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EEG/EOG 0.3-0.1/35, EMG 10/70
If E2 channel is 4 and E1 channel is 5, what do waves look like when pt looks up?
Waves move toward each other
What is the purpose of low frequency filter?
Eliminate undesired low frequencies
The symbol G1 and G2 represent…?
Exploring electrode (G1) and Reference electrode (G2)
What is the output of the following: G1 has -100 uV signal, G2 has -50 uV signal ?
-50 uV
What does a differential amplifier do?
It measures the difference between two signals
The frequency of an EEG signal can be determined by…?
Frequency is cycles/second or Hz…count the number of cycles in one second
How is wave amplitude determined?
Compare the wave to a calibration signal of known value
Amplitude is a measure of …?
Voltage
What is the purpose of a high frequency filter?
To filter out undesirable fast frequencies
What is the sensitivity setting?
The ratio of input signal voltage to the amplitude of the pen deflection
What is an appropriate EEG sensitivity setting?
5 uV/ mm or 50 uV/cm
When adjusting the sensitivity from 5 uV/mm to 10 uV/mm, what will happen?
It will reduce the pen deflection by half
The standard paper speed used for a sleep study is …?
10 mm/sec (this creates a 30 second epoch)
What is an appropriate filter setting for an EEG channel?
LFF 0.3 Hz, HFF 30 Hz
What is an appropriate filter setting for an EMG channel?
LFF 10 Hz, HFF 100 Hz
What is an appropriate filer setting for airflow / respiratory effort?
LFF 0.1, HFF 0.5
What is a major difference between AC and DC amplifiers?
AC amplifiers have a HFF, DC amplifiers do not (because changes in voltages are very slow)
The recording of eye movements is based on…?
The electrical potential difference between the cornea (positive) and the retina (negative)
E1 and E2 are referenced to opposite mastoids. An eye movement to the right should result in…?
Downward movement in E2, upward movement in E1
Amplitude is the measurement of the ____of a waveform, while frequency is the measurement of the ____ of a waveform.
Height / speed
EEG amplitude is measured in…?
Microvolts
EEG frequency is measured in…?
Hertz (Hz)
What is the equation regarding sensitivity?
Voltage / pen deflection (uV/mm)
The low frequency filter is associated with…?
The time constant
What is the recommended impedance level for EEG electrodes?
Less than 5k ohms
If the measurement from nasion to inion is 36 cm, what is the distance from Cz to Pz?
7.2 cm
If the measurement from nasion to inion is 32 cm, what is the distance from the inion to Oz?
3.2 cm
The distance from Cz to T4 is 14 cm. What is the distance from C4 to T4?
7.0 cm
The distance from ear to ear is 40 cm. What is the difference from Cz to C3?
8.0 cm
The pt’s head circumference is 56 cm. What is the distance from Oz to O1?
2.8 cm
The pt’s head circumference is 60 cm. What is the distance from O2 to T4?
12.0 cm
Which EEG site is half the distance from F8 to Fz?
F4
Which EEG site is half the distance from O1 to T3?
T5
The distance from FP1 to O1 through C3 is 24 cm. What is the distance from C3 to P3?
6 cm
The distance from Fp2 to T4 is 10 cm. What is the difference from Fp2 to F8?
5.0 cm
Which electrode site is half the distance between Fp2 and C4?
F4
The circumference of the pt’s head is 50 cm. What is the difference from T3 to Oz?
12.5
Which electrode site is half the distance from T3 to T4?
Cz
If G1 reads 60 uV, and G2 reads 10 uV, what is the output signal’s voltage?
G1 minus G2 equals 50 uV
What can happen if referencing electrodes have dissimilar metals?
Galvanized skin response
Which lead is a DC channel?
SpO2
The rate at which a wave repeats itself or oscillates is…?
frequency
A change in sensitivity produces a change in the —– of a wave.
Height
The frequency of a waveform can be altered by adjusting the —–?
Filter
What low frequency filter setting is preferred in the EEG channel?
0.5 Hz
What is the preferred high frequency filter setting in the EEG channel?
35 Hz
What is the preferred high frequency filter in the EMG channel?
70 Hz (best option in question in the book)
Which high frequency filter is preferred in the airflow channel?
5 Hz (best option in question in the book)
In which channel is the shape of the waves most important?
EEG