RPSGT Technology & Tools Practice Questions — Questions and Answers
Question 1: What is the minimum recommended sampling rate for EEG signals in digital PSG according to AASM guidelines?
- 128 Hz
- 200 Hz
- 256 Hz (Correct answer)
- 500 Hz
Correct answer: 256 Hz
AASM recommends a minimum sampling rate of 256 Hz for EEG to adequately represent frequencies up to 35 Hz per Nyquist theorem.
Question 2: A nasal pressure transducer is preferred over a thermistor for detecting hypopneas because it:
- Is more resistant to condensation artifact
- Better detects flow limitation via waveform flattening (Correct answer)
- Has a faster thermal response time
- Requires no calibration before use
Correct answer: Better detects flow limitation via waveform flattening
Nasal pressure transducers detect the characteristic flow-limited flattened waveform that precedes and defines many hypopneas better than thermistors.
Question 3: Piezoelectric effort belts used in PSG measure respiratory effort by detecting:
- Changes in thoracic electrical impedance
- Mechanical strain causing voltage changes (Correct answer)
- Infrared light absorption by chest wall
- Pressure changes transmitted through the belt
Correct answer: Mechanical strain causing voltage changes
Piezoelectric belts generate a voltage proportional to mechanical strain (stretching/compression) from thoracoabdominal movement.
Question 4: During a split-night PSG, CPAP titration should begin when which criterion is met?
- AHI ≥ 5 events/hr in the first 30 minutes
- RDI ≥ 10 events/hr after at least 2 hours of diagnostic recording (Correct answer)
- At least 3 REM episodes documented on diagnostic portion
- SpO2 drops below 85% for more than 5 minutes
Correct answer: RDI ≥ 10 events/hr after at least 2 hours of diagnostic recording
AASM criteria require an RDI ≥ 10 events/hr after a minimum of 2 hours of diagnostic recording before initiating CPAP titration in a split-night study.
Question 5: Which CPAP device feature automatically adjusts pressure breath-by-breath based on detected flow limitation?
- BiPAP ST mode
- CPAP with C-Flex
- Auto-titrating CPAP (APAP) (Correct answer)
- Volume-assured pressure support (VAPS)
Correct answer: Auto-titrating CPAP (APAP)
APAP devices use algorithms analyzing flow signals to continuously adjust pressure in response to detected apneas, hypopneas, snoring, and flow limitation.
Question 6: A technologist notices the chin EMG signal is flat throughout the recording. The FIRST troubleshooting step should be:
- Replace the EMG electrodes and reapply
- Check electrode impedances at the chin site (Correct answer)
- Switch to a backup chin EMG channel if available
- Increase the amplifier sensitivity setting
Correct answer: Check electrode impedances at the chin site
Checking impedance first identifies whether the problem is poor electrode contact (high impedance) before making hardware changes.
Question 7: End-tidal CO2 (EtCO2) monitoring during PSG is MOST indicated for which patient population?
- Adults with suspected obstructive sleep apnea
- Pediatric patients and those with suspected hypoventilation (Correct answer)
- Patients with insomnia undergoing MSLT
- Patients on supplemental oxygen therapy
Correct answer: Pediatric patients and those with suspected hypoventilation
EtCO2 monitoring is particularly valuable in pediatric PSG and for detecting nocturnal hypoventilation in adults with obesity hypoventilation or neuromuscular disease.
Question 8: Which filter setting is most appropriate for recording the EEG signal during a standard PSG?
- High-pass 0.3 Hz, Low-pass 35 Hz (Correct answer)
- High-pass 1 Hz, Low-pass 70 Hz
- High-pass 0.1 Hz, Low-pass 15 Hz
- High-pass 5 Hz, Low-pass 100 Hz
Correct answer: High-pass 0.3 Hz, Low-pass 35 Hz
AASM recommends a high-pass filter of 0.3 Hz and low-pass filter of 35 Hz for EEG recording during PSG.
Question 9: What is the recommended paper speed (or display sweep) for standard PSG epoch scoring?
- 5 mm/sec (30-second epochs)
- 10 mm/sec (30-second epochs) (Correct answer)
- 15 mm/sec (20-second epochs)
- 25 mm/sec (10-second epochs)
Correct answer: 10 mm/sec (30-second epochs)
The standard PSG display speed is 10 mm/sec, yielding 30-second epochs as recommended by AASM.
Question 10: A positive occipital sharp transient of sleep (POSTS) is best identified on which EEG derivation?
- F4-M1
- C4-M1
- O2-M1 (Correct answer)
- E1-M2
Correct answer: O2-M1
POSTS are maximal over occipital regions and best seen on O1/O2 derivations referenced to the contralateral mastoid.
Question 11: Which electrode impedance threshold must be met before beginning a PSG recording according to best practice?
- Below 50 kΩ
- Below 25 kΩ
- Below 10 kΩ (Correct answer)
- Below 5 kΩ
Correct answer: Below 10 kΩ
Electrode impedance should be below 10 kΩ (ideally ≤5 kΩ) to ensure adequate signal quality.
Question 12: In digital PSG systems, what does the term 'common mode rejection ratio' (CMRR) refer to?
- The ratio of differential signal gain to common-mode signal gain (Correct answer)
- The ratio of sampling rate to signal bandwidth
- The ratio of A/D converter bits to noise floor
- The ratio of electrode impedance to amplifier input impedance
Correct answer: The ratio of differential signal gain to common-mode signal gain
CMRR measures the amplifier's ability to reject noise common to both inputs while amplifying only the differential (brain) signal.
Question 13: During oximetry calibration, a signal averaging time of 3 seconds vs. 6 seconds primarily affects which oximetry characteristic?
- Absolute SpO2 accuracy at baseline
- Detection sensitivity for rapid desaturations (Correct answer)
- The probe's light wavelength output
- Alarm threshold levels
Correct answer: Detection sensitivity for rapid desaturations
Shorter averaging times (3 sec) detect rapid desaturations more sensitively, while longer averaging (6 sec) smooths out motion artifact.
Question 14: Which PSG channel is MOST useful for distinguishing cardiac artifact from true slow-wave EEG activity?
- EMG chin
- ECG (single-lead) (Correct answer)
- Respiratory effort belt
- Position sensor
Correct answer: ECG (single-lead)
The ECG channel allows identification of QRS-timed artifacts in EEG channels, distinguishing them from genuine delta waves.
