Apt artifact recognition & troubleshooting

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Identifying artifact and troubleshooting

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Apt artifact recognition & troubleshooting

  1. 1. Artifact Recognition & Troubleshooting
  2. 2. Artifacts <ul><li> </li></ul>
  3. 3. Artifacts <ul><li>Definition : A Weed </li></ul><ul><li>Can affect any channel </li></ul><ul><li>Range from annoyance to nightmare </li></ul>
  4. 4. An Ounce of Prevention… <ul><li>Electrode Impedances </li></ul><ul><ul><li>Low & Equal </li></ul></ul><ul><li>Common mode rejection </li></ul><ul><ul><ul><li>G1> Signal + BN + EN </li></ul></ul></ul><ul><ul><ul><li>G2 > - BN + EN </li></ul></ul></ul><ul><ul><ul><li>= Signal </li></ul></ul></ul>
  5. 5. Artifacts aren’t always easy to see at 4:00 am and the screen looks like this
  6. 6. Non-Physiologic Artifact <ul><li>60 Hz </li></ul><ul><ul><ul><li>Poor electrode connection </li></ul></ul></ul><ul><ul><ul><li>Importance of low impedance </li></ul></ul></ul><ul><ul><ul><li>Use of notch and High Frequency filters </li></ul></ul></ul>
  7. 7. 60 Hz Artifact Going………………..Going………………..GONE No filters applied
  8. 8. 60 Hz Artifact HFF at 35 Hz
  9. 9. 60 Hz Artifact HFF set at 15 Hz
  10. 10. <ul><li>Popping </li></ul><ul><li>Baseline sway </li></ul><ul><ul><li>Recording from too large an area </li></ul></ul>Non-Physiologic Artifact
  11. 11. <ul><li>HFR or sleep with a beat </li></ul><ul><li>Dissimilar metals </li></ul><ul><ul><li>Different impedance properties </li></ul></ul>Non-Physiologic Artifact
  12. 12. Sampling Rate <ul><li>Aliasing </li></ul><ul><ul><li>Sampling rate too low </li></ul></ul>
  13. 13. <ul><li>Power surges </li></ul><ul><ul><li>Surge protection </li></ul></ul><ul><li>Loose connections </li></ul><ul><ul><li>Headbox, amplifier, computer </li></ul></ul>Non-Physiologic Artifact
  14. 14. Non-Physiologic Artifact <ul><li>Amplifier blocking </li></ul><ul><ul><li>A type of overload, may be due to popping </li></ul></ul><ul><ul><li>Amplifier sensitivity may be too high if waveforms are clipped </li></ul></ul><ul><ul><li>Typically low so all amplitude waveforms get recorded </li></ul></ul><ul><ul><ul><li>This keeps high amplitude waves from clipping </li></ul></ul></ul><ul><ul><li>Low Sens Too High </li></ul></ul>150uV
  15. 15. Non-Physiologic Artifact <ul><li>Sampling skew - when all channels are not sampled simultaneously </li></ul>First Chan . Last Chan Erroneous output when data is Reformatted Simultaneous Data Sample Non- Simultaneous Data Sample
  16. 16. Physiologic Artifacts Sometimes its in the eye of the beholder
  17. 17. Physiologic Artifacts <ul><li>Muscle </li></ul><ul><ul><li>Reposition leads </li></ul></ul><ul><ul><li>Let patient fall asleep </li></ul></ul><ul><li>Movement </li></ul>
  18. 18. Movement & Muscle Artifact
  19. 19. Physiologic Artifacts <ul><li>Other Movement artifacts </li></ul><ul><ul><li>Eye movement </li></ul></ul><ul><ul><li>Bruxism </li></ul></ul><ul><ul><ul><li>Can resemble spike & wave complexes or synchronous delta </li></ul></ul></ul><ul><ul><li>Head Tremor </li></ul></ul><ul><ul><li>Tongue movement </li></ul></ul>
  20. 20. Physiologic Artifacts <ul><li>EKG Artifact </li></ul><ul><ul><li>Place reference leads high </li></ul></ul><ul><ul><li>Move references to earlobes </li></ul></ul><ul><ul><li>Join A1 & A2 </li></ul></ul><ul><li>Pulse Artifact </li></ul><ul><ul><li>Reposition leads </li></ul></ul><ul><li>Pacemaker </li></ul>
  21. 21. ECG Artifact *Atlas of Sleep Medicine – Nic Butkov
  22. 22. Physiologic Artifacts <ul><li>Respiration </li></ul><ul><ul><li>Raise LFF or </li></ul></ul><ul><ul><li>Lower TC </li></ul></ul><ul><ul><li>Reposition wires </li></ul></ul>
  23. 23. Respiratory Artifact
  24. 24. Physiologic Artifacts <ul><li>Sweat </li></ul><ul><ul><li>Cool patient off </li></ul></ul><ul><ul><ul><li>Remove blankets </li></ul></ul></ul><ul><ul><ul><li>Lower room temp </li></ul></ul></ul><ul><ul><ul><li>Add fan etc. </li></ul></ul></ul><ul><ul><li>Raise LFF or decrease TC </li></ul></ul>
