Download - Apt artifact recognition & troubleshooting
Artifact Recognition & Troubleshooting
Artifacts
Artifacts Definition : A Weed Can affect any channel Range from annoyance to
nightmare
An Ounce of Prevention… Electrode Impedances
Low & Equal Common mode rejection
G1> Signal + BN + ENG2 > - BN + EN = Signal
Artifacts aren’t always easy to see at 4:00 am and the screen looks like
this
Non-Physiologic Artifact
60 HzPoor electrode connectionImportance of low
impedanceUse of notch and High
Frequency filters
60 Hz Artifact
Going………………..Going………………..GONENo filters applied
60 Hz Artifact
HFF at 35 Hz
60 Hz Artifact
HFF set at 15 Hz
Popping Baseline sway
Recording from too large an area
Non-Physiologic Artifact
HFR or sleep with a beat
Dissimilar metals Different
impedance properties
Non-Physiologic Artifact
Sampling Rate
Aliasing Sampling rate too low
Power surges Surge protection
Loose connections Headbox, amplifier, computer
Non-Physiologic Artifact
Non-Physiologic Artifact Amplifier blocking
A type of overload, may be due to popping Amplifier sensitivity may be too high if waveforms
are clipped Typically low so all amplitude waveforms get
recorded This keeps high amplitude waves from clipping
Low Sens Too High
150uV
Non-Physiologic Artifact Sampling skew - when all channels are not
sampled simultaneously
First Chan.
Last Chan
Erroneous output when data is Reformatted
Simultaneous Data Sample
Non- Simultaneous
Data Sample
Physiologic ArtifactsSometimes its in the eye of the beholder
Physiologic Artifacts
Muscle Reposition leads Let patient fall asleep
Movement
Movement & Muscle Artifact
Physiologic Artifacts Other Movement artifacts
Eye movement Bruxism
Can resemble spike & wave complexes or synchronous delta
Head Tremor Tongue movement
Physiologic Artifacts EKG Artifact
Place reference leads high
Move references to earlobes
Join A1 & A2 Pulse Artifact
Reposition leads Pacemaker
ECG Artifact
*Atlas of Sleep Medicine – Nic Butkov
Physiologic Artifacts
Respiration Raise LFF or Lower TC Reposition
wires
Respiratory Artifact
Physiologic Artifacts Sweat
Cool patient off
Remove blankets
Lower room temp
Add fan etc. Raise LFF or
decrease TC
Sweat Artifact
Importance of Re-referencing to Troubleshoot Verify Impedance during the
recording to zero in on bad lead
Find the problem electrodeDid it come off, come out,
break? Re-reference if possible or use
back-up leads
Troubleshooting A1+A2
*Atlas of Sleep Medicine – Nic Butkov
Anticipate Exam
QuestionsIt will help in case you don’t have a bigger brain to pull
out during the exam
Exam Content Areas Related to Artifacts
Domain 2, Task 4 Observe cal tracings to verify
signals are artifact free and make adjustments
Consider questions related to: Correct software settings Amplifier function
Exam Content Areas Related to Artifacts
Domain 2, Task 5 Perform appropriate physiologic
calibrations to ensure proper signals Consider questions related to:
Appearance of any artifacts Troubleshooting prior to lights out
• As opposed to after lights out• Check leads, hookup, etc.
Poor impedance leads to what artifacts
Exam Content Areas Related to Artifacts
Domain 3, Task 3 Monitor study tracing quality to ensure signals
are artifact free and make adjustments Consider questions related to:
Troubleshooting after lights out• Determining bad lead• Re-referencing• Use/abuse of software filters
Change in environment Effect of reference or ground coming off Sensor displacement When to intervene
Exam Content Areas Related to Artifacts
Domain 3, Task 5 Document routine observations, changes
in procedure, and significant events in order to facilitate scoring and interpretation
Consider questions related to: What is important to document Documentation of:
• Electrode & sensor replacement
• Changes to the environment Accuracy & timeliness of documentation
Exam Content Areas Related to Artifacts
Domain 4, Task 1 Score sleep/wake stages by
applying professionally accepted guidelines
Consider questions related to: What artifacts impair scoring What to do if staging is
compromised Use/abuse of software filters
Exam Content Areas Related to Artifacts
Domain 4, Task 2 Score clinical events according to
current professionally accepted guidelines
Consider questions related to: What artifacts impair scoring What to do if event scoring is
compromised Use/abuse of software filters