Digital Polysomnography

CHRISTINA L. TROXELL

NOTE: This chapter corresponds to Chapter 26 in Fundamentals of Sleep Technology, 2nd edition.

1. Which one of the following is a bioelectrical potential signal?

A. ECG

B. Snore

C. Position

D. EtCO₂

2. Several metals have high conductivity, but gold is considered best for long sleep study recordings because it is:

A. More malleable

B. Impervious to cold and heat

C. The traditional choice

D. Resistant to corrosive effects

3. Ohm law tells us that when voltage is constant, increasing electrode resistance:

A. Reduces current

B. Increases radiant heat

C. Blocks the flow of ions in neurons

D. Is futile

4. Differential amplifiers reduce noise in EEG signals using:

A. Floating reference electrodes

B. Linked mastoid electrodes

C. Smoothing functions

D. Common mode rejection

5. By convention, EEG voltages are represented as:

A. Large triangles with multiple inputs

B. A series of sine waves of varying frequency

C. Negative voltage up

D. Nanovolts (10⁻⁹ V)

6. When the two inputs to the differential amplifier detect equal voltages, the output is:

A. Polarized

B. Zero

C. Rectified

D. Two times the voltage of the positive input

7. When the impedance of two inputs is not the same (impedance mismatch), the effect is to reduce the:

A. Voltage of the positive input

B. Voltage of the negative input

C. Effectiveness of the common mode rejection

D. Resistance to the flow of low-frequency signals

8. The filter typically used to remove power line electrical noise is a:

A. Line filter

B. Brita filter

C. Notch (60 Hz) filter

D. High-frequency filter

9. Accurate reproduction of a waveform requires analog-to-digital sampling at a rate at least twice that of the highest frequency of interest. This is known as the:

A. Nyquist theorem

B. Lord Adrian rule

C. Rule of doubles

D. Frequency conversion theorem

10. The American Academy of Sleep Medicine (AASM) recommends a minimum 12 bits for analog-to-digital conversion. This affects the:

A. Number of samples per second

B. Voltage or amplitude resolution

C. Frequency aliasing

D. Screen resolution

Matching

Match the proper phase or term with the appropriate definition.

11.	Conductivity	A.	Ratio of input voltage and output amplitude
12.	Polarity	B.	Opposition of alternating current flow by resistance and capacitance
13.	Impedence	C.	Used to attenuate a limited frequency band, such as power line frequencies
14.	Frequency	D.	Used to attenuate signals below the cutoff frequency
15.	Amplitude	E.	Ability to transmit voltage
16.	Sensitivity	F.	Duration of signal responses set by high- and low-frequency filters
17.	Notch filter	G.	Used to attenuate signals above the cutoff frequency
18.	High-frequency filter	H.	Represents the electrical voltage of wave
19.	Low-frequency filter	I.	Up or down referencing to the electric zero
20.	Time constant	J.	Width of wave expressed as cycles per second