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I POLY > Artifacts and Troubleshooting > Flashcards

Artifacts and Troubleshooting Flashcards

1
Q

____ refers to an extraneous
signal appearing in a recording
channel on the PSG.

A

Artifact

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2
Q

____ are electrical signals
recorded in a channel that cause
the desired signal to become
harder to read.

A

Artifacts

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3
Q

After electrodes are placed on the patient, an _____
should be performed to assess the quality of the signals.

A

impedance check

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4
Q

______ refers to
resistance to a current.

A

Electrical impedance

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5
Q

When electrical flow is impeded or resisted, a signal is more likely to be contaminated with ___ or extraneous electrical activity.

A

artifact

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6
Q

Impedance values should be __
and fairly ___ in measurement.

A

low / equal

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7
Q

The AASM recommends that
impedance values below _____ be achieved.

A

5 kiloohm

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8
Q

Low and equal impedance values
are associated with _____ that are less likely to contain artifacts.

A

higher-quality recordings

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9
Q

______ are associated with an increased chance of contamination with
artifacts and occur when an
electrode is not securely placed
against the skin or scalp, when the electrode site has not been
properly cleaned, or when the
sensor is faulty, broken, or dirty.

A

High impedance values

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10
Q

Artifacts can originate from the
____, the ____, or ____, and _____
vary.

A

patient, equipment, external
sources, corrective methods

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11
Q

_____ is a fast-wave
activity that depicts the
electrical activity of the
patient’s heart and appears in a
channel other than the ECG
channel.

A

ECG artifact

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12
Q

This is a common artifact in
patients with hypertension. The
increased blood pressure in
hypertensive patients causes
the ____ to be felt easily in
areas of the body away from
the heart.

A

pulse / ECG Artifact

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13
Q

_____ is most commonly
seen in the EEG,
electrooculogram (EOG), chin
EMG, and leg EMG channels
and presents itself as a single
fast wave appearing
approximately every ___,
depending on the underlying
heart rate.

A

ECG artifact / second

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14
Q

The ____ can be easily
identified by lining up the
extraneous signal with the
patient’s QRS complex in the
ECG channel.

A

artifact

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15
Q

The primary cause of ECG
artifact is _____

A

poor electrode
placement.

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16
Q

An electrode that is placed
directly over a ____ or an
_____ is likely to detect the
pulse and transmit this signal
to the polysomnograph.

A

large vein / artery

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17
Q

Correction of ECG artifact
relies on identification of the
_____.

A

source electrode

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18
Q

Because the ____ is usually associated with poor electrode placement, the best method of correction is to move any affected electrode to an appropriate ______.

A

artifact / alternate
location

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19
Q

For example, the reference
electrodes M1 and M2 are
usually placed on the ___
process behind the ear. If they
are recording the ECG, these
electrodes can be moved
higher up behind the ear or to
the earlobes.

A

mastoid

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20
Q

If ECG artifact is identified after
the patient falls asleep, it can
be corrected by either _____ or ____

A

re- referencing or double
referencing.

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21
Q

____
is accomplished by changing one of the channel’s inputs
(G2) to an alternate electrode.

A

Re-referencing

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22
Q

_____ is characterized by high-amplitude, high-frequency signals that obscure many or all of the channels and occur as a result of a body movement.

A

Movement artifact

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23
Q

_____ is probably the most
frequently occurring artifact during a sleep study.

A

Movement

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24
Q

Even small muscle
movements can cause ____, ____ changes as the skin moves across the tissues underneath it.

A

high- amplitude, high-frequency

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25
Q

During ____ and
_____ procedures, the
technologist should instruct the
patient to lie still, preferably in the supine position, reducing or
eliminating movement artifact.

A

impedance checks and calibration

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26
Q

_____ can be subdivided into several types that include sweat, respiratory, and sway artifact.

A

Slow-wave artifact

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27
Q

Slow-frequency artifacts are
characterized by a _____, usually _____ waveforms intruding into one or several channels.

A

slow frequency / high-amplitude

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28
Q

_____ is a type of slow-
frequency artifact caused by sweat on the patient’s skin.

A

Sweat artifact

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29
Q

___ from sweat causes a chemical reaction
that, in turn, causes slow changes in the frequency of electrical signals.

A

Salt

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30
Q

The ___ and ___
channels are most frequently
affected by sweat artifact.

A

EOG and EEG

31
Q

As the patient sweats from the
forehead, often the ground lead is affected, which serves as a
reference for all the ___ and ___ channels.

A

EOG and EEG

32
Q

______ is a slow-frequency artifact that it caused by slow, subtle head movements
associated with breathing.

A

Respiratory artifact

33
Q

____ is commonly caused by swinging movements of the electrode wires or the headbox.

A

Sway artifact

34
Q

This artifact is usually recognized
by ruling out the other two causes or visualizing motion of the head box. (____)

A

Sway artifact

35
Q

Slow-wave artifacts can be
masked by increasing the ______

A

low-frequency filter (LFF).

36
Q

If the artifact is caused by
breathing, as in a respiratory
artifact, repositioning the patient’s head on the ___ can be helpful.

A

pillow

37
Q

if a patient is sweating and slow artifact is noted, it is appropriate to ______ affected by the sweat, dry the area, replace them, and use a fan to keep the patient cool.

