Update on Bispectral Index monitoring.docx

Update on Bispectral Index monitoring.docx

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UpdateonBispectralIndexmonitoring

UpdateonBispectralIndexmonitoring

JayW.JohansenMD,PhD,1,,AssociateProfessorofClinicalAnesthesiology

EmoryUniversitySchoolofMedicine,DepartmentofAnesthesiology,GradyHealthSystem,49JesseHillJr.Drive,SE,Atlanta,Georgia30303,USA

Availableonline17March2006.

Since1997,bispectralindex（BIS;AspectMedicalSystemsInc.,Natick,MA）hasbeeninclinicalpracticeandawealthofexperimentalresearchhasaccumulatedonitsuse.Originally,thedevicewasapprovedonlyformonitoringhypnosisandhasnowreceivedanindicationforreducingtheincidenceofintraoperativeawarenessduringanesthesia.NumerousstudieshavedocumentedtheabilityofBIStoreduceintermediateoutcomessuchashypnoticdrugadministration,extubationtime,postoperativenauseaandshortenedrecoveryroomdischarge.Tworecentlarge-scaleoutcomestudiesusingBIS（onerandomizedcontrolledtrialandoneprospective,nonrandomizedhistoricalcohortstudy）identifiedanapproximately80%reductionintheincidenceofrecallafteranesthesia.BISprovidesclinicianswithuniqueinformationthatcanbeusedtotailorhypnoticdrugdosestoindividualpatientrequirements.BISdoesnotpredictmovementorhemodynamicresponsetostimulation,norwillitpredicttheexactmomentconsciousnessreturns.ThisreviewwillalsodiscussotherBISapplicationsincludinguseinpediatrics,intensivecareandforproceduralsedation.SomelimitationsexisttotheuseofBISanditisnotusefulforsomeindividualhypnoticagents（ketamine,dexmedetomidine,nitrousoxide,xenon,opioids）.BIStechnologyismovingoutoftheoperatingroomandintodiverseenvironmentswhereconsciousanddeepsedationareprovided.Anesthesiologistsneedtobeactivelyinvolvedinpromotingpatientsafetyandhelpingtransitionthistechnologyintobroaderuse.

Keywords:

bispectralindex;awareness;recall;technologyassessment;sedation

ArticleOutline

Background

HypnotictitrationusingBIS

Researchupdate:

clinicaloutcomestudies

KnownlimitationsofBISmonitoring4.1Signalqualityandelectricalinterference

HypnoticsnoteffectivelymonitoredbyBIS

DiseaseprocesseslimitingBISmonitoring

OtherapplicationsofBISmonitoring

Pediatrics

Sedation:

monitoredanesthesiacareandintensivecare

Conscioussedation

Summary

References

Thereleaseofthebispectralindexmonitor（BIS,AspectMedicalSystemsInc.,Natick,MA）inOctober1996providedanesthesiologistswithareliablebrainfunctionmonitorthatallowedhypnotictitrationoverthecompleterangeofcorticalactivity.Numerouscomments,editorials,reviews1J.C.Drummond,Monitoringdepthofanesthesia:

withemphasisontheapplicationofthebispectralindexandthemiddlelatencyauditoryevokedresponsetothepreventionofrecall,Anesthesiology93（2000）,pp.876–882.FullTextviaCrossRef|ViewRecordinScopus|CitedByinScopus（173）1,2and3andover550peer-reviewedpublicationsonBIShaveappearedoverthelast9years.InJanuary2004,BISreceivedanFDAapprovedindicationforreducingtheincidenceofintraoperativeawarenessduringgeneralanesthesia（510（k）,#K030267）Recently,twostudies4and5,promptedtheJointCommissiononAccreditationofHealthcareOrganizations（JCAHO）topublishaSentinelEventAlert（October6,2004）onpatientawarenessunderanesthesia.TheAmericanSocietyofAnesthesiologists（ASA）hasrespondedbyconveningtheTaskForceonIntraoperativeAwarenessandisattemptingtodevelopaPracticeAdvisoryonBrainFunctionMonitoring.Neartheendof2004,approximately34%ofallhospitaloperatingroomshadaBISmonitor,78%ofteachinginstitutionsutilizedthemonitorandithadaworldwideinstallationbaseofover25 000units.ThepurposeofthischapteristoprovidesomebackgroundonBISandtodiscusstheclinicalimplicationsofrecentoutcomeresearchandregulatoryactivity.

Background

Alinkbetweenthemeasuredelectricalactivityofthecerebralcortexandelectroencephalogram（EEG）wasfirstsuggestedin1937.6DrRampilhasprovidedanexcellentreviewandadetaileddescriptionofthevariousapproachestoEEGsignalprocessing,includingBIS.7EEGderivativessuchasthepowerspectraledge,medianfrequency,zero-crossingfrequency,etc.havebeenextensivelyinvestigatedandfoundgenerallyinsensitive,nonspecific,ordependentonspecificdrugcombinationsandwerenotmonotonicallyrelatedtodrugeffectorclinicalresponse.2and7OtherchaptersinthisvolumediscussotherEEG-basedbrainfunctionmonitorssuchastheAuditoryEvokedPotentialandEntropy.

Bispectralanalysisisastatisticaltechniquethatallowsstudyofphenomenawithnonlinearcharactersuchassurfbeatsandwavebreaking.8BispectralanalysisrepresentsadifferentdescriptionoftheEEGinthatinterfrequencyphaserelationshipsaremea