Technology & Tools Flashcards

What is the minimum recommended sampling rate for EEG signals in digital PSG according to AASM guidelines?

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.

A nasal pressure transducer is preferred over a thermistor for detecting hypopneas because it:

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.

Piezoelectric effort belts used in PSG measure respiratory effort by detecting:

Answer: Mechanical strain causing voltage changes

Piezoelectric belts generate a voltage proportional to mechanical strain (stretching/compression) from thoracoabdominal movement.

During a split-night PSG, CPAP titration should begin when which criterion is met?

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.

Which CPAP device feature automatically adjusts pressure breath-by-breath based on detected flow limitation?

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.

A technologist notices the chin EMG signal is flat throughout the recording. The FIRST troubleshooting step should be:

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.

End-tidal CO2 (EtCO2) monitoring during PSG is MOST indicated for which patient population?

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.

Which filter setting is most appropriate for recording the EEG signal during a standard PSG?

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.

What is the recommended paper speed (or display sweep) for standard PSG epoch scoring?

Answer: 10 mm/sec (30-second epochs)

The standard PSG display speed is 10 mm/sec, yielding 30-second epochs as recommended by AASM.

A positive occipital sharp transient of sleep (POSTS) is best identified on which EEG derivation?

Answer: O2-M1

POSTS are maximal over occipital regions and best seen on O1/O2 derivations referenced to the contralateral mastoid.

Which electrode impedance threshold must be met before beginning a PSG recording according to best practice?

Answer: Below 10 kΩ

Electrode impedance should be below 10 kΩ (ideally ≤5 kΩ) to ensure adequate signal quality.

In digital PSG systems, what does the term 'common mode rejection ratio' (CMRR) refer to?

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.

During oximetry calibration, a signal averaging time of 3 seconds vs. 6 seconds primarily affects which oximetry characteristic?

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.

Which PSG channel is MOST useful for distinguishing cardiac artifact from true slow-wave EEG activity?

Answer: ECG (single-lead)

The ECG channel allows identification of QRS-timed artifacts in EEG channels, distinguishing them from genuine delta waves.