Instrumentation

Question 1

A-D converter size?

Answer 1

8 bit minimum, 16 bit best

Question 2

How many Bits in a Byte?

Answer 2

8 bits=1 Byte

Question 3

How many steps in an 8 bit A-D converter?

Answer 3

2*8 (power) =256 steps

Question 4

Over Amplify could result in?

Answer 4

Waveform Clipping

Question 5

Sensitivity defined in?

Answer 5

uV/div (microvolts per division)

Question 6

With regards to sensitivity, do smaller or larger numbers result in greater amplification?

Answer 6

smaller

Question 7

Gain equals?

Answer 7

output/input

Question 8

sensitivity equals?

Answer 8

input/output

Question 9

The recording gain must be set to match … of the A-D converter for the most effective averaging?

Answer 9

vertical resolution

Question 10

Of a differential amplifier, input 1: Cz= 0.75 uV and input 2: A1= -0.21 uV, what is the output?

Answer 10

0.96 uV

Question 11

In order for Common Mode Rejection to work?

Answer 11

The resistance’s are equal between two electrodes

Question 12

What is the minimum Common mode rejection ratio?

Answer 12

10,000 to 1 or 80 dB

Question 13

What would the common mode rejection ratio be if the CMRR was 120 dB?

Answer 13

1,000,000 to 1

Question 14

Key Factor in common mode rejection?

Answer 14

Electrode impedance balance

Question 15

Salt Bridges never cause 60 cycle artifact? True or False

Answer 15

True

Question 16

Too much electrolyte (salt jelly) spread between two electrode may cause 60 cycle artifact or cancellation (flat lines)?

Answer 16

cancellation

Question 17

What would be the impedance of an electrolyte or salt bride?

Answer 17

less than 100 ohms

Question 18

In SSEPs, active electrodes must be in the negative or positive input?

Answer 18

negative input

Question 19

In BAERs, the active electrode must be in the negative or positive input?

Answer 19

positive input

Question 20

Best filter that causes no phase shift?

Answer 20

Digital Filter

Question 21

High Frequency Filters cause?

Answer 21

Phase Lag (the lower the filter, the later the latency)

Question 22

Low Frequency Filter cause?

Answer 22

Phase Lead (the lower the filter, the later the latency)

Question 23

If filters are changed during the case you must?

Answer 23

Reset Baseline

Question 24

High Filter to Low Filter Ratio

Answer 24

100:1

Question 25

When frequency equals filter setting?

Answer 25

70 % amplitude and 30 % attenuation

Question 26

I’m collecting my EEG at 1-70 Hz, what percentage of a 1Hz waveform will I see?

Answer 26

70% amplitude and 30% attenuation

Question 27

Troubleshooting 60 hz in all channels?

Answer 27

Check impedance 1st then adjust rep rate by .1/sec but not evenly divisible into 60, then check ground.

Question 28

Most common cause of 60 cycle artifact?

Answer 28

unequal electrode impedances

Question 29

If you see 16.6 ms in the question, the answer is?

Answer 29

60 Hz Cycle

Question 30

The Ultrasonic Aspirator (CUSA) produces?

Answer 30

Low amplitude-fast activity

Question 31

Plug equipment into?

Answer 31

Hospital-grade outlets

Question 32

What is the most common cause of 60 cycle artifact?

Answer 32

High electrode impedances

Question 33

Identify colors of 120v, neutral, and ground wire in an electrical cord?

Answer 33

120v = black
neutral = white
ground = green

Question 34

Capacitance Coupling

Answer 34

Electrical Noise

Question 35

Inductive Coupling

Answer 35

Magnetic noise

Question 36

Capacitance and Inductive Coupling reduced with?

Answer 36

braided electrodes

Question 37

Primary step in troubleshooting Evoked potentials or EEG?

Answer 37

View the raw signal or incoming EEG

Question 38

The Ratio of the amplitude of the stimulus locked components to the amplitude of the unrelated components?

Answer 38

signal-to-noise

Question 39

The EP can be identified when the S:N is … or better?

Answer 39

2:1

Question 40

If an evoked potential has a voltage of 10 uV and the associated noise has a voltage of 50 uV, what is the signal-to-noise after 100 averaged responses?

Answer 40

10/50 = 1/5 & N=100
1/5 (square root 100) = 1/5 (10) =10/5 = 2/1
answer 2:1

Question 41

Signal averaging results in

Answer 41

Reduction in the amplitude of the noise only

Question 42

post stimulus delay (positive delay) used to?

Answer 42

get rid of stimulus artifact

Question 43

If you are recording with electrodes of different metals, what might you expect to record?

Answer 43

Bias potentials from the differential amplification of the different charge of each metal

Question 44

Best recording electrodes?

Answer 44

Ag-AgCl

Question 45

Subdermal electrodes are more susceptible to noise due to having a higher impedance compared to surface electrodes. True or False

Answer 45

True

Question 46

Does impedance testing polarize the electrodes?

Answer 46

By using alternating current, impedance testing does not polarize the electrode.

Question 47

Constant Current Stimulation

Answer 47

As impedance increases at stimulation site, voltage output increases to maintain stim intensity.

Question 48

Artifact rejection rejects signals based on?

Answer 48

Amplitude

Question 49

Does Bipolar electrocautery saturate the amplifier?

Answer 49

No

Question 50

Microshock

Answer 50

Risk for patients with indwelling devices, arm to heart, <100uA

Question 51

If you get a shock from the equipment?

Answer 51

Disconnect the patient