1326页英语原文Empirical evaluation of a hybrid intelligent monitoring system using different measurWord文档下载推荐.docx

1326页英语原文Empirical evaluation of a hybrid intelligent monitoring system using different measurWord文档下载推荐.docx

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1326页英语原文Empiricalevaluationofahybridintelligentmonitoringsystemusingdifferentmeasur@#@3.2.Establishmentofthevalidationstages（phaseII）@#@Inaccordancewiththeproposedmethodology,thevalidationobjectiveswerefirstestablishedonthebasisofthesystemrequirements.Thesewerethenorderedinsixlevels,asrepresentedbydifferenttonesofgreyinFig.4.Thefirstfourlevelsdealwiththesystem’scapacityforobtainingcorrectdataonthebasisofananalysisoftheCTGrecordsorientedtodiagnosticuse.Theselevelshavebeenorderedtakingintoaccountwhicharethebasicparametersneededtodeterminetheothers.Thisway,inthefirstplaceweneedtoknowtheFHRbaselineinordertoobtainitsvariability.Basedonthesetwoparameterswecanapproachthedetectionofaccelerativeanddecelerativepatterns.Andfinally,aclassificationiscarriedoutoverthislastkindofpatterns.@#@Level5referstothesystem’sfinalinterpretationofthetest（reactive/non-reactive,normal/abnormal）and,therefore,ofthefoetalstate.Finally,level6referstotheappropriatenessofthetherapeuticrecommendationsandthefoetaloutcomeprognosismadebythesystem.Aswementioned,wewillfocusourattentiononthevalidationoflevels1-4.@#@3.3．Selectionofthevalidationstrategy（phaseIII）@#@Theadvantagesofaprospectivevalidationagainstfoetaloutcomeareevident,butsincethesystemoperatesinacriticalenvironmentitisnotpossibletoobtainareferencetoestablishwhethertheinterpretationoftheFHRsignalmadebythesystemiscorrect.Therearefollowingtwomainreasonsforthis:

@#@@#@1．Someoftheindicationsformulatedbythesysteminordertomanipulatetheenvironmentwillnotbeexecuted.@#@2．Abadprognosismadebythesystemcouldnotresultinarealbadoutcome,duetoclinicalintervention.@#@Ourvalidationwas,thus,approachedfromaretrospectivepointofview.@#@3.4.Constructionofalibraryofexamples（phaseIV）@#@Thevalidationwascarriedouton3450minofCTGrecordscorrespondingto53patients.Thesewerehigh-riskpregnancieswithgestationalageabove31weeks.Patientsweretakenastheyentrythemonitoringunitwithnootherselectioncriterion.Thevalidationstartedwhenitwasdeterminedthatthesetofavailableexamplesincludedallthekindofpatternswewantedtotest.@#@Threeexpertsparticipatedinthevalidationprocess.ExpertAisdirectorofahospitalMaternal-FoetalHigh-RiskSectionandhasbeenpractisinginthefieldsofobstetricsandgynaecologysince1967.ExpertsBandCarebothdoctorsinthesameunit,expertBsomewhatmoreexperiencedthanexpertC（thealphabeticalorderofthenomenclaturereflecttheirlevelsofexperience）.AllofthemperformNSTsonadailybasisandareregardedasexpertsbytheirpeersandsuperiors.@#@Thethreecliniciansanalysedtheavailablerecordsseparately.Theywerefirstrequiredtoindicatethegeneralstateoftheparametersincludedinthetest.Then,theywereaskedtocarryoutamoredetailedanalysisofthesignals,bymarkingallthedifferentpatternstheycouldidentify（accelerations,decelerations,typeofdecelerations,abruptchangesinthebaseline,suddentachycardiasandbradycardias,theappearanceofsilentorsaltatoryrhythms,etc.）.Thesedataformedthebasisforthevalidation.@#@3.5．Initialvalidationwithunlabelledexamples;@#@crossed-validation;@#@analysisandinterpretationofresults（phasesV-VII）@#@Forthecalculationofthepairs’test,contingencytablesandgrouptest,SHIVA[31],avalidationtoolforintelligentsystems,wasemployed.@#@AsshallbeseeninSection4,thisinitialvalidationpermittedanadequatecharacterisationofthesystemcomparedtothegroupofexperts.Nevertheless,thereweredisagreementsthatremainedunresolved,andsoinaccordancewiththeproposedmethodology,anothervalidation,thistimecrossed,wascarriedout.Thereasonwhyacrossed-validationisnecessaryisthatinthefirstvalidationcliniciansonlyhavetoconfirmpatternsbutnotrejectanyone.Ontheotherhand,anautomaticsystemactssystematicallyinordertodetectallexistingpatterns,afactthatapparentlycausesittogenerateahighnumberoffalsepositivescomparedtotheexperts.Wesuspectedthatsomeofthesefalsepositiveswererealpatternsthatclinicianssimplyhadoverlooked.ThisaffectsespeciallytothedetectionofaccelerationsanddecelerationsandoccurssometimeswhentheanalysisofthesignalgetstoapointinwhichitisalreadypossibletoestablishadiagnosiswithouthavingtoexploretherestoftheCTGrecord.Sotheaimofthecrossed-validationwastogivethesepatternstoclinicianstoobtainfromthemanexplicitconfirmationorrejection.Furthermore,buttoalesserextent,thecalculationoftheindexoffalsenegativesproducedbythesystemisalsoaffected.@#@Inordertoresolvethisproblem,themost