  25. 25. Sweat Artifact
  26. 26. Importance of Re-referencing to Troubleshoot <ul><li>Verify Impedance during the recording to zero in on bad lead </li></ul><ul><li>Find the problem electrode </li></ul><ul><ul><li>Did it come off, come out, break? </li></ul></ul><ul><li>Re-reference if possible or use back-up leads </li></ul>
  27. 27. Troubleshooting A1+A2 *Atlas of Sleep Medicine – Nic Butkov
  28. 28. Anticipate Exam Questions It will help in case you don’t have a bigger brain to pull out during the exam
  29. 29. Exam Content Areas Related to Artifacts <ul><li>Domain 2, Task 4 </li></ul><ul><ul><li>Observe cal tracings to verify signals are artifact free and make adjustments </li></ul></ul><ul><ul><li>Consider questions related to: </li></ul></ul><ul><ul><ul><li>Correct software settings </li></ul></ul></ul><ul><ul><ul><li>Amplifier function </li></ul></ul></ul>
  30. 30. Exam Content Areas Related to Artifacts <ul><li>Domain 2, Task 5 </li></ul><ul><ul><li>Perform appropriate physiologic calibrations to ensure proper signals </li></ul></ul><ul><ul><li>Consider questions related to: </li></ul></ul><ul><ul><ul><li>Appearance of any artifacts </li></ul></ul></ul><ul><ul><ul><li>Troubleshooting prior to lights out </li></ul></ul></ul><ul><ul><ul><ul><li>As opposed to after lights out </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Check leads, hookup, etc. </li></ul></ul></ul></ul><ul><ul><ul><li>Poor impedance leads to what artifacts </li></ul></ul></ul>
  31. 31. Exam Content Areas Related to Artifacts <ul><li>Domain 3, Task 3 </li></ul><ul><ul><li>Monitor study tracing quality to ensure signals are artifact free and make adjustments </li></ul></ul><ul><ul><li>Consider questions related to: </li></ul></ul><ul><ul><ul><li>Troubleshooting after lights out </li></ul></ul></ul><ul><ul><ul><ul><li>Determining bad lead </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Re-referencing </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Use/abuse of software filters </li></ul></ul></ul></ul><ul><ul><ul><li>Change in environment </li></ul></ul></ul><ul><ul><ul><li>Effect of reference or ground coming off </li></ul></ul></ul><ul><ul><ul><li>Sensor displacement </li></ul></ul></ul><ul><ul><ul><li>When to intervene </li></ul></ul></ul>
  32. 32. Exam Content Areas Related to Artifacts <ul><li>Domain 3, Task 5 </li></ul><ul><ul><li>Document routine observations, changes in procedure, and significant events in order to facilitate scoring and interpretation </li></ul></ul><ul><ul><li>Consider questions related to: </li></ul></ul><ul><ul><ul><li>What is important to document </li></ul></ul></ul><ul><ul><ul><li>Documentation of: </li></ul></ul></ul><ul><ul><ul><ul><li>Electrode & sensor replacement </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Changes to the environment </li></ul></ul></ul></ul><ul><ul><ul><li>Accuracy & timeliness of documentation </li></ul></ul></ul>
  33. 33. Exam Content Areas Related to Artifacts <ul><li>Domain 4, Task 1 </li></ul><ul><ul><li>Score sleep/wake stages by applying professionally accepted guidelines </li></ul></ul><ul><ul><li>Consider questions related to: </li></ul></ul><ul><ul><ul><li>What artifacts impair scoring </li></ul></ul></ul><ul><ul><ul><li>What to do if staging is compromised </li></ul></ul></ul><ul><ul><ul><li>Use/abuse of software filters </li></ul></ul></ul>
  34. 34. Exam Content Areas Related to Artifacts <ul><li>Domain 4, Task 2 </li></ul><ul><ul><li>Score clinical events according to current professionally accepted guidelines </li></ul></ul><ul><ul><li>Consider questions related to: </li></ul></ul><ul><ul><ul><li>What artifacts impair scoring </li></ul></ul></ul><ul><ul><ul><li>What to do if event scoring is compromised </li></ul></ul></ul><ul><ul><ul><li>Use/abuse of software filters </li></ul></ul></ul>

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