CARESCAPE Monitor Addendum for E-EEG Supplement to User Documentation

Due to continuing product innovation, specifications in this manual are subject to change without notice. For technical documentation purposes, the abbreviation GE is used for the legal entity names, GE Medical Systems Information Technologies, Inc. and GE Healthcare Finland Oy.

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Contents 1

EEG and AEP ... 7 Intended use of this supplement ... 7 EEG safety precautions... 7 EEG warnings... 7 EEG cautions... 8 EEG indications for use ... 8 EEG measurement limitations... 8 EEG points to note... 8 EEG measurement setup ... 9 EEG equipment to patient connection ... 9 EEG module keys ... 9 EEG electrode sites... 9 Connecting the EEG leadset ... 10 Attaching EEG electrodes within hair area ... 10 Attaching EEG electrodes outside hair area ... 10 Preconfigured EEG leadsets... 11 BASIC montage... 11 GENERAL montage... 11 Checking the EEG measurement... 12 EEG measurement on the monitor screen ... 12 Using the EEG measurement ... 12 Starting the EEG measurement... 12 Selecting your own EEG montage... 12 Selecting the EEG scale... 13 Selecting the EEG sweep speed ... 13 Selecting EEG numeric parameters ... 13 Selecting the SEF%... 13 Selecting the EEG frequency scale... 13 Selecting the EEG impedance cycle time... 14 Selecting the CSA view... 14 Selecting the time scale for CSA... 14

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Selecting the EEG numerical view ... 14 Checking EEG electrodes ... 14 Defining an EEG montage... 14 Printing EEG ... 15 Stopping the EEG measurement ... 15 EEG practicalities... 15 EEG measurement description... 15 EEG frequency bands... 16 Compressed spectral array (CSA) ... 16 How to interpret the EEG values... 17 Normal EEG frequencies ... 17 Abnormal EEG characteristics ... 18 EEG reactivity... 18 Examples of typical EEG patterns ... 18 Technical artifact and EEG... 18 EEG troubleshooting ... 20 Measuring auditory evoked potentilas (AEP) ... 21 Preparing the patient for AEP measurement ... 21 AEP montage ... 22 Using the AEP measurement... 22 Starting the AEP measurement ... 22 Selecting the AEP channels ... 22 Selecting the number of AEP responses ... 22 Selecting the AEP stimulus frequency... 22 Selecting the AEP stimulus intensity ... 23 Selecting the AEP sweep length ... 23 Selecting the AEP filter ... 23 Selecting the AEP cycle ... 23 Selecting the AEP size ... 23 Saving AEP responses ... 24 Selecting a reference AEP ... 24 Erasing an AEP reference... 24 Printing an AEP report... 24 Stopping the AEP measurement ... 24

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AEP practicalities... 25 AEP measurement description ... 25 Main peak categories (AEP)... 25 Examples of typical AEP patterns... 25 AEP troubleshooting... 26 Messages related to EEG and AEP measurements ... 27 EEG and AEP skills checklist... 28 EEG and AEP alarm specifications ... 29 Alarm delay specifications for EEG alarms... 29 Alarm priorities and escalation times for EEG and AEP ... 29 EEG parameter specifications ... 30 EEG standards compliance... 30 EEG performance specifications ... 30 EEG default settings ... 31 EEG montage default settings... 32 AEP default settings ... 33 E-EEG module and N-EEG headbox specifications ... 34 EEG accessories ... 35

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EEG and AEP Intended use of this supplement

This supplement must be used in conjunction with the CARESCAPE monitors user manual for important safety information regarding the whole system, and with the supplemental information manual for various monitor default settings that include the EEG parameter. Make sure the supplement is stored with these manuals. This supplement is to be used with the following products: ●

E-EEG-00 *

●

N-EEG-01 *

*The E-EEG-00 module and N-EEG-01 headbox have not been verified to meet the recent standard requirements as per IEC 60601–1:2012, 3.1 edition.

EEG safety precautions EEG warnings

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WARNING

DEFIBRILLATOR PRECAUTIONS. Patient signal inputs labeled with the CF and BF symbols with paddles are protected against damage resulting from defibrillation voltages. To ensure proper defibrillator protection, use only the recommended cables and leadwires.

