GE CARESCAPE - Stopping the Entropy measurement; Entropy measurement basics; Entropy measurement description; Entropy parameters

Entropy
3.Selecttheparameter(REorSE).
NOTE
Ifthefeatureisnotactive,thealarmlimitsaregreyedout.
SelectAlarmOntosetthealarms.
StoppingtheEntropymeasurement
1.RemovetheEntropysensorfromthepatient.
2.Disconnectthesensorfromthesensorcable.
3.Discardthesensor.
Entropymeasurementbasics
Entropymeasurementdescription
EEGsignalsreecttheunderlyingstateofbrainactivity.Asapersonfallsasleepor
isanesthetized,thebrainfunction(activity)startstodecreaseandbecomesmore
orderlyandregular.EEGchangesfromirregulartomoreregularpatternswhen
anesthesiadeepens.Similarly,frontalEMGquietsdownasthedeeperpartsofthe
brainareincreasinglysaturatedwithanesthetics.
EntropymeasurementisbasedonprocessingofrawEEGandFEMGsignalsby
usingtheEntropyalgorithm,aGEapplicationofSpectralEntropy.Thealgorithmis
published:Viertiö-OjaHetal.DescriptionoftheEntropyalgorithmasappliedinthe
Datex-OhmedaS/5EntropyModule.(ActaAnaesthesiologicaScandinavica2004;
Volume48:Issue2:154-161,2004).
EntropymeasuresirregularityofEEGandFEMG.TheGEEntropymeasurementdevices
areresponsibleforEEGandFEMGsignalacquisition,amplication,lteringand
digitizationandelectrodeimpedancemeasurement.
Entropyparameters
REisafastreactingparameter,whichmeasuresEEGandFEMGinthefrequency
range0.8Hzto47Hz.Itsreactiontimeistwoseconds.Itmaygiveanindication
ofthepatient’sreactiontoexternalstimuli,suchasintubationandskinincision,if
neuromuscularblockingagentsarenotused.
SEisamorestableandrobustparameter,whichmeasuresEEGinthefrequencyrange
of0.8Hzto32Hz.Itsreactiontimeis15seconds.SEmaybeusedtoassesstheeffect
ofcertainanestheticdrugsonthebrain.
Entropyfrequencyanddisplayranges
Parameter
DisplayrangeCorticalEEG,
frequencyrange
FacialEMG,
frequencyrange
RE
0to1000Hzto32Hz32Hzto47Hz
SE0to910Hzto32Hz
nomeasurement
HowtointerprettheEntropyvalues
HighvaluesofEntropyindicatehighirregularityofthesignal,signifyingthatthe
patientisawake.AmoreregularsignalproduceslowEntropyvalues,whichcanbe
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