neonatal cerebral function monitoring


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neonatal cerebral function monitoring

  2. 2.  Cerebral Function Monitor (CFM),or An amplitudeintegrated EEG, is a device used to measure background electrocortical activity in the brain.  The cerebral function monitor provides information on global cerebral activity. to indicate the generalized level of electrical activity occurring across the entire brain.
  3. 3.  CFM technology was initially developed in the 1960s for adults suffering from neurological depression or injury or undergoing surgery.  technology was introduced in the mid 1980s by neonatologists. Research showed it could be a sensitive tool for predicting severity of hypoxic-ischemic encephalopathy, if applied in the first 6–12 hours following perinatal asphyxia.
  4. 4.  this mean it has predictive value on acute neurological conditions and long term neurodevelopmental outcome.  The CFM has also demonstrated itself as a valuable detection tool for neonates with clinical or subclinical seizures.
  5. 5. Intended use of CFM  Continuous monitoring and recording of brain activity.  Aiding detection and treatment of siezures.  Monitor the effect of the drugs and other therapy in the brain.  Aiding in identifying the HIE and predicting the long- term outcome.  Improving the accuracy of neonatal neurological examination
  6. 6. Indications: • Hypoxic – Ischemic Encephalopathy • Seizures or clinical scenario mimicking seizure disorders (e.g., apnea, hypertension, tachycardia) • Significant neurological disorders (e.g., congenital brain malformations, vascular lesions) • Post cardiac arrest • Inborn error of metabolism (e.g., urea cycle disorders, hypoglycaemia, hypocalcaemia) • Neonatal abstinence syndrome (e.g., alcohol/opiate withdrawal)
  7. 7. Principle of CFM  Using a single lead (single channel), consisting of three wires placed over the biparietal or frontal region;  the machine filters, rectifies compresses the electric brian signal. and
  8. 8.  Filtering and rectifying mean Frequencies <2 and >15 Hz are selectively filtered to reduce artefacts caused by movement, ECG and other electronic equipment.
  9. 9. Compression  mean time compression The signal is displayed on an x-y axis, using a very slow chart speed (6 cm/h).  The CFM focuses on changes in amplitude in the EEG — it is referred to as aEEG — amplitude-integrated EEG.  The amplitude of the trace can be assessed by measuring the upper and lower margins of the trace against.
  10. 10. Applying electrodes Placement • Biparietal is the optimal location this is the watershed area between the posterior and middle cerebral arteries. This area is least likely to be affected by scalp muscle activity and eye-movement artifacts.
  11. 11. Impedance  Measures quality of electrode contact and should be  as low as possible. It is also used to detect lead motion artifact.  The CFM 6000 monitor will Alarm if > 20kΩ.
  12. 12.  Hydrogel electrodes — can be used on scalp (biparietal) or forehead Requires aggressive preparation for cleaning to assure adequate adherence. These electrodes should be replaced every 24 hours.  Low-impedance needle electrodes Insert sub-dermally in parietal position These electrodes can be left in place for days, if needed.
  13. 13. General interpretation • Presence of Sleep/Wake cycle • Amplitudes of the upper and lower margins of the trace — in micro-voltage (μV) • Variability — narrow or broad trace. • Brain Activity Continuous (normal) — dark central band of continuous activity, with normal amplitudes Discontinuous (abnormal) — a wide trace with no central band of activity; appears universally gray • Presence of seizure activity
  14. 14. • Continuous normal voltage (CNV) — a narrow band on the aEEG with dark central band indicating a continuous normal high level of activity with little variability
  15. 15.  Discontinuous normal voltage (DNV) — a wide band on the aEEG that appears universally gray, indicating increased variability in activity primarily due to intermittent lower levels of activity
  16. 16. Understanding aEEG Quiet/active cycling — also known as sleep/wake cycle — trace is narrow when infant is awake (or in active sleep) and widens during quiet sleep; typically cycles every 90 min, but is dependent on infant condition. Early return of sleep wake cycling (SWS) after an asphyxial insult is also a good prognostic sign.
  17. 17.  • Flat EEG — a relatively flat trace at the bottom of the aEEG scale
  18. 18. Burst suppression (BS) — a comb like pattern in the aEEG due to A severely abnormal trace is characterised by a general suppression of amplitude so that the trace appears narrow and of low voltage. may be accompanied by brief bursts of higher voltage spikes, which appear as single spikes above the background activity. usually seen with severe encephalopathy and often accompanied by seizure activity.
  19. 19. seizures can be detected if there is sudden(rising and narrowing) in the aEEG. Status epilepticus = continuous seizures ≥ 30 min.
  20. 20.  It is important to inspect the underlying EEG  to confirm the presence of seizures .  distinguish artifacts from real signal.
  21. 21.  underlying EEG usually shows a repetitive spike and wave discharge .  Seizures may only be identified if they are sufficiently prolonged, more than 2-3 minutes. Shorter lasting discharges may be missed since the CFM is recorded at a very slow speed.
  22. 22. Classification of the CFM 1. Normal  The upper margin of the trace is above 10 microvolts and the lower margin is greater than 5 microvolts.  sleep/wake cycling.  the width of the trace varies from approximately 10-40 microvolts.
  23. 23. Normal CFM voltage. Sleep wake cycling can be observed. Movement artefact is present in part of trace.
  24. 24. 2. Moderately abnormal The upper margin of the trace is greater than 10 microvolts and the lower margin is less than 5 microvolts. No SWC. This appearance can be seen in infants with:  moderately severe encephalopathy.  immediately after administration of drugs such as anticonvulsants and sedatives.  This pattern may also be seen in preterm infants (below 36 weeks gestation).
  25. 25. Severely abnormal The upper margin of the trace is less than 10 microvolts. The lower margin is usually less than 5 microvolts Presence of burst suppression spikes. No sws.(FLAT TRACE) seen with severe encephalopathy and often accompanied by seizure activity.
  26. 26. Scoring Prediction of HIE Outcome and
  27. 27.  Points to Note  Focal abnormalities in the EEG may not be identified because the .signal is obtained from a single channel.  If the CFM trace looks odd or is not consistent with the clinical picture use the EEG display facility on the CFM to check for artefacts.  Movement artefact associated with head bobbing due to breathing  position of the head or supporting the head with a roll may lessen the artefact.
  28. 28.  Pulse artefact may be difficult to distinguish from seizure on the EEG. The pulse artefact is regular with the pulse. Place the electrode away from the fontanelle may help.  Medications may affect the record. Anticonvulsants or sedatives such as morphine or chloral hydrate may transiently suppress the CFM record. So Administration of drugs or other clinical events should be marked to
  29. 29. Pitfalls to watch for • Background voltage appears elevated — Possible causes: • ECG artifact • Handling • Muscle activity • High-frequency ventilation • Status epilepticus • Gasp artifact • Background voltage appears depressed — Possible causes: • Severe scalp edema • Leads significantly too close together • Significant sedation