WARNING

DEFIBRILLATOR PRECAUTIONS. Proper placement of defibrillator pads in relation to the electrodes is required to ensure successful defibrillation.

WARNING

Make sure that the electrodes, leadwires, and connectors do not touch any electrically conductive material including earth.

WARNING

When using an electrosurgery unit, note that the measurement cables do not incorporate means to protect against burns in case of a defective ESU return electrode. To avoid burns at the monitor measurement sites, ensure the following: ●

Proper contact of the ESU return electrode to the patient.

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ESU return electrode near the operating area.

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Measurement electrodes, leadwires and probes far from the surgical site and the ESU return electrode.

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WARNING

Single-use products are not designed to be reused. Reuse may cause a risk of cross-contamination, affect the measurement accuracy and/or system performance, and cause a malfunction as a result of the product being physically damaged due to cleaning, disinfection, re-sterilization and/or reuse.

EEG cautions CAUTION

Do not cover the EEG headbox as it may overheat.

CAUTION

EEG measurement is inherently very sensitive. Radiated electromagnetic fields may cause erroneous measurements at various frequencies. Do not use electrical radiating equipment close to the EEG measurement module. Details regarding radiated field strengths are given in the technical specifications.

EEG indications for use The EEG module, E-EEG, and the headbox, N-EEG, and accessories are indicated for the monitoring of electroencephalograph (EEG), frontal electromyography (FEMG), and auditory evoked potentials (AEP) of all hospital patients. The device is indicated for use by qualified medical personnel only.

EEG measurement limitations ●

This measurement is not available in the NICU software package.

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E-modules are not suitable for use with neonatal patients.

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External radiating devices may disturb the measurement.

EEG points to note

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This equipment is suitable for use in the presence of electrosurgery, as tested according to IEC 60601–2–49:2011–02

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For information on materials used in accessories and their biocompatibility, refer to the instructions for use in the accessory package.

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EEG is a very small signal and prone to artifacts such as movement, shivering, sweating, eye movement, frontal EMG, external electrical interference (other electrical devices), and internal (ECG) electrical interference.

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Good electrode contacts are imperative for high-quality EEG measurement.

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Keep electrical devices as far away from the patient as possible.

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Use short cables, or braid the long ones.

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Keep the headbox as close to the patient's head as possible.

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EEG findings are usually sensitive but not specific to the underlying cause.

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EEG findings should be assessed in conjuction with: ￭

other monitor data and clinical assessment

￭

neurological status of the patient

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￭

●

factors that influence EEG (like blood flow, neurological pathologies, underlying illnesses, and temperature).

A cloth bandage over cup electrodes and around the patient's head may enhance good contact.

EEG measurement setup EEG equipment to patient connection

1.

Module with EEG, AEP and FEMG measurement capability

2.

EEG headbox and cable, N-EEG

3.

EEG leadset: preconfigured or your own montage. EEG electrodes (cup or adhesive)

4.

Earphones are required for AEP (auditory evoked potentials)

CAUTION

Do not cover the EEG headbox as it may overheat.

NOTE

When measuring both AEP and BIS or Entropy be aware of possible interference issues. Familiarize yourself with all of these measurements and their safety statements.

EEG module keys There are two keys on the module: EP Start/Stop

Starts and stops auditory evoked potential measurement with the defined settings.

Imp. Check

Starts the manual measuring of the electrode impedance.

The same keys can be found on the headbox.

EEG electrode sites ●

Follow the electrode manufacturer’s instructions for the frequency of changing the electrodes.

●

Only use electrodes that are intended for EEG measurement.

●

Use one type of electrodes in the whole montage.

International 10–20 system The international 10–20 system’s standardized electrode locations:

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The numbers and letters of the 10-20 system refer to electrode locations: ●

Odd numbered electrodes: placed on the left

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Even numbered electrodes: placed on the right

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Letters: F = frontal; T = temporal; C = central; P = parietal; O = occipital; Z = midline electrodes

Connecting the EEG leadset 1.