A

remove electrodes

38
Q

Lastly, resecuring the head box
can effectively eliminate ____ if
that is the source of the artifact.

A

sway

39
Q

____ is an artifact caused by snoring.

A

Snore artifact

40
Q

This usually appears in the EEG
channels or in the chin EMG.

A

Snore Artifact

41
Q

____ appear as high-
amplitude, high frequency bursts of activity for a short period of time, corresponding with and ending when the snore ends.

A

Snore artifacts

42
Q

Snore artifact is not correctable by changing filter or gain settings, but it will correct itself when the patient ___.

A

stops snoring

43
Q

When an electrode is broken or
disconnected from the patient or
head box, it works as an ___
and detects electrical activity from ____.

A

antenna / external sources

44
Q

This electrical activity is often
referred to as ___ and is usually in the frequency range of ___, because
this is the frequency used by most electrical devices and outlets in the United
States.

A

electrical noise , 60 Hz

45
Q

This ____ usually ___ signal appears to dominate any affected channel,
obscuring relevant waveforms.

A

high frequency, / high-amplitude

46
Q

Occasionally ______
may be present when all
connections are stable, but an
electrical device resides close to
the diagnostic equipment.

A

60-Hz interference

47
Q

Today’s sleep diagnostic systems
include a built-in 60-Hz filter, also called a ___ or a ____.

A

notch filter / line filter

48
Q

This sets a special frequency filter from _____ to help reduce 60-Hz artifact.

A

59 Hz to 61 Hz

49
Q

____ filters merely
attenuate signals outside the filter ranges rather than completely eliminate them.

A

frequency

50
Q

Therefore, if a ___ signal is present, it will likely
affect the quality of the tracing
even if the notch filter is applied.
As with other artifacts, the optimal method of correction is at the ___.

A

60- Hz / source

51
Q

The most common cause of 60-Hz artifact is ____ or improper cleaning of the site.

A

poor electrode application

52
Q

Faulty, broken, or disconnected
electrodes can permit the entrance of _____ into the pathway, as can loose cable connections or electrical devices sitting close to the diagnostic equipment.

A

60-Hz signals

53
Q

_____ and other ____
items touching the electrode also can be potential sources of 60-Hz interference.

A

Metal jewelry and other metal

54
Q

_____ occurs when high- frequency muscle activity
contaminates a channel that is not designed to collect muscle activity.

A

Muscle artifact

55
Q

___ appears to mimic the
activity that is collected in the EMG channels.

A

artifact

56
Q

On a sleep study, muscle artifact is commonly seen in the __ and ___ channels when a patient is
anxious or clenches the jaw or
grinds his or her teeth.

A

EEG and EOG

57
Q

______ is most often
observed when the patient is
awake and tends to gradually
disappear as the patient relaxes
and enters sleep.

A

Muscle artifact

58
Q

______ is characterized by occasional pops or bursts of 60- Hz activity in a channel.

A

Electrode popping

59
Q

This is usually caused by a loose
connection in the signal pathway or a faulty or broken wire.

A

Electrode Popping

60
Q

_______ often displays
itself as just one fast high-
amplitude wave, or it may pop for a few seconds at a time before returning to normal.

A

Electrode popping

61
Q

______ is characterized by a blocking of the pens at the highest and lowest points of the channel parameters.

A

Pen blocking

62
Q

This artifact occurs when the gain setting in a channel is too high, causing the pen to attempt to reach beyond the upper and lower parameters of the channel.

A

Pen blocking

63
Q

_____ are two terms used interchangeably to describe the amplitude settings on the polysomnograph.

A

Gain and sensitivity

64
Q

Although the _____ of
the signal remains unchanged and is defined at the source of the signal (the patient), the display of the height of the signal can be adjusted.

A

actual amplitude

65
Q

When the ____ is increased, the height of the waveform display increases.

A

gain setting

66
Q

The sensitivity setting is
measured in terms of _____

A

microvolts
per vertical millimeter (μV/mm).

67
Q

the ______ is
increased, the waveform appears shorter in height.

A

sensitivity setting

68
Q

Some polysomnographs use a
_____, some use a _____, and some have options to use either one or both.

A

gain setting / sensitivity setting

69
Q

Changing the gain setting
from _____ would double the height of the waveform, while changing the sensitivity from ____ μV/mm would half the display of the waveform.

A

1 to 2 / 20 to 40

70
Q

______ can also
negatively affect the signals on a
PSG.

A

Improper filter settings

71
Q

As a general rule, ____ should not be used to correct artifacts
because it is likely to eliminate
relevant waveforms intended to be recorded from the patient.

A

filters

72
Q

If the LFF on an EEG channel is
increased from the recommended setting of ____, it will attenuate the ____ and _____ will be missed.

A

0.3 to 3 Hz / slow EEG waves / delta waves

73
Q

If the HFF is decreased from the
recommended setting of ____, it will attenuate _____, _____, and other _______.

A

35 to 10 Hz / alpha waves, spindles, and other fast EEG waveforms.

74
Q

Because of the potential effects of over ____, frequency filters
should be used conservatively.

A

filtering

I POLY (6 decks)

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