BRM3 aEEG Monitor Clinical In-Service Notes

Objectives * This information is provided for general educational purposes. It is not substitute for adequate medical training and medical literature.*

• Provide the skills required to integrate the BRM3 into the routine monitoring of any infant with questionable neurological status to:

► Obtain a more complete picture of the infant‟s neurological condition

► Show effects of care and therapies ► Help assess the infant‟s recovery

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Overview

• History • Applications • What is the BRM3 – how an EEG becomes an aEEG • Examples – ► Continuous Normal Voltage ► Discontinuous Normal Voltage ► Burst Suppression ► Isoelectric or Flat ► Seizure

• Impedance and Artifact Copyright 2008 DOC-001708B

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History – aEEG Monitoring is Not New • Developed in late 1960‟s in London by Maynard and Prior • Investigated in Europe for use in infants with neonatal encephalopathy • In the original cerebral function monitor, the amplitude-integrated EEG (aEEG) signal was printed on paper (6 or 30 cm/h)

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What monitoring devices are used for sick neonates in the NICU? Temperature Blood Pressure

Heart Rate

End Tidal CO2

Sa02

Respiratory

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What Do We Want to Know?

• What is the neurological status of the patient?

► Is there cerebral injury? ► What is the severity of the illness? ► What changes are occurring over time? ► What is the impact of NICU treatments to the patient‟s brain function?

• Is the patient having seizures?

► Are the seizures responding to medical therapy?

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Why Monitor the Infant‟s Brain • Term encephalopathic infants

► Increases in perinatal survival rates drive clinical focus on improving long term outcomes

► Poor neurological outcomes are associated with poor background brain activity

• Pre-term infants

► EEG and aEEG patterns change with increasing maturation ► Emergence of sleep-wake cycling is evidence of increasing brain organization

• Seizure identification is difficult via clinical means

► Impossible if baby is paralyzed or sedated ► Management of anti-convulsant medications is problematic and often ineffective Copyright 2008 DOC-001708B

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How is aEEG Used at the Bedside? • Used as a monitoring tool by bedside clinicians ► Validate suspicious neurological activity ► Validate seizures

• Provides the opportunity to monitor long term trends – up to 30 days

► Conventional EEG provides a „snapshot‟ of diagnostic information ► Conventional EEG is the „gold standard‟ diagnostic tool ► aEEG is a monitoring tool

• Provides information during off peak hours –

► Especially nights, weekends, and holidays when conventional EEG is not readily available

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Who Should Be Monitored? - Clinical Applications

• Infants that have experienced a sentinel event during delivery and are at risk for hypoxic ischemic encephalopathy (HIE)

► Evaluate brain injuries associated with HIE ► Determine if clinical criteria for hypothermic treatment are met ► Assist in identifying and predicting outcome from hypoxic-ischemic encephalopathy (HIE)

• Infants receiving hypothermia treatment for HIE • Infants with definite or questionable seizures (clinical or subclinical)

► To determine severity, duration, and frequency ► Monitor drug effects and therapies

• To assist in identifying need for further neurological examination, i.e., full EEG

• To monitor general neurological status/changes Copyright 2008 DOC-001708B

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Who Should Be Monitored? - Clinical Applications

• Potential candidates for monitoring include (but not limited to) infants with/that are:

► Muscle relaxed ► Unexplained neurological symptoms • Apnea and/or desaturation

► Grade 3 or 4 IVH ► Inborn errors of metabolism (e.g. urea cycle disorders, hypoglycemia, hypocalcemia)

► Neonatal abstinence syndrome (e.g. alcohol/opiate withdrawal) ► Post surgical ► Post cardiac arrest ► Enrolled in research protocols including aEEG

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How Does EEG Become aEEG?

• Two Channel EEG (5 electrodes) • Special Filtering • Rectification • Compression • Very Slow, Trend Display

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Channels

• One pair of electrodes (plus a ground electrode) are needed to create a single channel

• BRM3 creates two channels via 2 pairs of electrodes (and one ground electrode)

• EEG waves reflect electrical voltage differences between these four electrode sites Copyright 2008 DOC-001708B

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Two EEG Channels

• 5 Electrodes

► 4 Active ► 1 Ground - (Green)

• Lead Placement and Electrode Type: ► C3/P3 and C4/P4 placement ► Low-impedance needle electrodes ► Hydrogel electrodes ► Any compatible 1.5 mm electrodes • Disk Electrodes

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Filtering

• The EEG signal is filtered 2–15 Hz • Reduces muscle and other artifacts • Specially shaped filter

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Rectification

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Linear and Logarithmic Display

Logarithmic

Linear

Logarithmic Linear

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Raw EEG and Compressed aEEG

10 seconds of raw EEG data

10 seconds of raw EEG data

3.5 hours of compressed aEEG

3.5 hours of compressed aEEG

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Basic aEEG Traces

• Continuous Normal Voltage • Discontinuous Normal Voltage • Burst Suppression • Continuous Low Voltage • Isoelectric or Flat • Seizures

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Margins

Upper Margin Lower Margin Copyright 2008 DOC-001708B

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Continuous Normal Voltage Raw EEG ± 50 µV

Upper Margin aEEG Quiet Sleep

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Active Sleep or Awake

• Sleep Wake Cycling • Upper margin >10 µV • Lower margin > 5 µV • Limited variability

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