Connect the headbox to the module.

2.

Select a suitable preconfigured leadset or your own montage.

3.

Connect the leadset to the headbox.

4.

Attach the electrodes to the patient as indicated in the leadset or according to your own montage.

5.

Observe the results of the electrode check. Reconnect the electrodes if the impedance is too high.

Attaching EEG electrodes within hair area Preferably use cup electrodes if montage includes placements within hair area. 1.

Mark the spots on the patient’s head according to the montage you have chosen.

2.

Comb or cut the hair away from the spots and rub the skin with abrasive paste to remove oil and grease.

3.

Clean the skin with alcohol.

4.

Attach the electrodes using conductive paste. NOTE

Use water to detach the electrodes.

Attaching EEG electrodes outside hair area Preferably use adhesive electrodes if all montage placements are within skin area.

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1.

Clean the skin with alcohol.

2.

Remove the electrode from its package and attach it to the desired location.

3.

Press the electrode gently for several seconds to attach it.

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Preconfigured EEG leadsets A preconfigured leadset tells the monitor which montage (electrode positioning) is used. Therefore, no menu selections are necessary. You can also define your own montage. Your own montages will not be automatically recognized when you start the measurement. NOTE

Since the monitor sets lead positions automatically according to the identification pin, make sure that you use preconfigured lead positions. If you change them, always update the montage settings according to the instructions.

BASIC montage

1.

Ground

Montage

Settings

Electrodes

1. A1 -Fp1

Two channels, bipolar

Five adhesive electrodes

2. A2 - Fp Ground

GENERAL montage

1.

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Montage

Settings

Electrodes

1. Fp1 - T3

Four channels, bipolar

Nine cup electrodes

2. Fp2 - T4 3. C3 - 01 4. C4 - 02 Ground

Checking the EEG measurement 1.

Check that the EEG waveforms are displayed after you have completed patient connections.

2.

Perform impedance check to ensure proper electrode contact. When the leads are disconnected, the message Leads off is displayed.

3.

Always check the electrode quality.

EEG measurement on the monitor screen In addition to the numeric parameters and the CSA (Compressed Spectral Array), you can also see the graphic presentation of EEG in the parameter window. This is a useful tool as it gives you a graphic presentation of the EEG numeric parameters. 1. EEG channel (numbers 1 to 4), for example Fp1–T3. 2. Blue vertical line represents the parameter selected for Numeric 2 (e.g., amplitude measured in μV). 3. Red horizontal line represents the parameter selected for Numeric 1 (e.g., SEF measured in Hz. 4. Black line ends touching the red and blue lines represent the channel-specific parameters for Numeric 1 and Numeric 2 (for instance, SEF and amplitude).

Using the EEG measurement Starting the EEG measurement EEG measurement starts automatically. 1.

Observe the results of the electrode check.

2.

Reconnect the electrodes if the impedance is too high.

Selecting your own EEG montage If you are using your own montage, you will have to select it from the list. Preconfigured montages will be automatically recognized. 1.

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Select the EEG parameter window.

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2.

Select EEG tab > Montage.

3.

Select the montage from the Select Montage list.

NOTE

Since the monitor sets lead positions automatically according to the identification pin, make sure that you use preconfigured lead positions. If you change them, always update the montage settings according to the instructions.

Selecting the EEG scale This setting defines the scale for EEG parameter windows, waveform and spectral displays 1.

Select the EEG parameter window.

2.

Select EEG tab > Setup.

3.

Select a value from the Scale µV list.

Selecting the EEG sweep speed This setting determines the drawing speed for the EEG waveform. 1.

Select the EEG parameter window.

2.

Select EEG tab > Setup.

3.

Select a value from the EEG Sweep Speed list.

The smaller the value, the slower the sweep speed. NOTE

This setting is available in EEG, BIS, and Entropy setups. Regardless of where you change it, it will affect all three parameters.

Selecting EEG numeric parameters EEG numeric trends are available in the ED, ICU, and NICU software packages. 1.

Select the EEG parameter window.

2.

Select EEG tab > Setup.

3.

Select a parameter from the Numeric 1 list.

4.

Select a parameter from the Numeric 2 list.

Selecting the SEF% Set the percentage of the spectral power to define the edge frequency. 1.

Select the EEG parameter window.

2.

Select EEG tab > Setup.

3.

Select a value from the SEF % list.

Selecting the EEG frequency scale The frequency selection affects the screen only, numeric parameters are always calculated from the entire measurement range. This selection affects the curve frequency scale in EEG parameter windows, CSA displays, and trend displays.

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1.

Select the EEG parameter window.

2.

Select EEG tab > Setup.

3.

Select a value from the Freq. Scale Hz list.

Selecting the EEG impedance cycle time You can set the time interval for the automatic impedance check. 1.

Select the EEG parameter window.

2.

Select EEG tab > Setup.

3.

Select a value from the Imped. Cycle list.

Selecting the CSA view You can choose to view a graphical view of the spectrum as a single, continuously updating curve, CSA. 1.

Select the EEG parameter window.

2.

Select EEG tab > View.

3.

Select CSA. Changing the view will erase the previous CSA content.

NOTE

You can use the default time scale or select a value from the CSA Time Scale list.

Selecting the time scale for CSA 1.

Select the EEG parameter window.

2.

Select EEG tab > Setup or View.

3.

Select a value from the CSA Time Scale list.

NOTE

Changing the scale will erase the previous CSA content.

Selecting the EEG numerical view You can choose to view a numeric list of all EEG parameters on all channels. 1.

Select the EEG parameter window.

2.

Select EEG tab > View.

3.

Select Numerical.

Checking EEG electrodes Press the Imp. Check key on the module or headbox, or: 1.

Select the EEG parameter window.

2.

Select EEG tab > View.

3.

Select Check Electrodes.

Defining an EEG montage You can define your own montage by plugging the leadwires directly into the headbox or by building your own leadset.

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NOTE

Since the monitor sets lead positions automatically according to the identification pin, make sure that you use preconfigured lead positions. If you change them, always update the montage settings.

1.

Select the EEG parameter window.

2.

Select EEG tab > Montage.

3.

Select a montage (Montage 4 to Montage 8) from the Select Montage list.

4.

Go through the different menu items and select the options to suit the application. For instance, to rename the selected montage: select Name Montage, remove the previous name, type the new name in the Name field, and then select Enter. The name can contain nine characters at the most.

5.

You can save the montage for later use by selecting Save Montage > Yes.

Your own montages will not be automatically identified by the monitor. You must select them from the menu when starting the measurement. NOTE

If you select Factory, all settings, including the name, will return to factory defaults.

Printing EEG You can print the currently displayed EEG view. 1.

Select the EEG parameter window.

2.

Select EEG tab > View.

3.

Select Numerical or CSA.

4.

Select Print Page.

Stopping the EEG measurement 1.

Disconnect the electrodes.

EEG practicalities EEG measurement description The EEG signal is continuously measured from up to four channels. This supports the international 10-20 system. Measurement can be referential or bipolar. On the signal, a spectral analysis is performed using Fast Fourier Transform (FFT). The result is a spectrum, which indicates what frequencies are present in the EEG signal. EEG is traditionally divided into four frequency bands: delta, theta, alpha and beta. In addition to the continuous EEG measurement, it is also possible to measure the response of the brain to external auditory stimulation by measuring evoked potentials, EP. When measuring auditory evoked potentials, AEP, auditory stimuli are delivered to the patient’s ears by earphones or headphones, and the resulting signal is measured from above the cortex. During auditory evoked potential measurement, EEG is also simultaneously measured from the same electrodes. Frontal muscular activity is also assessed by electromyography, EMG, from one of the EEG channels.

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EEG frequency bands To characterize the spectral content of the signal, the following parameters are calculated: 1. Delta 2. Theta 3. Alpha 4. Beta 5. Peak frequency 6. 50% of power 7. Median frequency 8. 95% of power 9. Spectral edge frequency, SEF

Delta% =

Power in delta range Total power

x 100%

Parameters: ●

Spectral edge frequency, SEF: The frequency below which nearly all of the power is present.

●

Median frequency, MF: Divides the spectrum in half: 50% of the power is below and 50% above this frequency.

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Frequency band ratios (Delta%, Theta%, Alpha%, Beta%) define what portion of the power is in a certain frequency band. For example, Delta% = power in delta band / Total power. The spectrum is displayed graphically as a single, continuously updating curve, or compressed spectral array (CSA), where spectra are stacked one on top of the other to form a trend display.

●

Burst suppression pattern is also detected, and burst suppression ratio (BSR) - the ratio of suppressed EEG in a time period of 60 seconds - is calculated.

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Amplitude (Amp.) of EEG is calculated as a root mean square (RMS) value in microvolts.

Compressed spectral array (CSA) The spectrum is displayed graphically as a single, continuously updating curve, or compressed spectral array, CSA, where spectra are stacked one on top of the other to form a trend display. EEG split screen displays the compressed spectral array of all the monitored channels on the left hand side of the screen.

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EEG CSA SEF

5 min 1. Channel (e.g. Fp1–T3, C3–01) 2. Spectral edge frequency, SEF (red line in the display) 3. Stacked spectra

How to interpret the EEG values To evaluate certain EEG results, for example to distinguish epilepsy from other conditions, it is necessary to assess these findings together with other symptoms, including unconsciousness. EEG findings are usually non-specific, and consequently they indicate a malfunction but do not reveal the reason for it. Distinguishable characteristics to look for are: ●

Frequency and amplitude

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Rhythm location and specific waveforms

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Artifact

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Reactivity

Normal EEG frequencies EEG frequencies look basically the same in all areas. They are symmetrical. However, in normal EEG the alpha waves are predominant on parietal areas.

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Frequencies

Appearance

Delta (< 4 Hz)

In children; in adults with deep sleep

Theta (4 to 8 Hz)

Light sleep, early childhood

Alpha (8 to 13 Hz)

Adults, awake with eyes closed

Beta (> 13 Hz)

High activity or drugs

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Abnormal EEG characteristics Distinguishable characteristics to look for are: ●

Asymmetrical EEG between the left and the right hemisphere

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Burst suppression

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Suppression and low amplitude

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Delta activity

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Epileptic spikes

EEG reactivity Existing reactivity in the EEG is a sign of healthy brain activity. Accordingly, reduced reactivity may indicate a disorder in the brain activity, which requires action.

Examples of typical EEG patterns ● Pathologically slowed rhythms:

● Seizure activity:

● Periodic patterns: Distinct waveforms

repeating with regular intervals (from 0.5 to several seconds). Periodic patterns that are characterized by sharp waves or spikes are known as epileptiform. ● Burst suppression: High amplitude

EEG patterns with intervening low amplitude activity. The duration may vary from <0.5 seconds to several seconds.

Technical artifact and EEG To decrease technical artifact, the electrode-to skin-impedance should be low and electrode wires short. Wrapping the electrode wires together or adjusting ground electrodes may also help.

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Typical EEG recordings with electrical interference ● Electrical currents (AC): These are a

common source of interference. Try using different low-pass or notch filters to eliminate them.

● Eye movements: Patient eye movements

cause typical patterns in the EEG waveform.

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● ECG: Cardiac electrical activity can affect

the EEG waveform.

● EMG: Activation of frontal muscles can

cause high frequency interference in the EEG.

EEG troubleshooting Problem

Solution

What can I do if the signal looks noisy and there is a message indicating artifact?

Electrodes are poorly connected, or electrical interference is coupling to electrode cables. ● Check that the electrodes are properly connected

and not dried out. ● Check the electrodes’ contact with skin. ● Perform electrode impedance check. ● Calm the patient since frontal muscle activity can

cause artifact ● Remove sources of external electrical noise (for

example, some lamps) from the vicinity of the patient’s head. ● ECG may cause artifact; change electrode

positioning. ● Check that there are not two identical

measurement modules in the system. Why are all EEG waveforms not drawn even if electrodes and cables are OK?

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The number of channels in the montage is smaller than the number of channels connected to the patient.

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