSG channels and is MOST commonly caused by: