Cerebral Function Monitoring Amplitude-Integrated EEG – aEEG Denis Azzopardi

1. Cerebral Function MonitoringAmplitude-Integrated EEG – aEEGDenis Azzopardi Acknowlegement: Ted Weiler, Olympic Medical / Natus

2. The EEG in the newborn EEG is useful in neonatal intensive care to: • detect seizures • assess prognosis • aid diagnosis • Brain Dev 11:115-120, 1989. • Neuropadiatrie 10:209-225, 1979.

3. Limitation of standard EEG • skill required for recording • difficult to interpret • not widely available • not available immediately

4. Basic knowledge for clinicians • terminology • montage • influential factors • gestation • sleep state • sedation • artefacts

7. EEG in preterm infant

8. EEG in preterm infant (36 weeks)

9. EEG in full-term during wakefulness

10. Healthy full term infant: eyes closed and drowsy

11. EEG in full-term during quiet sleep

12. EEG in full-term during trace alternant quiet sleep

13. EEG in asphyxiated infant:burst suppression

14. EEG in asphyxiated infant:suppression

15. EEG in asphyxiated infant:seizures

16. Ambulatory EEG • 2-4 channels of EEG • long term recordings • aids assessment and diagnosis • skill required • time consuming • Arch Dis Child 71:F97-F102, 1994.

17. What is CFM • Single EEG Lead (3 wires) • Bi-parietal or bi-temporal • Monitor Global Electrocortical Activity • Special Filtering • Compression • Very Slow, Trend Display

18. The Lectromed CFM by Lectromed UK The Olympic CFM 6000 by Olympic Medical / Natus USA The CFAM4 by RDM ltd UK The BRM2 by BrainZ and GE

19. Single EEG Lead • 3 Electrodes • 2 Active • 1 Noise Suppression • Bi-parietal placement with Needles or Disks • Bi-Temporal (forehead) with Hydrogel

20. Global Electrocortical Activity • Limited number of electrodes • Global activity only • Will not localize lesion • May not see focal seizures • High level = high activity • Low level = suppression

21. Filtering

22. Compression

23. Very Slow, Trend Display

24. Normal CFM • Sleep/Wake Cycling • Upper Margin > 10 µvolts • Lower Margin > 5 µvolts • Limited Variability

25. Sleep/Wake Cycling μ

26. Upper/Lower Margins

27. Impedance • Measure of quality of electrode contact • Want it as low as possible • Alarm if > 20 kOhm • Can be used to detect lead motion artifact

28. Impedance - Normal

29. Impedance - Noise

30. Impedance – Loose Lead

31. EEG • Signal on which CFM is based • ± 100 µVolts • 25 mm/sec display speed • Full screen = 7 seconds

32. EEG

33. Moderately Abnormal • No Sleep/Wake • Upper Margin > 10 µVolts • Lower Margin < 5 µVolts • Increased variability

34. Moderately Abnormal

35. Moderately Abnormal

36. Severely Abnormal • No Sleep/Wake • Upper Margin < 10 µVolts • Greatly reduced variability

37. Severely Abnormal

38. Burst Suppression

39. Different background patterns recorded on a CFM 5330 (Lectromed). (A) Continuous normal voltage; (B) discontinuous normal voltage; (C) burst suppression; (D) continuouslow voltage; (E) flat trace. de Vries, L S et al. Arch. Dis. Child. Fetal Neonatal Ed. 2005;90:F201-F207

40. Seizures • Injured brain has increased variability • Onset of seizure → continuous, high activity • Causes CFM to narrow and rise up

41. Seizures

42. Seizures

43. Seizure EEG

44. Burst Suppression

45. Arterial Pulse

46. Cerebral Function MonitoringAmplitude-Integrated EEG – aEEGFundamentals of EEG and aEEG Denis Azzopardi