FREE BRPT Performing and Verifying Physiologic Calibrations Questions and Answers

Question 1

What is the primary purpose of performing physiologic calibrations (biocals) before starting a sleep study recording?

Accepted Answer

To verify the integrity and proper response of all recorded signals.

Answer

Biocals are essential to confirm that all electrodes and sensors are working correctly and responding appropriately to the patient's physiological changes. This process verifies signal integrity, confirms correct channel derivations, and ensures high-quality data will be collected.

Question 2

During EOG calibrations, the technologist asks the patient to 'look left, then look right'. What is the expected signal response in the LOC-M2 and ROC-M1 channels?

Accepted Answer

The signals should be out-of-phase (move in opposite directions).

Answer

When the eyes move, the cornea (positive potential) moves toward one electrode and away from the other. This creates opposite deflections in the two EOG channels, resulting in an out-of-phase signal, which confirms proper electrode placement and function.

Question 3

During physiologic calibrations, a flat line is observed in the C3-M2 channel, but the impedance check was low (under 5 kΩ). What is the most likely cause?

Accepted Answer

A salt bridge has formed between the C3 and M2 electrodes.

Answer

A 'salt bridge' occurs when conductive paste or gel from two nearby electrodes (like C3 and the reference M2) makes contact. This shunts the electrical potential between them, resulting in a flat line because there is no potential difference to measure, even though the individual electrode impedances are good.

Question 4

What is the purpose of asking the patient to hold their breath for 5-10 seconds during calibrations?

Accepted Answer

To confirm the function of the respiratory airflow and effort channels.

Answer

Asking the patient to hold their breath creates a voluntary central apnea. This allows the technologist to verify that the respiratory effort belts (thoracic and abdominal) and the airflow sensor (thermistor/cannula) correctly detect and display the cessation of breathing and effort.

Question 5

To verify the function of the chin EMG channels, what command should the technologist give the patient?

Accepted Answer

Clench your teeth together.

Answer

Asking the patient to clench their teeth or jaw activates the submental muscles. This should produce a high-frequency, high-amplitude burst of activity in the EMG channels, confirming that the electrodes are placed correctly and are detecting muscle tone.

BRPT - Board of Registered Polysomnographic Technologists Practice Test

BRPT - Board of Registered Polysomnographic Technologists Practice Test

FREE BRPT Performing and Verifying Physiologic Calibrations Questions and Answers