RST Study Preparation and Instrumentation Questions and Answers — Questions and Answers
Question 1: When preparing a patient for a polysomnogram, what is the maximum acceptable impedance level for scalp and facial electrodes to ensure a high-quality recording?
- 10 kΩ (kilo-ohms)
- 5 kΩ (kilo-ohms) (Correct answer)
- 15 kΩ (kilo-ohms)
- 1 kΩ (kilo-ohm)
Correct answer: 5 kΩ (kilo-ohms)
According to the American Academy of Sleep Medicine (AASM) guidelines, electrode impedances for EEG and EOG channels should be at or below 5 kΩ. This ensures a strong, clear signal with minimal artifact, which is crucial for accurate sleep staging and event scoring.
Question 2: A 6-year-old child is scheduled for a polysomnogram and is visibly fearful of the electrodes and sensors. Which of the following is the MOST effective technique to facilitate the hookup process?
- Ask the parent to leave the room to avoid distractions.
- Inform the child that the procedure is painless and they must hold still.
- Use a "tell-show-do" approach, demonstrating the sensors on a doll or the parent first. (Correct answer)
- Restrain the child gently to complete the hookup as quickly as possible.
Correct answer: Use a "tell-show-do" approach, demonstrating the sensors on a doll or the parent first.
The "tell-show-do" technique is a well-established method for reducing anxiety in pediatric patients. By first explaining the procedure in simple terms (tell), then demonstrating on a non-threatening object like a doll or parent (show), and finally applying the sensor to the child (do), the technologist demystifies the process and builds trust.
Question 3: Which of the following statements BEST describes the primary operational difference between a thermal sensor (thermistor) and a thermocouple for monitoring respiratory airflow?
- A thermocouple provides a quantitative airflow measurement, while a thermistor provides only a qualitative measurement.
- A thermistor measures temperature changes based on resistance, while a thermocouple measures temperature changes based on voltage. (Correct answer)
- A thermistor is placed in the nose, while a thermocouple is placed in front of the mouth.
- A thermocouple is used to detect apneas, while a thermistor is used to detect hypopneas.
Correct answer: A thermistor measures temperature changes based on resistance, while a thermocouple measures temperature changes based on voltage.
The fundamental principle of a thermistor is that its electrical resistance changes predictably with temperature. In contrast, a thermocouple operates on the Seebeck effect, where a voltage is produced when two junctions of dissimilar metals are at different temperatures.
Question 4: A patient is scheduled for an MSLT following an overnight PSG. The technologist is reviewing the patient's medication list and sleep diary. Which of the following findings would be MOST critical to report to the physician before starting the MSLT?
- The patient's sleep diary shows an average of 6.5 hours of sleep per night for the past two weeks.
- The patient has a history of claustrophobia but tolerated the PSG well.
- The patient took a prescribed dose of zolpidem two nights ago.
- The patient has been taking an over-the-counter antihistamine for allergies daily. (Correct answer)
Correct answer: The patient has been taking an over-the-counter antihistamine for allergies daily.
Many medications, including common over-the-counter antihistamines, have sedating properties and can suppress REM sleep. Their presence can significantly alter sleep latency and the occurrence of sleep-onset REM periods (SOREMPs), potentially leading to a false-negative or invalid MSLT result. This requires physician consultation before proceeding.
Question 5: During physiological calibrations prior to starting a polysomnogram, the technologist asks the patient to look left, then right, then up, then down. What is the primary purpose of this specific set of maneuvers?
- To verify correct signal response and polarity of the EOG channels. (Correct answer)
- To test the integrity of the respiratory effort belts.
- To establish a baseline for the patient's resting heart rate.
- To confirm proper functioning of the audio-video recording system.
Correct answer: To verify correct signal response and polarity of the EOG channels.
These specific eye movements create predictable, out-of-phase deflections in the left and right electrooculogram (EOG) channels. This bio-calibration allows the technologist to confirm that the EOG electrodes are placed correctly and are functioning with the correct polarity, which is essential for accurately identifying the rapid eye movements that define Stage R sleep.
Question 6: According to the AASM Manual for the Scoring of Sleep and Associated Events, what are the recommended low frequency (LFF) and high frequency (HFF) filter settings for the electrooculogram (EOG) channel?
- LFF = 1.0 Hz, HFF = 100 Hz
- LFF = 10 Hz, HFF = 70 Hz
- LFF = 0.1 Hz, HFF = 15 Hz
- LFF = 0.3 Hz, HFF = 35 Hz (Correct answer)
Correct answer: LFF = 0.3 Hz, HFF = 35 Hz
The AASM Manual for the Scoring of Sleep and Associated Events specifies a low frequency filter setting of 0.3 Hz and a high frequency filter setting of 35 Hz for EOG channels. These settings are optimized to record both slow and rapid eye movements accurately while filtering out unwanted physiological and electrical noise.
RST Study Preparation and Instrumentation Questions and Answers
When preparing a patient for a polysomnogram, what is the maximum acceptable impedance level for scalp and facial electrodes to ensure a high-quality recording?