amplitudeintegrated EEG, is a device used
electrocortical activity in the
The cerebral function monitor
provides information on global
cerebral activity. to indicate the
generalized level of electrical
activity occurring across the
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.
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
Intended use of CFM
Continuous monitoring and recording of brain
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
Principle of CFM
Using a single lead (single channel), consisting of three
wires placed over the biparietal or frontal region;
compresses the electric brian signal.
Filtering and rectifying
mean Frequencies <2 and >15 Hz are selectively
filtered to reduce artefacts caused by movement, ECG
and other electronic equipment.
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
The amplitude of the trace can be
assessed by measuring the upper and lower margins of
the trace against.
• 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.
Measures quality of electrode contact and should be
as low as possible. It is also used to detect lead motion
The CFM 6000 monitor will Alarm if > 20kΩ.
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.
• 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
• 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
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
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.
• Flat EEG — a relatively flat trace at the bottom of
the aEEG scale
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
usually seen with severe encephalopathy and
often accompanied by seizure activity.
can be detected if there is sudden(rising and
narrowing) in the aEEG.
Status epilepticus = continuous seizures ≥ 30 min.
It is important to inspect the underlying EEG
to confirm the presence of seizures .
distinguish artifacts from real signal.
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.
Classification of the CFM
The upper margin of the trace is above 10 microvolts
and the lower margin is greater than 5 microvolts.
the width of the trace varies from approximately 10-40
Normal CFM voltage. Sleep wake cycling can be observed.
Movement artefact is present in part of trace.
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).
The upper margin of the trace is less than 10
microvolts. The lower margin is usually less than 5
Presence of burst suppression spikes.
No sws.(FLAT TRACE)
seen with severe encephalopathy and often
accompanied by seizure activity.
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
position of the head or supporting the head with a roll
may lessen the artefact.
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
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
Pitfalls to watch for
• Background voltage appears elevated — Possible causes:
• ECG artifact
• 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